# A new attempt at making piston rings



## Brian Rupnow (Apr 21, 2021)

Let me start out by saying that I have made my own piston rings in the past---and failed dismally. I was so disheartened by my failed attempt that I went to Viton o-rings and never looked back. Now I have ten or twelve years engine building experience, and I am going to try again. I have a 1" bore side shaft engine which I built a few years ago with a Viton ring, and it runs very good, and has incredible compression. I have chosen this engine because I can undo the con-rod bolts and remove the piston without disturbing any of the other engine settings. This will require that I machine a new piston and two rings.


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## Brian Rupnow (Apr 21, 2021)

After considerable reading of books by Malcolm Stride, Philip Duclos, L.C. Mason and various posts by George Britnell, I have  compiled this list of things related to ring making. This information is not "absolute", as some of the information given by one author tends to disagree with information given by a different author.
After considerable reading of books by Malcolm Stride, Philip Duclos, L.C. Mason and various posts by George Britnell, I have  compiled this list of things related to ring making. This information is not "absolute", as some of the information given by one author tends to disagree with information given by a different author.


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## Brian Rupnow (Apr 21, 2021)

The drawings below show the piston "as built" for one 1/16" cross section Viton o-ring, and the same piston redrawn for a piston that accepts two cast iron o-rings to match the rings supplied by Debolt. (I will be making these rings to the same dimensions as two rings purchased from Debolt for my Vertical i.c. engine-2021). Note that nothing on the piston changes except the information relating to ring width, depth, and location.


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## Vietti (Apr 21, 2021)

I look forward to your conclusions re. 0 rings vs cast iron rings from a performance stand point, esp coasting times.


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## Brian Rupnow (Apr 21, 2021)

The first thing I wanted to check was---Does my .062 wide cutting tool cut an .062" groove in cast iron on a straight in plunge cut. Apparently not. The cutting tool does actually mike at .062 wide", but the slot it cuts in cast iron on a straight in plunge measures 0.057" wide. The top of my cutting tool has a strange shape to it (as bought) so next thing I'll try is grinding it flat and then do this test again.


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## Brian Rupnow (Apr 21, 2021)

Okay--After a regrind of the top surface of my parting off tool so that it is absolutely flat and a second groove cut in cast iron, the groove is still measuring .057" wide. That's okay. As long as I know, then I can live with that. I could regrind an hss toolbit to give me an exact .062" groove, but I don't really want to have to do that.


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## Brian Rupnow (Apr 21, 2021)

I was able to part off 6 rings with no problem.  The math is a little weird, and I don't really know why. The ring closest to the right side of the page is 0.070" wide, but was supposed to be .062" wide. I set my parting tool against the end of the piece in the lathe, then using my DRO I moved it 0.125" towards the headstock. In theory that should have taken a cut .0625" wide and left a ring .0625" wide. After cutting and measuring the first ring, I moved the cutting tool 0.005" towards the headstock and took another cut to clean up the end of the stock. All subsequent moves were limited to 0.115" and that yielded rings approx. 0.065" wide. That should be about right because the rings still have to be cleaned up on both sides with some fine emery paper.


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## Tim Wescott (Apr 21, 2021)

If that first ring had been 0.068 it would make sense -- 0.125 - 0.057 = 0.068.  Maybe it's 0.068 with .002" worth of roughness or tilt screwing up the measurement?


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## Brian Rupnow (Apr 21, 2021)

Here we have the six rings, polished on both sides with 150 grit, then 600 grit emery paper on a flat cast iron surface with some wd40. The thickness of each ring is printed inside the ring. I will lap that 0.064" ring a bit more and bring it down to 0.061" thickness.
I don't know if I can bring the 0.070" ring down in thickness by lapping, but I will find out. The recessed fixture that I held the rings with while lapping them is in the picture, with an 0.040" recess in the face, but it doesn't show up very well. One of the websites I looked at before undertaking the making of these rings suggested deburring the inside corners/edges with a circular porcelain stone. I don't have such a thing, but will call around to my tooling suppliers in Barrie and see if I can buy one.


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## Brian Rupnow (Apr 21, 2021)

The two rings that were "overthick" both came down to 0.061" with a bit more lapping. I've read so much about making rings in so many different places, I can't remember where I read about the porcelain sharpening stone that was used to deburr the inside edges of the rings. Maybe I had it wrong. Maybe it was "ceramic" sharpening stone. It looked to be about 3/8" diameter x 4" or 6" long, and would have to be a reasonably fine grit. If anybody knows where I can buy such a thing in Ontario, Canada, please let me know.---Brian


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## rklopp (Apr 21, 2021)

I have made dozens of rings from 3/4" - 1-1/4" adhering closely to the Trimble method published in Strictly IC. They work great and I don't think I have ever broken one. I parted them using a ThinBit carbide grooving tool. No toolpost grinder here.


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## jack620 (Apr 21, 2021)

I'm late to the party Brian, but Mr Crispin on YouTube did a couple of videos on making piston rings. He also covers breaking and heat treating the rings. 

Might be worth a look: 

Part 1: 
Part 2:


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## Brian Rupnow (Apr 21, 2021)

Thanks jack---I've watched Mr. Crispin's videos.---Brian


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## Brian Rupnow (Apr 21, 2021)

Due to Covid shutdowns and my own impatience, I will wrap a piece of 220 grit emery cloth around a wooden dowel and use that to deburr the inside/edges of my rings. Someday, when this damned plague is over, my wife and I will drive down to Vaughn and pick up one of these tools from Lee Valley Tools.


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## Brian Rupnow (Apr 21, 2021)

And here we have a quick and nasty round ceramic file (220 grit emery paper glued around a turned broom handle), and my rings are all deburred on the inside/edges. Tomorrow I will break them in a vice, file the ends, try them for size in a cylinder, and then heat treat them.


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## bobden72 (Apr 22, 2021)

Brian Rupnow said:


> And here we have a quick and nasty round ceramic file (220 grit emery paper glued around a turned broom handle), and my rings are all deburred on the inside/edges. Tomorrow I will break them in a vice, file the ends, try them for size in a cylinder, and then heat treat them.


Liking your mini series on rings I to have struggled in the past.  Will be interested in the final results, keep up the good work.


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## Steamchick (Apr 22, 2021)

Hi Brian, from my limited (industrial) knowledge, care keeping the top and bottom faces parallel is paramount. Industry uses a surface grinder and is incredibly precise on ring thickness and parallel faces. Not tooling in the hobby workshop. The fine linishing you are doing is excellent - the finer finish the better! I suggest the groove in your tool should be the target depth of the thickness of your rings? Do you work the whole in circular or figure of 8 patterns on the linishing paper? Avoid straight back and fro motion when doing this. I would suggest a rotation of the ring holder of between 50 and 70 degrees after maybe every  5 figure of eights? I am sure you are well experienced doing this, but I have learned by getting it wrong!
Well done for another excellent tutorial.
K2


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## dsage (Apr 22, 2021)

Just a couple of questions / observations.
How did you measure the width of the ring groove to cut in the piston? I'm perplexed by how it came out narrower than the width of the parting tool. Try some feeler gauges in the slot for an accurate measurement.

If you are lapping the rings to thickness then be careful that the two sides are parallel by measuring them in various places around the ring. I've found that even using the tool you mentioned to hold them, hand pressure can result in unevenness. Rotating the ring periodically can help.

Finally DO NOT follow the instructions by Mr. Crispin. He made all the classic mistakes and many people pointed them out in the comments in his first video. So much so that he made a second video where he made new rings, correcting some of the issues but still made mistakes. In the end he admitted they where "Good enough" and moved on. They might be good enough for his steam engine.


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## dsage (Apr 22, 2021)

BTW. One more thing. Your solution to use the stick and emery cloth was sufficient to knock off the burr on the inner edges. No need to purchase a special ceramic stone. You're not trying to round the edges. Just a light touch to be sure they are not razor sharp.

Good stuff. Looking forward to your results.


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## Harglo (Apr 22, 2021)

Brian Rupnow said:


> The drawings below show the piston "as built" for one 1/16" cross section Viton o-ring, and the same piston redrawn for a piston that accepts two cast iron o-rings to match the rings supplied by Debolt. (I will be making these rings to the same dimensions as two rings purchased from Debolt for my Vertical i.c. engine-2021). Note that nothing on the piston changes except the information relating to ring width, depth, and location.


Hi Brian
I have been through the same ups an downs with the cast or "O" ring piston seals. I had much trouble getting the O rings in the bore using the dimensions  form charts seems had to keep changing the width but once the O ring just touches is all  you need. Suspect the charts dimensions are in general for a different applications. The compression seems a bet more with the O rings at lest in one of my engines. Big + is no risk in put them on the piston an once some lube they are good to go for extended run times with just some lube for the piston. Would be interested to hear if you were successful using the charts grove values.
Harvey


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## tornitore45 (Apr 22, 2021)

I started making rings with the Chaddock method.  A real pain, extra fixtures and much scaling.
Following the advise of an old fellow I met at Cabin Fever I tried his technique.
Next engine I machined the ring tube to a Diameter = Bore + OpenGap/pie
After slicing the ring I milled out the OpenGap + The Working Gap
My ring now has a "lenght" = Bore x Pie - Working Gap
It springs inside the bore to fit "just right".
If one goes to the excruciating math to calculate the shape of a gapped ring that becomes circular under under uniform radial pressure, he will find out the ring I made is all wrong.
After running 1/2 an hour inside the engine the ring show axial wear marks all around indicating all of its periphery touches the cylinder.  Compression is good and the engine runs well.


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## Brian Rupnow (Apr 22, 2021)

The rings have all been split. This is a very simple procedure where part of the ring is clamped in the vice and one half sticks out the end of the vice where it can be grabbed by my finger and them and gently pushed back and forth until it cracks. You have to be careful with your pushing and pulling, as you don't want to snap the ring in two pieces. At this point in the game, the rings are still the same i.d. and o.d. as they were when machined.


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## dsage (Apr 22, 2021)

Depending how thick (wide ?) your rings are it's probably less risky to lay the ring on the table with a piece of wire under a section of the circumference. Wire maybe #22 or so. Then put a thumb on either side of the wire and press down hard. it'll snap right over the wire. Also it helps to score the ring where you want it to break. If you have heavy duty rings this doesn't work very well as it's hard on the thumbs. But it works in most cases.

Using the vise I wouldn't bend the ring back and forth attempting to break it. I think you'd stress the material.

If you get into making a lot of rings consider making the cleaving (cutting) tool George Britnell showed in another thread here. It's actually a copy of the one detailed in (I think) the George Trimble full article. I recently made one after having trouble using my wire method on some beefy rings. It works very well and gives a controlled perfect break right where you want it.


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## Brian Rupnow (Apr 22, 2021)

I have made a heat treat fixture on which to mount the rings. Trial and error showed me that making the inside diameter of the fixture 0.942" diameter and forcing the rings over it resulted in a 1/8" gap between the ends of the ring. I truly felt that if I spread the rings any wider they were going to break. The rings are tightly compressed between the two discs to keep the broken ends of the rings perfectly in line. The back-side of the fixture has been hollowed out so it will have less mass to heat up. I will heat fixture and rings to a cherry red with my oxy acetylene torch, being sure not to let the torch flame play directly on the rings. The ring ends will be filed after the heat treat is finished and the rings demounted.


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## dsage (Apr 22, 2021)

Such is the nature of messages on forums. People don't get to comment until it's possibly to late.
I hope you didn't heat the rings too much. This was one of the controversial issues with the Trimble article.
Many thought that he heated the rings far too hot.
The correct temperature - it has been decided - is DARK CHERRY red.
That means that in subdued light (almost dark) you just barely see the fixture beginning to turn a red colour.
A propane torch would be plenty to save from going too far.
Then you hold it there for a few minutes (depending on mass) and let it cool slowly.
I hope you didn't heat them too much.
I think the pitfall is that the cast iron metallurgy will be affected. Not sure how.

A side effect of heating them too much is they develop a scale on the outside. If properly heated they come out darkened but with no scale.

How were your results.


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## Brian Rupnow (Apr 22, 2021)

After being heated cherry red, and left to air cool, then a little bit of clean-up, the rings have all taken a new "set" and the gaps remain open about 1/8" after they are removed from the fixture. I have seen on Youtube where some people heat the rings to cherry red, then drop them into a bucket of oil or water while they are still cherry red. I have no idea why they do that, and I've never read anything saying that this is a part of the process. My next step will be to square up the broken ends and test fit them into a cylinder to check that I have about 0.004" gap between the ring ends.


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## dsage (Apr 22, 2021)

Looking good.
Terry Mayhugh described a light mask you can make from a plug of plastic or anything really that you put in place in the inside hole of the ring when it's in the cylinder. It has lip on it that stops it from dropping through that is just shy of the cylinder diameter. Once in place you can shine a bright light behind it and look down the cylinder for light passing between the ring and the cylinder wall. The mask blocks all the light from passing through the center leaving only that leaking around the ring. If you move it around you should not see any spots of light between the ring and the cylinder You can decide if you've succeeded or failed. Terry said he has a few failures out of a group of ten rings or so. He only accepts those with no light leakage.
He described this process with pictures elsewhere recently. Worth a look.
Give it a try.


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## Brian Rupnow (Apr 22, 2021)

The six rings are finished and properly gapped to 0.004" when installed squarely into the cylinder. As far as I can tell, I've made six good rings.---A funny thing about cast iron---it grows when it's heated, and when it cools off, it doesn't return to the dimension it was before. It is always a bit larger, even after it cools down. I knew about this from a previous experiment and I know that the two stroke airplane engine crowd will sometimes heat up a piston to "grow it a little" if they aren't running tight enough to get good compression. It shows up here because after these rings were split they would still fit down into the 1" cylinder bore perfectly. After being heat treated, before having the ring gap filed, they would no longer fit into the cylinder. I expected that, but it's still kind of surprising.


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## Brian Rupnow (Apr 22, 2021)

This is the side shaft hit and miss engine that I will be trying these rings on. It runs like a charm with the single Viton ring on the piston. I'll know after I make a new piston and put a couple of these new rings on it how successful I was at ring making.


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## dsage (Apr 22, 2021)

Do the light test I mentioned above.


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## G54AUST (Apr 22, 2021)

G'Day again Brian,  et al.

     I seem to remember an article,  I think it was Tom Walshaw in Model Engineer (_happy to stand corrected_),  about piston ring and their wall pressure for various cyclinders.   Went something like Steam - 6 to 8 PSI,  Petrol - 16 to 18 PSI and Diesel - 38 to 40 PSI.   Dealt with cylinder pressure/compression ratios etc.   It also gave ratios for ring dimensions to bore/stroke etc.   Someone clueyer than I might have the article,  a reference or a clever search engine.

     I've also viewed Mr Crispins' Youtube articles on Piston Rings and thought the dimensions were a little excessive.  (_Good entertainment,  that bloke._)

     I was so impressed with Terry Mayhughs' recent article on Piston Rings that I printed it off for future reference.   (_Straight to the library it went._)   Would like to get the copies from SIC magazine with the full written "Trimble" article when the exchange rate is more favourable.     George Britnells' articles are also a very valuable reference source (_printed and in the binder already_).

Kind Regards,
Stay safe,
Don't be good,

Trevor,
Melbourne, AU.


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## mayhugh1 (Apr 22, 2021)

Trimble's method has science behind it and relies on the use of a specific set of dimensions for the rings and the fixture used to heat treat them. Here's a photo that I posted in one of my builds that contains a summary of those dimensions. Before giving up on an another approximate scheme that may not work, give it a try. The dimensions of the heat treatment fixture are just as important as the ring dimensions. - Terry


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## werowance (Apr 22, 2021)

Hi Brian, i do not have any expert advise to offer but i will respectfully throw in my experience on ring making which alot came from other members.  

first attempt.  perlitic gray fine grain continuous cast cast iron was recomended.  i used what was advertised as this and heated and cut the rings like you have i found that they would break on install.  yes i have used store bought rings and the had much more spring to them than the ones i made. 

i then found some scrap old cast iron. did some test cuts and the grain seemed to be better and darker.  (especially compared to window sash weights - do not even try those)  it was a part to an old stoker coal furnace i finallly learned.  it cut much the same as the store bought  cast iron but the powder left was much darker and if rubbed between fingers i could actually feel a slight difference betweeen the 2.  just a guess its more graphite in the scrap iron?  that said after emory cleanup, spliting, heating and a final cleanup the scrap was so much better than the store bought.  

oh,  and on splitting. i was using the vice and a machinist clamp with a little tweak to split them until another member suggested to use some wire side cutters.  aka wire cutters.  worked great and didnt leave the dent or angle like if cutting a piece of copper wire. it just "popped" the split in the ring without making an angled dent or  cut mark on them. which also didnt tweak them / warp them which is easily done using the vice / clamp to tweak enouhg to split it.


now all that said i kept making rings until it finally worked, i am really happy you are experimenting and posting a write up on it so hopefully i / others can follow and make them easier.

thank you for showing us.


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## Gordon (Apr 23, 2021)

I am always amazed at the ring making methods we use. It seems that one person uses all sorts of crude methods and the rings work just fine. The next person holds tolerances to .0001 and the rings will not work.

For what it is worth, the last set of rings I made I heated them to 1100° for an hour in my old ceramic kiln and then left them to cool in the kiln overnight and they seem to be working fine. I had made some ring prior to that for the same engine and heated them just to 1100° and shut off the kiln and that set did not work. Others seem to have success with placing the rings on a brick and heating them with a torch. Skill or dumb luck?


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## L98fiero (Apr 23, 2021)

Brian Rupnow said:


> If anybody knows where I can buy such a thing in Ontario, Canada, please let me know.---Brian


Gesswein.ca and Lee Valley would be good places to start(to find "ceramic" sharpening stones ).


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## Brian Rupnow (Apr 23, 2021)

This is the new cast iron rings mounted on the new cast iron piston. The old piston with Viton ring is setting beside it. No real drama. Lots of lubricating oil and a bit of breath holding, and the new rings went into place without threatening to break as they were being installed. Next test will be to see if new piston with rings will fit into a 1" reamed cylinder.


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## Brian Rupnow (Apr 23, 2021)

This was the last test prior to putting the piston back into the engine. I had to absolutely convince myself that the new piston and rings would indeed pass thru a 1.000" diameter hole. If not, that's a good way to break rings or bugger up the end of the cylinder. It did show that the cylinder needs about a 20 degree overall tapered lead-in to compress the rings as the piston enters, but once in there it slides along nicely without any scraping or gouging.  The hit and miss engine this is going back into doesn't have a lead machined into the cylinder, so it might get interesting. I am not going to disassemble the engine to machine a tapered lead into the cylinder, so I will have to create some kind of ring compressor to get the piston back into the engine.--Maybe a hose clamp?


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## Rocket Man (Apr 23, 2021)

Hasting Piston ring company sells Rings any size, any diameter, any thickness, any type, any design, $3 per set of 3 rings plus postage.  

They do not sell by engine cereal numbers.  I rebuild a 65HP Mercury outboard engine NO boat dealer could give me rings without the correct cereal number, Hasting sold me 4 sets of rings, $9 total plus $4 postage.  

I had 6 used lawn mowers rings at lawn mower shops was $135 but Hasting sold me 6 sets of rings, $12 plus $4 postage.


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## Gordon (Apr 23, 2021)

Make a sleeve about 1" long with 1" bore and a taper on one end. Push the piston into the sleeve from the tapered end and then place the 1" end over the engine bore.


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## Tim Wescott (Apr 23, 2021)

Brian Rupnow said:


> ... I will have to create some kind of ring compressor to get the piston back into the engine.--Maybe a hose clamp?



If that thing you've built is open on the other end and will fit -- it's your spring compressor.  I've been watching engine rebuild videos on YouTube, and that's the fancy way to do it.  The less-fancy way is a dedicated adjustable ring compressor.  When hose clamps are mentioned, it's in the context of "don't do that, it'll just break rings.

You probably do want a slight chamfer on the very end of your cylinder, but only enough so that any slight mismatch between your slip-fit piston and the bore can't cause the edge to catch a ring.  And if the assembly doesn't just push in -- don't force it.


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## Gordon (Apr 23, 2021)

Look at:






						Piston ring expander and compressor
					

What do use for installing rings on a piston and how do you install the piston with rings in the engine? I have not found any good ring expander or compressor similar to what is used for an automotive engine. I have tried to make an expander and just tried to ease the ring over the edge of the...




					www.homemodelenginemachinist.com


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## Brian Rupnow (Apr 23, 2021)

The piston and rings went back into place with flat screwdrivers, fingernails, and prayer. Everything is back together and hooked up. I'm getting pops and farts but no continued action. Considering that the new rings do have to "wear in" a bit for a really good seal, I may move my operations out to the main garage and hook it up belt driven by my electric motor.---I'll leave the sparkplug electrics turned on, and if I've lived right it should begin to fire after its ran in for a while.


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## Tim Wescott (Apr 23, 2021)

Or you can cheat.  Motor Honey -- it's not just for selling clapped out used cars!


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## Brian Rupnow (Apr 23, 2021)

No Joy. Everything is hooked up and is currently being driven from a  a 1/4 hp electric motor out in my main garage. Ignition is on and there is fuel in the tank. No puffs of smoke, no backfires--nothing. I pulled the sparkplug out and had a look at it, and it fires when laying out on the block at the correct time in the cycle. I even tried a squirt of "quick start" ether, but nothing happened. I'm going to let it run out there for an hour, and if it doesn't do something interesting I will put the old piston with the viton ring back in it to make sure it runs. That video link I posted is from about three years ago, the last time I had it running. I have discovered one thing related to cutting ring grooves and parting off rings. That little (1/16") wide parting off tool that I have isn't stable. It flexes when in the cut, so you can't trust what it is doing. Before I go any farther down this road, I will grind a 3/8" HSS tool to give me an exact .062" width. It makes me crazy when you know that a tool of a given width is cutting a different width than the width of the tool itself, on a plunge cut.


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## Tim Wescott (Apr 23, 2021)

Two things, from a fairly uneducated position: model airplane ringed engines start right off, maybe with extra oil in the fuel (it's always so easy to cheat and add castor when it's a two-stroke!).  But -- that's when you're buying an engine from someone experienced at making rings, and who possibly test-runs their engines.  And model airplane engines generally call out breaking the engine in at operating temperature.

I'm wondering if you didn't cause problems with your motorized break-in procedure, either because of temperature, or not enough lubrication.


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## dnalot (Apr 23, 2021)

Did you rough up the cylinder bore. O-rings require a polished surface, cast iron rings require the bore to be a little rough to wear in the rings. 

Mark T


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## Brian Rupnow (Apr 23, 2021)

Mark--I didn't hone the bore on the cylinder, and you're right, it has a glass smooth finish. Before I tear things down, I will try and get a hone in their and break the wall finish down a little, to see if that will let the rings "bed" better.


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## Brian Rupnow (Apr 23, 2021)

Two pictures here----One shows the set-up in my garage trying to get the motor to fire with it's new piston and rings---didn't work!!---Don't know why yet. Second picture shows a tool ground by Philip Duclos to part rings off with or to cut ring grooves in a piston. Damn----that's a lot harder to do than it looks.  I tried to more or less "free hand" such a tool, but it didn't come out nearly as nice as the Duclos tool. Tomorrow I will dummy up some guides on my grinder and try again to grind this tool from HSS.


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## SmithDoor (Apr 23, 2021)

Great job
One most important part of machine work is grinding the tool bit right

Dave



Brian Rupnow said:


> Two pictures here----One shows the set-up in my garage trying to get the motor to fire with it's new piston and rings---didn't work!!---Don't know why yet. Second picture shows a tool ground by Philip Duclos to part rings off with or to cut ring grooves in a piston. Damn----that's a lot harder to do than it looks.  I tried to more or less "free hand" such a tool, but it didn't come out nearly as nice as the Duclos tool. Tomorrow I will dummy up some guides on my grinder and try again to grind this tool from HSS.


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## rklopp (Apr 23, 2021)

The up-front price on a carbide system like Nikcole Mini-System (Nikcole Mini-Systems – Niko Nikcole) is worth it for years down the road. Travers sells kits and parts. I've had mine for 15 years +/- and use it often. Amortized over 15 years, the return on the investment is outstanding.


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## minh-thanh (Apr 24, 2021)

Hi ALL !
I usually choose the OD of the ring = ID of cylinder  + 0.3 mm
About temperature: I usually heat the rings to about 1000 degrees Celsius (I'm not sure, based on little experience in the past and Look at the red hot color and guess the temperature, I don't have an thermometer )
I slowly increase the temperature of the rings, and decrease it slowly, I try to increase the temperature of the rings evenly.
(These are also based on previous experience, increasing and decreasing the temperature can affect the stretching of the material ...)
I also tried heating the rings to about   800 degrees C and more than 1100 degrees C, I just noticed that with different temperatures the hardness of the rings is different and they are fine for me.


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## dsage (Apr 24, 2021)

Did you try a simple Compression test ????


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## Brian Rupnow (Apr 24, 2021)

All of the rings have been individually placed into the cylinder and the end gap set to 0.004". Is it too stiff?--Well, it feels a lot stiffer to turn the engine than it did with one viton o-ring. Is it sealing? It is very hard to tell, but I don't think it is. My next move here is to put the old piston and viton o-ring back in and make damned sure the engine will run that way. As I said in an earlier post, the last time that engine ran was about three years ago when I made the video. Is it firing?--yes, but very intermittently.


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## Brian Rupnow (Apr 24, 2021)

That was settled quickly. New piston and rings out, old piston with Viton ring in---and engine runs lovely. Engine is MUCH easier to turn over by hand with old piston and o-ring. The rings aren't round. They have shiny wear spots in some areas and seemingly "untouched spots" in other areas. George Britnell questioned the fixture I made to expand these rings when heat treating them, and it appears he was right. The new piston I made seems fine. Onward and upward---try a different way of making some new rings.


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## rklopp (Apr 24, 2021)

As I've said before, I'm batting 1000 following Trimble's Strictly IC method to the "T." The new piston "seems fine." Does that mean it moves nicely if you put it in the engine but omit the rings?


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## Brian Rupnow (Apr 24, 2021)

I am going to try my next ring and piston combination on this engine, just because the piston is easier to get at and the cylinder is easy to remove. Also, this engine runs a bit faster and I don't have any hit and miss mechanism to think about.


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## Brian Rupnow (Apr 24, 2021)

Time for Ringmaking-Take2.   I am now going to make 4 more rings using the Trimble? method. I do have a 0.020" slitting saw. So---the rings will be turned to (3.142+.020)-3.142=1.006" o.d. and 0.898" inner diameter. This will give an inner diameter the same as rings I have purchased form Debolt. They will be cut to 0.063" thick. Instead of being broken, these rings will be cut using my 0.020" slitting saw. No farther work on cleaning up the i.d. nor the o.d. nor the thickness, until I have spread them individually over a 3/16" piece of steel inserted into the sawn gap and heat treated them to cherry red and then allowed them to air cool. Then they will be polished to 0.062" wide and cleaned on a sheet of emery paper on a flat surface, then positioned in the cylinder bore and if needed the gap will be filed to give a 0.004" wide gap.


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## Brian Rupnow (Apr 24, 2021)

So here we are---Just like Deja-vu all over again. These rings are identical to the first rings I made, except the o.d. is 1.006" and they are saw cut with a 0.020" slitting saw instead of being broken by hand.  Heat treat comes next.


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## Alec Ryals (Apr 24, 2021)

After making my rings and they have been cracked i put them between 2   1/8 " stainless washers and heat to dull red then quintch they work great!
Alec


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## Brian Rupnow (Apr 24, 2021)

This is a picture of my heat treat fixture and the new rings--the rings were individually spread over the vertical pieces of 1/8" plate and the torch was applied more or less on the center of the rings. The rings heated up very quickly and dropped off the fixtures, and have taken on that 0.125" distance between the ring ends. I have cleaned up the i.d. and the o.d. and dressed the sides with emery paper laid on a flat surface.  The only observation I made is that it certainly didn't take much heat to get that sawn 0.020" gap to open up to 0.125". Tomorrow I will pick the best two rings and  put them on the new piston and try this experiment again.


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## Brian Rupnow (Apr 24, 2021)

And to close out the day---When these rings were pushed squarely into the cylinder, they had a 0.004" gap, without me having to do any filing on them.---Amazing!!! Then with much breath holding, butt clenching, and #30 lubricating oil, the rings were installed on the piston. They were much harder to get on the piston than the previous set I had made. I was sure I was going to break them, but they did slide on, very reluctantly, and snuggled down into the ring grooves on the piston. The next question was "Will the piston fit into a 1" bore with these new rings on it?"  I have a round piece of cast iron with a 1" reamed hole through it, and a 20 degree tapered lead to help compress the rings while the piston is persuaded to fit into it. It did fit. Not easily, but it did.  Tomorrow I am going to put this new piston and rings into my Rupnow Vertical Engine and hope it will run. I did start it today, as can be seen in the video, so with nothing changed except the piston and rings I am off to bed. Wish me luck for tomorrow!!!---Brian


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## Brian Rupnow (Apr 25, 2021)

Piston and newest set of cast iron rings has been installed on my old Rupnow Vertical Engine. I am getting firing and smoke from exhaust but it's not a self runner yet. This is promising though. I never even got firing on the sideshaft hit and miss engine when I had the piston and rings on it. I have it set up with the electric motor right now, and I'll give it an hour and a half to help bed the rings in. If that doesn't work, I will pull the cylinder off and hone it to give a cross-hatch pattern on the inside of the cylinder.


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## dsage (Apr 25, 2021)

If the rings were turned 1.006 then they certainly are NOT going to be round when you put them into a 1" bore. The fact that a 20thou gap closed to .004 should tell you that.
Again. Maybe I missed something in your description.
When the rings are turned over diameter there is another procedure and more fixtures to make to turn them round again.
Make the light mask I mentioned before to check for gaps before you run those rings in your cylinder and risk damaging it.

Never mind. You just posted while I was typing and I see you've gone ahead anyway.


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## Brian Rupnow (Apr 25, 2021)

Dsage--I'm not discounting your help. I have three books here, authored by Philip Duclos, Malcolm Stride, and L. C. Mason, plus help from George Britnell. All are "more or less" the same information. I know about the "light mask" you are referring to. I am learning, but it is a very slow process.-----Brian


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## dsage (Apr 25, 2021)

OK. Soldier  on.
Thanks.


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## minh-thanh (Apr 25, 2021)

Hi Brian !
I think you re-measure the heights of the rings and grooves.
Because with both the small engine ( homemade) and the big engine ( car..), changing the new rings never causes the engine to be too heavy to start.


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## Brian Rupnow (Apr 25, 2021)

After being ran by the electric motor for 1 1/2 hours, the compression has improved, and when I try to start the motor with my electric drill it fires right along as the drill turns it under power, but when I remove the drill the motor just runs down and quits. The inside of the cylinder was a mirror finish from running it so many times with a Viton o-ring on it.--So---I pulled the cylinder off and set it up on my mill with a 3 stone brake-cylinder hone, and gave it 20 linear strokes with lots of wd40 at about 100 rpm. This has removed the mirror finish and left a herringbone hone pattern on the inside of the cylinder. Now the engine is out in the garage being "run in" with an electric motor for another hour to see if the compression will come up after an hours running.


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## Brian Rupnow (Apr 25, 2021)

The cross hatching didn't really help at all. At this point in the game I've tried everything I can think of, and had no real success.---Ah Poop!!!    So----What did I learn today? Well, for one thing, the heat from an oxy-acetylene torch is way too hot. I barely touched the rings with the flame and they immediately turned bright yellow and fell off the 1/8" steel spreaders they were hanging from. That can't be right. Tomorrow I will buy a refill for my propane cylinder, and hopefully use a cooler flame to heat treat any future rings.  What else--Well, although the rings I am waiting on from Debolt are 1/16" thick, the actual rule of thumb for home made rings is that they should be from 1/25 to 1/30 of the bore diameter. I have a 1" bore, so the rings should be from 0.040" thick to 0.033" thick. That is one heck of a big difference from 1/16".  In his book "The Shop wisdom of Philip Duclos", he gives a tutorial on making piston rings, and he arbitrarily chose a radial ring thickness of 0.050" and it worked well for him. If it worked for him, then it should work for me. I think I have one stub of fine grained cast iron left, so maybe tomorrow I'll make some rings using Philip Duclos' measurements.


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## Gordon (Apr 25, 2021)

I think that you either have to follow the Timbrel method which you have not done or you have to make the rings oversize and make a fixture to turn them to final size. Your method is not making a true round ring when it is inserted into the engine. Also based on my recent experience the heat treating is critical. I made some rings which I had heated to 1100 and then let cool and they did not seal properly. I took some more of the same batch and heated them to 1100 for three hours and left them in the kiln overnight and those worked. Maybe that was just blind luck, True round is more critical when you are making 1" dia rings as opposed to large 3" dia automotive rings.


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## Brian Rupnow (Apr 25, 2021)

I just found an article which says that the width of the spreader used in the heat treat fixture should be 15% of the bore diameter. In my case that would be 0.150" (For a 1" bore). That is slightly less than the 3/16" used in the Duclos' book and slightly more than the 1/8" which I used today.


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## dnalot (Apr 25, 2021)

Gordon said:


> 1100 for three hours and left them in the kiln overnight and those worked



When I made George Brintnell's Holt 75 George talked me out of using o-rings and suggested the Timbrel method. I heated my rings to a little over 1100 degrees F for an hour in my foundry furnace and let them cool over night in the furnace. They turned out well and I had good compression even before breaking in. 

Mark T


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## doc1955 (Apr 25, 2021)

I know my longer videos don't seem to be liked but here is a video anyway on heat treat and how not to put a ring on lol now this it for a .750 bore. When I finished the engines it took a little bit to get them running but ran just fine with them after I gt the timing and fuel mixer sorted out.


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## dsage (Apr 26, 2021)

doc1955:
Unfortunately you didn't cover what outside diameter you turned the rings to in the first place.
Perhaps you can elaborate.


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## Brian Rupnow (Apr 26, 2021)

This morning I got up and machined 5 new rings from a piece of grey cast iron to 1.006" o.d. x 0.906" i.d. x 0.055" thick. I'm going up to the local hardware and buy a tank of propane. When cut with a 0.020" slitting saw heat treated and and taken down to 0.050" thick on some emery paper on a flat surface they will be exactly as built in the Philip Duclos book. I will recut new ring grooves on my test piston and then see what happens.


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## dsage (Apr 26, 2021)

Sorry to interfere with your process. And yes I see your book. Lots of bad information is out there. The Trimble method is the defacto "correct" way of making rings.

But I will re-iterate that a ring that is turned 1.006 diameter CANNOT BE ROUND when you squash it to put it into a 1.000 cylinder regardless of what you do with the gap.
Think about it a bit and I think you'll see that. At best the ring will touch at only two points beside the gap and the point directly across the cylinder from the gap.
If that process worked you could make all your blanks one diameter and squash them into any size cylinder and call it good by making the appropriate gap. Not so.
You need to turn the rings EXACTLY the diameter of the cylinder first.
i.e It starts out round at the exact cylinder diameter and returns round and the exact same diameter with a bit of spring from the heat treating and a gap for expansion on heating. The gap is only there for installation and to make space for expansion. NOT to allow for deforming an oversized ring into a small cylinder.

Unless you are following the Chaddock method where you make a jig to take the 6thou off after you heat treat the ring to make it 1.000 and round afterward. I haven't looked at the Duclose method but you never mentioned making any extra jigs.

Also you have now worn your cylinder with the previous bad rings so you're starting from a bad place.

I'll leave it at that.


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## Brian Rupnow (Apr 26, 2021)

-I'm making this set exactly to Philip Duclos's book, "The shop Wisdom of Philip Duclos". The only real difference between this set of rings and the last set is that these rings are only 0.050" thick and are spread on 0.150" pins, ready for heat treat.


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## doc1955 (Apr 26, 2021)

dsage said:


> doc1955:
> Unfortunately you didn't cover what outside diameter you turned the rings to in the first place.
> Perhaps you can elaborate.




The dia of the rings I cut I use the formula to calculate the circumference then add the slitting saw width then turn the sum back into a dia. That formula has worked for all the engines I have built so I know it works.


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## Brian Rupnow (Apr 26, 2021)

I am using the formula that Doc talks about in the previous post. That is the formula given in "The Shop Wisdom of Philip Duclos"


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## Brian Rupnow (Apr 26, 2021)

This is the third batch of rings immediately after heat treat. I bought a new cylinder of propane, and there is a huge difference in the heat from a propane torch and that of an oxy acetylene rig. It took longer to heat each ring to a cherry red and it gave me a chance to heat the rings more uniformly before they dropped off the 0.150" diameter spreaders they were mounted to. Next step will be to deburr the inside and outside and bring the sides down to a uniform 0.050" thick.


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## doc1955 (Apr 26, 2021)

dsage said:


> Sorry to interfere with your process. And yes I see your book. Lots of bad information is out there. The Trimble method is the defacto "correct" way of making rings.
> 
> But I will re-iterate that a ring that is turned 1.006 diameter CANNOT BE ROUND when you squash it to put it into a 1.000 cylinder regardless of what you do with the gap.
> Think about it a bit and I think you'll see that. At best the ring will touch at only two points beside the gap and the point directly across the cylinder from the gap.
> ...


 Thats right there is a lot of bad info on the net. Now for one thing you need to get the thought of the ring bending in one spot lol that is not the case it will bend and deform on the entire circumference thus it will be round. Rings when installed bend on the intire circumference  not in abit here and a bit there that is where you are making your mistake. So Brian keep it up you are on the right path.


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## dnalot (Apr 26, 2021)

Brian Rupnow said:


> there is a huge difference in the heat from a propane torch



I like to use Mapp gas. It is hotter than propane

Mark T


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## doc1955 (Apr 26, 2021)

You don't want a real hot flame even propane turned up all the way is a little to hot for our small rings.


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## mayhugh1 (Apr 26, 2021)

doc1955 said:


> Thats right there is a lot of bad info on the net. Now for one thing you need to get the thought of the ring bending in one spot lol that is not the case it {will bend and deform on the entire circumference thus it will be round. Rings when installed bend on the intire circumference  not in abit here and a bit there that is where you are making your mistake. So Brian keep it up you are on the right path.



Actually, when inserted into the cylinder, the ring will deform at the point of highest stress which will be directly across from the gap and then contact the bore in only two points. This stress point is where, in your video (and I do enjoy watching your videos), your rings broke during installation. 

As Dave said, the rings made by the "Duclos" method will never have 360 degrees of contact with the cylinder. Of course, that's not saying that they won't be 'good enough' for some engines to start and run. If the rings are made properly with 360 degrees of contact, the engine won't need to be spun for long periods with an external power source to wear the rings and bore into each other. And, by the way, during that 'run-in' time if the engine is sucking fuel through the carb from a filled tank, the rings will likely be washed with raw fuel and wear quickly away even quicker at those two points of contact. However, after a while, those points on the ring will wear down enough for the bore to begin changing shape. At some point, the clearances between the rings and bore might be reduced enough to get the engine started, but the now non-circular cylinder will be forever mated to those particular rings. None of this is optimal, but serendipity might help the engine eventually start. And that might be OK for an engine that was built for display and just needs to run for a few minutes before being put up on a shelf.

Another concern I would have with the 'Duclos method' is heating the rings without a fixture to keep them flat. I'd be worried about the rings warping during heat treatment especially in a bench top setup where the heating is quick and relatively non-uniform. The rings need to wind up flat because their lower surface is an important sealing surface to the piston during combustion. 

A light test is easy to do, but a fixture in conjunction with a bright flashlight in a dark room is needed. Significant diffraction effects limit what can be seen with the naked eye while holding the ring up to a window and such a cursory check can't be relied upon. Also, when heated uncontrollably in open air, there can be a bit of scale build-up on  the rings' o.d.'s that needs to be polished away. This scale will also affect the contact area as well as light test results.

There's very little additional work involved with with Trimble's method which is time proven and has science and common sense behind it. As others have said there is a lot of misguided info out there on ring making. 

All in all, though, a very entertaining thread. - Terry


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## Brian Rupnow (Apr 26, 2021)

No real progress today. I'm all worked out!!


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## IC-man (Apr 27, 2021)

Dsage is right, you have to start with the right diameter I.e. fits the cylinder perfectly, before any heat treatment or splitting.


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## minh-thanh (Apr 27, 2021)

Today, I test with some of my rings
With a slightly small piston, with this piston I'm sure the engine has almost no compression
And with a small part of the ring that is not in complete contact with the cylinder, with a little bit of W40 oil, they have good compression






Edit : The upper ring is similar to the 2nd ring , but less so . I forgot to take picture


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## Harglo (Apr 27, 2021)

Brian Rupnow said:


> And to close out the day---When these rings were pushed squarely into the cylinder, they had a 0.004" gap, without me having to do any filing on them.---Amazing!!! Then with much breath holding, butt clenching, and #30 lubricating oil, the rings were installed on the piston. They were much harder to get on the piston than the previous set I had made. I was sure I was going to break them, but they did slide on, very reluctantly, and snuggled down into the ring grooves on the piston. The next question was "Will the piston fit into a 1" bore with these new rings on it?"  I have a round piece of cast iron with a 1" reamed hole through it, and a 20 degree tapered lead to help compress the rings while the piston is persuaded to fit into it. It did fit. Not easily, but it did.  Tomorrow I am going to put this new piston and rings into my Rupnow Vertical Engine and hope it will run. I did start it today, as can be seen in the video, so with nothing changed except the piston and rings I am off to bed. Wish me luck for tomorrow!!!---Brian


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## Harglo (Apr 27, 2021)

Brian Rupnow said:


> And to close out the day---When these rings were pushed squarely into the cylinder, they had a 0.004" gap, without me having to do any filing on them.---Amazing!!! Then with much breath holding, butt clenching, and #30 lubricating oil, the rings were installed on the piston. They were much harder to get on the piston than the previous set I had made. I was sure I was going to break them, but they did slide on, very reluctantly, and snuggled down into the ring grooves on the piston. The next question was "Will the piston fit into a 1" bore with these new rings on it?"  I have a round piece of cast iron with a 1" reamed hole through it, and a 20 degree tapered lead to help compress the rings while the piston is persuaded to fit into it. It did fit. Not easily, but it did.  Tomorrow I am going to put this new piston and rings into my Rupnow Vertical Engine and hope it will run. I did start it today, as can be seen in the video, so with nothing changed except the piston and rings I am off to bed. Wish me luck for tomorrow!!!---Brian


Hello Brian
Just watched the struggling to get the top ring on an bingo its become 2 pieces. It some what common practice to take a few thou of the top end of the piston up to the grove. That said should reduce the risk of breaking. I have a star engine with just one ring compression is good. 
Harvey


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## Brian Rupnow (Apr 27, 2021)

I'm six days in on what was supposed to be a fairly simple project. So far, I have not been successful. I am getting lots of advice from people who have plainly never made piston rings, and though I know they wish to help, it only confuses things. I have tried the Philip Duclos method of ring making, and people have immediately jumped in and told me that is a terrible way to make rings, and they will end up crooked and it's no wonder they don't work.  It worked for Philip, and he was sure enough of the method to include it as part of his book. His method for machining the ring outer diameter was #1--Calculate ring o.d. (Same as i.d. of cylinder.) #2 Since he cut the rings with a 0.020" slitting saw he multiplied the diameter x pi to get circumference, then added the slitting saw thickness to the resultant circumference and then divide the answer by Pi  to achieve his final ring diameter (which in my case turned out to be 1.006")I don't have a heat treat furnace, and don't plan on buying a heat treat furnace. I did find out that the flame from an oxy acetylene flame was far too hot, so I went and bought a bottle of propane and it worked much better with a cooler flame. I have looked at simple fixtures which the rings are mounted on and then held flat by means of a big flat washer bolted to the fixture to squeeze the rings flat during heat treat. I'm not sure if the fixture should be the same diameter as the i.d of the rings before they are cut, after they are cut, or after they have been stretched over a spigot to spread the gap. Some people advocate turning the o.d. of a stack of rings held in a fixture (after heat treat) to ensure they are perfectly round on the o.d.  This sounds like it would be the answer, but the rings are definitely not round on the i.d. at this point after being split and heat treated.


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## Brian Rupnow (Apr 27, 2021)

I have not been successful----yet. A fellow from Switzerland has posted his rings and fixtures on another forum, based on the Chadock method and he has had good success. This is the method that makes the rings a couple of thou oversize and then clamps them in a fixture and takes a skim off the outside diameter to ensure that the rings are perfectly round. Since the rings actually "float" a bit on the piston, the o.d. doesn't have to be perfectly concentric with the inside diameter.


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## stevehuckss396 (Apr 27, 2021)

Hello!

I thought you said you have a pottery kiln. If so why not build the proper fixture and heat them to 1100 for 3 hours and be done with it. Just wondering.

Just spreading them .150 isn't enough. They need to be in the fixture to hold the ring correctly.  If not the stress of being spread is being transferred to the spot directly across from the gap. When heated the ring can deform and create a flat spot across from the gap. The fixture helps to spread the stress evenly around the ring and greatly reduce the chance of distortion. 

The heat treat is another thing that needs to be done fully or no point. 1100 for 3 hours. It is done to stress relieve the material. It takes a long time to fully relieve all the stress. If not then the ring will slowly lose wall pressure.

The Trimble method is the most work of all the ring making methods. If all steps are followed without any shortcuts it will yield the best rings of them all.


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## Brian Rupnow (Apr 27, 2021)

No pottery kiln here, just oxy acetylene, propane, and wifes kitchen oven which I have been warned to stay away from.


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## minh-thanh (Apr 27, 2021)

Hi Brian !


stevehuckss396 said:


> Hello!
> 
> 
> Just spreading them .150 isn't enough. They need to be in the fixture to hold the ring correctly.  If not the stress of being spread is being transferred to the spot directly across from the gap. When heated the ring can deform and create a flat spot across from the gap. The fixture helps to spread the stress evenly around the ring and greatly reduce the chance of distortion.
> ...



That's exactly what I thought and did, but I don't have the furnace. I just heat the rings with a gas torch, heat them very slowly ,   try to heat the ring in all directionsand try to stay at that hot temperature for at least 5 minutes.
I've tried the ways everyone says it, and I've been successful,  In some cases, the rings that look "good" are less  (or I made a mistake in those cases).
 I've been several times with this way and the rings are always fine with me


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## tornitore45 (Apr 27, 2021)

The moral of the story and the reason there is so much debate about this subject is that there is more than one way to skin this cat and as long as proper procedure and attention to detail are observed different methods may produce a running engine.
I love math, but as an engineer practical consideration force me to asses when accurate is accurate enough.
There is much debate about the shape of the ring once is compressed inside the cylinder.
The Chaddock/Trimble method involve predistortion by forcing the gap open and annealing.
The method approximate the theoretical shape required to a high degree, at least theoretically.
On the typical 1" bore of our engines the circularity error by using the "cold" method may be 0.0001" an then the ring may still conform to the cylinder but with different radial pressure around the circle.
The method I described previously (I did not invent it and have no emotional attachment to it) makes a ring with a longer circumference and then remove the excess leaving a gap. Squeeze the gap close to slide in the cylinder. No annealing required.
Other people have made engines that work.  Do they reach the highest theoretical compression exhibiting the least drag?  Probably not, but the engines run.
Any engine would have zero compression at 0.01 RPM but when the compression phase happens in 50mS (600RPM) a small arc of daylight between ring and cylinder is not goin to impact compression.  Let's not mention the presence of oil and the fact that the pressure of ignition pushes the ring into contact with the cylinder from behind.
Brian since this is your first attempt at making ring you will find out, like all of us do, that after studying the literature you still have to develop your personal mojo.  Listen to everyone and then make up the ring with your own method.
When talking about the gap one has to specify whether he refer to the relaxed gap or the compressed gap when inside the cylinder.   For all practical consideration the compressed gap is there for expansion regardless of the process used to make the ring it can be accounted in the machining OD or neglected entirely and filed away later either way wont change the result much.


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## GRAYHIL (Apr 28, 2021)

Hi Brian
I hope at the end of your ring saga you will write a preferred method.
I have made several engines and only two have run and they have all finished up for show and not for running, always through lack of compression be it rings or valve
seating.
Graham


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## jack620 (Apr 28, 2021)

Brian Rupnow said:


> I am getting lots of advice from people who have plainly never made piston rings, and though I know they wish to help, it only confuses things.



Welcome to the internet Brian.


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## Gordon (Apr 28, 2021)

I do wonder how much of the loss of compression and leakage comes from the width and the depth of the groove. According to some articles which I have read a part of the seal is caused by the gases getting behind the ring and pushing the ring against the cylinder wall. Obviously you can have a perfect fitting face but if the groove is too wide and/or too deep the gases can leak around the ring. Where is this point? I have had cases where the groove is not deep enough and the piston will not fit in the cylinder. I have also had cases where I have tried to run the engine and when I removed the piston and the ring was stuck in the groove after removing the piston. 
Gordon


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## minh-thanh (Apr 28, 2021)

minh-thanh said:


> Today, I test with some of my rings
> With a slightly small piston, with this piston I'm sure the engine has almost no compression
> And with a small part of the ring that is not in complete contact with the cylinder, with a little bit of W40 oil, they have good compression
> View attachment 124910
> ...



One more thing: there will be 3 cases:
1 / My cylinder is not really round
2 / The ring is not round
3 / (1) + (2)
So check your cylinder is round?
  Because if the cylinder is not round you will not know where you are wrong


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## tornitore45 (Apr 28, 2021)

Gordon, as long as the ring is free to move without excess freedom the ring would press against the upper surface of the groove when the piston accelerate downward. This seals the top but some gas must escape to create pressure behind the rings.  Every engine has some blow-by pressurizing the crankcase but must be minimal.


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## SailplaneDriver (Apr 28, 2021)

Damn. You guys just put me down the rabbit hole of Circularity vs. Roundness.


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## doc1955 (Apr 28, 2021)

minh-thanh said:


> So check your cylinder is round?
> Because if the cylinder is not round you will not know where you are wrong



That would be my guess as a lot of honing by hand to get cylinder really smooth as for _o_ ring set up may have egg shapped cylinder same thing goes for emery paper on the lathe to much emery paper and you will have a shaft that is not truly round.


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## werowance (Apr 28, 2021)

Brian, please dont hate me for adding my method for making rings - which i have only made them for 1 engine.
1. measure the dia of the ring groove on the piston.  bore the cast iron to slightly larger so the ring can compress past the major dia of the piston.
2. turn down the cast iron until it just fits into the cylinder.  not a sloppy fit.  i used 500 grit emory cloth to hit the fit when it was getting close
3. part the rings, check to see if the rings edge will fit nicely in the ring groove of the piston.  if not i used a surface plate and 500 grit sand paper until it was that nice slide in fit.
4. snap the ring using side cutters.  at first i thought this would dent and deform the ring at the cut but it didnt.  it just caused them to snap.
5. i just barley filed the gap.  didnt even bother to measure it.  just so there was a very little gap.
6. used a rod to spring the ring gap to the size i wanted and heated them to red over a bed of sand.  some fell of the rod as other instructions said they would and some did not.  but they all at least started to move on the rod as they were spread on the rod at an angle and gravity started making them hang straight down.
7. dont think this mattered whatsoever but i put them in the toaster oven at its highest setting which i believe was 450 f. i then went and worked on other things for a few hours. - i let ring cool naturaly.
8. test the fit in the ring grove just by stick the side of the ring in,  not actually spreading and installing the ring.  if it swelled from the  heat then i hit it on the surface plate / 500 grit again till it would slide in

only issue i had was the ring kept breaking on instilation.  i switched over from store bought cast iron to some old scrap cast iron i had.  was later learned it was a piece to a stoker coal furnace but thought it was old farm scrap.  that iron worked great and did not break on installing.

i probably just got lucky as i was not nearly as precise and acuratley measuring and doing all that math as you are doing now.  i envy the fact that you understand all those calculations.

and i should note that the engine - the upshur vertical runs just fine for me


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## awake (Apr 28, 2021)

SailplaneDriver said:


> Damn. You guys just put me down the rabbit hole of Circularity vs. Roundness.


Are you saying that you feel like we keep going round and round on this issue?


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## Brian Rupnow (Apr 28, 2021)

werowance---Thank you. Any knowledge is good knowledge. There is a lot more to making rings that actually work than most people think.---Brian


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## Brian Rupnow (Apr 28, 2021)

.


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## Brian Rupnow (Apr 28, 2021)

---Time for an update on what is happening with this. I don't have any problem with machining the rings to size on o.d., i.d. nor width. The width is easier than you would think, because cast iron machines very easy and is very easy to cut down in width on a piece of emery paper on a cast iron surface plate. Solution there is to make sure and cut the rings a few thou "over-width". Cutting the ring grooves in the cast iron piston is easy, but you have to really pay attention to the width of the groove you cut. This is one of those weird times when "what you see" isn't necessarily "What you get".  I don't know why, but a 0.062" parting off tool gives me a 0.055" wide slot on a straight in plunge cut. You need to have the ring in your hand and keep trying it for fit in the groove you are cutting. Recommended groove width is 0.001" wider than the ring, with square sides, no taper. The groove should be .003" to 0.004" deeper than the radial width of the ring. When pushed down into place in the groove, the groove has to be deep enough for the ring to set below the outer surface of the piston.------------I don't have any problem breaking the ring on one side by putting the ring partially into the vice and pressing sideways on the ring with my fingers.------I don't have any problem cutting the ring with an 0.020" slitting saw like Philip Duclos recommends. Heat treating the ring and doing the same heat treat to all of the rings with a "gag" piece holding the ring open doesn't seem to be a problem, except that you can't really use an oxy aceytlene torch.--Too hot. Too fast!!!! Flame from a propane torch seems to do a much better job.----I don't have a problem setting the heat treated ring into the cylinder squarely  and checking the gap, and no problem filing the gap with an ignition points file until it reaches 0.004" wide.-------------Fitting the ring over the piston and down into the groove isn't as much of a problem as you would think---just use lots of #30 lubricating oil and a bit of thumb pressure and patience.--------It's not a problem to hold the cylinder up to a bright light and check that no light is coming past the sides of the ring (Which means that that ring is bad and won't seal.)-----The problem comes when after all of these things are looked after properly, the rings are not sealing in compression. My belief, and that of many people reading this post, is that the outer diameter of the ring is not perfectly circular, and as a consequence is not tightly contacting the wall of the cylinder.  Chadock (A ring guru) agrees with me/us. So---What to do? The only thing left to do is to assemble all of the rings on a fixture, align all of the rings with a slide on fixture that aligns the outside diameter, and then clamp them, remove the slide on alignment tool, and then take a cutting pass on the outside diameter of the rings to ensure that they are perfectly round. The outer diameter of the ring does not have to be completely concentric with the inner diameter. This cutting pass can be made by either a very sharp tool or by a toolpost grinder, or by lapping.----and should be less than 0.001" deep.


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## leerkracht (Apr 29, 2021)

groove width smaller than cutting  tool 
look at the PDF  drawing  for info


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## Charles Lamont (Apr 30, 2021)

I have found that the final OD finishing cut is better done with one ring at a time. Don't know why, but I could not get the buggers to all run true as a stack. They can be done individually without touching the tool setting.


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## Charles Lamont (Apr 30, 2021)

tornitore45 said:


> Gordon, as long as the ring is free to move without excess freedom the ring would press against the upper surface of the groove when the piston accelerate downward. This seals the top but some gas must escape to create pressure behind the rings.  Every engine has some blow-by pressurizing the crankcase but must be minimal.


I don't think this is right. AFAIK the idea is that the gas pressure on the firing stroke causes the ring to push down on the bottom side of the groove.


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## Alec Ryals (May 1, 2021)

Charles Lamont said:


> I don't think this is right. AFAIK the idea is that the gas pressure on the firing stroke causes the ring to push down on the bottom side of the groove.


Yes it pushes dowd and outwards


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## Tim1974 (May 1, 2021)

Brian Rupnow said:


> ---Time for an update on what is happening with this. I don't have any problem with machining the rings to size on o.d., i.d. nor width. The width is easier than you would think, because cast iron machines very easy and is very easy to cut down in width on a piece of emery paper on a cast iron surface plate. Solution there is to make sure and cut the rings a few thou "over-width". Cutting the ring grooves in the cast iron piston is easy, but you have to really pay attention to the width of the groove you cut. This is one of those weird times when "what you see" isn't necessarily "What you get".  I don't know why, but a 0.062" parting off tool gives me a 0.055" wide slot on a straight in plunge cut. You need to have the ring in your hand and keep trying it for fit in the groove you are cutting. Recommended groove width is 0.001" wider than the ring, with square sides, no taper. The groove should be .003" to 0.004" deeper than the radial width of the ring. When pushed down into place in the groove, the groove has to be deep enough for the ring to set below the outer surface of the piston.------------I don't have any problem breaking the ring on one side by putting the ring partially into the vice and pressing sideways on the ring with my fingers.------I don't have any problem cutting the ring with an 0.020" slitting saw like Philip Duclos recommends. Heat treating the ring and doing the same heat treat to all of the rings with a "gag" piece holding the ring open doesn't seem to be a problem, except that you can't really use an oxy aceytlene torch.--Too hot. Too fast!!!! Flame from a propane torch seems to do a much better job.----I don't have a problem setting the heat treated ring into the cylinder squarely  and checking the gap, and no problem filing the gap with an ignition points file until it reaches 0.004" wide.-------------Fitting the ring over the piston and down into the groove isn't as much of a problem as you would think---just use lots of #30 lubricating oil and a bit of thumb pressure and patience.--------It's not a problem to hold the cylinder up to a bright light and check that no light is coming past the sides of the ring (Which means that that ring is bad and won't seal.)-----The problem comes when after all of these things are looked after properly, the rings are not sealing in compression. My belief, and that of many people reading this post, is that the outer diameter of the ring is not perfectly circular, and as a consequence is not tightly contacting the wall of the cylinder.  Chadock (A ring guru) agrees with me/us. So---What to do? The only thing left to do is to assemble all of the rings on a fixture, align all of the rings with a slide on fixture that aligns the outside diameter, and then clamp them, remove the slide on alignment tool, and then take a cutting pass on the outside diameter of the rings to ensure that they are perfectly round. The outer diameter of the ring does not have to be completely concentric with the inner diameter. This cutting pass can be made by either a very sharp tool or by a toolpost grinder, or by lapping.----and should be less than 0.001" deep.


Or just run in for a while maybe turn engine over with a drill and let them bed in ?


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## DKGrimm (May 1, 2021)

Following all with interest.  I'm just now making rings for a 3/4 in bore 4-cyl inline of my own design.  I'm using the Prof Chaddock method pretty much by the book, just getting ready for the skim cut.  I've actually done that before with good results, so there should be minimum drama. (he said, hopefully).


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## coulsea (May 1, 2021)

My experience with making rings.
22mm cast iron bore, aluminium piston.
rings are cast iron 22.1mm , i only have vernier calipers so exact measurement is debatable 1.5mm thick and 1.5mm from outside edge (bore) to inside edge (bottom of ring grove), I tried 2mm and they snap every time.
cut the gap with a junior hacksaw and file edge to fit into the bore.
put a screwdriver into ring gap and heat with propane until it falls off the screwdriver. i would assume that the ring will bend most opposite the gap.
Result
The engine runs but nowhere near as much compression as if it had an o ring. the grey look of cast iron will become more chrome like as it wears so you can see how round it is after a bit of running. mine have 3 or 4 areas that don't touch, a result of the heating on the screw driver and bending when fitting to the piston.
while i say that the compression is not good it will now start with a flick of the flywheel and it is getting better the more it runs, the crank will bounce off compression. I always use a bit of 2 stoke oil in the fuel, either shellite or pump petrol.
I did two engines at the same time, both pretty much the same result. i have an engine with bought rings (28mm) and it was good from the start and quite a few with o rings which never gave any problems.


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## Brian Rupnow (May 10, 2021)

There is no joy in Mudville today. I put a new piston and two rings I had purchased from Debolt  in the newest vertical i.c. engine-2021 and had no compression. I squirted some oil down the sparkplug hole and had lots of compression. The new rings are not sealing. I drove the engine for 2 hours with an electric motor, hoping that the rings would "bed in" and seal, but it's not happening.----So---I have one trick left. That is to build a fixture as per Mr. Chaddock, and turn the o.d. of the rings to be perfectly cylindrical. That is exactly why I bought the toolpost grinder. I doubt my ability to take a 0.0005" depth of cut with a lathe tool, but with the grinder it may be possible.


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## dsage (May 10, 2021)

I wouldn't  be destroying the rings you bought. You can be sure they are (well at least were) round. Probably not any more.
What is likely the case now is that your cylinder is not round after running in all your previously failed rings.
Unfortunately it won't help to hone / bore the cylinder now because it won't be 1" diameter any more.
What you might try is starting over. If you can't bore the cylinder - Make a plug maybe half the length of the cylinder of aluminum of an appropriate size to fit the cylinder and use it to hone the cylinder with a coating of fine grinding compound on it. Being a plug, hopefully it will even out the surface in the cylinder leaving the low areas and honing off the high areas until its round again. (It's all I can think of).
Then measure it really accurately and make a new piston and rings the correct size. Make the new rings by the proper methods you mention and see how you make out.


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## Tim Wescott (May 10, 2021)

Brian Rupnow said:


> ... I drove the engine for 2 hours with an electric motor, hoping that the rings would "bed in" and seal, but it's not happening. ...



If I got onto stunthanger.com and told the folks there that I was going to do that I'd get yelled at.  Quietly by a couple of guys who own businesses making, reworking, and selling competition model airplane engines, and loudly by at least one guy who spends a lot of his spare time evaluating engines and sharing the results with all and sundry.  All of whom are people who one ignores at peril of being "that guy" who shows up at a contest and never puts in a good flight, because his engine is misbehaving.

I really think that if you're not at the point that you could start the engine with the rings freshly installed, then no amount of driving the thing from the outside, at temperatures markedly different from normal operating temperature, is going to make the thing run right.


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## Brian Rupnow (May 10, 2021)

Here we have Mr. Chaddocks fixture for turning the outer diameter of piston rings to make them truly round. The sleeve in my hand has an internal bore of 1.00". The rings are sprung into the sleeve, the sleeve with rings in it slides over the part held in the chuck, then the washer on the very end is tightened down with the bolt, which squeezes all of the rings together. The o.d. of the 1/4" thick washer is slightly smaller than 1", so after the bolt is snugged up tight, the sleeve is slid off over the washer, leaving the rings ready to be turned or ground to a perfect diameter. I am going to use my toolpost grinder to do that.---And no, those aren't the rings I bought from Debolt. Those are rings that I made, and truly, I see no difference between the Debolt rings and the ones I made.


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## johwen (May 11, 2021)

Hi Brian, I believe the reason that the rings did not bed in when running with an electric motor is that you are only relying on the ring tension to apply wall pressure when  with the engine running you have the addition of  combustion pressure putting pressure on the rings to seat them. John


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## dsage (May 11, 2021)

No compression - No combustion


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## ranger (May 11, 2021)

Brian Rupnow said:


> Here we have Mr. Chaddocks fixture for turning the outer diameter of piston rings to make them truly round. The sleeve in my hand has an internal bore of 1.00". The rings are sprung into the sleeve, the sleeve with rings in it slides over the part held in the chuck, then the washer on the very end is tightened down with the bolt, which squeezes all of the rings together. The o.d. of the 1/4" thick washer is slightly smaller than 1", so after the bolt is snugged up tight, the sleeve is slid off over the washer, leaving the rings ready to be turned or ground to a perfect diameter. I am going to use my toolpost grinder to do that.---And no, those aren't the rings I bought from Debolt. Those are rings that I made, and truly, I see no difference between the Debolt rings and the ones I made.


Hi Brian, been following this intently, one question? If you compress your rings into a sleeve that has the actual finished bore size, clamp tight, and then machine/grind to a “perfect circle”, you must surely be reducing the o/d of the ring to less than the bore size? Would it perhaps be better to start off with a slightly larger diameter ring and sleeve then grind down to the size required? I’m thinking that the ring in the sleeve, before machining, will not be in full contact with the bore 360deg, so will end up smaller after grinding down to the lowest point to obtain a true circle,and when expanded into the engine cylinder, could perhaps have the same issues as before machined. I don’t know, I may be wrong, I usually am.
Doug.


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## doc1955 (May 11, 2021)

Unless you start with a sleeve larger than your bore you will most diffidently end up with out of round condition when you reduce the dia then put them back into the 1.000 bore on your engine. I would venture to say they are closer to round than they will be after doing what you are proposing. make your starting sleave a few thosands bigger that your engine bore and then finish to your bore size.


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## doc1955 (May 11, 2021)

I still say your cylinder bore is egg shapped from all the honing you have done on it. You can check quick by putting it in a 4jaw and trying to dial it in and see if it will run true. Just because it will run with o ring does not mead it is round as o rinds are very forgiving of and out of round cylinder.


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## Brian Rupnow (May 11, 2021)

I'm not absolutely sure of what I'm doing here, but that has never stopped me before.  I wanted to have a good "visual" on the rings to know when I had reached a point of perfect roundness, so I coated everything with blue layout dye before I went to bed last night. This morning I mounted my toolpost grinder and taking .002" depth of cut, I made repeated passes over the rings until all the blue was gone. At this point, knowing my rings are perfectly round, I will dismount them from the grinding jig and try them into a cylinder.


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## Charles Lamont (May 11, 2021)

Put some newspaper or something over the bed ways to keep the grinding grit out.


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## ranger (May 11, 2021)

100% agree, oiled and then on top, water wet kitchen roll, as long as not too many sparks!


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## Brian Rupnow (May 11, 2021)

I didn't "true the wheel" with a diamond dresser. I did buy a diamond dresser to true the wheel, but didn't use it this time. (I still have to cobble something up to hold the diamond dresser while I do that, just haven't got that far yet.)  Keep in mind, I haven't done this before, and mostly I wanted to try it out for "process". The rings were extra rings that I had made, but they weren't that great. I don't expect to actually use these rings, but I had to try the new fixture and grinder out for "process".  There are a couple of things I will change, but they mostly relate to the tooling. I find that when using my 3 jaw lathe chuck that if I take anything out of the chuck, it is almost impossible to put it back in the chuck and not have the outboard end wobbling.  I am going to investigate using a tailstock support for the free end to make it run true, but I have to investigate and see if I have room to do that.  I will clean up the lathe when I get this sorted out.


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## ranger (May 11, 2021)

How about using one of the “soft blank” morse taper arbours to fit your headstock, you can machine it as the  fixture, and know it will always run true again after removing and replacing. Added benefit, no dismantling of 3 jaw chuck to clean out grinding dust. Or if you have a suitable collet, hold the fixture in that.


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## ranger (May 11, 2021)

Has anyone tried making a heat treating fixture along the lines of an expanding mandrel/ reamer, using a taper to expand the ring inside a sleeve, heating, then “expanding” fully to force the heated ring into close contact with the bore of the sleeve, then complete the heat treatment? Would this give a more uniform pressure against the cylinder wall by keeping the ring truly circular during treatment?


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## Gordon (May 11, 2021)

Mark your fixture as to where each jaw contacts the fixture. Jaw #1, Jaw #2, Jaw # 3. Also mark the overhang from the chuck. Machine the fixture and mark it before you remove it and then when you put it back in the lathe have it in the same position.


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## Brian Rupnow (May 11, 2021)

A part of this goose-chase is going to be building an independent support for the diamond wheel dresser. I will have to build this as an independent stand alone item, because I have nothin else that will work to hold it.


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## SmithDoor (May 11, 2021)

You make a simple holder for tailstock.  Just use morse tapper holder with holder for wheel dresser.
Keep the dresser very short in holder I just keep the stick out front ¼" to ½" .
I made mind out 1" bar stock and #2 morse taper 

Dave



Brian Rupnow said:


> A part of this goose-chase is going to be building an independent support for the diamond wheel dresser. I will have to build this as an independent stand alone item, because I have nothin else that will work to hold it.


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## Steamchick (May 12, 2021)

Hi All. A lot of chat about "the weather" here, but Brian's post of using Mr. Chadwick's fixture in post #117 is correct. Exactly the same process as used in piston ring factories. I.E. machine the rings close to "EXPANDED" size - leaving 0.002" or 0.003" for finish grinding. Cut the split. Fit in a "sized" bore on the fixture, then tighten to clamp and hold the ring at that diameter. (Sorry Doc, not an oversized bore!). BUT you need the sizing diameter to be concentric on the clamping fixture. Otherwise, you'll make rings that are clamped eccentrically - so will need grinding under-size to get them round. IF the cylinder is a precise sliding fit on a shaft at "finished" diameter,  and slides forward over the rings to be clamped, then concentricity can be assured before grinding. Brian will understand, I am sure, without a drawing.
At Hepworth and Grandage (Piston ring factory) in Sunderland in 1990 they had packs of dozens of rings going onto the mandrels and being clamped for grinding. The long cylinder would locate on a long shaft on the inboard end - at true concentric size in the grinder - to ensure the rings were concentric.  There was just enough relief at the end of this shaft for the grind-stone to finish the cut.
Anyone need a drawing? I have a pencil I can sharpen...
Enjoy!
K2


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## Chiptosser (May 12, 2021)

Brian,    Don't you have a four jaw chuck for your lathe?
Dale


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## Steamchick (May 12, 2021)

Oh, My Father made a fixture - basically the same as Mr. Chadwicks - and used his model cylinders as the gauge for setting the rings for size. He didn't have a grinder on his 1930 3" lathe, but just took the finest cut with a freshly sharpened and dressed tool. He had compression straight off. 
Brian, Winding the engine by electric motor probably won't bed-in rings against the bore, as the rings in service rely upon gas pressure for most of their tangential force to push them against the bore. Wound by motor, they are more likely just to "float" over the lubricant - sorry, lapping paste? - rather than apply enough pressure to "cut metal". Hepworth's just did a short lapping with lapping paste in dummy cylinders, which rotated maybe 20degrees  between each stroke, and on a crank arrangement so the rings effectively saw the few degrees oscillation of their true axis in relation to the axis of the bore, as they will in a finished engine. This "barrelling" effectively "took the corners off" and was only measurable at very high magnification. But it meant that the rings assembled to an engine didn't really need running-in, as they were already run-in to a circle of bore size. Without the factory machine, we have to run-in models - typically at half-load and half max. speed for an hour or more. (Maybe we don't all manage that?). It takes a long time on models and real engines that are without the lapping compound used in the factory, but with lubricating oil instead.
Therefore, there is some advantage of bought rings... but we usually "get by" with the imperfections we can't overcome in our workshops.
My plan is to make some wire rings. But only after I have made the rest of the engine? - Next winter, possibly? First I'll try O-rings though? 
Hope this helps?
K2


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## minh-thanh (May 12, 2021)

*Steamchick  !*



Steamchick said:


> Anyone need a drawing?
> Enjoy!
> K2


Please !


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## Steamchick (May 12, 2021)

Please be patient, I have to make time to do this.
K2


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## doc1955 (May 12, 2021)

Steamchick said:


> Hi All. A lot of chat about "the weather" here, but Brian's post of using Mr. Chadwick's fixture in post #117 is correct. Exactly the same process as used in piston ring factories. I.E. machine the rings close to "EXPANDED" size - leaving 0.002" or 0.003" for finish grinding. Cut the split. Fit in a "sized" bore on the fixture, then tighten to clamp and hold the ring at that diameter. (Sorry Doc, not an oversized bore!). BUT you need the sizing diameter to be concentric on the



But how do you grind to the correct dia when they are clamped at the dia of the cylinder. If you take a ring insert it into a sleeve the same dia as the cylinder and clamp it you have no material to grind unless you grind it under sized. That was the point I was saying. The sleeve you use has to be slightly larger than the finish size you want.


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## Steamchick (May 12, 2021)

Ok. I agree. 
In the H & G factory I saw the cylinders, but can't remember the details of sizes. I now remember they set the ring gap correctly. Does that help?

K2


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## Brian Rupnow (May 12, 2021)

And there it is---My version of "Diamonds are forever". This stand holds the diamond for truing the grinders abrasive wheel. it doesn't look like much, but there's a days work in that thing. My bandsaw really, really doesn't like cutting 1 1/2" thick plate. It's so slow that I feel like I'm going to start growing moss while I wait for it to finish a cut. I still have to make the plate that goes across under the lathe ways and the piece of 1/2" all thread rod that comes up thru the vertical plate and gets a nut on it to hold everything stable. Those of you who are sharp of eye will see that the design changed a little bit from the model I posted yesterday.--Two 1/2" threaded rods are overkill.


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## doc1955 (May 12, 2021)

Steamchick said:


> Ok. I agree.
> In the H & G factory I saw the cylinders, but can't remember the details of sizes. I now remember they set the ring gap correctly. Does that help?
> 
> K2


And the od would have to be set over sized to allow for grinding.


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## Steamchick (May 13, 2021)

Hi Brian. (Spell check pre-emptied my typing with "Brain").
Another nice bit of work. Next you'll make a dross collector with pipe for attaching your vacuum cleaner, to catch the dressed swarf from the stone. Some of that carborundum dust is smoke fine... (depends on the stone?).
K2


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## Brian Rupnow (May 13, 2021)

The diamond support tower is finished. It all goes together nicely and locks securely in place. Now I am getting posts that say the diamond support shaft should be tilted down 15 degrees. That is not a major problem, just a bit more work. Are we agreed that the diamond itself should still be on the same centerline as the grinder shaft?


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## Gordon (May 13, 2021)

I am not an expert on tool post grinders but why would it make any difference where the dresser contacted the wheel? The goal is to make the wheel truly round and as long as it contacted the wheel in a straight line it would seem to be able to do that.


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## James Barker (May 13, 2021)

A Concise Guide to Single Point Diamond Dressers — Continental Diamond Tool
					

Learn about diamond classifications and 10 tips for using single point diamond dressers.




					www.cdtusa.net
				




this article has some good information ....

BC1
Jim


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## Brian Rupnow (May 13, 2021)

One more time with feeling---This time the diamond support is set at an angle of 15 degrees with the center of the diamond on centerline of grinder spindle and chuck all in the horizontal plane. It isn't quite as pretty as the first time around, but form follows function.


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## Brian Rupnow (May 13, 2021)

Ahhhh Jeez---Now I'm being told that the diamond tool should be 15 degrees opposite to what I made it.---that it should be angled down at the front where it contacts the wheel.


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## Brian Rupnow (May 13, 2021)

Third times a charm!!!--We're setting at 10 degrees angle and diamond is at or just below spindle centerline. And the moral to this story is Research-Research-Research. I spent two minutes on Google and found all kinds of information about what I am doing here, even drawings. Luckily, I didn't have to make any new fixtures---Just relocated the hole for the shaft which holds the diamond. Anything from 5 degrees to 15 degrees is suitable, so I'm good with this. Arrrrggghhh!!--Let that be a lesson to me.


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## sawyer massey (May 13, 2021)

I make my rings +.002 on the o.d. bigger then the bore and ad ,001 for every inch of bore.
The grooves I cut T least .06 deeper then the thickness of the ring
I cut ALmost threw the ring ......put it in a vice with the partially cut edge close to the vice jaw break the ring 90 degrease from the jaw face with an unsharpened h.s.s tool bit and small hammer..........light tap is all it takes .....then with a needle file I fit the gap I need checking it often in the bore ......after the gap is right I put them on a1/4 key stock
Heat the area 180 degrees from the split to blue .......propane is lots ring will stay spread when   cool I make my rings 1/8 thick .......they are in a1.25 bore you may have to go smaller on the thickness ....to put them in I slide part in the groove ...remember it is deeper and work around in telling is in ....you will have to compress the rings to get them on the bore ......brass shim and a hose clamp....works ...the force from the ring itself will go round to your bore ..........made lots like this for steam engines and the completion will hold the engine on a ramp while loading .......the depth of the groove s not important the. Seal is made in the fit of the width .......this I fit like you said but I fit the ring to the groove lapping them on a stone in a figure 8 pattern the closer the better ...hope this help it is for steam never tried it on a ignition engine.....if you can find some durabar cast iron it centrifugaly spun gray iron real nice stuff and a bit more flexible if you know what I mean  but just gray iron works


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## coulsea (May 14, 2021)

is that 15 degrees down with the wheel turning clockwise or anticlockwise?
just kidding, maybe, my luck would be that i would buy a grinder for a left handed lathe.


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## Badhippie (May 14, 2021)

Brian 
I set up my diamond on center line and no angle. Only when I set up the wheel at a angle I then also angle the diamond point downward at about a 8-10 degree angle


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## Tim1974 (May 15, 2021)

Yes no need for angles with that set up the use of angle is more for surface grinder you angle it so it’s behind the wheel incase you dig in it don’t jam up if I make sene


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## johwen (May 15, 2021)

Hi Brian, Nice set up to  dress the grinding wheel for any future grinding. But why go to all this trouble to make piston rings when following the "Trimble" method in "SIC" will generate perfectly round rings every time. The big wide rings you are using will if not perfectly round will take ages to run in because of the larger surface area.
In an auto engine the ring width to bore diameter is significantly narrower and bed in quickly. In my case I halve the width as determined using the "Trimble" formula and fit two rings with the gap at 180 degrees apart in each grooves. A couple of revolutions of the crank by hand and I get full compression after first run.
I machine the rings to .001 over bore size split the rings on a tapered mandrill and heat treat in the crucible as per the "Trimble" dimensions, and then gap the rings according to bore size. Hope this helps Brian. John Samphier


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## Brian Rupnow (May 15, 2021)

Johwen---I have been a complete failure at making my own rings. I have tried more than once and not had any success.  In 40 engines I have built, I have never made a set of cast iron rings that worked, only used Viton, which gives instant compression. I have two engines running with purchased cast iron rings and they work fine. The third set of purchased rings as used on my Vertical i.c.-2021 don't seal worth a damn, although it runs fine with a Viton ring on it. I've decided that the next big milestone for me is to master ring making, so I've spent a bit of money for the grinder and heat treat oven.


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## Tom Watson (May 16, 2021)

Has anyone tried to make "Dykes" rings?


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## Brian Rupnow (May 16, 2021)

I have purchased two sets of rings in the past. One set was for a 1" bore engine, and one set was for a 1.25" bore engine. They both worked "right out of the box" with good compression and both engines ran fine. The third set of rings I purchased for my current vertical i.c.-2021 engine didn't work---. Absolutely no compression in an engine that ran just fine with a Viton elastomeric ring. I don't do compression tests other than "can I feel it when turning the engine by hand". I don't do leak down tests.  The only other tool I have at my disposal is a fitting that screws into the sparkplug hole and lets me put air pressure into the cylinder with the piston at top dead center on the power stroke. That lets me diagnose the intake valve, the exhaust valve, and the rings. In all of the forty engines I have built, the rings are the only thing that I have not mastered. I've spent about a thousand dollars in the last three weeks, buying equipment to let me know that my "process" in ring making doesn't have some flaw. I keep hearing from others who make rings and have no trouble with them, and I certainly hope that I will come up with a repeatable process for making 1" diameter rings that hold compression.---Brian


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## dsage (May 16, 2021)

Maybe it's your cylinder.? Honing (with a brake hone etc) won't correct an out of round cylinder. It may even make it worse.
I know you said you tried the light trick using the mask etc. But it's a very tricky process with a very bright point source of light where you try to aim the light at the cylinder/ring interface while moving it and your head around as if you're trying to bounce the light around the ring - so to speak.


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## Brian Rupnow (May 16, 2021)

dsage--You could be right. I found that holding the cylinder up to a bright light and looking for gaps between the ring and the cylinder to be very difficult. That engine runs great with a Viton ring, but a Viton ring is probably more forgiving than cast iron rings. I reached the point of not knowing what to do (that happens more often than you would think). I decided to just walk away from it for a while and concentrate on getting a toolpost grinder and a small heat treat oven to help me make better rings for future engines. The rings I'm currently using are purchased rings, and I made a new piston to suit the rings. Once I get my new equipment all up and running I will revisit the issue. Might make a new cylinder. Don't really know quite yet.


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## minh-thanh (May 16, 2021)

Brian !
There is a way - make a ringless piston fit the cylinder: If the engine has no compression (or little compression) -> your cylinder has a problem


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## Badhippie (May 17, 2021)

Brian
Going back through the post I seen were you stated you had honed the cylinder smooth so you could run orings. Is it possible you have taken out all the crosshatch and the bore is to smooth you will never seat rings if the bore is to smooth. Maybe it’s time to look at all the basics first. Your cylinder would have to be way out of round before it would loose enough compression not to start. But if there is no crosshatching on the bore it can be a total lose of compression. And when you added oil to the cylinder it would seal the combustion chamber and of course give you compression. Just making you think of some other things 
Thanks 
Tom


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## Steamchick (May 17, 2021)

Sorry Brian, I am trying to teach an expert here, but I guess you have blued the piston, slid it through the cylinder and checked contact? Then, assuming the cylinder is OK,  I would blue the bore and try rings to see contact points...?
I have never done this but it seems like a good idea.... ?
I have blued valve seats and valves....but I assume you have already eliminated valve leaks?
Have you tried soapy water around the cylinder head joint when spinning the engine? - I had a 2 stroke motorcycle twin that blew the gasket under full load (made a load squeak!), because the studs didn't have enough pre-tension. Increasing the torque 10% over the book value cured that! I also experienced an engine where the head was tightened onto a casting flaw, preventing the load being applied to the head gasket. Soapy water found that!
Enjoy "the Search for the lost compression".
K2


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## Tim1974 (May 17, 2021)

Run in oil is a biggy too


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## Gordon (May 17, 2021)

Brian:
If you think that your cylinder is out of round perhaps you should try to lap it. A lap will make it round and if result is that the bore is oversize you can make rings to fit.


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## Steamchick (May 18, 2021)

I remember as a teenager in the machine shop there was a Delapina Hone (American possibly?) with expanding mandrel(s) for lapping small bores. Used (by me) for sizing small ends on car con-rods after fitting new bushes (Bronze, made and fitted by me). I learned a lot working there. My father made his lap (I still use it) from a piece of broom handle (hard-wood) with a groove, springs, and 1/4" square stone slip fitted. His standard bore was 1". I remember talking to him about whether it would taper the bore, and as he was only taking the finest polish lap he explained "possibly, but not measurably, by him". It was a prototype, as he planned a mild steel version with setting screws to set the stone parallel, and for progressing the cut. But that did not become necessary.
Before I inherited that lap, I used a piece of wood dowel with layers of paper taped-on, using grinding paste on the top layer of paper, or with the top layer being 1000 grade wet and dry paper (oiled). With the paper very tight, you can increase the cut by adding a single layer of paper (+0.002" radius?) if not adequate pressure at the first attempt. It takes a lot of care and fiddle to get the cylinder fitted onto the lap, but remember, you should only be taking the peaks off the bore machining, not actually removing metal in any measurable amount. The finest grinding paste I have used (on brass cylinders) is toothpaste. ALWAYS thoroughly clean all bores after lapping. (And after they have written long texts like this one!). I think the paper lap may have "belled" the ends of the bores slightly, but I couldn't measure anything. The piston just didn't feel so tight a sliding fit at the ends... But I had the same effect when using a bought sprung lap. As a teenager, on car bores, with a tolerance of 0.001" max total variance, care was always taken to prevent any taper or belling of the ends. (DTI measured 0.0001" intervals. most bores were within 0.0004~5" variance measured in about 10 places anyway. Compared to typically 0.004" wear (or more!) on bores before we did the re-bore, it was good enough).
I am sure Brian can make a good lap anyway.
K2


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## Brian Rupnow (May 21, 2021)

It's time to pursue cast iron rings that seal properly again. I've just dropped about $1100 on a toolpost grinder and a heat treat oven and controller, and have them set up to work the way they are supposed to. They were bought solely for the consistency they would give  to my ring making process. People on all three forums on which I post have suggested that my cylinders might not be perfectly round.--this would be one good reason that a flexible Viton o-ring will seal perfectly but cast iron rings will not.---I don't really believe that, but there is always a chance that I am wrong. All of my cylinders are made by drilling, then reaming, then honing to remove machining marks. Sometimes I lap them with brass laps, sometimes I don't. Since I still have the two rings I bought from Debolt, (Which I assume to be correct) mounted on a piston especially made for them, I guess my next trick will be to make a new cylinder and bore it to 0.005" undersize (not ream) and then lap it with one of my Acrolaps to a perfect 1" diameter, and see if the Debolt rings and dedicated piston will give a good seal in it.


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## DKGrimm (May 21, 2021)

Looking forward to your report, Brian.

Don


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## Charles Lamont (May 21, 2021)

Lapping out 0.005" on diameter is a lot. Such a large lapping allowance increases the risk of getting the bore 'bell-mouthed'. I would aim for boring no more than 0.002" undersize.


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## Brian Rupnow (May 21, 2021)

Okay Charles---.002 undersize.


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## Brian Rupnow (May 21, 2021)

Tomorrow I get to play detective.---if I do any work. The weather here today was just magnificent, 84 F and sunny. I spent the day mowing lawns, trimming lawns, and helping good wife put bands of adhesive around all of our deciduous trees. We are infested by Gypsy Moth caterpillars this spring, and if they can climb the trees they eat off all the leaves and can kill them. The caterpillars are very small, about 1/16" long and they spin webs. Nasty!!!    I will pull the cylinder off the Vertical 2021 engine and check the cylinder bore for roundness using "snap" gauges that are spring loaded---they expand inside the bore, get locked in place, and then are taken out and measured with a micrometer. This will tell me if there is any  "out of round" condition in the cylinder. I will visually check the cylinder bore to see if anything weird is going on inside the bore. Then I will visually inspect the rings to see if there are any noticeable difference in "wear patterns" on the surface of the rings. I know that the ring grooves in my piston are cut deep enough---if they weren't the piston with rings on it wouldn't fit into the cylinder. I know that the rings aren't sealing because with a couple of squirts of oil down the sparkplug hole there is lots of compression---without the oil, there is none. If I don't see anything wrong, I will make a second cylinder and see how the piston seals in it.


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## Charles Lamont (May 22, 2021)

I question the need, in our little engines, to hone a cross-hatch pattern in the bore. Some on this forum seem to assume it is necessary, but I would ask if they have any evidence. Looking through the classic books, Westbury mentions lapping but I have not seen mention of honing. Stride says hone lightly "if desired" "just to polish off any marks" but says it should not be needed if boring was done with a sharp tool and slow feed. Mason makes a passing reference to lapping, but is otherwise mute.


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## Steamchick (May 22, 2021)

If you think of brake cylinders on cars, they are ground and highly polished (smooth) and very similar size to the cylinders in question. But designed for zero leakage with slow motion, oil lubricated, and elastomeric seals at much higher pressure than our models. However my Father used on and converted it to a steam cylinder, with just a machined and polished cast iron piston. Very successful.
On infernal combustion engines, back in the 1960s, many engines ran long after the cross-hatching had worn off. But on car engines today, with steel wire rings, better manufacture, lower tangential ring pressure, better lubrication and clean air and oil, the cross-hatching can last up to 100,000 miles... There is no doubt in car engines cross hatching is necessary for lubrication, to prevent wear, but if your do tiny amounts of running - compared to the hours in a car - then probably unnecessary. But if the engine is hauling kids around the 5in park track every weekend, you will probably benefit from this extra process.
K2


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## Makin chips (May 22, 2021)

I have to agree with Steamchick. Honing gets rid of the ridges left by boring. Look at a bored or turned surface under a microscope, looks like a fine thread. Honing or lapping will take all the sharpness off the high points or smooth them completely if enough material is removed. Depending on how course the stones or lapping compound is there will still be hills and valleys but a perfectly polished bore for an IC engine IMO leaves no room for oil to hide. I believe honing gives you a better surface for the rings to ride on (yes with a good crosshatch). Lapping can be just as effective but I would shy away from diamond compound as the cast iron we use for sleeves is soft and the diamond will impregnate in and not be able to be effectively cleaned out. I use silicon carbide compound when lapping with good results. Just my $.02 good luck on your quest Brian.


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## Steamchick (May 22, 2021)

The intention of good honing, is to remove sufficient off  the peaks of the machining to provide a non-wearing bearing surface, but not too much. A Doctor of tribology explained to me (if I've  remembered correctly?) that too little flattening of the peaks means the oil film has excessive pressure, breaks down and Wear (running-in) occurs. The swarf dirties the oil and wears other bearing surfaces. Too much flattening of the peaks leaves larger surface area of oil, which is under low stress so maintains the oil film, but there is an excess of the film in shear, causing higher shear stress on the oil than necessary, heating it more and wasting power from the fuel. The correct honing, (about half the depth of the valleys) is a compromise that is the best between all the various factors. Hones should be fine enough that they do not cut fresh metal, but naturally stop cutting when the right amount (whatever that is!) of material has been removed from the peaks of the machining. I.E. too fine a stone will do insufficient honing, too coarse will cut the bore away from circular.
When I was a teenager, we had coarse stones to cut the glaze, on glazed bores, then fine stones (whatever grit I don't know) for finishing, or honing machined bores. The boring bar tool had a sharpish edge for boring the cast iron bores, but with maybe a 0.5 mm radius (about the same as the feed-rate of the boring bar?) to a relief behind the cutting point of just a few degrees. It was sharpened in a jig. But not by me.
I doubt that this helps much, but it is what I was taught by specialists, in both machining and tribology. 
Ken


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## johwen (May 23, 2021)

If the ring is not sealing the gas pressure goes between the cylinder bore and the ring face and can hold the ring away from the bore and hence prevent correct sealing. The ring needs to seal very quickly and then combustion pressure behind the ring will facilitate early full sealing. The Trimble method of making rings is fool proof if one follows the formula as presented in machining and heat treating. When the ring is compressed to the bore it conforms to a perfect circle and has worked every time for myself You just have to be patient and not rush the process but be strict tithe the formula for the ring dimension's. John


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## Aerostar55 (May 24, 2021)

I've made replacement rings for a couple of model airplane two strokes as well as my 1" bore four stroke.  Used the method in Vincent Gingery's book "building the Atkinson Cycle Engine"  in addition I referred to Strictly IC magazine's article by George Trimble which helped, although I did not use the heat treating cup.  Cast iron rings will take a few runs to "wear in" properly, or seat.  You can see the piston and to it's right is a fixture I use to hold an individual ring for finishing in the lathe.


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## Brian Rupnow (May 25, 2021)

Well Sir, Well Sir--I just got a surprise----It might even be a good surprise. I have the two rings I purchased from Debolt installed on a new piston made especially to suit these rings in my Vertical 2021 engine. I couldn't get it to fire. I drove it with an electric motor for 1 1/2 hours hoping to seat the rings. Nothing worked. It had absolutely no compression. I've been busy buying and setting up a heat treat oven and a toolpost grinder, and just today got back to this compressionless engine. I unbolted it from the test bench in my garage, brought it into my office to do some detective work, and as soon as I removed the cylinder head it became apparent that the head gasket was broken and a piece of it was missing.  HUH!!! I put my big fat thumb over the top of the cylinder and turned the engine over by hand, and their is lots of compression and suction. so---First order of things is to make a new head gasket, reassemble the engine, and try to start it again.


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## Aerostar55 (May 25, 2021)

Brian Rupnow said:


> Well Sir, Well Sir--I just got a surprise----It might even be a good surprise. I have the two rings I purchased from Debolt installed on a new piston made especially to suit these rings in my Vertical 2021 engine. I couldn't get it to fire. I drove it with an electric motor for 1 1/2 hours hoping to seat the rings. Nothing worked. It had absolutely no compression. I've been busy buying and setting up a heat treat oven and a toolpost grinder, and just today got back to this compressionless engine. I unbolted it from the test bench in my garage, brought it into my office to do some detective work, and as soon as I removed the cylinder head it became apparent that the head gasket was broken and a piece of it was missing.  HUH!!! I put my big fat thumb over the top of the cylinder and turned the engine over by hand, and their is lots of compression and suction. so---First order of things is to make a new head gasket, reassemble the engine, and try to start it again.


Glad you found the problem.  I have used DeBolt rings on my "Midget" engine succesfully.  An easy way to make a gasket for the head is to use some Permatex high temp RTV silicone.  It's orange/red in color but it works well.   You can pick it up at any local auto parts store for about $6.00 per tube, which should last for alot of
 engines!
*High Temp. RTV Silicone Sealant, -65 to 650°F Temp. Range, Full Cure 24 hr, Red, 3 oz*


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## Gordon (May 25, 2021)

A couple of years ago I bought a Silhouette Portrait cutter/plotter and it works great for these small engines.  

Something else for Brian to buy.


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## Brian Rupnow (May 25, 2021)

Nothing is as simple as it seems. The only reason the piston was pushing or sucking on my thumb was because of the oil I had squirted down the sparkplug hole on an earlier test. So, the rings aren't sealing after all. I made a new head gasket, but that's not really where the problem lies. I have pulled the cylinder off and measured it with telescoping gauges and a micrometer, and the top bore taken two places at 90 degrees measures 1.003" and one at 1.004". The bottom measurement taken at two places at 90 degrees apart is the same. I am going to stick my neck out and say that a difference of 0.001" means that the cylinder has not "worn oval shaped". the inside of the cylinder looks fine when held up to a light. After I eat some lunch, I will pull the piston off the con rod and see what wear patterns are on the rings.


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## Gordon (May 25, 2021)

Take the head off and cover the top of the cylinder with your hand and see what kind of pressure/suction you have. If you have suction it means that the rings are OK so the problem is in the valves or the head. Valves can be tricky little rascals.


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## Brian Rupnow (May 25, 2021)

I'm not sure that it shows up in this picture or not, but there is a very uneven wear pattern on the Debolt piston rings. Some areas are shiny and you can tell they have been in contact with the cylinder wall. Other parts of the ring are still grey/black and you can tell they have not been making contact with the cylinder at all.  Now I have to use my secret weapon. None of you have seen this at all, but this piece of tooling was first brought up by Ted Hansen in a 2018 copy of the home Shop Machinist. Its use is to bring the outer diameter of a ring into perfect roundness.


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## mayhugh1 (May 25, 2021)

Brian Rupnow said:


> Nothing is as simple as it seems. The only reason the piston was pushing or sucking on my thumb was because of the oil I had squirted down the sparkplug hole on an earlier test. So, the rings aren't sealing after all. I made a new head gasket, but that's not really where the problem lies. I have pulled the cylinder off and measured it with telescoping gauges and a micrometer, and the top bore taken two places at 90 degrees measures 1.003" and one at 1.004". The bottom measurement taken at two places at 90 degrees apart is the same. I am going to stick my neck out and say that a difference of 0.001" means that the cylinder has not "worn oval shaped". the inside of the cylinder looks fine when held up to a light. After I eat some lunch, I will pull the piston off the con rod and see what wear patterns are on the rings.


Brian,
A thousandth is the limit of the measuring capability of a snap gage. You really need a dial bore gage for these measurements, and a cheap imported one is good enough. But, if your measurements are correct and you haven't made a typo in your post, you've found your problem. Your 1" commercial rings are designed to work in a 1.000" bore and not in a 1.003" bore and certainly not in one that in addition is out of round by another whopping thousandth. Your Debolt rings are showing uneven wear patterns because they expanded to an out-of-round condition because your cylinder is much too large. When talking about cast iron piston rings you need to be thinking in tenths and not in thousandths. Also, if the pistons don't show compression immediately upon assembly, no amount of 'running them in' is going to fix the problem, and you risk damaging the cylinder and/or the rings. 

When I machine rings, my biggest problem is turning the ring blanks with the proper i.d.'s and near perfect circularity. Less than half the material remains stable and within a couple tenths for days after being machined and before the rings are parted off. In my experience, three tenths out of round will cause a ring to fail my light test and are discarded. 
As far as cylinders are concerned, mine are typically steel, fairly beefy, and once lapped are within a tenth and stable over time. Since your lapped cylinder is so far out of round, it may be a measurement problem. - Terry


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## Brian Rupnow (May 25, 2021)

This is the first ring after 20 full "strokes" of the fixture using 400 grit compound with the lathe turning at 60 rpm and 20 full strokes with the lathe running a 60 rpm with 600 grit paste. All of the wear surfaces on the o.d. of the ring have taken on a uniform color and wear appearance.


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## Brian Rupnow (May 25, 2021)

Terry---Really??? I'm getting lost in this stuff.  I have always used Viton rings, and they are very forgiving of bore diameters. I'm doing my best here to come up with a workable solution to making my own cast iron rings, but I'm not having any luck. It's easy enough for me to make a new cylinder with an exact 1.000" bore. I never thought that a difference  of .002 or .003" of cylinder diameter would have such a negative effect on the way the cast iron rings work. I'm running out of tricks and I'm still unable to get an engine to run using rings purchased from Debolt.  I'm not going to badmouth Debolt rings, because I have used them on a couple of other engines and they worked fine. I'm doing something wrong and I don't know what. Any help you can give me would certainly be appreciated. No one else in this part of Ontario builds small engines, so when things don't go well for me, I have no one I can ask about it.---Brian Rupnow


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## mayhugh1 (May 25, 2021)

Brian Rupnow said:


> Terry---Really??? I'm getting lost in this stuff.  I have always used Viton rings, and they are very forgiving of bore diameters. I'm doing my best here to come up with a workable solution to making my own cast iron rings, but I'm not having any luck. It's easy enough for me to make a new cylinder with an exact 1.000" bore. I never thought that a difference  of .002 or .003" of cylinder diameter would have such a negative effect on the way the cast iron rings work. I'm running out of tricks and I'm still unable to get an engine to run using rings purchased from Debolt.  I'm not going to badmouth Debolt rings, because I have used them on a couple of other engines and they worked fine. I'm doing something wrong and I don't know what. Any help you can give me would certainly be appreciated. No one else in this part of Ontario builds small engines, so when things don't go well for me, I have no one I can ask about it.---Brian Rupnow


My first suggestion is to make a new cylinder that is lapped exactly 1.000" in diameter and use your Debolt rings that haven't yet been modified. I'd also invest in an import dial bore gage so you can be sure of your cylinder's i.d. and circularity.

If you've already modified them in any way, then I'd consider them scrap and a lesson learned. Then I suggest you follow the time and science proven Trimble method to make your own and make no changes to his process or his fixture. You won't need the toolpost grinder but the oven will allow you to properly heat treat them. When turning blanks for the rings make sure to mike them in two orthogonal directions to be sure they're round to within a tenth or two. Don't be surprised if only a small portion of the blank will pass this circularity test. Allow the blanks to rest a few days before parting in order to verify they're still circular. After parting, follow the Trimble process. Make a light test fixture using a high intensity led flashlight and, before installing the rings, make sure they pass the light test in a dark room. Don't be surprised if a few more end up discarded. 

I find it easier to make my rings match my cylinders which always end up a thou or two oversize because I build multi-cylinder engines and lapping 4 or 12 cylinders to exactly the same size usually doesn't allow me to hit a specific diameter target. So, every engine I build winds up needing its batch of rings, and I end up with plenty of leftovers that will never be used in another engine. In your case, most of your engines are single or two cylinders and usually the same diameter. If you can really hit your 1.000" bores, then you can make a lifetime batch of rings in one setting with little more effort than needed to do a couple for just one engine.

You can look back on my builds for the Offy, Knucklehead, Merlin or any of the radials. I went into a lot if detail on my ring making process including the issues with getting good ring blanks. Since I too was learning along the way, my last build, the Offy, is probably my best reference.

Don't run the rings in with an external power source. If you don't have compression, disassemble the engine and figure out why. If the rings are at fault (most likely they're not if you followed the above) you stand the chance if damaging the cylinder wall.

That's my two cents
Terry


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## Gordon (May 25, 2021)

mayhugh1 said:


> My first suggestion is to make a new cylinder that is lapped exactly 1.000" in diameter and use your Debolt rings that haven't yet been modified. I'd also invest in an import dial bore gage so you can be sure of your cylinder's i.d. and circularity.
> 
> If you've already modified them in any way, then I'd consider them scrap and a lesson learned. Then I suggest you follow the time and science proven Trimble method to make your own and make no changes to his process or his fixture. You won't need the toolpost grinder but the oven will allow you to properly heat treat them. When turning blanks for the rings make sure to mike them in two orthogonal directions to be sure they're round to within a tenth or two. Don't be surprised if only a small portion of the blank will pass this circularity test. Allow the blanks to rest a few days before parting in order to verify they're still circular. After parting, follow the Trimble process. Make a light test fixture using a high intensity led flashlight and, before installing the rings, make sure they pass the light test in a dark room. Don't be surprised if a few more end up discarded.
> 
> ...


Can you give us a brief rundown on the process and steps you use in boring a cylinder and holding it round within .0005. That is a degree of precision I have never attained but like Brian I do not have nearby experts but I am willing to learn.


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## mayhugh1 (May 25, 2021)

Gordon said:


> Can you give us a brief rundown on the process and steps you use in boring a cylinder and holding it round within .0005. That is a degree of precision I have never attained but like Brian I do not have nearby experts but I am willing to learn.


I lap the last couple thousandths with a barrel lap. - Terry


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## Nerd1000 (May 26, 2021)

Gordon said:


> Can you give us a brief rundown on the process and steps you use in boring a cylinder and holding it round within .0005. That is a degree of precision I have never attained but like Brian I do not have nearby experts but I am willing to learn.


With care you can get a bore within 0.001" of the target diameter using only the boring bar, no lapping required. But that's not a big deal on a single cylinder, you just get within 0.005" and make the piston and rings to match. Boring bars naturally cut a true circular bore (taper is another matter, make sure your lathe is in good condition and well aligned) subject to the circularity of your headstock bearings. My lathe uses wheel bearings from a truck, which should have at most 0.0002" deviation from circularity. Far better than I can measure.


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## goldstar31 (May 26, 2021)

Nerd1000 said:


> Boring bars naturally cut a true circular bore (taper is another matter, make sure your lathe is in good condition and well aligned) subject to the circularity of your headstock bearings. My lathe uses wheel bearings from a truck, which should have at most 0.0002" deviation from circularity.



I'm not 'into piston rings etc' but  I've successfully  bored the parallel 1" bores that form the base bars of the Quorn tool and cutter grinder. Theoretically there are THREE sets and are 3.5" apart.

There are TWO in line boring bars and provided the lathe is  true, there is no question that ALL three bores will be of equal size and truly parallel.  If the tail stock is 'out'. the bores wull ALL be oversize but will  still remain  truly parallel and concentric to one another.

The priciple is explained in Geo Thomas's Model Engineer's Workshop Manual.

He asserted that he could  finish his boring to a greater finish that could be obtained by using reamers etc.
The book was written to suggest that today's carbide tools and the then high speed  steel actally produced inferior finish to that produced using the age old carbon steel tooling properly tempered and honed.

Worth a read- my opinion of course

Norman


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## Tim1974 (May 26, 2021)

All and I mean all rings need to bed in it’s a fact ! But I’m following with interest Brian the right oil can be the secret? Maybe I’m learning too of course but you do need a break in oil that I’m shore .


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## Steamchick (May 26, 2021)

Much like the final linishing and barrelling rig I saw in the H & G ring factory. At the end of each return stroke, the cylinder was roared something like 20 or 30 degrees.... it was mounted on a pivoting frame  - like an oscillating engine - and the linear motion generated by a crank, as in the real engine. The idea being that the changing forces from the crank would simiulate the tiny oscillation of the piston rotating on the gudgeon pin (piston-pin for the West Atlantic tribe). The tiny oscillation forces "barrel" the surface of the rings, so the "spherical linishing" ensures a full line contact of the ring as the piston oscillates. Otherwise this needs a running-in to develop naturally in the engine. Steel wire rings are formed using die rollers that imbibe the shape to the outside surface of the ring without the need for the "barrelling" process. I think in the USA there is a company "Perfect Circle" who make steel wire piston rings?
Well done Richard for finding the ovality in the bore. 
K2


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## Steamchick (May 26, 2021)

Tim, the Running-in oil is generally very rich in detergents, to aid cleaning and clearing microscopic swarf from the bearing surfaces,
 It still has good lubricity, like any other lubricant, but has a lower shear strength, so is the opposite of EP Gear oil (EP = extreme pressure). The "LP" sort of grade permits the microscopic contacts of running-in that knock-off high spots a bit easier than normal oil would permit by a break-down of the oil film. It should be replaced with proper lubricating oil after a relatively short running-in period.
Never use Molybdenum during running-in. This excellent anti-scuffing compound should be used to slow further wear after the first normal oil change period, not before.
Hope this helps?
K2


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## Harglo (May 26, 2021)

Brian Rupnow said:


> Nothing is as simple as it seems. The only reason the piston was pushing or sucking on my thumb was because of the oil I had squirted down the sparkplug hole on an earlier test. So, the rings aren't sealing after all. I made a new head gasket, but that's not really where the problem lies. I have pulled the cylinder off and measured it with telescoping gauges and a micrometer, and the top bore taken two places at 90 degrees measures 1.003" and one at 1.004". The bottom measurement taken at two places at 90 degrees apart is the same. I am going to stick my neck out and say that a difference of 0.001" means that the cylinder has not "worn oval shaped". the inside of the cylinder looks fine when held up to a light. After I eat some lunch, I will pull the piston off the con rod and see what wear patterns are on the rings.


Brian
I can't tell form the material list. What is the honing jig cly made of? If its not hard during the honing  which will wear in the cly or the ring?
Harvey


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## minh-thanh (May 26, 2021)

Before, I wasn't sure if my cylinder was good enough  , so I made a ringless piston and used it, if the engine runs well then my cylinder is fine, and vice versa the cylinder is not good enough
just my thoughts, if the engine runs well with a ringless piston it will eliminate other possible causes of the cylinder:  whatever shape
   Anyway making a round piston is not too difficult and it is much faster than making a new cylinder
   And one more thing worth paying attention to: the bottom surface of the groove, it contributes to sealing .


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## Gordon (May 26, 2021)

Brian Rupnow said:


> This is the first ring after 20 full "strokes" of the fixture using 400 grit compound with the lathe turning at 60 rpm and 20 full strokes with the lathe running a 60 rpm with 600 grit paste. All of the wear surfaces on the o.d. of the ring have taken on a uniform color and wear appearance.


I am confused about this fixture. The drawing says the ring should float between the two discs. Then you say that you ran the lathe at 60 RPM. If the rings are not retained in the fixture they are going to turn with the outer sleeve and just wear the sides of the rings. The rings are going to be no better than the outer sleeve ID and once you start moving the sleeve is going to wear and soon be oversize. If it is just moving laterally it is no different than putting the rings on the piston and moving it back an forth in the engine cylinder.


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## Brian Rupnow (May 26, 2021)

Mayhugh1-You said that you make your cylinders out of steel. What material do you make your rings and pistons from?  Hot rolled steel is about 1/4 the price of cast iron, but I have never used it for a cylinder. I have always used cast iron, but would gladly change to hot rolled steel is it does a good job and there are no unusual friction or wear problems.---Brian Rupnow


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## Brian Rupnow (May 26, 2021)

Gordon--I don't know if the rings turn inside the fixture during lapping or not. I never used this tool before. I only made it two days ago. I'm thinking it probably does turn a bit, based on the beautiful matt finish on the rings o.d. after the lapping tool is used.----Brian


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## Brian Rupnow (May 26, 2021)

I must admit to being totally flummoxed. Lapping the o.d. of the rings with my newly made tool has given a beautiful finish to the outside diameter of the rings. They STILL don't seal in the cylinder. The i.d. of the cylinder looks perfect. The rings look perfect. The piston was made deliberately 0.002" smaller in diameter than the nominal 1.000" cylinder bore. The cylinder actually mikes at 1.003" to 1.004" inside diameter. In a worst case scenario, the piston may be 0.005" smaller than the cylinder bore. I could deliberately make a new piston that was lapped into the bore and needed no rings at all, but this entire exercise is about successfully making rings. I truly am at the point where I don't know what to do next.----Brian


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## doc1955 (May 26, 2021)

I mentioned a way of checking for out of roundness. A very simple way is take your cylinder put it in  afour jaw chuck on the lathe. Clamp it only enough to hold it your not machining it only using lathe as a gauging device. Now try dialing the bore in with a dial indicator it will show you out of roundness but remember lightly clamp just to hold cylinder. If you can dial it in then all is good if not it will show how far you are away from being perfect. Snap gauges are only as good as your feel and takes a lot of practice and what brand snap gauges you have. Plus a snap gauge will measure a bore dia bigger than it really is (for me) usually about .0002-.0005 bigger than it really is on a 1 inch bore. The larger the bore is the more the measurement will be off also.


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## Steamchick (May 26, 2021)

Hi Brian, this is just an idea - not proven - but when I was an apprentice, I was taught that the Delapena Hone we had - that I used for con-rod small end bearings - could only make a round hole, not elliptical or multi-faceted. Therefore I would suggest a "rigid" hone. The Delapena machine could turn on 10ths of thou cut form the stone, as it had mandrels of many sizes and used a tapered shaft to expand the stones. So it could not make an ellipse or other shape, which spring-loaded stones would do.
Use of a reamer, or so I was taught, would make a multi-faceted hole, with the number of facets equal to the number of cutting edges plus 1. Although I can't recall anyone else ever saying this, I believe it is true "mathematically".  So don't use a reamer.
Having eliminated spring loaded hones, and reamers, you have broaching (who has a broach when you need one?), or "proper" honing with a "rigid" set stone arrangement. Is it possible that the cylinder was squeezed when clamped for boring? Or maybe it got hot and was distorted when bored? (Therefore out-of-true when cooled?).
What is the hardest wood (or aluminium?) you have in 1" diameter? Machine a slot and insert a fine stone slip (1/4" square or smaller? - maybe 3/16"?). Shim it to be EXACTLY the size you want (1.0032"?)and use as a hone - then shim with another fag paper (or the foil from the inside of the fag packet?) and repeat - until you get to the 1.004" you require? Remember it will be "grinding" on the corners, not the flat face. The hone should be between centres, with the cylinder worked axially to give the diamond cross hatch.
But I am sure you know this - or did it already? - But someone else may not have tried this.
Regards,
K2


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## Steamchick (May 26, 2021)

Hi doc1955: I didn't know bore gauges gave larger bores than measured... I thought they had small radius ball ends to accommodate the bore curvature? - Or maybe I misunderstood your info? - I use inside callipers myself, although I bought some "spring-loaded lockable" bore gauges, I still just use the inside callipers.... set to the bore, then compared to a mic. - Never had a problem that I know about.
Cheers.
K2


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## doc1955 (May 26, 2021)

Steamchick said:


> Hi doc1955: I didn't know bore gauges gave larger bores than measured... I thought they had small radius ball ends to accommodate the bore curvature? - Or maybe I misunderstood your info? - I use inside callipers myself, although I bought some "spring-loaded lockable" bore gauges, I still just use the inside callipers.... set to the bore, then compared to a mic. - Never had a problem that I know about.
> Cheers.
> K2


I think its the spring pressure and vers size of bore not the curvature of ends of the snap gauge. checking for out of roundness using a lathe is quite simple though. I have inside mic for small bores I use occasionally.


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## Brian Rupnow (May 26, 2021)

Snap gauges are only as good as the "feel" the user develops from using them. I don't have any other device here for gauging bores. I have just checked out some bore gauges on Ebay that will have the range to measure a 1" diameter hole, and the cheapest is about $75 USA money which translates to $100 Canadian money plus shipping. I've blown my budget on the heat treat oven and controller and toolpost grinder.


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## Steamchick (May 26, 2021)

Nerd1000 said:


> With care you can get a bore within 0.001" of the target diameter using only the boring bar, no lapping required. But that's not a big deal on a single cylinder, you just get within 0.005" and make the piston and rings to match. Boring bars naturally cut a true circular bore (taper is another matter, make sure your lathe is in good condition and well aligned) subject to the circularity of your headstock bearings. My lathe uses wheel bearings from a truck, which should have at most 0.0002" deviation from circularity. Far better than I can measure.


Not sure about your comment on taper... but maybe you have the work-piece in the chuck and the boring bar in the tail-stock or something?
GEOMETRICALLY - and professionally in all the factories and machine shops I have seen... the correct way (that everyone uses) is to fix the cylinder, and traverse the rotating boring bar through the bore, along the axis required. In fact I use a boring bar in my mill-drill, and NOT the lathe for boring. I bore vertically down through the cylinder... Then fit a hone and hone on the same centre.
But when I have needed a proper bore on the lathe, the work-piece is mounted on a fixture on the saddle, then the boring bar (between centres) rotates and the work-piece traversed past the rotating tool. That way guarantees a round bore - and no taper... And I can still fit a hone instead of the boring bar, so I hone on the same centre. Remember - Geometrically: you should "Describe a circle with the tool then traverse axially".
But maybe not everyone knows this?
Incidentally, the lapping/honing is necessary (in the professional world) to get the correct surface finish for durability, longlevity, lubrication and low friction while providing a suitable surface for good gas tight sealing.

N.B. If there are any professional machinists or toolmakers (which I am NOT!) who can correct my errors, I seriously would appreciate your advice. I may have been doing it the wrong way all my life? - I am human, not a machine. Toolmakers taught me a lot in my work....
Cheers!
K2


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## minh-thanh (May 26, 2021)

Brian Rupnow said:


> I truly am at the point where I don't know what to do next.----Brian


Hi Brian !
Put it aside, don't think about it, 1-2 days later, check everything again !


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## L98fiero (May 26, 2021)

Steamchick said:


> Use of a reamer, or so I was taught, would make a multi-faceted hole, with the number of facets equal to the number of cutting edges plus 1. Although I can't recall anyone else ever saying this, I believe it is true "mathematically".  So don't use a reamer.


That used to be true but at least better quality reamers don't have evenly spaced flutes and that eliminates the problem.


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## L98fiero (May 26, 2021)

Brian, check your messages


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## mayhugh1 (May 26, 2021)

Brian Rupnow said:


> Mayhugh1-You said that you make your cylinders out of steel. What material do you make your rings and pistons from?  Hot rolled steel is about 1/4 the price of cast iron, but I have never used it for a cylinder. I have always used cast iron, but would gladly change to hot rolled steel is it does a good job and there are no unusual friction or wear problems.---Brian Rupnow


Brian,
I made the cylinders for my radials out of 12L14 and then had them hot-blued. The rest of my cylinders were usually made from Stressproof (1144). I usually make my pistons from 6061 but sometimes from 7075 depending upon what I have laying around. 
Be careful, don't head down another rabbit hole on advice from others who don't have actual hands-on experience with ring making for model IC engines. Terry


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## Brian Rupnow (May 26, 2021)

Terry--That is the biggest problem with taking advice from the internet. It's not that people deliberately mislead you, It's just that there is too much advice on how to do something from people who have never done it themselves.---Brian


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## werowance (May 26, 2021)

Brian Rupnow said:


> Snap gauges are only as good as the "feel" the user develops from using them. I don't have any other device here for gauging bores. I have just checked out some bore gauges on Ebay that will have the range to measure a 1" diameter hole, and the cheapest is about $75 USA money which translates to $100 Canadian money plus shipping. I've blown my budget on the heat treat oven and controller and toolpost grinder.


Brian, would a set of gauges like this picture work?  i just googled for the image.  i have a set like this that was given to me that i will never ever use. the wood chest they came in was pretty much destroyed when it was given to me,  water damage and abuse.  but the gauges must be stainless or something because they did not rust.  and they were individually wraped.  looked like most had never been used.  at anyrate if you think something like this would help you can have them for the shipping cost.  and ill send a picture first along with the guage sizes of course.  there are more of them that this stock photo i googled for shows.


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## Brian Rupnow (May 26, 2021)

Werowance--thanks for the kind offer, but those are go/no go gauges. They are used when trying to make a hole between specified lower and upper limits. My engines are all 1" bore, so I don't think you would have gauges that reach that range.---Brian


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## Brian Rupnow (May 26, 2021)

--I thought that a ring .062" wide as purchased was too wide. Everything I have read about it (And I have read a lot) suggests making the ring  1/30 to 1/25 of the bore size. With a 1" diameter bore, that comes out to a ring 0.033" wide to 0.040" wide. My reading material also suggests that a ring which is square in cross-section is proportionally correct. I purchased these rings from Debolt and then machined a piston to match the rings, with a ring gap 0.063" wide x 0.055" deep. (The rings are 0.051" thick). I paid $50 for two rings, so I haven't been rushing to throw them away, but I think I've just about ran out of things to do to make them work. I'm more or less "lost in space" now. I could make another cylinder with an exact 1.000" bore and see if that worked with the existing piston and rings. I could make new rings and a new piston to suit  my cylinder "as is". I know I could make a new oversize piston and lap it into the existing cylinder and not use any rings, but the whole point of this exercise is to make my own cast iron rings with my own equipment.---Brian


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## Nerd1000 (May 26, 2021)

Steamchick said:


> Not sure about your comment on taper... but maybe you have the work-piece in the chuck and the boring bar in the tail-stock or something?
> GEOMETRICALLY - and professionally in all the factories and machine shops I have seen... the correct way (that everyone uses) is to fix the cylinder, and traverse the rotating boring bar through the bore, along the axis required. In fact I use a boring bar in my mill-drill, and NOT the lathe for boring. I bore vertically down through the cylinder... Then fit a hone and hone on the same centre.
> But when I have needed a proper bore on the lathe, the work-piece is mounted on a fixture on the saddle, then the boring bar (between centres) rotates and the work-piece traversed past the rotating tool. That way guarantees a round bore - and no taper... And I can still fit a hone instead of the boring bar, so I hone on the same centre. Remember - Geometrically: you should "Describe a circle with the tool then traverse axially".
> But maybe not everyone knows this?
> ...


I put the cylinder in the chuck and the boring bar is mounted to the lathe toolpost. To my knowledge this is the usual way of boring on a lathe? Anyway, it's 100% possible for my way to make a tapered bore:

Firstly too greedy of a cut can 'spring' the bar leading to a tapered bore. You can clean this up with spring passes but it is a trap for the unwary (such as me). Secondly, any twist or wear in the lathe bed will cause taper, just the same as when OD turning. This is a constant problem for me because my floor shifts whenever the temperature or humidity changes, I have to re-level the lathe every time I use it.


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## Nerd1000 (May 26, 2021)

Brian Rupnow said:


> --I thought that a ring .062" wide as purchased was too wide. Everything I have read about it (And I have read a lot) suggests making the ring  1/30 to 1/25 of the bore size. With a 1" diameter bore, that comes out to a ring 0.033" wide to 0.040" wide. My reading material also suggests that a ring which is square in cross-section is proportionally correct. I purchased these rings from Debolt and then machined a piston to match the rings, with a ring gap 0.063" wide x 0.055" deep. (The rings are 0.051" thick). I paid $50 for two rings, so I haven't been rushing to throw them away, but I think I've just about ran out of things to do to make them work. I'm more or less "lost in space" now. I could make another cylinder with an exact 1.000" bore and see if that worked with the existing piston and rings. I could make new rings and a new piston to suit  my cylinder "as is". I know I could make a new oversize piston and lap it into the existing cylinder and not use any rings, but the whole point of this exercise is to make my own cast iron rings with my own equipment.---Brian


Given all your struggles, I think you should control as many variables as you can. Probably a good idea to make a new cylinder (bored rather than reamed), piston and rings. Then just change one thing at a time (be that your ring making technique, the ring dimensions, bore surface finish, etc) and keep track of what changes result.


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## minh-thanh (May 27, 2021)

Brian !
If I remember correctly, you have an engine that runs with rings, right?
if correct, measure and compare between 2 cylinders, if the figures are the same with very little error: you can be confident that your cylinders are ok
And just focus on rings. I don't think the rings will bother you
The way I make the rings is based on the information on the forum
with my tests in comment 86 : With a slightly small piston - it's a piston that is too small and I wouldn't accept when making an engine and with a ring that is not in full contact with the cylinder - that ring I won't use - unless I only have one (I usually make more rings than I need : i need 8 , i will make 15 , 18... ) : and they're fine
About the ringless piston: it's just one way I test the cylinder before, if the engine runs well with the cylinder and  ringless  piston I can be confident it can run with the ring and I just focus on the ring - of course Of course that's just the way I think and do
I haven't made 1 inch large diameter rings yet, hope you don't mind my comments


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## ranger (May 27, 2021)

Is it possible with your toolpost grinder setup, to internally grind the cylinder bore, avoiding the ‘spring’ of a boring bar, and producing a decent finish? Then maybe a few strokes with a hone to finish off.


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## minh-thanh (May 27, 2021)

Hi All !
This is the tool I usually use
It helps to keep the temperature relatively uniform between the inside and outside of the ring when firing
That's just the way I usually do it , hope it helps , or just an idea for you to improve...


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## johwen (May 27, 2021)

Hi Brian,
first of all a couple of thou in Bore variation won't matter at all in the sealing of the ring. As I see it from your photos it appears to me that the ring is too wide for a one inch bore  and the other question how thick is the ring because if it is too thick it will not be flexible enough to seal with behind the ring pressure from compression or combustion. Now that you have the ring groove machined I would turn up two rings half the width but to the section as described by Trimble Turn the rings one thou oversize split on a tapered mandrel  and gap to correct clearance and heat treat in enclosed cup as per Trimble using the correct gap spacer. Lap the edges of the ring to achieve correct side clearance don't lap the OD of the ring just use the fine turned surface  for easy sealing in the bore. The important aspect of the ring is the  ratio of the thickness to the width and bore diameter Put two rings in the wider groove with the gaps 180 degree apart.
The other important issue is in the heat treatment Take the time to make up the heating cup as per the Trimble and make a dozen rings fore one inch bore for your next engines But before closing the cup wrap some clean white pare around the rings filling the gap so when the whole unit is heated the paper burns using all the oxygen in the space so that the ring surfaces do not oxidize, the rings come out blue. It is important not to oxidize the metal as this could easily change the surface of the ring in reference to circularity Hope this helps Brian


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## dsage (May 27, 2021)

Brian Rupnow said:


> The cylinder actually mikes at 1.003" to 1.004" inside diameter.



If your cylinder measurement is accurate at 1.004 and your rings are still meant for a 1" cylinder then that's your problem.  A 1" ring will not be round when it has to expand to 1.004.
But who knows where you are now if you have also worn the rings.
As Mayhugh1 suggested - and now that you have the equipment - you need to start over.
Make a new test cylinder and follow the Trimble method exactly for the rings.
Make the test cylinder first to completion including a VERY LIGHT honing. Measure it a dozen times if you have to and then make the rings to suit it.

Do not use any of your existing pieces (including the purchased rings). At this point they are all suspect.

BTW. If you want to test your "feel" for snap gauges. Find yourself a large bearing and measure the inside diameter. They are dead accurate. Repeat the measurement of that until you get a feel for what it takes to get the right measurement.


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## Brian Rupnow (May 27, 2021)

Today I will try a new trick. Conventional wisdom says that a cast iron piston should be 0.002" less than the cylinder bore. Conventional wisdom also says that the piston rings will take care of sealing that .002" diameter difference between the piston and cylinder. I am going to work from the assumption that my new piston, grooved for my purchased rings is perfect. I am going to assume that my purchased rings are perfect. I will make a new cast iron cylinder with a bored hole of 0.996" then use the new 0.998" diameter piston (with the rings removed) to lap the hole in the cylinder to as perfect an air-tight fit as I can get. Then I will put the rings back on the cylinder and fly with that. That is what I did on my vertical hit and miss engine, and it has wicked compression.


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## Steamchick (May 27, 2021)

Brian Rupnow said:


> Terry--That is the biggest problem with taking advice from the internet. It's not that people deliberately mislead you, It's just that there is too much advice on how to do something from people who have never done it themselves.---Brian


I am one of those Brian, so please consider my advice with a "total lack of experience"!
Do you have a large bucket of salt to hand?
K2


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## Brian Rupnow (May 27, 2021)

On two previous engines I have used purchased cast iron rings. They both performed very well. I am at a loss why this engine has no compression when dry, and by dry I mean no pool of oil setting on top of the piston. I have just looked in detail at both previous engines where the purchased rings worked fine, and in both cases I see that I lapped the cylinder with the piston which was to be used in the engine, then added the rings to the piston afterwards. On this current engine where I am having so much difficulty, the piston was deliberately machined to 0.002" less than the cylinder bore. On my engine "Thumper" I made a note to myself saying that even though I had used the piston to lap the final cylinder bore, it wasn't a tight enough fit to run without the rings. There is a lesson for me there. Even though I have read in numerous places that the piston should be 0.002" smaller than the cylinder bore, that doesn't work for me. I just paid $32 for another piece of cast iron 2 1/2" diameter x 4" long to make a new cylinder. I will bore it to almost final size, then use my new piston to lap the bore to final size.


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## mayhugh1 (May 27, 2021)

The 1.000" rings need to be used in a 1.000" cylinder bore in order to seal properly. If you do the math to compute the leak created by a .999" ring in a 1.000" bore and then compare that with the leak created by a .004" ring gap in a properly fitted ring/piston/bore, you'll find the leak created by the poorly fitting ring is 400 times greater than that of the ring gap.

 If your previous 'successful' rings were used in a cast iron cylinder on a cast iron piston that was lapped for a very close fit inside the bore, then the rings probably weren't actually doing anything for you since the sealing was between the piston and the bore. 

Aluminum pistons, however, need to be a couple thousandths smaller than the cylinder bore because the aluminum will expand faster than the bore and wind up seized inside it. The cast iron rings on them though still need to be the same diameter as the bore but they need a tiny gap to prevent them from being broken by differential expansion between them and the cylinder. The top rings will always expand more than the much more massive cylinders. - Terry


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## Brian Rupnow (May 27, 2021)

Terry--Everything you have said makes sense. I am currently making a new cast iron cylinder and hoping to use my new rings and piston in it. I have removed the rings from the piston until I finish the bore on my new cylinder. I currently have a new piece of cast iron up in my lathe and am closing in on the correct diameter bore. I currently have the bore down very close to that last 0.001" of diameter, and am proceeding with great caution not to overbore it. I will complete the new cylinder tomorrow morning. How much clearance to you recommend on a cast iron piston in a cast iron cylinder?---Brian


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## mayhugh1 (May 27, 2021)

Brian Rupnow said:


> Terry--Everything you have said makes sense. I am currently making a new cast iron cylinder and hoping to use my new rings and piston in it. I have removed the rings from the piston until I finish the bore on my new cylinder. I currently have a new piece of cast iron up in my lathe and am closing in on the correct diameter bore. I currently have the bore down very close to that last 0.001" of diameter, and am proceeding with great caution not to overbore it. I will complete the new cylinder tomorrow morning. How much clearance to you recommend on a cast iron piston in a cast iron cylinder?---Brian


I assume you're lapping that new bore to its final diameter. I've never used a cast iron piston in a cast iron bore, but I assume the same clearance as used for an aluminum piston would be just fine. - Terry


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## Steamchick (May 28, 2021)

I ran a 3/4cc diesel model for a few minutes before it "ran-in" and "wore-out". It had a cast iron piston in a cast iron bore at sliding clearances. - as Brian's lapped piston. The piston will get hotter and expand more than the cylinder, but at model sizes (1"dia.), less difference that you can probably measure. If too tight it may tighten a bit, but rarely seize, but a good lap will make it the right size. (less than 0.001"?). But 2 good laps will make it too big. 
Or so I was taught in the 1960s, when we still had some engines to re-bore that had cast iron pistons. It was my job to hone the bores "size-on-size" to the pistons, after cleaning any surface rust staining from the piston with 400~1000 grade emery. It isn't aluminium so doesn't expand enough to "fit when hot" to need such big clearances - it will just slap loudly....
But I have only experience of a few small infernal combustion model engines...
K2


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## Gordon (May 28, 2021)

I find this discussion interesting and confusing. Some folks are insisting that everything MUST be held within .0005. Obviously if that were strictly true many of the folks here would never get a running engine. Many are working in a home shop with old or less than precision equipment and their only means of measuring things are a dial caliper and seat of their pants. Some are saying that the the ring must be a minimum width and other say that is not important. Others say the the thickness of the ring must be absolute minimum not more than the width and others say it does not matter. Some are saying that the finish on the side and bottom of the ring groove must be highly polished and very precise and others are having success with less than precise operations. Obviously most of us are working with less than ideal equipment using manual machining and not a lab quality shop. Looking at engines built by some of the old timers like Rudy, Elmer etc. using old worn equipment in a small shop it is interesting how successful they were. 

I am not criticizing any of the folks contributing here but obviously ring making theory is not an exact science. There are articles and videos showing successful results using everything from very crude to super precision.  

Gordon


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## leerkracht (May 28, 2021)

Finally 

all you need to know about  piston rings



			https://www.ms-motorservice.com.tr/fileadmin/media/MAM/PDF_Assets/Piston-Rings-for-Combustion-Engines_53094.pdf
		


all you need to know about  cast iron   > stres relieving and temp range 



			Sec. 7 Introduction
		


the engines I designed and made are two  12 cylinder engines bore 24 mm with overhead camshafts 

two radial engines   7cil and 9 cil   al works fine 

the rings are made the Trimble way    nodulair cast iron GGG 40  (meehanite ) ring section  1x1mm 
cast iron GGG40 liner    min 24 mm  max 24.02mm nominal    lapping  toolmarks free  not honing  , my opinion is you dont need the croshatch pattern  (injection pumps have also no pattern and are very smooth )  under a magnifying glass you can see small spaces between the nodulair molecules and this is where the oil can settle
0.02mm taper for the cilinder boring is no problem  (smal dimension on top ) some modelengines have a taper boring for max rpm and power due less friction at the end of the power stroke  
rings are 0 to 0.02 mm greater than cilinder  bore   cut by an 0.2mm thick sawblade  > ring clamped in a fixture  not a vise 
als mentioned  section 1x1mm  ( for 24mm to 26 mm bore )   thicknes 1mm+0.02mm   for flat lapping  in a ring holder  on a flat plate  grinding pasta 600 grid 
 heat treatment in a closed cylinder fixture(for ring gap of 2.5mm )(see article George Trimble) 800 ° C ) 
when the ring is closed in the cilinder boring you notice that the ring gap is almost 0mm due to material growth  Now you can check with backlight whether the ring fully touches the bore. (most of the time  95% of the rings are good ) bring the ring gap to 0.1mm to 0.2mm  for oil blow by if you need  
modern cars also have low section rings (and low tension also for less friction)

The japanese manufacturer  of model OS engines>> OS rings for four stroke engines (bore 24mm are 0.2mm gap wenn new )

pistons are 7075 T6     dimention 23.95mm (better are high silicone pistons) groove with = ring +0.02 mm (not a sloppy fit )
these  combination works for me   ( i run mine on methanol  and 4% Klotz oil )
thats for now 
enjoy
video 12 cilinder 






7cilinder radial parts


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## Brian Rupnow (May 28, 2021)

So here we have it---Old cylinder in background, new cylinder, and piston acting as a final lap. Bore was brought to "almost" with Acrolap and 600 grit paste, then final bit was done with 600 grit paste and using the piston as a lap. For first stage of lapping, acrolap was held in lathe chuck and cylinder was held in my hand. For second stage of lapping cylinder was held in lathe chuck, and T handle of piston was held in my hand. This can be very, very "grabby"--You have to know when to let go of the handle. Twice it grabbed so bad that I had to let go and shut the lathe off and take piston and cylinder out to my arbor press and use a short length of wooden dowel to press the stuck piston out of the cylinder. Definitely not for the faint of heart!!!


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## Gordon (May 28, 2021)

Brian Rupnow said:


> Today I will try a new trick. Conventional wisdom says that a cast iron piston should be 0.002" less than the cylinder bore. Conventional wisdom also says that the piston rings will take care of sealing that .002" diameter difference between the piston and cylinder. I am going to work from the assumption that my new piston, grooved for my purchased rings is perfect. I am going to assume that my purchased rings are perfect. I will make a new cast iron cylinder with a bored hole of 0.996" then use the new 0.998" diameter piston (with the rings removed) to lap the hole in the cylinder to as perfect an air-tight fit as I can get. Then I will put the rings back on the cylinder and fly with that. That is what I did on my vertical hit and miss engine, and it has wicked compression.


How do you get a .998 dia piston in a .996 hole to use the piston as a lapp?


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## Brian Rupnow (May 28, 2021)

Very Carefully!!


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## mu38&Bg# (May 28, 2021)

leerkracht has done his homework. There just isn't anything to add.


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## minh-thanh (May 28, 2021)

Brian Rupnow said:


> So here we have it---Old cylinder in background, new cylinder, and piston acting as a final lap. Bore was brought to "almost" with Acrolap and 600 grit paste, then final bit was done with 600 grit paste and using the piston as a lap. For first stage of lapping, acrolap was held in lathe chuck and cylinder was held in my hand. For second stage of lapping cylinder was held in lathe chuck, and T handle of piston was held in my hand. This can be very, very "grabby"--You have to know when to let go of the handle. Twice it grabbed so bad that I had to let go and shut the lathe off and take piston and cylinder out to my arbor press and use a short length of wooden dowel to press the stuck piston out of the cylinder. Definitely not for the faint of heart!!!



I have the same tool to lap the cylinder and piston when make  Glow plug engine , It is really .....
So I made some improvements for safety, at least for my hands  
And of course , I only make small diameter cylinders ( < 19 mm )
I don't know if it's ok with 1 inch cylinder !!??
If you or someone else is interested, I'll redraw it (because I didn't do that engine for a while, so I changed the tool for something else).


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## Brian Rupnow (May 28, 2021)

Every time I use a T handle tool like that, it scares me right to death.---And every time I swear that I am going to make a nice round handwheel with no projections on it to wind me up in the lathe. I haven't made the handwheel yet, but I haven't got wound up in my lathe either. I actually have a better tool than that cobbled up connecting rod and cross handle, but I searched high and low for it today and couldn't find it. Best advice I can give is "Kids, don't try this at home!!!"


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## jack620 (May 28, 2021)

mayhugh1 said:


> Aluminum pistons, however, need to be a couple thousandths smaller than the cylinder bore because the aluminum will expand faster than the bore and wind up seized inside it.



And doesn't that prove that the fit of the piston in the cylinder isn't terribly critical for a piston with rings? Because if it was, a cold aluminium piston wouldn't develop enough compression to start the engine.



Gordon said:


> Some folks are insisting that everything MUST be held within .0005. Obviously if that were strictly true many of the folks here would never get a running engine.



True. And my clapped out old lawnmower would be impossible to start. And yet it does start, despite offering little resistance to the pull cord and developing little power.


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## jack620 (May 28, 2021)

Brian Rupnow said:


> Every time I use a T handle tool like that, it scares me right to death.



Brian, a VFD will solve that problem. When the speed is very slow, the torque is low enough that you can stop the lathe with your hands. You would have absolutely no trouble stopping my lathe with your T handle.


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## Brian Rupnow (May 28, 2021)

Jack620--the problem with that is that it takes a LOT of torque to make the lapping work. I'm a big strong old guy, and it takes everything I have to hold that T handle so it doesn't turn. If I was a better machinist, I would take more metal out of the bore before I tried to lap it, but I find that there is only a wink between leaving enough metal in the bore for lapping and having the piston fall through the bore.


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## jack620 (May 28, 2021)

Fair enough Brian. I haven’t tried lapping a big piston.



Brian Rupnow said:


> but I find that there is only a wink between leaving enough metal in the bore for lapping and having the piston fall through the bore.



which confirms my thinking that the fit of the piston isn’t critical for a piston with rings. There are thousands of engines being mass produced every day without lapped pistons.


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## leerkracht (May 29, 2021)

Hello 

ring fixture for annealing and  attach the ring  to the piston 

lapping fixture  cast iron GGG40   diameter  0.2mm  less  than cilinder  , lapping paste grid 600  thinned with petrol   >  paste 600 between lap and cilinder wall   you only remove 0.02 mm   less than 0.001 inch  start with little pressure and 200rpm  slowly as the pressure decreases increase it 
Make sure there is sufficient paste that is diluted, turn the cylinder regularly by 180° and pay attention to parallelism. 

succes


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## Tim1974 (May 29, 2021)

2 thow interference fit come on check you mic that’s rubbish! That’s a very tight press fit on a 1 inch bore ! Your not laping faith that fit no way


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## leerkracht (May 29, 2021)

Hello
for  dimentions see reply 227

0.02 mm is the amount that are removed from the cilinder wall ,for a good surface  round and cilindrical  boring >> not the interference fit

by the way an ABC cilinder piston(wihtout ring)  unit has a negative fit in the top of the cilinder , the fit is correct wen the engine is  on temperature


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## Brian Rupnow (May 29, 2021)

The news is positive. With new cast iron cylinder, piston, and rings, the engine has high (to coin a new word) Suckability!!! It fired, it ran for three short blasts, but I'm having head gasket issues. The aluminum head has a ring of material that fits down into the top of the cylinder about 0.060". Or, let me rephrase that--It is supposed to extend down into the cylinder about 0.060" minus the 0.030" thickness of the head gasket. A close examination of the cylinder head shows that that ring of material is "hanging up" on the inside of the bore and not letting the head bolts tighten the cylinder down evenly all the way around. I'm going to set the cylinder head up on the lathe and trim a tiny bit off that diameter that is giving me problems.


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## Brian Rupnow (May 30, 2021)

I'm having a no work Sunday---I need it. But the old brain cells keep clicking away. Every thing I read about rings recommends that the ring thickness should be  1/30 to 1/25 of the cylinder bore (and the depth of the ring can match the width so your ring actually has a square cross section). On a 1" bore, that gives a ring width of 0.033" to 0.040". The width of the groove in the piston should be 0.001" greater than the width of the ring itself. So---If I made my rings 0.038" wide, then the groove in the piston should be 0.039"---And 1 millimeter is .0394". Okay, cool!!! Now, where do I buy a 1 mm wide grooving tool? I have googled this and still have no clear answer. I can turn a lathe tool for general purpose turning from HSS, but I don't trust myself to be able to make a 1 mm wide grooving tool. I don't want to spend a zillion bucks on this either. My lathe has a 12" swing, and it has a quick change toolpost on it. I prefer 3/8" square tooling, but in a pinch I can mount 1/2" square tooling.  I'm not averse to using inserted carbide if the price for the carbide and the appropriate holder don't break the bank. Since the piston groove will be in cast iron or aluminum, I could even work with  1mm wide HSS and a 3/8" square shank.---Thanks.---Brian


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## Gordon (May 30, 2021)

Brian Rupnow said:


> I'm having a no work Sunday---I need it. But the old brain cells keep clicking away. Every thing I read about rings recommends that the ring thickness should be  1/30 to 1/25 of the cylinder bore (and the depth of the ring can match the width so your ring actually has a square cross section). On a 1" bore, that gives a ring width of 0.033" to 0.040". The width of the groove in the piston should be 0.001" greater than the width of the ring itself. So---If I made my rings 0.038" wide, then the groove in the piston should be 0.039"---And 1 millimeter is .0394". Okay, cool!!! Now, where do I buy a 1 mm wide grooving tool? I have googled this and still have no clear answer. I can turn a lathe tool for general purpose turning from HSS, but I don't trust myself to be able to make a 1 mm wide grooving tool. I don't want to spend a zillion bucks on this either. My lathe has a 12" swing, and it has a quick change toolpost on it. I prefer 3/8" square tooling, but in a pinch I can mount 1/2" square tooling.  I'm not averse to using inserted carbide if the price for the carbide and the appropriate holder don't break the bank. Since the piston groove will be in cast iron or aluminum, I could even work with  1mm wide HSS and a 3/8" square shank.---Thanks.---Brian


>.040 cut off blades are fairly common. Another alternative is to use your new tool post grinder to grind down a wider blade like grind 1/16 wide blade to .040 on the end. You only need a short piece on the end ground down.






						HHIP 2000-6008 P1N Cut-Off Blade: Amazon.com: Industrial & Scientific
					

HHIP 2000-6008 P1N Cut-Off Blade: Amazon.com: Industrial & Scientific



					smile.amazon.com


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## kuhncw (May 30, 2021)

Brian,  

AR Warner sell high speed steel 0.031 inch grooving inserts, along with 0.015 and 0.062 widths.  You can buy a kit with holder or individual inserts.

Chuck

Kit #21 3/8 inch Cutoff Groover Right Hand


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## Ghosty (May 30, 2021)

Brian, This is what I use, 1mm groove cutter for circlips, will go to a depth of 2mm(80 thou)
Cheers
Andrew


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## Nerd1000 (May 31, 2021)

Just grind one from a HSS blank, it's easier than you'd think. I started my 0.8mm grooving tool by hacking a chunk out of the side of a 1/4" HSS blank using an angle grinder with a cutoff disc. Then I ground the sides, you don't have to keep them parallel so long as they get narrower as you move back from the point and are relieved towards the bottom. You can leave the end of the HSS blank alone as it is already square and relieved. Once I got close I got my micrometer and started doing very light touches on each side, followed by a check with the mic across the tip. Finally once it was on size I honed the tip sharp. No need for rake or anything, just leave it flat.

Alternatively, as you have a toolpost grinder and are using cast iron pistons, why not mount a 1mm cutoff wheel for a 5" grinder and grind your grooves in?


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## Harglo (May 31, 2021)

Brian
Ive run into this piston grove cutting tool think. I hand grind it as close as can than cut the piston grove FIRST  then make the ring height to fit even if its a thou or two on way or another. Its just seems easer to adjust the ring height than changing the piston grove 
Harvey


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## Gordon (May 31, 2021)

I have always had a problem getting the groove to the correct depth. I have used the dial on the cross feed and when I put the ring in the groove and try to put the piston in the cylinder it will not go in because the groove is not deep enough. When the groove is only .030 to .040 wide it is hard to measure. The only thing I have which will fit in that narrow groove is the depth end of my dial calipers and I cannot get the same reading twice. I do have a depth mic and I may have to sacrifice that by grinding down the end so that it will fit in the groove. 

What do others use?

Gordon


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## L98fiero (May 31, 2021)

Gordon said:


> I have always had a problem getting the groove to the correct depth. I have used the dial on the cross feed and when I put the ring in the groove and try to put the piston in the cylinder it will not go in because the groove is not deep enough. When the groove is only .030 to .040 wide it is hard to measure. The only thing I have which will fit in that narrow groove is the depth end of my dial calipers and I cannot get the same reading twice. I do have a depth mic and I may have to sacrifice that by grinding down the end so that it will fit in the groove.
> 
> What do others use?
> 
> Gordon


Measure across the largest feeler gauge you can fit in the groove and piston with a caliper or mike and subtract the width of the blade and the piston should give the depth of the groove. Obviously the closer the feeler gauge is to perpendicular to the axis of the piston, the more accurate the result will be.


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## Gordon (May 31, 2021)

L98fiero said:


> Measure across the largest feeler gauge you can fit in the groove and piston with a caliper or mike and subtract the width of the blade and the piston should give the depth of the groove. Obviously the closer the feeler gauge is to perpendicular to the axis of the piston, the more accurate the result will be.


This got me to thinking and I looked online and found digital depth gage and I have a narrow probe that fits on the end of a dial indicator. If I make a sleeve to fit on the shoulder of the indicator I can just let the probe stick out of the end of the sleeve I can place it on a flat surface, zero it out and read the depth on the indicator. Just never really looked for a good alternative. Again "Too soon old and too late smart"

Gordon


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## Steamchick (May 31, 2021)

jack620 said:


> Fair enough Brian. I haven’t tried lapping a big piston.
> 
> 
> 
> which confirms my thinking that the fit of the piston isn’t critical for a piston with rings. There are thousands of engines being mass produced every day without lapped pistons.



Hi Tim, the piston manufacturers work to 0.0002 mm when machining, but the maching of measured pistons to bores needs better than that so the pistons and bores are measured, given size grades, and matching grades are selected on the assembly line. This applies to bores, crank journals, gudgeon pins to pistons and con-rods, rings, bearing shells to cranks, con-rods and crank-case journal mounts. A big part of the longlevity of the engine, so it can be driven from new as if it has been run-in already. And then last 100 of thousands of miles before it needs a re-bore or crank re-grind.
In the mid-1960s cars needed a re-bore at 20, 000 miles (I did dozens!), and crank re-grind at 40,000miles. In the 1970s I had a well-tuned motorcycle that wore the rings so I had compression loss after 3 ~5000 miles! Nowadays, that would be quite a low performance engine! As standard I changed the rings at 10,000 miles, to regain good compression. Poor by today's standard, but that is the same technology and machining capability achieved by our model workshops... 
It was a revolution in machining in the1970s that made engines to better tolerances, partly driven by the fuel crisis and public and national interest in economy, partly following the small wealth boom of industries that survived the 1960s, who invested in new machinery with better capability. Yet in the late 70s I worked with 4 other engineers, and we all had new Company cars, built in the same week, and with the "same" engine. Top speed varied fromantic about 90 mph indicated to nearly 110mph, and a clear difference in performance as driven, and fuel economy. - We compared then together over 12 months and 20 - 30,000 miles per car. As we were working on a job 350 miles from home we did the same commute and long trips. One was showing definite worn engine symptoms at 30,000 miles (losing some compression, and burning oil), one just seemed like new. Very variable quality! Not in the industry today.
Enjoy,
K2


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## cwelkie (May 31, 2021)

Another overlooked way to cut a (ring) groove is with a saw blade. They come in many and various thickness of numerous tooth counts. An arbour that mounts in the toolpost is straight forward such that the cutting edge can be rotated into position at the correct height.
... or give grinding one a go; it's surprising how close one can be done by hand with care and patience.
Charlie


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## cds4byu (May 31, 2021)

Brian Rupnow said:


> My lathe has a 12" swing, and it has a quick change toolpost on it. I prefer 3/8" square tooling, but in a pinch I can mount 1/2" square tooling.  I'm not averse to using inserted carbide if the price for the carbide and the appropriate holder don't break the bank. Since the piston groove will be in cast iron or aluminum, I could even work with  1mm wide HSS and a 3/8" square shank.---Thanks.---Brian



I recently figured out a setup on my Sanford surface grinder that makes it trivial to grind grooving tools.  Send me a blank, and I'll make the tool and send it back to you.  PM if interested.

Carl


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## Brian Rupnow (May 31, 2021)

Carl---I'm in Ontario, Canada. Where are you?--Brian


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## Vixen (May 31, 2021)

Hi Ghosty

Do you have the maker and part number for those grooving inserts

Thanks

Mike


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## Ghosty (May 31, 2021)

Vixen said:


> Hi Ghosty
> 
> Do you have the maker and part number for those grooving inserts
> 
> ...


Mike, I only have the holder # as I bought the cutters from a machine shop getting rid of new old stock, I bought 5 which gives me 15 cutters.


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## L98fiero (May 31, 2021)

Vixen said:


> Hi Ghosty
> Do you have the maker and part number for those grooving inserts


For one offs the Nickole inserts are probably the least expensive way, I think MSC has 1mm inserts for about $32 USD and the holders are easy to make from a piece of square stock.


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## Vixen (May 31, 2021)

Thanks, I will have a look at each of those.

Mike


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## jkimberln (May 31, 2021)

If you want Nickole inserts, buy them at Victornet.com.  Cheapest vendor I've found at  $19.50.  I have a few of these and they are not cheap anywhere but are a good product.  I used to use Thinbit but they are beyond my economic interest.


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## petertha (Jun 1, 2021)

I used a Nickole for the ring grooves on my radial pistons, mostly because I already have the toolholder set. You could just as well use self made HSS parting type tool because the depth is so shallow. I didn't make the groove width in one go. Stepping over is no big deal especially with DRO or indicator. But it provides the opportunity to creep up on dimension using a feeler gauge stack so you hit your target dimension exactly. A blade micrometer is handy in these instances, or alternately mic off a pair of parallel feeler gages or gage blocks

What is important is the cutter should have a square, sharp corner. Or re-phrased, any tool corner radius should be less than the slight chamfer you have on the ID corners of the ring such that there is no chance the ring will hang up on what would become a micro fillet in the groove. These pistons (which dimensionally mimic the top end of an OS-56) also have a slightly reduced diameter crown from piston top to ring groove. I presume that's for easier ring installation & has no adverse effect on performance.


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## KenC (Jun 1, 2021)

rklopp said:


> I have made dozens of rings from 3/4" - 1-1/4" adhering closely to the Trimble method published in Strictly IC. They work great and I don't think I have ever broken one. I parted them using a ThinBit carbide grooving tool. No toolpost grinder here.


Me too. I have made many rings sticking very closely to the Trimble method with no problems at all. I thought that it had already become the standard way of making rings. I use a 1/16" wide parting tool ground at a slight angle to part close to the right, and I break the rings using a purpose-built cleaver.


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## cds4byu (Jun 1, 2021)

Brian Rupnow said:


> Carl---I'm in Ontario, Canada. Where are you?--Brian


I'm in Utah, USA


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## Stefan-K (Jun 1, 2021)

Steamchick said:


> the piston manufacturers work to 0.0002 ????


This is  2 ten thousands of a millimeter! Are you sure about this ?? Every small temperature change, which you have several times a day will change the dimension of this piston by far more. No one in the Massproduction Industrie will manufakture to such small tolerances.


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## Brian Rupnow (Jun 1, 2021)

Time has come to cry FAIL!!!! I can not get the engine to fire, even with new piston, purchased new cast iron rings and new cast iron cylinder. Valve timing has been reset, ignition timing has been reset, carburetor has been adjusted to every possible configuration, and the engine doesn't fire. Compression feels cheesy when flywheel is turned by hand. If I squirt a bit of oil down the sparkplug hole, the engine has great compression and starts right up and runs like a trooper until the oil on top of the cylinder has burned away. Then it quits. This is purely the result of too low or no compression due to leaky piston rings and "fit" of piston in cylinder. I have monkeyed with this engine (which ran just great with a Viton o-ring) until I am sick of it. I have received a lot of interesting opinions on ring making, piston making, and state of the world in general from forum members and yes, I do read and pay heed to all of it, thank you. Later in the summer, when I have had time to digest all the new information and I'm not so burned out, I will use my new heat treat oven and toolpost grinder and make a new set of rings 0.038" wide and possibly another new piston with grooves to accept the new rings, I may try again. For now though, I'm whipped. Thank you to all of you who have followed this thread, and for the information given.----Brian


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## Gordon (Jun 1, 2021)

You have said a couple of times that your information says ring thickness should be about the same as ring width. According to Mr Trimble who some feel has the ONLY answer the width should be 1/25 to 1/30 of bore. With 1" bore that would be .040 to .033. He says that thickness should be .043 to .045 x bore which would be .043 thick. Using your .038 width for thickness of .038 according to the graph with Trimble that would make the wall pressure below 30 PSI which would give low compression. Next time perhaps try making the rings thicker. 

Lots of information out there on model rings. Read 10 articles and get 30 different opinions.

Now put it on the shelf and enjoy summer.


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## Tim Wescott (Jun 1, 2021)

Brian Rupnow said:


> Later in the summer, when I have had time to digest all the new information and I'm not so burned out, I will use my new heat treat oven and toolpost grinder and make a new set of rings 0.038" wide and possibly another new piston with grooves to accept the new rings, I may try again.



+1!  The three ways that, as an engineer, I've learned how to get through a brick wall are: (1) find a door, (2) explosives, (3) just beat your head against it until it gives up.

That last one sometimes requires that you take a break.


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## DKGrimm (Jun 1, 2021)

[QUOTE=". . . For now though, I'm whipped. Thank you to all of you who have followed this thread, and for the information given.----Brian
[/QUOTE]
I am where you are with an Atkinson differential engine.  Three sets of cylinder, pistons, and rings, and no compression, no explanation.  That's why I have been following this thread.  My plan has been 1) give it a rest and do something else for a while, and 2) come back and fix it later.  All this conversation actually helps.


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## Brian Rupnow (Jun 1, 2021)

This is a good time to ask a theoretical question. If I had a Viton ring on a piston, and shoved the piston half was down a length of cylinder, there would be no leakage at all past the Viton ring. A Viton ring seals perfectly around it's full circumference. If I stood the cylinder on end and filled the top half with Varsol or any other fluid, none of it would leak past the Viton ring---ever. That is a given. I have done that.---Now, if I take a piston with two cast iron rings on it, each ring having a 0.004" gap between the ends, and the gaps set at 180 degrees to each other, it will leak. If placed half way down a cylinder and stood on end, and if I fill the top half of the cylinder up with Varsol or some similar fluid and left overnight, some of the Varsol would leak past the rings and be puddled in the bottom half of the cylinder. Iron rings are not a perfect seal. The only reason that they work in an engine is that during a typical engine cycle, there isn't enough time for the compression to leak down past the rings. Some does--but there isn't enough time for the compression to degrade below a point where ignition is no longer possible. I ask this, because I would like to make a testing rig which would let me know if a piston and rings were "good enough" to make an engine run.-----------Why would I do that? ---Because on a real engine there is always a lot more involved in changing the rings and piston than just the cylinder bolts. All I can think of is a leak-down pressure test. Problem is, the volume of a 1" bore x 1" stroke engine is so small, it would require far better and more sensitive equipment to do a leak down pressure test than anything I currently have.---And even a leak down pressure test is only comparative. I would have to perform the test on a "good" piston and ring set to form a baseline from which I could measure the effectiveness of my own piston and rings. The ONLY way I know how to test the effectiveness of a ring and piston set, it to put it in an engine and see if the engine runs.---Any comments???


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## mayhugh1 (Jun 1, 2021)

It's normal for oil to leak past cast iron rings in an upside-down cylinder over an extended period of time. Checking a radial engine for hydrolock before starting is is s.o.p. in both model and full-size engines. I even remove the lower plugs during storage on my radials. These leaks occur through the ring gap and also between the rings and cylinder walls because without combustion, the ring's spring pressure alone isn't enough for a perfect seal.

I was confused about your last attempt. I may be wrong, but your posts seem to say you were lapping your new piston to your new cylinder and also adding store-bought rings that had received some lapping of their own in another setup. If this is all true, I don't think the rings were trustworthy because your previous lapping changed their o.d. if not their circularity. The piston should be a loose sliding in the cylinder and not a close-lapped fit. There may have been too much friction for the little engine to overcome under those conditions.

The only thing thing I can (re)suggest for a fixture to predict a ring's performance is a good light leak fixture like I've described earlier.

I was also curious about your lapping technique. I hold my cylinders in my hand and power the lap with a battery powered drill in the other hand. Lapping is intended to be a slow and easy process. I never try to take off as much at a time as you described and for me, removing a total of .002" from a bored cylinder is near the limit of my patience at the metal removal rate I use. I mentioned earlier that I lap all my cylinders as a group and only a tiny bit at a time in order for all the cylinders to arrive at the same diameter. Sometimes I overshoot a particular cylinder because I misjudged the amount I turned the screw on the lap and the lap jammed in the cylinder creating a scratch that I have to work out. Sometimes this means increasing the size of all the other cylinders as well. Are you sure you didn't damage your cylinder when you (over)powered that .002"(over) lap into the cylinder. Also, I'm not convinced your measurements are as good as you think. We don't have traceable measurement standards in our home shops, but a micrometer over a dial bore gage so you're depending on repeatability rather absolute numbers is almost as good. - Terry


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## petertha (Jun 1, 2021)

Gordon said:


> Using your .038 width for thickness of .038 according to the graph with Trimble that would make the wall pressure below 30 PSI which would give low compression. Next time perhaps try making the rings thicker.



The Trimble article says '_The first characteristic to consider is is cylinder wall pressure. When installed and operating, the ring must exert sufficient pressure against the cylinder wall by virtue of its own springiness to resist being sucked away from the wall by vacuum in the combustion chamber. It is not unusual for a 4-cycle engine to develop 10 psi suction during during intake strokes under low throttle, high rpm throttle conditions. Using a safety factor of three to allow for our ignorance with respect to uniformity of pressure exerted by a less than perfect ring in a less than perfect cylinder, we can deduce that an acceptable ring should produce at least 3x10=30 psi wall pressure_'.

Maybe I've misunderstood this issue all along, but I always assumed the Trimble 30 psi constraint curve was more about low pressure induction stroke, not high pressure power stroke. The was based on notion that combustion pressure was also acting behind the annular gap of ring & piston groove so if anything would assist sealing pressure, additive to ring wall pressure (but still no match for bad / open ring geometry). Attached screen grab from one of Terry.M's posts, possibly the 18-cyl radial. Maybe he can comment. And excerpt from PDF document leerkracht provided.

I've actually lost track of what Brian's ring dimensions ended up being. And of course trying to position his ring on the Trimble chart its complicated with some unknowns; actual bore diameter, heat set dowel diameter (equivalent) & several other factors. But anyways FWIW, here is a spreadsheet version of the Trimble calcs and corresponding plot of constraint curves. I've been re-writing it lately so if anyone spots any errors, please let me know by PM. Trimble's article referenced his own 1"bore V8 which I believe is the same bore as this subject project. So actually, no calculations were even required.

For consistency, Trimble used the word thickness (T) to mean the radial ring dimension viewing piston from top. And width (W) to be the axial dimension viewing ring from side. I've inserted the recommended T/B and D/B target & range notes from his article in the spreadsheet for quick reference, but obviously the article provides more complete basis for these values.


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## petertha (Jun 1, 2021)

Brian Rupnow said:


> Time for Ringmaking-Take2.   I am now going to make 4 more rings using the Trimble? method. I do have a 0.020" slitting saw. So---the rings will be turned to (3.142+.020)-3.142=1.006" o.d. and 0.898" inner diameter. This will give an inner diameter the same as rings I have purchased form Debolt. They will be cut to 0.063" thick. Instead of being broken, these rings will be cut using my 0.020" slitting saw. No farther work on cleaning up the i.d. nor the o.d. nor the thickness, until I have spread them individually over a 3/16" piece of steel inserted into the sawn gap and heat treated them to cherry red and then allowed them to air cool. Then they will be polished to 0.062" wide and cleaned on a sheet of emery paper on a flat surface, then positioned in the cylinder bore and if needed the gap will be filed to give a 0.004" wide gap.



I know this is going back a ways (post #57) and please don't take this criticism of what methods & effort you eventually employed. But the Trimble? (question mark) is appropriate because its just not the Trimble method on multiple fronts. I'm not saying what's right or wrong, just reading the SIC article and making the comparison.

- nowhere does Trimble mention a slitting saw. He goes into quite a bit of detail saying consistent success eluded him until he eventually settled on cleaving the rings. Basically trying to get as close to a zero width part such that the rest of the procedure & heat setting apparatus would ensue with a known reference. The only gap treatment prior to heat setting was minor clean. Basically eliminating a micro carrot of material stuck on one side of ring which originated from corresponding carrot hole on other side. The protrusion had to be levelled so the two faces aligned properly to the dowel diameter as intended.

- other folks have offered input as to how to compensate the OD if a slitting saw is uses. No comment because of many examples where it obviously works. I'm just saying it wasn't in Trimble's method. The post heat treat gap width calculation is defined in the writeup.

- the pre-heat set Trimble ring OD & ID are fully defined in his description. The OD has a very minor +tolerance but he says toss any rings that come out under bore B. The ID is a calculation result of the T/B ratio, not related to the piston or anything else. ID = OD - 2*T

- re heat set, there is an interesting chart in the article (Fig-12). It took me a while to digest it & anyone please comment if I'm misinterpreting. He is showing the effect of supporting the open ring on a rectangular spacer block as opposed to on the dowel. However the gap opening between the two setups are identical. The difference is that the ring is supported on its inner corners in the case of rectangle plate vs. resting on the ring neutral axis tangent point in case of dowel spacer. The resultant plot then shows the X-axis around the bore and Y-axis delta R (radius in inches) deviation to the bore. The rectangle spread curve deviates as much as 0.0035" from bore wall vs. the dowel based curve which he is saying is the theoretical perfectly circular curve plot (consistent radial seal). '_the dotted line shows the same data for the ring spread with a spacer as in fig 11, it has the proper curvature in two places where the dotted and solid lines cross, Everywhere else the curvature is too large or too small. Particularly disturbing is the area near the gap where the curvature is less than the cylinder curvature, There is no way for this area of the ring to touch the cylinder when installed because it is more sharply curved than the cylinder itself_. So this seemingly minor subtlety with the same effective opening results in basically a barn door sized opening relative to high pressure gas. The significance of varying the dowel diameter would be greater still, which is why he provides the  T/B vs D/B constraint chart.

Also note, the calculated dowel diameter is not actually the maximum opening for ring during heat set. I had to stare at those unfortunately teeny SIC diagrams & re-read the verbiage to realize - its the combined effect of his mandrel diameter, dowel diameter & their relative spacing on the fixture that positions the ring with the correct opening with dowel contact at the neutral axis as described above. And this fixture is intended to assist so its hard (er) to misalign ring in spread mode.


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## minh-thanh (Jun 1, 2021)

You use oil in the combustion chamber to test compression, and you have compression (I only use a little oil at the rings - very little -), so
Check everything: is it completely airtight?
Valve ? spark plugs? cylinder head...
Because can leak and with oil it gets better
With the CI ring and piston there is a bit of a leak so things get worse: too little compression,
   check the cylinder and rings with light: the cylinder and ring must be dry and clean, if they have some oil you won't be able to know if it's good enough


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## Tom Watson (Jun 2, 2021)

during my motor cycle racing days when i was young and stupid, I used Dykes rings. See attached diagram. (a am poor artist). They were a fairly low pressure on the bore, but the combustion pressure caused a much higher pressure on the back of the ring. This gave a lowering of the ring friction of the ring on the bore but the compression was  excellent. They only gave good compression while the engine was running not when pulled over  very slowly. 


 when turned over slow the compression was poor. The ring was located level with the top of the piston.
I don't know how they would work on our small diameter rings. I should try one.


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## johwen (Jun 2, 2021)

HI Brian,
As a last ditch effort. Why not follow the Trimble method to a T, and get a ring that works. From your descriptions you seem to dodge around the full method describe by Trimble. The heat treatment as described is an important part of of the construction particularly the spread of the gap too much and you end up with a ring out of round and too little and you end up with too little wall pressure. BUT MOST IMPORTANTLY DON'T GIVE UP as the Trimble method is proven and works. John


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## jack620 (Jun 2, 2021)

Steamchick said:


> the piston manufacturers work to 0.0002 mm when machining



I seriously doubt that.


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## Gordon (Jun 2, 2021)

petertha said:


> The significance of varying the dowel diameter would be greater still, which is why he provides the  T/B vs D/B constraint chart.
> 
> Also note, the calculated dowel diameter is not actually the maximum opening for ring during heat set. I had to stare at those unfortunately teeny SIC diagrams & re-read the verbiage to realize - its the combined effect of his mandrel diameter, dowel diameter & their relative spacing on the fixture that positions the ring with the correct opening with dowel contact at the neutral axis as described above. And this fixture is intended to assist so its hard (er) to misalign ring in spread mode.


Most of Trimble math and calculations are beyond my ability to understand them but I am unsure if a slight deviation in dowel size is a problem as long as the mandrel diameter and the offset are adjusted accordingly. With the small dowel as calculated it is difficult to get a pin sized to the correct diameter. For instance in his 1" bore example the dowel is .150. 5/32 is .156 and is a standard rod size. Would using the oversized dowel be a problem as long as the mandrel and offset are adjusted accordingly? A 1 1/8 bore would give a dowel of .16875. Would a 5/32 diameter be too much variation?

Gordon


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## kuhncw (Jun 2, 2021)

Gordon,  you can make the end of the dowel a common drill size to fit the hole in the flange of the mandrel and the turn the part of the dowel that contacts the rings to the calculated size.  That has been my solution. 

Chuck


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## Tim Wescott (Jun 2, 2021)

Hey Brian:

I'm not sure if this is useful, or if there's a way to make a formal test out of this, but with a model airplane engine I rotate the prop through a compression stroke and feel how long it holds compression.  It's all touchy-feely, but it's worked well for me.

I'm just going to tell you what I do, and if it's helpful you can translate this into a fixture:

For a model airplane engine, if you've got compression when you give it a good hard flip it'll start and run at full speed.  If you can rotate it through TDC at about one rotation per second without palpable loss of compression then it'll probably idle reliably.  All the engines I've owned have been lapped -- a lapped engine in really good shape will retain palpable compression at TDC for at least a second, but if it's doing that well it's just gravy.

Another good way to assess piston/cylinder seal on a model two-stroke is to make sure there's some fuel in the cylinder, then rotate the thing through TDC while watching the piston through the exhaust port (so -- definitely a two stroke thing).  You'll always see some bubbling from air leakage, but less is better and more is worse.


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## Tim Wescott (Jun 2, 2021)

Could you make a small-bore pressure gauge that just directly screws into your spark plug hole? 

Or cheat: hie thee to the nearest auto store, buy an el-cheapo tire gauge and replace the business end with something that screws into your favorite size spark plug hole.  I'm not sure of the details of what's inside of those, but it's got to be lower displacement than your 1" bore engine.

(And I'm suggesting a tire gauge on purpose because they capture the maximum reading automagically, with all the mysterious stuff that's inside them).

((Now I have to look and see how one is made)).

Even with some error due to the gauge's displacement, you should still get a comparative pressure reading.


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## DKGrimm (Jun 2, 2021)

Tim Wescott said:


> Could you make a small-bore pressure gauge that just directly screws into your spark plug hole?


I've had good luck with this homemade leak-down compression tester.  I put a regulated 40 psi on the input and measure the cylinder pressure with the gauge.  There's only a tiny hole for the air to get to the cylinder, so a compression leak will drop the cylinder pressure.  Another advantage is that you can listen to see if the leak is coming through a valve or through the crankcase via the rings.

Don


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## petertha (Jun 2, 2021)

Gordon said:


> Most of Trimble math and calculations are beyond my ability to understand them but I am unsure if a slight deviation in dowel size is a problem as long as the mandrel diameter and the offset are adjusted accordingly. With the small dowel as calculated it is difficult to get a pin sized to the correct diameter. For instance in his 1" bore example the dowel is .150. 5/32 is .156 and is a standard rod size. Would using the oversized dowel be a problem as long as the mandrel and offset are adjusted accordingly? A 1 1/8 bore would give a dowel of .16875. Would a 5/32 diameter be too much variation?



The answer to your question is found by looking at how any T/B and D/B coordinates land relative to the plot. The only math is dividing two numbers.  It might fall within the recommended guidance range, or it may push/exceed one or more of the boundaries. I happen to know that several commercial & operational rings land around the periphery of the 4 constraint curves, which I suppose is good news. To what degree, or how well they run, or reliability of measured dimensions is different discussion. But if you have to make rings from scratch & you accept the Trimble methodology, why not follow the recipe? Aim for the bullseye or consciously target an area that makes sense to your engine and/or skills?

To your second point (IMHO) if someone can produce the other 99% of a typical model engine up to and including the last but critically important bits: a finicky, thin section cast iron ring, a matching piston, both to +/- 0.0005" & appropriate finish, I just don't see how turning a 1" long straight dowel shaft to within 0.001" is a significant or time consuming challenge by comparison. The dowel seems easy by comparison. What is achieved by swapping in a different sized nominal 32nds stock at hand & making mandrel / spacing adjustments on the fly? This is just my own view but I accept there are many ways to get the job done.


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## Steamchick (Jun 2, 2021)

jack620 said:


> I seriously doubt that.


Aye, got my powers of 10 wrong there. 20micron sound better? Just figured out when typing micron, as spell check changed it to mm. - typing 0. 0 2  mm was changed to 0.0002mm! Flipping smell checker again!
Thanks for spotting that one.
K2


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## Brian Rupnow (Jun 4, 2021)

General Question--When you make rings, do you machine the outside diameter of the rings after they have been heat treated? I'm trying to get a handle on this. The Trimble method does have a final "Skimming" step where the o.d. of the rings is turned after the ring is heat treated.  I believe that many people make rings quite successfully without this final machining operation.---Brian


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## mayhugh1 (Jun 4, 2021)

Brian Rupnow said:


> General Question--When you make rings, do you machine the outside diameter of the rings after they have been heat treated? I'm trying to get a handle on this. The Trimble method does have a final "Skimming" step where the o.d. of the rings is turned after the ring is heat treated.  I believe that many people make rings quite successfully without this final machining operation.---Brian


The Trimble method doesn't use a turning operation after heat treatment. That's the whole point of his technique. You need to invest a few dollars in reprints of the original Strictly IC articles. - Terry


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## Brian Rupnow (Jun 4, 2021)

Terry-I can't find out where to buy them. Do you have a link that will get me to wherever I can buy them?---Brian


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## minh-thanh (Jun 4, 2021)

When i finish heating the ring i usually leave everything as is and put it on the lathe and clean the outside surface with sandpaper (that's one of the reasons i usually make the ring diameter bigger than the cylinder diameter 0, 3mm , although using sandpaper it changes very little ring diameter )
 I only clean the surface because I like rings with "nice surface" , I haven't done that before but they are fine


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## doc1955 (Jun 4, 2021)

Nope and I have always used the process as described in The Shop Wisdom Of Philip Duclos.
And have never had much of a problem getting them to seat and give me good compression.


LOL maybe I've just been lucky lol


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## Gordon (Jun 4, 2021)

Brian Rupnow said:


> Terry-I can't find out where to buy them. Do you have a link that will get me to wherever I can buy them?---Brian





			http://www.strictlyic.com/pit01.htm


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## Brian Rupnow (Jun 4, 2021)

Thanks Gordon--I've just sent off for the three magazine articles that cover Trimble's method of making rings in strictly I. C. Magazine in the USA.


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## awake (Jun 4, 2021)

Can anybody sum up the Trimble method in a nutshell, and likewise for the Duclos or any other methods? I'm not talking about step-by-step comparison, but is there something in particular that characterizes and distinguishes each method?


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## Brian Rupnow (Jun 4, 2021)

This video pretty well sums up the Philip Duclos method of ring making.---Brian


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## DKGrimm (Jun 4, 2021)

awake said:


> Can anybody sum up the Trimble method in a nutshell, and likewise for the Duclos or any other methods? I'm not talking about step-by-step comparison, but is there something in particular that characterizes and distinguishes each method?


A quote attributed to Albert Einstein comes to mind:  "Everything should be as simple as possible but not simpler."

I don't mean to be flippant about it, but I think there are a lot of similarities between the methods, but some critical differences in the details.


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## petertha (Jun 5, 2021)

Just for interest, I manually altered the Trimble recommended T/B, D/B, W/B factors in order to force the resultant dimensions that Duclos showed for his OD (taken to be Bore), thickness, width & dowel pin (yellow spreadsheet cells). It then superimposes on the Trimble plot like so. Not sure if I'm interpreting correctly, but it doesn't exceed cast iron max operating stress, or max installation stress. But the ring would exert 'something' below 30 psi wall pressure. To what degree I cant say. The SIC article didn't provide underlying formulas or line gradations. So the ring would provide less sealing pressure during induction stroke on that basis & I believe less total sealing pressure under additive combustion pressure. Whether that is  appropriate or acceptable to that engine is for others to speculate. The Duclos ring (axial) thickness at 0.036" is 0.014" thicker than Trimble's at 0.022". The article discusses his rationale which I wont reiterate. For comparison, last 2 screen grabs are same bore but using Trimble recommendations.

Notice that he cleaved the ring, he did not slit saw a gap. Its still not exactly apples to apples comparable to Trimble heat set jig which ensures the dowel contact is applied on the neutral axis. I'm pretty sure there is no valid way to similarly reverse plot a slit ring. Calculating the effect of a wider ring, yes, as long as it was cleaved.


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## johwen (Jun 5, 2021)

Hi Brian,
I'm sorry I did not know you had no access to Trimble articles, so having a full copy of SIC I have copied all the article and put them on 2 PDFs for you.
Hope this helps you overcome your difficulties with the rings. Frances Washburn was suppling copies but the web site is not working so maybe she is no longer able to continue. If you have any questions give me a shout. Cheers John. These files are the basic Trimble method that I follow however the full Trimble description is more detailed in many issues. J.

EDIT: The "Strictly IC" article attachments had to be deleted as they are still under copyri8tht. The "Strictly IC" website is till active. The link to the back issue order form is:


			Welcome to Strictly IC
		

Staff HMEM


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## johwen (Jun 5, 2021)

Brian Rupnow said:


> General Question--When you make rings, do you machine the outside diameter of the rings after they have been heat treated? I'm trying to get a handle on this. The Trimble method does have a final "Skimming" step where the o.d. of the rings is turned after the ring is heat treated.  I believe that many people make rings quite successfully without this final machining operation.---Brian


Brian I just turn to size one thou cover bore size just a fine turn finish then Heat treat.  The minute highs on the surface rub down and seat very quickly John


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## Skipper (Jun 5, 2021)

Brian Rupnow said:


> This video pretty well sums up the Philip Duclos method of ring making.---Brian



Great video!  What about RING GAP?  When the piston and rings get hot the ring needs some gap for thermal expansion.  WHAT DO YOU GUYS THINK?


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## Skipper (Jun 5, 2021)

johwen said:


> Hi Brian,
> I'm sorry I did not know you had no access to Trimble articles, so having a full copy of SIC I have copied all the article and put them on 2 PDFs for you.
> Hope this helps you overcome your difficulties with the rings. Frances Washburn was suppling copies but the web site is not working so maybe she is no longer able to continue. If you have any questions give me a shout. Cheers John. These files are the basic Trimble method that I follow however the full Trimble description is more detailed in many issues. J.
> 
> ...


Couldn’t open pdf file


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## Skipper (Jun 5, 2021)

What about RING GAP FOR THERMAL EXPANSION ? 0.004.


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## petertha (Jun 5, 2021)

Yes, I was looking for the Duclos (post heat treat) ring gap dimension too, didn't see that mentioned. Maybe its in the comments or another video but I didn't pursue.

And I think this illustrates the potential for likely inconsistencies of saying The Trimble Method or the The Duclos Method or The Brian Method.... There are at least a dozen or so input parameters that might indicate or define how a ring was made. So naming a method, or naming a method & omitting/altering/skipping mention of key parameters is only going to cause confusion for others down the line, seeking help & reading these posts. That's why I posted #271. And that's just discussing the ring. As others have mentioned, the ring, the bore, the piston equally factor into things.

I'm no expert in this stuff but that's really what motivated me to make a spreadsheet. Its not necessary but helps me digest & visualize things. Its too bad Trimble didn't release the underlying 'source code' & inquisitive minds today could evaluate it on its engineering basis. But I wonder how many actually would & unfortunately he is no longer around to weigh in. The SIC article (pg-4, Feb-Mar-1989) indicates he would have '_The accompanying chart and equations cover all the practical sizes and proportions and are easy to use. On the other hand, if our Editor has sufficient demand, I would be happy to furnish him with a blow-by-blow description of the mathematics and the the method solution including the HP 32S program_'. I think fair to say he did the heavy lifting, distilled it to its minimum straightforward steps & made the knowledge available. SIC was one of the key model engineering 'forums' at that time, so it is what it is.


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## dsage (Jun 5, 2021)

The first thing that struck me on the video is that he made the tube he was going to part the rings off of "a nice slip fit" inside the cylinder. Even after doing measurements to try to make it the SAME diameter as the cylinder
The rings are therefore smaller than the cylinder. A problem before he even gets going. This and many other "close enough" errors are what leads to problems.
He also did the light test without a mask to cover the central hole. The mask is a must because staring into a bright light you're never going to see tiny pin pricks or slivers of light leaking around the rings which is what you're looking for.
And yes he never mentioned the ring gap.

BTW Who the heck is Earl (the Guy this Guy is apparently following) and why should we believe Earl or this Guy.

IMHO  I would rate this video as just another one to add to the pile of sketchy ring making methods not to be followed.


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## Brian Rupnow (Jun 5, 2021)

I have just received and read thru the Trimble method of making piston rings. It is very well done, and a bit "long haired" so it will require a bit of concentration to re-read and fully understand exactly what Trimble is saying. He treats the subject "in depth" and does provide very good guidelines for making compression and oil rings for small engines. I would recommend it to anyone who has had trouble making their own rings.---Brian


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## Brian Rupnow (Jun 5, 2021)

WOO-HOOOO---I just got my second covid shot this morning. Wife and I drove to a nearby town and after they confirmed that we had our first shot in early march and that we were "essential caregivers" to my 100 year old mother they went ahead and injected both of us. Arm is not sore, no hives, no sick feeling (at least so far).


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## petertha (Jun 5, 2021)

Since this post seems to be a current collection point for ring making methods & we seem to be on a roll, I’m going to throw out some cartoon visuals of things I’ve wondered about regarding the heat setting aspect. Brian if you feel this is more appropriate in another post, I’m happy to relocate. And what follows is above my pay grade so I may be barking up the wrong tree. I’m trying to be careful here because others have constructed rings using alternative heat set methods that obviously work. Now do they work to 70% of what a Trimble ring could have yielded or 105% we will likely never know. I’m just trying to provide common starting point visuals for discussion purposes.

But if one assumes the Trimble heat method set as being the correct starting point basis for the underlying theoretical reasons he mentions, it might be interesting to visualize deviations to that. This cartoon sketch shows my takeaways from the SIC article. The ring is cleaved, not slit sawed. It is supported on a dowel pin of calculated diameter. The dowel tangent contact point occurs on the ring’s neutral axis. This arrangement is by intent & comes about by the resultant mandrel diameter, dowel diameter & center distance using his formulas. So, the reaction force aligned to neutral axis. Even heat is then applied with ring supported in this manner. The intended result is once the ring is heat set, it exerts consistent pressure radially to the bore wall along its circumference once installed in the bore.

(My visualization) if you unfolded the ring, applied heat & the reaction force to the ends it would become some slightly altered dimension once heat set. But the takeaway is that the force acts through the neutral axis while ring is hot & relaxing, so the ring strip would stay in a straight line. So theoretically this ‘matches’ a similarly unfolded bore. For reference this unfolded ring strip would be 3.14” long with rectangular section 0.043” x 0.023”. A pretty skinny, delicate stick of cast iron.


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## petertha (Jun 5, 2021)

Here I’m showing another heat set mode. Identical ring OD & thickness, but this time supported on a plate of same thickness as dowel and again evenly heated. Whether it drops off or just heated is yet another variable but let’s just say perfectly heated. It looks very similar but one could visualize the reaction forces applied at an angle, not consistent with neutral axis. The ring is allowed to relax under heat & freely adopts its new shape because its only supported on the ring corners. But visualizing as a strip, it is no longer straight, it becomes curved. Using the analogy of fitting to a similarly unfolded straight bore, it would result in unequal bore pressure. Or likely worse if it bridges across bore resulting in non-contact annulus. That’s exactly what the Trimble Fig-12 graph & description was all about as I mentioned in #271 post. His graph shows an open gap between ring & bore of ~0.003” on a 1” OD.


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## petertha (Jun 5, 2021)

Here is a circular dowel support with the ‘heat until it drops off’ method. I’m having trouble visualizing this comparatively. Maybe it was supported near the neutral axis for majority of heating? Or maybe the last point of contact was the outer ring corner which might be a variation of the plate gap example? What is probably evident is that the equivalent gap is going to be influenced by the (top view ring) thickness & dowel diameter combination. The Trimble dowel diameter is not equal to the maximum ring gap opening, its whatever it took to position the contact tangent at the neutral axis at the appropriate opening. So that’s what his fixture was about – controlling these variations.


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## petertha (Jun 5, 2021)

Lastly heat application. One can visualize if the heat s not evenly distributed across the ring while setting, the ring could take on non-uniform shape on that basis alone. I could see this particularly happening with a high heat torch in ring suspended mode where say the mid-section gets hotter than the open ends. Or maybe the gap support / plate acts as a heat sink so is colder there. Eventually the ring drops off whenever the gap has sufficiently enlarged, but that could occur prematurely (and incorrectly) with a hotter mid section.


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## petertha (Jun 5, 2021)

This is what I was visualizing regarding the unfolded heat set ring to the unfolded bore. Straight to straight is good. Curve to straight is bad. Hope this makes sense.


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## Brian Rupnow (Jun 5, 2021)

Perertha--I think your posts are right at home here. I have read thru the Trimble method about three times now, and I probably can get my head around about 80% of it. Only four things really jump out at me. #1---He uses a calculated diameter of round pin on the neutral axis of the ring as his "gag" when spreading the rings for heat treat. #2--He clamps the rings flat in a fixture for heat treating, which makes sense, because that keeps the two ends of the ring in perfect alignment whereas spreading the rings on a "gag" but not clamped flat does allow the rings to "squirm" a little bit and become misaligned. #3--He uses an expanding collet style fixture to mount the rings on one at a time to deburr the inner and outer diameter of the rings on the "blind side" which couldn't be deburred when parting off from the original parent stock. and #4--He is quite adamant about not trying to do any further work on the o.d nor on the i.d. of the ring before mounting it on the piston. To me, his rings look awful damned thin at 0.022" on a 1" piston. I could not make the 1/16" wide rings as purchased from Debolt work for me. That is probably my fault, not Debolt's.  I am buying a 1 mm (0.039") wide grooving tool to put the ring grooves into my piston, I'm going to make my new piston from aluminum, not cast iron, and my compression rings will be made 0.038" wide x 0.038" radial thickness.----Brian


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## Gordon (Jun 5, 2021)

Trimble says that the width is critical only because of the friction against the cylinder so a few.001 is not going to make a lot of difference within reason. If you make the rings.038 thick you are into the. T/B area on his diagram which makes wall pressure under 30 psi which he says is too low.


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## petertha (Jun 5, 2021)

I've wondered about this too.

Article says '_4-cycle engine to develop 10 psi suction during intake strokes under low throttle, high rpm operating conditions. Using a safety factor of three to allow for our ignorance with respect to uniformity of pressure exerted by a less than perfect ring in a less than perfect cylinder_'.

Multiplying 10 psi by 3 = 30 psi is what sets the graph constraint curve. Which btw I eyeballed off his graph to mimic. I have no idea if lower SF would look like this sketch, parallel-ish lines at 20 & 10 psi which would open up the target window. But I'm not clear if this is solely regarding induction effect - mitigating I guess reverse blow-by where you are sucking charge past the rings? Or if this is bundled with overall ring seal force. For example 30 psi resting ring pressure + 50 psi behind ring pressure = 80 psi total sealing pressure under combustion stroke. Vs say 10 + 50 = 60 psi & now maybe entering range of blowby if the combustion pressure was say 75 psi. I have no idea if these values are reasonable, just pulling numbers from my rear end. Maybe a low CR hit-n-miss this is OK but not for his V8 & similar engines which might explain variable results?


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## Brian Rupnow (Jun 5, 2021)

I think Mr. Debolt probably knows what he's doing, and he sells a ring that is 1/16" wide for a 1" piston. I have never seen a subject that brings in such widely varying answers which all seem to work---or not!!!


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## Gordon (Jun 5, 2021)

I am also just amazed. One person cuts them with a hack saw and heat treats them with a  BIC lighter and they work just fine. The next person holds everything within.0005 heats them to+/- 5* and they will not work. Moon phase or black magic?


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## Nerd1000 (Jun 6, 2021)

Gordon said:


> I am also just amazed. One person cuts them with a hack saw and heat treats them with a  BIC lighter and they work just fine. The next person holds everything within.0005 heats them to+/- 5* and they will not work. Moon phase or black magic?


Perhaps you need to make an appropriate sacrifice to the piston ring gods? I think some blood (from accidentally cutting yourself on a burr) and a brief prayer ("Ouch, darn it!") might appease them.


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## DavidLloyd2 (Jun 6, 2021)

dsage said:


> The first thing that struck me on the video is that he made the tube he was going to part the rings off of "a nice slip fit" inside the cylinder. Even after doing measurements to try to make it the SAME diameter as the cylinder
> The rings are therefore smaller than the cylinder. A problem before he even gets going. This and many other "close enough" errors are what leads to problems.
> He also did the light test without a mask to cover the central hole. The mask is a must because staring into a bright light you're never going to see tiny pin pricks or slivers of light leaking around the rings which is what you're looking for.
> And yes he never mentioned the ring gap.
> ...




I would rate this video as another rabbit hole


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## dsage (Jun 6, 2021)

**** Caution ****
I believe it is a well documented error in the Trimble article that he got the temperature wrong for the heat treating.
He had it too high.
Do some further research and others can comment here. I won't quote a temperature here for fear of getting it wrong.
Terry:
Maybe you can quote the proper figure. Or link back to where you have already quoted it.
I know that the proper (lower) temperature amounts to a very dull red glow of the fixture in a dimly lit room. Very evenly applied, preferably using a furnace over a period of time.
Brian:
Please get this corrected temperature figure before you proceed. And post it here to make this complete.


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## Nerd1000 (Jun 6, 2021)

Random thought: two compression rings is standard nowadays, but prior to the 1950s it was pretty common for engines to have three due to the inferior precision of manufacturing in those days causing poorer sealing. 

Would it be worth adding a third ring if you're having compression problems?


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## mu38&Bg# (Jun 6, 2021)

Why not go with 7 or 10 rings? Production model aircraft engines have had _one_ ring for a very long time. Cylinders and rings have to be made correctly to seal. Adding more parts that don't seal won't help.


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## Gordon (Jun 6, 2021)

If I remember correctly, not a given, only one of the three rings was a compression ring. One was to lubricate the cylinder wall, one was to seal the oil in the crankcase from getting into the combustion chamber and one was for compression. The only justification for more compression rings is the chance that one of them would work properly.


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## petertha (Jun 6, 2021)

Trimble used 2 compression rings and 1 oil control ring on his SIC article V8 but I don't recall reading his justification for 2 vs 1. He discusses his testing results & requirements for oil control ring, but likely had a lot to do with his pumped/distributed oil lubrication system.


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## minh-thanh (Jun 6, 2021)

Brian!
Maybe you'll hate me - Again, Cylinder
   You already have a cylinder (not just one)
Make the engine run with ringless pistons (make aluminum pistons because aluminum is easy to work with)
   If the engine has no compression,  lap that cylinder and make a new aluminum piston
  With a little of my experience , the cylinder is the most important and the hardest part - which of course everyone knows .
  So first you have to make sure your cylinders are good enough, otherwise you buy rings or you make rings they are also hard to compress.


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## Brian Rupnow (Jun 6, 2021)

minh-thanh--- I don't hate anyone. I am not a hater. I envy some people their skill or luck, but hate is a big word to use on people with the same hobby as myself. There are some people on the forums, that I like better than others, but that's more about their attitude than their mechanical abilities.


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## Badhippie (Jun 6, 2021)

http://users.tpg.com.au/agnet/make%20piston%20rings.html
		

Brain if this has already been posted to you sorry about the repost. If it has not then please take a look it has some of the most defined information about rings, pistons, cylinders, anywhere. Also one of the easiest ways to make rings there is without all the misguided information. If you follow the links inside the page you will find information from some of the words leading experts that back up the findings with 100% pure facts.

Good Luck
Tom


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## Brian Rupnow (Jun 6, 2021)

Badhippie--Thank you. I have seen this before, but I will read it thru again. There is a lot of information there.---Brian


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## Charles Lamont (Jun 6, 2021)

Brian Rupnow said:


> General Question--When you make rings, do you machine the outside diameter of the rings after they have been heat treated? I'm trying to get a handle on this. The Trimble method does have a final "Skimming" step where the o.d. of the rings is turned after the ring is heat treated.  I believe that many people make rings quite successfully without this final machining operation.---Brian


In Prof. Chaddock's method, there is a final skim.


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## Brian Rupnow (Jun 6, 2021)

After finally getting the complete Trimble method of ring making, I see that I have been misinformed. Trimble does not call for a final "cut" on the outer diameter of the rings. In fact, he strongly recommends against it. He strongly suggests that the o.d. of the rings be brought to a very high degree of finish in the initial sizing before being parted off. He suggests that the rings be machined to about 0.0015" to 0.002" oversize, then using a "fine India stone" to remove all tooling marks, then brought to final size with 400 grit paper on a flat strip of metal. He recommends a "mirror finish" on the o.d. of the rings, and that the o.d. of the rings is the same as the bore of the cylinder.. He also disagrees with breaking the ring manually in a vice, and provides design for a "cleaver" which cuts the ring much more cleanly than breaking them.
*Revised 07-june---I misread the tolerance.*


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## Badhippie (Jun 6, 2021)

Brian 
Your welcome yes there is a lot of information there. I hope some of it will help you in your quest. 
Thanks
Tom


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## Jasonb (Jun 7, 2021)

Brian Rupnow said:


> He suggests that the rings be machined to about 0.010" oversize, then brought down to within 0.0015" to 0.002" over using a "fine India stone" to remove all tooling marks, then brought to final size with 400 grit paper on a flat strip of metal



Read it again or you will be there all day with that India stone.

To save others getting confused this is what he says 

He roughs the OD to +0.010" then bores. 

He then turns with his finest feed and best finish possible the OD to + 0.0015 to 0.002"

Then get out the stone and take it down to +0002 to 0.0005"

Then polishes it down to finished size with abrasive paper.

To be able to do this you really need to know the exact size of your bore, don't just assume all yours are 1" as your reamer may be cutting oversize and any honing or lapping will increase the bore and an old digi calliper is not the most accurate tool to measure it with.


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## Steamchick (Jun 7, 2021)

Gordon said:


> If I remember correctly, not a given, only one of the three rings was a compression ring. One was to lubricate the cylinder wall, one was to seal the oil in the crankcase from getting into the combustion chamber and one was for compression. The only justification for more compression rings is the chance that one of them would work properly.


Hi Gordon, I guess we come from different parts of the industry, and possibly at different times. 
I started in the mid-1960s and I think the oldest engines I re-bored and honed came from the 1930s. At least a few Austin 7 side vale engines, some old diesels (with cast-iron pisotns, rings etc.)...
I have only ever come across a single oil control ring used. But if this is a proprietary oil ring design it may be a pair of steel rings with a spring steel carrier. No use for models anyway. 
But I do remember 3 compression ring pistons, and (memory may be wrong...) I think these were old diesels with cast iron pistons, but there may have been some Ali pistons for diesels with 3 comp rings. 
The principle of multiple rings is simply to replicate the multi-staging of pressure drop, as with labyrinth seals, Tesla's non-return valve, turbines, etc... to reduce the volume of blow-by gases that pressurise the crankcases. But the principle of mimic is in the number of rings is to reduce friction, accepting the increased blow-by.
If you have a 2-stroke engine using the crankcase as the charging pump, then increased blow-by can be tolerated, as on the next stroke this just means a tad more gas in the cylinder.
I'll reiterate what I remember of the Hepworth and Grandage ring manufacture (as they made millions of rings every year that went into engines in a pre-run-in condition):
1. Machine the ring blank to correct diameter for being "sprung open". 
2. Slit, with a gap equal to final gap plus amount of sprung-open gap that will dissappear when compressed.
3. Install in a cylinder of size plus finish grinding diameter, and clamp a pack of rings onto the mandrel.
4. Install mandrel with rings in grinder and finish grinding to size.
5. Install rings on a loose mandrel in a slave bore of size, and "Barrel" finish with finest lapping compound  oscillating axially in the bore and rotating 10 to 30 degrees between each oscilation. This is to maintain the perfect circle from grinding, not make an out-of-round into a circle. This simply finishes the surface, so from first start in the factory, the engine has the planned compression and blow-by, and surface finish to avoid the need for running-in. (Modern customers don't know what "Running-in" is all about!).
If good enough for the car industry, it should work for the model... I think?
Perhaps the issue is the sizing of bores as setting gauges, lapping bores, etc...or the amount of spring in small rings? (Is that the reason for annealing?). Maybe the fitting process is distorting the rings from their perfectly made circular shape? Perhaps the annealing is changing the shape of the cast iron (it does!)...?
Try making steel rings from rolling flat wire instead?
Perhaps it is the bore, not the rings?
What does marking blue show the contact points to be?
Maybe I should try making some myself so I can learn to eat humble pie when I am wrong?
Enjoy,
K2


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## DKGrimm (Jun 7, 2021)

OK, Brian.  I've followed this thread for four weeks, now.  I've read and re-read every thread.  I've downloaded and read and studied all the references.  It's crunch time.  I've got a 4-cylinder scratch-designed engine that needs only the rings to put it together, so it's time to choose a method and bite the bullet.  I'm going to go with the Tom Walshaw / Prof Chaddock method.  I've used these methods before, once with very good luck, and two or three times not so much.  I've developed some rationale for doing it this way, and have some opinions about why this is the best way to try to proceed, but I don't think I'll add those to the pool here until after I see how it works out.  

Wish me luck.

Don


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## Steamchick (Jun 7, 2021)

Good luck Don!
To boldy go.....
K2


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## Gordon (Jun 7, 2021)

I seem to be missing something using the Trimble method. I have an engine I have been working on and have used the Trimble dimensions and methods but I apparently have missed something. I can put the piston with rings in the cylinder and I have good compression. I try starting the engine and it starts and runs for a short time  but before I can get the adjustments made I am loosing compression. When I remove the piston the rings are stuck in the bottom of the groove. I can clean things up with carb cleaner and the rings again are free  again in the groove. Reinstall and repeat above. I have checked the depth of the groove and if anything I am just a little too deep. I can insert a .002 feeler gauge in next to the installed ring. I have checked the bore and it is right on with a dial bore gage. No taper or out of round. Piston is 1.25 dia aluminum. Cylinder is cast iron.

Trimble shows an expanding mandrel to bring the ring to the proper width where he talks about taking off a few thousands but earlier he talks about starting with the ring only about .001 over width and then getting to final size with wet/dry sandpaper on a flat surface. 

The only thing I can think of is that I am using the wrong aluminum but it is the same aluminum I have used before. Any idea what I am missing?

Gordon


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## Brian Rupnow (Jun 7, 2021)

Please note that I have changed the tolerance on the Trimble note on post #325.  I had it wrong.---Brian


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## DKGrimm (Jun 7, 2021)

Gordon said:


> I seem to be missing something using the Trimble method. I have an engine I have been working on and have used the Trimble dimensions and methods but I apparently have missed something. I can put the piston with rings in the cylinder and I have good compression. I try starting the engine and it starts and runs for a short time  but before I can get the adjustments made I am loosing compression. When I remove the piston the rings are stuck in the bottom of the groove. I can clean things up with carb cleaner and the rings again are free  again in the groove. Reinstall and repeat above. I have checked the depth of the groove and if anything I am just a little too deep. I can insert a .002 feeler gauge in next to the installed ring. I have checked the bore and it is right on with a dial bore gage. No taper or out of round. Piston is 1.25 dia aluminum. Cylinder is cast iron.
> 
> Trimble shows an expanding mandrel to bring the ring to the proper width where he talks about taking off a few thousands but earlier he talks about starting with the ring only about .001 over width and then getting to final size with wet/dry sandpaper on a flat surface.
> 
> ...


Weird!  Almost seems as if some foreign agent hacked your break-in lube.

Don


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## mayhugh1 (Jun 7, 2021)

Gordon said:


> I seem to be missing something using the Trimble method. I have an engine I have been working on and have used the Trimble dimensions and methods but I apparently have missed something. I can put the piston with rings in the cylinder and I have good compression. I try starting the engine and it starts and runs for a short time  but before I can get the adjustments made I am loosing compression. When I remove the piston the rings are stuck in the bottom of the groove. I can clean things up with carb cleaner and the rings again are free  again in the groove. Reinstall and repeat above. I have checked the depth of the groove and if anything I am just a little too deep. I can insert a .002 feeler gauge in next to the installed ring. I have checked the bore and it is right on with a dial bore gage. No taper or out of round. Piston is 1.25 dia aluminum. Cylinder is cast iron.
> 
> Trimble shows an expanding mandrel to bring the ring to the proper width where he talks about taking off a few thousands but earlier he talks about starting with the ring only about .001 over width and then getting to final size with wet/dry sandpaper on a flat surface.
> 
> ...


You may have debris circulating in your oil, and it may be getting trapped in between your valves and their seats and causing the loss in compression. Everything must be really clean before being final assembly. What you're discovering trapped in your ring groove may be a symptom and not the root cause of your problem. 

By the way, that ring groove is a sealing surface for the ring needs to be machined using good practice for a smooth surface finish. Also, heat treatment may leave crud on the rings, and that on the ring exteriors is most easily polished off while the rings are still stacked in the Trimble heat treat fixture. I polish the individual sides of my rings after heat treatment on a glass plate using 600g grease with the ring a simple hand-held fixture. This is when I remove the final thousandth for their fit in the piston groove. I doubt that the piston alloy you used is the source of your problem unless it was so soft that you got a lousy surface finish on the grooves. 

To me, it sounds more like a cleanliness problem. To be honest, I see lots of posted photos of model engine interiors that appear (admittedly they could be photo illusions) to be so full of crud on their surfaces that I wonder how the engine ever runs at all. 

As careful as I try to be with my ring making and final assembly cleanliness, always including the use of magnetic drain plugs, I still see a very fine metal accumulation on the drain plug over time. Since most of the metal in my engines is aluminum, I can only assume this crud is coming from the rings as they polish themselves to the cylinders. I'm pretty sure that after all my efforts on the valve seats, I don't want that stuff ending up in them or in the engine's bearings - especially if they're open ball bearings. - Terry


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## Brian Rupnow (Jun 7, 2021)

Today I had one of those wonderful, drop in, 8 hour jobs from an old customer. Design fixtures in the morning, send off to customer for approval, get immediate approval, make detail drawings, then machine like a fiend until suppertime. I don't want any "big" jobs, but I love those one day deals. I'm having a grooving tool ground for me at a local shop to make piston grooves, and todays work will pay for that with money left over.


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## dsage (Jun 8, 2021)

Terry:
Could you post the annealing temperature you use for rings. As I mentioned above I believe it is the one mistake in the Trimble article and it should be avoided.


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## Brian Rupnow (Jun 8, 2021)

My current understanding is 3 hours at 1100 degrees.----Brian


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## dsage (Jun 8, 2021)

1100 what? C or F.
Where did you get that?
Trimble says 1475 F which has been disputed by some as damaging to the cast iron.
I'm not saying your wrong I'm just pointing out that some believe a mistake was made in the article.
Don't start until this has been confirmed.

I usually heat to a dull red in a dark room. Which would be a litle lower than the 1100 if you meant F.
Although these types of things are usually stated in C.
I'm not saying I'm right either.
That's why I had hoped Terry would chime in. He has done a lot of research (as usual).

Here is a chart. Down the page a bit. There's a big difference between 1100 F and 1475 F in color.







						Know Temperature when metal glows red
					

:   It doesn't really matter what the emitter is...stainless steel, cast iron, tungsten in your light bulb, the temps are about the same for a given color. Generally accepted colors/temps are:     ::C ----- ::F ---- Color   400 -- 752 -- Red heat, visible in the dark 474 -- 885 -- Red heat...




					www.hearth.com
				




I'm sure others will chime in on how they just "Blast them with a torch". But I think it behooves you to get it right.

BTW if you read it Trimble does not state a time. Only that the rings themselves must truly reach the correct temperature being that they are inside a fairly heavy fixture. I guess there's no "too long" so.....


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## Brian Rupnow (Jun 8, 2021)

That would be 1100 degrees F with a 3 hour soak time. I have tons of input on this one, and everybody is recommending something different. This is why I bought a heat treat oven. I am hoping that I can make working rings, and that I can set up a standard and repeatable process for doing so.


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## werowance (Jun 8, 2021)

Brian, remind me,  did you use store bought rings in the Webster engine? or which engine was it you used store bought ones?  the first engine you used store bought ones (incase you did multiple ones)
reason I ask is thought maybe that engine would be best to "test" with since you know that engine already works on store bought ones


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## dsage (Jun 8, 2021)

I don't think your far off and have certainly backed it down from what was considered an error at 1475 F in the article.
I just wanted to be sure you don't go off on too much of a tangent.

BTW.
Make the clever that Trimble recommends in the article. It's only a bit of simple machining work and careful grinding for the knives. It makes wonderful breaks / cuts or whatever the term is with no other imperfections to the ring surface. And no chance of "bending" the ring in such processes others have suggested like holding them in a vise and stressing then sideways until they break.


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## Brian Rupnow (Jun 8, 2021)

A local milling machine cutter sharpening service is currently making this tool for me to groove aluminum pistons for 0.038" wide rings. Actually, his price for a tool as shown here was $60, but a lot of that must have been set-up, because he also quoted me on a double ended tool for 75$. I ordered the double ended tool and will have it sometime this week.


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## Brian Rupnow (Jun 8, 2021)

I used a viton ring on my Webster. I used purchased cast iron rings on my vertical hit and miss engine and on Thumper, the engine I hoped would run my sawmill edger (but didn't). In both cases the rings were 1/16" thick and worked perfectly . the only time I made rings myself and ran them on an engine was on the Canadian Cub, a one cylinder version of Malcolm Strides Bobcat. It ran very poorly at about 2000 rpm, but it wouldn't idle and ran poorly.


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## Stuart Walker (Jun 8, 2021)

Tubal Cain in his article in ME dated 15July 1994, clearly states that heating cast iron rings to 1475 deg F not only reduces the Brinell hardness, Young's modulus and the transverse rupture stress, but also the fine pearlitic structure designed into the metal is lost due to metallurgical changes which occur as the metal passes through the lower critical temperature (about 1328 deg F).  As a consequence, the metal is softer, will wear more rapidly and will not be able to develop the required outer ring pressure seal. 
For low pressure CI piston rings (up to 15 lb/sq in) he recommends that a temperature of 1100 deg F be used and held for 15 minutes before being slowly cooled.


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## DKGrimm (Jun 8, 2021)

Stuart Walker said:


> For low pressure CI piston rings (up to 15 lb/sq in) he recommends that a temperature of 1100 deg F be used and held for 15 minutes before being slowly cooled.


That's what I have used.  I have found that the specimen in the oven takes quite a while to reach thermal equilibrium with the oven temperature, so a allow around 30 extra minutes for that.

Don


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## Jasonb (Jun 8, 2021)

I hope that cutter is going to work for you and not run on the sides as you don't seem to have shown any side clearance angles

Would have thought one of the Mini-thin holders and inserts would have been a similar price over there as they work well and are available in small width increments.


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## mayhugh1 (Jun 8, 2021)

dsage said:


> Terry:
> Could you post the annealing temperature you use for rings. As I mentioned above I believe it is the one mistake in the Trimble article and it should be avoided.


Dave,
I've been using 975F for a couple hours.
Terry


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## Gordon (Jun 8, 2021)

__





						Piston ring heating
					

What temperature do you use for heating piston rings? Trimble says 1400° Others say 1100° and I just read Chaddock says 950° I have an old kiln which means that I can control the temperature. What have others been using?




					www.homemodelenginemachinist.com
				




This is what I got when I asked a while back.


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## Brian Rupnow (Jun 8, 2021)

I called the toolmaker this afternoon about the cutting tool he is making me and asked about side clearance.  He was out, but I left a message. He emailed me back and this is what he had to say.
_"Hi Brian_ 
_Sorry I missed your call. I was driving. 
I intend to put side clearance on the tool. Probably only 2-3 degrees per side. I would put more because it’s aluminum but it’s pretty small. I will also make the tool narrower at the base. Only by .001/.002 but it will give you a cleaner cut. Both clearances will stop the aluminum from smearing and give you a better cutting action. I should have them ready tomorrow and I’ll let you know. Thanks"_

 Okay--I never claimed to be a tool designer.  This guy is good. He has sharpened cutters for me before, and I was impressed by his background and knowledge.


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## Steamchick (Jun 9, 2021)

Keep up the good work Brian, we are all learning a lot from this thread.
I understood (just generally) that once the parts ahd reached the required temperature, the fine structure (Not Molecular? but Crystaline structure?) was changed naturally, and prolonged heating would simply burn-out carbon thus changing it further to some un-controlled structure? ~ Can a metallurgist or other expert advise? - I know that endurance testing engines on Dynos during engine development proof testing, the exhaust manifolds would change size and shape as the metal "shrank" when anything over dull red heat was realised. The shrinkage was measured as part of the post-test analysis. - More than 1/8" in 12" span of the bolts holes. Some was distortion, but the metallurgical analysis revealed the "carbon content loss", confirmed by metal thickness measurements on separate studies in controlled ovens. I don't know the details, but depending on the engine and tuning, this was used to determine whether cast iron was OK, or spheroidal graphite iron was needed. 
So don't "over-cook" your rings in both time and temperature. Maybe you can ask "Perfect Circle" (a US ring maker or high repute) for advice? (The only link I found was this one... https://r.search.yahoo.com/_ylt=Awr...on_rings/RK=2/RS=MpKkIHhhm.PX5nEeIwySBUl6cMM-)

Hope you are fit and well!
K2


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## johwen (Jun 9, 2021)

dsage said:


> 1100 what? C or F.
> Where did you get that?
> Trimble says 1475 F which has been disputed by some as damaging to the cast iron.
> I'm not saying your wrong I'm just pointing out that some believe a mistake was made in the article.
> ...


Trimble says, and I use his description all the time, it is a red heat for 15 minutes. That is the crucible with the correct gap spacer you wrap the space around the rings with paper to burn up the oxygen in the air space so the ring surface does not oxidize and the rings come out blue have very good wall tension. What I'm seeing if you are heating the rings with an open flame the depth of oxidation could vary in thickness if one side of the ring is heated more than another causing an out of round ring once the oxide is removed. I have 4 different crucibles that over the years have covered the bore sizes I have standardised on. They are made so they are air tight by being a close fit in so the paper is enough to burn all the existing oxygen. The structure of the crucible dimensions is in the Trimble article. John.


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## dsage (Jun 9, 2021)

mayhugh1 said:


> Dave,
> I've been using 975F for a couple hours.
> Terry



Thanks Terry. I would take that as Gospel. I'm sure (as usual) you did your research.

And thanks for digging up the old post Gordon.

For those without a furnace. That would correspond to the color chart I posted earlier and my observation of a dark red when viewed in a dimly lit room that has worked for me.
Of course the indication that you have not gone hot enough or for long enough is that the rings do not maintain their "set" and spring closed when removed from the fixture.

Sorry to interject with all of this. But I thought if Brian was going to try to perfect the process he should have all of the correct information. And I knew that it was concluded over time by other "experts" that the Trimble article got it wrong.


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## Gordon (Jun 9, 2021)

Brian and others: You are having the tool bit ground to .039 width. I assume that your ring is going to be .038. That means that you are going to do a plunge cut. You have experienced in the past that the groove comes out undersize. I have seen a few other references to taking a final finish cut to clean up the side. I am wondering if it would be better to cut the groove undersize and then move over a couple of thousands and clean up the side of the groove. Common wisdom seems to be that the bottom of the groove is the critical surface so just moving over a slight bit would minimize the chatter typically encountered with a plunge cut. I have no experience with this. I am just asking for opinions and/or insight. Would it be better to plunge cut with the .039 tool, move over .002 and make your ring .040?

Gordon


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## Jasonb (Jun 9, 2021)

Easier to just measure the width of the plunged cut and make any adjustments to the ring if your tool is cutting undersize. I don't tend to get chatter on such narrow plunge cuts, using one of the Nikcole Mini Thin inserts


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## Brian Rupnow (Jun 9, 2021)

I plan to plunge cut, and hopefully a good sharp tool is going to leave smooth sides on my pistons ring grooves. I will then measure the groove with feeler gauges and make my rings to 0.001" less . This is all becoming a "try it and see what happens" exercise.


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## minh-thanh (Jun 9, 2021)

Gordon!
My ring is 0.8 mm wide , i sharpen the grooving tool to 0.7 mm wide ,
When groove has enough depth, I will move the tool towards the bottom edge of the groove and make the groove width slightly wider than the ring.
Note that my grooving tool has 2 parallel sides,  
I don't know how it works with other tools


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## Brian Rupnow (Jun 9, 2021)

Yesterday I ordered a "fine India stone" from Norton.  They don't cost much, and I don't have a lot in the way of sharpening stones.  I bought a 1" x 4" stone. I have one big double sided stone that I inherited from my dad, and it works fine for sharpening jackknives and kitchen cutlery but isn't something you would use on material chucked in a lathe. Trimble recommends a "Fine India stone" as part of his write up on ring making.


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## Gordon (Jun 9, 2021)

With all of this discussion I have gone back and reread the Trimble article again. One thing which I don't remember reading before is how he installs the ring. He talks about spreading the ring apart by prying your hands apart with your knuckles. I have no idea what he is talking about but he says that if you pry the ring apart by the gap it will ruin the ring. I don't doubt that others are also expanding the rings by spreading the gap. 

How are you spreading the rings?

Gordon


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## Brian Rupnow (Jun 9, 2021)

Cover piston and ring with #30 motor oil. Lay ring on top of piston and spread ring as far apart as you think you can without breaking it with your thumbs  and start one side of ring (right at the gap) down over the side of the piston. Work your way around until the ring is spread out enough to set down over the top of the piston. Then tease it down incrementally until it goes into the ring groove and relaxes. Damn, it's harder to explain it than it is to do it.


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## oldengineguy (Jun 9, 2021)

FWIW   I make a tapered plug the same size as the piston about 1 inch long and about 060 or less smaller at the little end.  Hold the plug tightly on top of the piston and slide the ring down with oil. When you get to the piston just keep on sliding till it drops in the groove.  Colin


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## DKGrimm (Jun 10, 2021)

Brian Rupnow said:


> Cover piston and ring with #30 motor oil. Lay ring on top of piston and spread ring as far apart as you think you can without breaking it with your thumbs  and start one side of ring (right at the gap) down over the side of the piston. Work your way around until the ring is spread out enough to set down over the top of the piston. Then tease it down incrementally until it goes into the ring groove and relaxes. Damn, it's harder to explain it than it is to do it.


My dad taught me to install rings when I started working for him in the family auto shop as a kid.  It cost him a few broken rings to let me learn, but once you've learned it you don't even think about it.  I start the ring over the piston opposite the gap, keep some pressure inward on each side about 120 degrees from the gap while I gently urge the gap ends over the edge of the piston.  To slide the ring over the piston and the intermediate ring grooves, its basically the same thing:  keep some inward pressure on the rings at 120 degrees from the gap while opening the ring at the gap.  What you are really trying to do is spread the bending force around the ring rather than just opposite the gap.

Like you said, the explanation is much harder than actually doing it.

Don


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## Brian Rupnow (Jun 10, 2021)

Today I picked up my 1 mm (0.039"0 lathe tool from Can-cut, a local sharpening service. Yes, it does have a bit of side relief on it. He made it using a surface grinder. ---Yes, I paid $75 for it, but this is still only about 1/2 of what I would pay for a carbide and toolholder out of USA.  Next step will be to machine a holder for this tool and see exactly what width of cut it actually makes in a 1" diameter piece of aluminum round stock.----And yes, I agree with the sentiment "More money than brains".


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## Gordon (Jun 10, 2021)

Probably do what I did not do. Use lots of WD-40 and the sides should be much smoother.


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## Brian Rupnow (Jun 10, 2021)

Something very fishy is going on, and I don't know what. My new tool is setting at exactly the correct height (centerline of spindle), perfectly square to the long axis of the lathe, and the tool is ground perfectly square across the end. I made three plunge cuts, using the cross slide to advance the tool into the cut, with lots of wd40 as lubricant. My new tool is set up with very little unsupported "stick out". Then I cut the aluminum round blank on my bandsaw to expose a cross-section of the cut. All of these cuts look crooked to me. I don't think there is any way that a ring can seal against either side of the plunge cut.  My cross slide is set at 90 degrees to the long axis of the lathe.  Does anyone have an explanation of what may be going on here?


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## Brian Rupnow (Jun 10, 2021)

Cancel that last question.--Investigation shows that tool was setting crooked in holder. I will make a better tool holder and try this again.


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## Brian Rupnow (Jun 10, 2021)

Okay---Proper tool holder gives perfect grooves. The grooves measure 0.040" wide with my Vernier caliper, so I'd say it's good. The grooves appear at a proper 90 degrees to long axis of part. I'm happy with the new tool.


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## Steamchick (Jun 11, 2021)

Well done Brian! - So good when someone actually makes a mistake, then works out the solution and gives the whole unadulterated story. Teaches us more than just machine work. Makes me look harder at what I am doing to try and improve myself. 
Someone clever once told me "Don't be proud of making mistakes, be proud of the performance of how you found the mistake and recovered from it, learned lessons and taught others, so they don't make the same mistakes.
Now  you (I.E. "someone clever") have done just that and set an example for those that want to learn.
There's more in this than just making Models!
Goodonya Sir!.
K2


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## Chiptosser (Jun 11, 2021)

That is one more reason to use a ground spacer for tool bit spacing.  I have had to remachine the Aloris tool copies.  Check everything on the copies for parallelism and squareness.   Quality always prevails.   The material that the holders are made of is of lower quality also.


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## BaronJ (Jun 11, 2021)

Hi Guys,

A rookie error !  I wouldn't have had several parts holding that blade in the holder. The guy who ground that toolbit would have made sure that it was ground dead square and it should have been clamped in the QCTP tool holder sat flat on the bottom !  No shims or other bits in there, just properly clamped by the screws.  There is height adjustment on the QCTP in order to set the tool on centre height.

Glad you spotted it before you ruined a piston.


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## Brian Rupnow (Jun 11, 2021)

I just got a quote from Caliber Industrial Supply in Ontario for one Thin-bit holder and two very narrow carbide tips (which they sell in minimum quantities of 10) for a grand total of $429.00 Canadian funds. This makes the $75 I just paid for a double ended HSS tool look pretty darned cheap by comparison.---Brian


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## Gordon (Jun 11, 2021)

Brian Rupnow said:


> I just got a quote from Caliber Industrial Supply in Ontario for one Thin-bit holder and two very narrow carbide tips (which they sell in minimum quantities of 10) for a grand total of $429.00 Canadian funds. This makes the $75 I just paid for a double ended HSS tool look pretty darned cheap by comparison.---Brian


Why didn't you just use a .040 parting blade?


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## petertha (Jun 11, 2021)

Nikcole's are not exactly cheap, but very high quality tools IMO. Toolholder set, toolholder + 4 inserts (8 edges) from KBC Canada ~207$CAD




__





						Results Page 1 :: KBC Tools & Machinery
					






					www.kbctools.ca
				



The toolholder alone 110 $CAD.




__





						NIKCOLE,THE-7-1/2-R MINI-THIN HOLDER,1-293-003,KBC Tools & Machinery
					

NIKCOLE,THE-7-1/2-R MINI-THIN HOLDER,1-293-003,KBC Tools & Machinery




					www.kbctools.ca
				




Nikcole inserts are sold individually ~$30 so I guess $15/edge. But I have yet to dullen mine on quite a bit of aluminum, mild steel & CI. The geometry is very sharp & accurate. They come in several widths, round profiles (O-rings), 60-deg V (threading). A $ investment to be sure but just making you aware of options.

Nothing wrong with HSS, its perfect for this application. Recognize that whenever you dress sharpen your HSS, it will no longer be the original target width anyways. As mentioned in prior post, another method is make the finished groove in 2+ stepover cuts using a slightly thinner width tool. The advantages are 1) uses a universal vs dedicated cutting tool, so available for multitude of other work 2) dimensional control - regardless of the actual tool width variation, you can still achieve groove of final tolerance dimension & finish. A single tool, single plunge is fine as long as its perfect profile & the material cooperates.

I'm not sure if your caliper measurement was just a sanity check, but personally I wouldn't trust it for things like this. Its better to have an over/under feeler gauge stack or sample ring section to do a fit test. Even though the depth is shallow, the fit can be influenced by the inside & outside corners, micro burrs etc. Especially aluminum which can be a bit gummy.


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## L98fiero (Jun 11, 2021)

Brian Rupnow said:


> I just got a quote from Caliber Industrial Supply in Ontario for one Thin-bit holder and two very narrow carbide tips (which they sell in minimum quantities of 10) for a grand total of $429.00 Canadian funds. This makes the $75 I just paid for a double ended HSS tool look pretty darned cheap by comparison.---Brian


Brian;
 KBC sells one .039 Nikole insert for 27.70 and the holder is just simple milling on a 3/8 or 1/2 in square piece of CRS NIKCOLE,GIE-7-GP-1.0-R-N C2 GROOV.&CUTOFF INSERT,1-2932-021,KBC Tools & Machinery total cost is probably another $10 for courier and a half hour on the mill including clean up.


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## petertha (Jun 11, 2021)

L98fiero said:


> NIKCOLE,GIE-7-GP-1.0-R-N C2 GROOV.&CUTOFF INSERT,1-2932-021,KBC Tools & Machinery



Never noticed the +/- width spec before, that pretty good.


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## L98fiero (Jun 11, 2021)

petertha said:


> Never noticed the +/- width spec before, that pretty good.


The nice thing about KBC Tools too, is that if the Toronto branch doesn't have it it's two days from Detroit instead of next day. And they'll almost always sell inserts one at a time.


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## petertha (Jun 11, 2021)

L98fiero said:


> the holder is just simple milling on a 3/8 or 1/2 in square piece of CRS



I went down this path for a custom cutter. Not impossible & will save some bucks, but... you have to get the pocket milled correctly to contain the insert. I find getting the corner radius sharp for a proper fit is a bit fiddly. Also need the appropriate screw (available separately). Maybe you have that corresponding tap, maybe not... Model engineers can tackle anything. I can say from personal experience the shank steel is hardened, tough sh*t so maybe the stiffness & rigidity is part of why it works well. You can indicate off the shank & confirm its set up perpendicular.


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## Brian Rupnow (Jun 11, 2021)

Gordon---where do I buy an 0.040" parting blade?---Brian


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## Gordon (Jun 11, 2021)

Amazon.com. Spend less. Smile more.
					

Free shipping on millions of items. Get the best of Shopping and Entertainment with Prime. Enjoy low prices and great deals on the largest selection of everyday essentials and other products, including fashion, home, beauty, electronics, Alexa Devices, sporting goods, toys, automotive, pets...



					www.amazon.com
				



HHIP 2000-6008 P1
Michigan drill 703 P1N

Shars SKU 404-1662

I have purchased them from a couple of different sources.
Alternate is to buy 1/16 and grind it down.


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## Brian Rupnow (Jun 11, 2021)

Thanks Gordon--Best answer--I didn't know about them.----Brian


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## petertha (Jun 11, 2021)

Gordon, you might actually be seeing a metric 1mm wide tool re-labelled for the N-Am market. Shars is famous for that, trying to being helpful I suppose. Parting tools are typically not precision ground for width though, its more of a nominal size thing. The N-Am basis is /64, /32" (unstated +/- tolerances). If you just suggesting this as starting point stock to finish grind then disregard. But I'm pretty sure the typical parting T profile has no side clearance on the upper portion, at least they don't show on sketch. That's typically what the thinning is about on the lower portion.


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## L98fiero (Jun 12, 2021)

petertha said:


> I went down this path for a custom cutter. Not impossible & will save some bucks, but... you have to get the pocket milled correctly to contain the insert. I find getting the corner radius sharp for a proper fit is a bit fiddly. Also need the appropriate screw (available separately). Maybe you have that corresponding tap, maybe not... Model engineers can tackle anything. I can say from personal experience the shank steel is hardened, tough sh*t so maybe the stiffness & rigidity is part of why it works well. You can indicate off the shank & confirm its set up perpendicular.


I didn't find it much of an issue, mill the bottom of the pocket with a new, sharp 1/8" endmill, cut clearance for the tip and then clear the remainder, angle the vise for the end stop and that's done. Then it's just a matter of going to the, in my case, KBC catalog and find a toolholder/boring bar that uses the appropriate XXXT insert and buy a replacement screw, most are metric flat head Torx screws appropriate for the 60° countersink in the insert and then picking up the hole location for drilling and tapping. The hole location is a bit of a judgement call but you want it to pull back and down so it seats. If you're just going for function you can even use a socket head cap screw in a pinch.
As for how hard the holder is, if you're planning a long production run or heavy machining it would be something I'd be concerned about but keep the overhang limited and if it's only for a few ring grooves in cast iron or aluminum you'll have no problem.


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## DougB (Jun 12, 2021)

Hi Guys,


I have read a few of the comments about the use of custom cutters and while there is no doubt they will work I however found using a slitting saw and rotary table far more reliable and predictable.

Regards,

Doug


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## Gordon (Jun 12, 2021)

petertha said:


> Gordon, you might actually be seeing a metric 1mm wide tool re-labelled for the N-Am market. Shars is famous for that, trying to being helpful I suppose. Parting tools are typically not precision ground for width though, its more of a nominal size thing. The N-Am basis is /64, /32" (unstated +/- tolerances). If you just suggesting this as starting point stock to finish grind then disregard. But I'm pretty sure the typical parting T profile has no side clearance on the upper portion, at least they don't show on sketch. That's typically what the thinning is about on the lower portion.


Actually, within reason the width is not important. If a .040 parting tool cuts .042 you just adjust the width of the ring accordingly. Not having side clearance could be a problem since you want smooth sides.

I just checked my .040 parting tool and it does have side clearance. The top section is tapered in a a slight angle.


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## Brian Rupnow (Jun 12, 2021)

This is a video I made today, 11-june-2021 of my vertical i.c. engine 2021. I have been trying to make a set of  cast iron rings for the piston, and as part of that I built a new cylinder and new piston to accept cast iron rings, but ultimately I was not successful. Finally I decided that I should put this engine back together, so I enlarged the top ring groove to .093" wide x 0.058" deep and put a Viton ring on it. This engine can now go up on the shelf with all of my other engines. I am still after cast iron rings that actually work, but will be trying them out on a different engine that is a lot simpler to take apart and access the piston.----Brian


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## Brian Rupnow (Jun 12, 2021)

And this is one of my other engines which I tried to run cast iron rings on and failed miserably. I have restored the original piston with a Viton ring on it, and of course it runs like a trooper. I wanted to make sure that both engines ran well before putting them back up "on the shelf". This engine is a noisy devil, because the spur gears are not enclosed in a metal housing. I am still pursuing the cast iron ring magic, but I'm not there yet. I have another engine to try cast iron rings on, but it is a much simpler engine to change pistons on.----Brian


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## Brian Rupnow (Jun 14, 2021)

I am going to try this one more time, but there is a possibility that the cast iron I purchased may not be right for the job. Does anyone know if there is a place in Ontario that sells "Meehanite"? I'm having a problem finding it.---Brian


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## Gordon (Jun 14, 2021)

I am not sure but is ductile iron a better choice for piston rings instead of grey iron? I think that Meehanite is a trade name as opposed to a type of cast iron.


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## L98fiero (Jun 14, 2021)

Brian Rupnow said:


> I am going to try this one more time, but there is a possibility that the cast iron I purchased may not be right for the job. Does anyone know if there is a place in Ontario that sells "Meehanite"? I'm having a problem finding it.---Brian


Brian;
Here's a link discussing what Meehanite is, can't say for sure but you probably don't really need Meehanite, just good cast Durabar. Meehanite As I've posted before Terranova Steel sells it and probably Metal Supermarket, McKinnon in Woodbridge and even AtoZ in Barrie


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## doc1955 (Jun 14, 2021)

Gordon said:


> I am not sure but is ductile iron a better choice for piston rings instead of grey iron? I think that Meehanite is a trade name as opposed to a type of cast iron.


You are correct on both counts.


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## Tim1974 (Jun 15, 2021)

I was told gray iron not that dura bar stuff ? Hard to find I no but when you do is cheep post cost me more than the 800 mm bar I got ?


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## Fidlstyks (Jun 15, 2021)

Brian, I am a new member here. Have read posts here a few years now, I belong to several web pages and have not taken the time to post everywhere.
    I always liked making rings, so this thread has caught my eye.
   Several things come to my mind to try and help you along. Sorry I have not the time to read all the posts here, so I may be redundant in some advice.

Here are somethings that come to mind.
  Please note I think of things later or in post-proof reading and change my words. So if I misspell or quote, look later, I may change what I said. I finally learned to shut off the auto correct which got me in trouble a time or two. 

So here is my advice.
  Remeber in the begining, all engines ran on tempered cast rings, it is O rings new to engines. 
  One important point is when using rings, get it clear in your mind, the cylinder breaks into the rings.  Rings do not break into the cylinder. That is why they hone a cylinder. It must have swirls to wear in. This is a problem with alot of people. You need to have a nicely honed cylinder, and fit the piston to the cylinder. If you make a piston first, you cannot set a close tollerance, honing later makes an improper clearance. 

   This breakin may not be happening in your case, as I believe you did not temper the ring. Very important. It takes a harder than the cylinder ring to break in. 
   If you look at any new cast iron ring, they have a blue tint to them. And they snap when forced to do things they not want to do. This color is the temper, not a snazy paint job. 
   To make a ring and  temper it, I machine a cylinder to my bore diameter and anywhere from square to .050 ring depth. So engine bore 1.250, make cast iron tube 1.250. It then has 1.200 bore, to make a ring .050 thick.  It is nice to make all engine bores to hone fit to the same size. But the ring can fit slightly different sizes of bore.
    I part the ring with a tool bit ground to look like a parting tool, with relief on each side behind the cutting edge to be sure and not damage the ring edges. 
   I set the compound at an exact right angle to lathe center line. Then I run the bit past the front of the tube I of cast iron. That way then you shut off lathe. Pull bit back, then turn compound down .062 plus width of tool bit which is usally .0625 so I get as many rings as are wasted. 
   I have already cut my piston groove at .0625 wide x .0625 deep.

   After the ring is parted off, where I drug the tool bit back there usually is a scratch. I take an exacto blade and cut-groove in the cast ring all around. Like glass cutting, the cast breaks where the scratch is. Some times I use a jewlerys saw.
   I then place the ring in a machinist vise with the scratch at the edge of vise. I then tap the ring at this edge with a drift and hammer. It usually just snaps there. I then raise the ring a bit, using a point file I flatten the roughness and reverse the ring and flatten the other end. This becomes my ring gap. Which is an absolute must as when a ring heats, it expands length like as if the ring were a straight piece. Sometimes I think I make .002 gap, per inch of bore. I think in large hot operating engines people use .007 per inch of bore.  A minimum is very important, the maximum us not as important as too much gap makes very little difference. Side clearance looses more compression than end gap. Always out the gap up as the pistons in engines rise under compression. Don't ask me who figured that One out. They say like air in the atmosphere, compressed air rises.
I run the ring through the groove to test fit. And place on oil stone to get a nice fit. 1/4 of .001 makes a better fit. But carbon buildup seizes tight fits. I have made the ring exactly the same size as the groove. But I am not a professional and just make every thing hand fit. 
    On a bore of 3.500" a ring side clearance over .0015 looses compression according to ring manufacturers.  I am not a real authority on this measurement for side clearance.
   The tempering is important than anything.  One needs spring in a ring and The ring needs to be harder than the bore to break in a bore. 
    Next I place the ring on a flat piece of steel. Maybe what I have or 1/8" thcik. I cut and place a wedge in the ring gap, thicker as the bore increases. I use 1/8"  gap creating wedge on 1.250 bore.
  Then with a torch, I heat from the bottom the steel and ring to an orange color and dunk it into oil to freeze it. Ring is very hard and brittle at this point. Do not manipulate. 

   Next I polish this hard ring. Like in blacksmith shops where as my grandpa had when he hammered plow shares on a trip hammer, which I have,  you always see a polishing wheel on the grinding mandrel, you must polish the ring to temper it at the right temp. The science here is to be able to control the tempering temperature of the ring by eye-color.
   To prevent easy snap breaking and create spring, you must  temper the ring. To temper, one anneals the ring to a heated temperature that turns polished steel to a desired temp, dark black blue to a deep  blue or bright blue color. I forget the colors-temps. I have a color chart I look at by a forge where I usually do this.  Old age is hard on my memory. I think it is around 810° and dark blue. 
   I do this back on the flat piece of steel I have also polished to be sure and watch the temperature change closely. This is a very interesting scientific way to develop a temperature by eye-color change, rather than a lieing needle on a furnace or pyrometer.
  Some people say that like when they temper a knife blade, they dunk the piece at this blue color into water. I drop them on a rag, but one may dunk the whole thing.   I have made many rings and knives, and hardened and tempered many pieces of steel, mainly spring making and determined that once a piece hits the blue color desired, it cannot keep getting hotter if the heat source is removed. If you have not polished the piece holding the ring? you can loose control and over heat. I like it to set at the tempered color a bit as it is sure to remove internal stress, rather than dunking again. When making a knife I use a 1" long piece of steel. When making springs I Some times cheat and hang it on a wire.


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## dsage (Jun 15, 2021)

Not that any of the following will help you make rings but you may be interested in what "the big boys" do for rings.
This is Steve Morris of Steve Morris Engines in Michigan. He makes engines with turbos making upward of 3000hp.
Interesting what he uses for rings in his engines. Most of it not within our model sized machining capabilities.
But is interesting that he use a steel first ring. In one of the Model engine builder magazines there is an article on making rings from steel (rather than cast iron).
So Brian - You are not limited to cast iron. Another wrench in the works. LOL.
BTW this is a new video as of today. You might want to watch the next one that he says will have to do with cylinder bore finish.
As a matter of fact you should subscribe to him and go to his channel. He has a lot of really interesting information on engine internals.


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## Fidlstyks (Jun 15, 2021)

I make castings in cast iron. I can mail you a sprue to make rings and pistons from if you like. What size bore do you have. Most of my sprues are under 1.250. 
   As far as material, you may have gotten something bad. Some people use window weights. They claim the no 2 cast springs wider. Another guy who made them stumbled across some weigts made of fine no 1 cast. I like the no 1. No 2 was usually almost throw away cast when new in my opinion.  I think they had weight molds made when they poured, so if they had good cast left in the pot, they made some weights rather than pig iron?


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## dsage (Jun 15, 2021)

Proper cast iron whether it be ductile cast or gray cast - whatever you choose to use in continuous cast bar form is cheap from a reputable dealer. Don't use scrap iron. You'll just be in a world of hurt.
As they say. Garbage in - garbage out.


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## James Barker (Jun 15, 2021)

I can not take it anymore. At 20 pages in length, and countless methods and opinions about what materials and processes to use, Brian is still no closer to producing live functioning rings. May I suggest to you Brian, that you go back to basics and just do what your instincts tell you is the proper thing to do and forego all of the mumbo-jumbo, "scientifical" -ish methods. Good Lord. I am by no means an expert here, but I have been successful in making several sets of rings following simple instructions such as outlined in the articles and examples that I sent along to you. Everyone it seems has their "perfect", "surefire" recipe for success in making rings. Good for them if it works, but to me quite a bit of unnecessary labor is expended by many. Not to mention the added expenses incurred along those paths. Cut the rings to size, remove the burrs, split them, gap them using a fixture, wrap same in iron wire and place in the charcoal BBQ fire. Go to bed. In the morning, retrieve, unwrap, polish and install. Simple as that. All of these numbers and what-not, are I believe clouding the issue. Piston rings are being made, not a rocket launch to the moon. I will sit down and shut up now, but I would really like to see you have success in overcoming your challenge.

BC1
Jim


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## Fidlstyks (Jun 15, 2021)

I could agree that 20 pages is enough. But it really goes to show how we all are infatuated with the subject of rings. I finally joined the site so I could comment on the subject matter.

At 18 yo, I made drawings, wood patterns and cast my own kits starting back in 1980. It always amazed me when some ones model would not run. It seemed that no one ever wanted advice. They would talk about it like Brian, weigh the thoughts of others and then do their own thing. The reason most models never ran is usually either the compression or the cam timing. I have tried to show people how their cam was off, and they said they would figure it out. Must be my dumb look.
   For a first post, maybe I went on too long. But I have read several of Brian's posts and just was surprised he never tackled the ring-compression issue. I learned to make rings from Bob Manske of Kansas.  He was a great model maker. I also knew personally all of the greats from the LeSuer Mn show and when they had the NAMES show at the Domino's Farms Office Park at Anarbor Mich.  Which is an event center S of Detroit owned by the former owner of Domino's Pizza, Tom Monaghan . I think they said he was worth 10 billion back then.
  But of course with me,  I knew his brother, James, who was a model maker too. He had a steam launch and a separate-buddy fridge in his shop, full of beer and cheese.  Back early on he traded his half the business for the VW Beetle they started deliveries with. Poor me.
   I met Georg Luhrs there who taught me to lap the piston to .0005 to .001 fit with a small oil groove and no ring.
   When I started in 1980, you could buy rings for like 2-3 dollars. Fred Ellis formerly of Deperse Mo sold them, (ask me someday what happens when you store fireworks in your basement-foundry, such a sad story, what a waste). As did Coles, whose owner now just lets everything set. Or have things changed there?  They both being no more, I am not even sure where people buy rings.
   When I started it was a matter of scrounging and making everything. If I wanted to buy it, I would not have wanted it. I liked seeing what I could do. It is a "The journey is the destination" thing for me, and would love to see Brian make rings.
   If I had a CNC operation, I would buy new cast iron. It is just the achievement thing for me. I use to buy castiron rounds that were pressure cast in carbon dies. Very good material. If they are 40 bucks a foot now, it is still a good deal, I am sure.
   The casting sprues lay around here until I melt them down again. People used to buy them from me.  I just think it is fun to make some thing of them. The tall 1 1/4" are usually hole free . I also use the vents for welding rods. I poke holes in the sand with a 3/16" rod for vent holes, they fall off of the castings, and I store them up, using Brazealoy no 5 flux. I weld alot of cast iron, collecting hit and miss engines.
  If you use a piece of scrap, cut off a bit and break it. Then look at the crystal structure. A few times makes one an expert. I look for fine grains. Number 2 cast like most window weights have large looking structures. As I had said, the one man liked the large structure grains. He swore they sprung better. But the window weights are made of Garbage iron for the most part. Always full of holes and grains that very from one end to the other. They used what ever would melt in them to save money.
   I like making things from anything John Deere. But it is hard to find anything now. Always staying away from anything that was run in oil, as the oil stays in the cast like a seasoned skillet. I melted the wheels from cast mowers to start with in my early days. Fine grey iron.
  I have turned my dials wrong and ruined more castings than where I had the iron be bad, when once I would have a part almost all machined out. But I did learn the hard way to never melt motor blocks of  HP Dodge's, Pontiacs or diesel. They do have nickel in them. It makes a good ringing bell though, no machining!  I like 350 Chevy blocks, not truck blocks. They are so soft one can carve them with a pocket knife.

Also I melt in crucibles,  never use Carbon Bonded Silicon Carbide Crucibles. Always use the Clay Graphite ones. I treat my iron with 3 different aditives too. Mostly it machines. But have had to toss a couple of pots in the past.
   Kinda like a mistake I made when I put a stick of stressproof in the mill and started cutting gears. On tooth 25 of a 28 th gear, the cutter got dull, I then seen sparks fly. The stick turned hard in an instant. A dull bit will make stressproof with manganese hard in an instant. Looking back 30 years, all I had to do was skip that area, use a new cutter and finish the 12" stick. Instead I always thought it looked cool laying around the shop. If in a good mood when people asked me what it was, I told one story. If it was a cloudy day, I just grumbled.
   Some people also make rings eliptic, (turn the outside, then move over the blank in the chuck a little ways to make it off center, the idea is so they spring out more, like a feathered edge. Others cast the cast iron blank, with a pollywog on the inside. A lump that makes the cast iron have a different structure in that place, by having a mass that lengthens cooling time changes the casting structure, which when machined with the gap cut at 180° away caused the ring to spring in the center more.
  I have had people tell me they heated the finished ring like discribed being put into the fire. But studying metallurgy I see no point in that. Maybe if done prior to machining. If not queenched first, I see no point in that.

There are steels people make knives of where they Normalize the steel prior to heating and quenching and then tempering which is done by annealing to your color chart. One guy heats his finished blade then cools in lime twice before he heats and quenches. Then he tempers by annealing his polished blank to a specific color.

Of course to quench harden one checks for the heated piece to become nonmagnetic with a magnet, plus then estimate 50° hotter before quenching in oil, slicing the oil to keep it uniform. Which is a said standard. I quench my springs and knives that way. Then polish and anneal to color for my temper. The darker the color, the harder your piece stays. Light blue makes a lighter duty spring.b
   As I was saying before, lay a new factory ring by your ring being tempered for color range reference and anneal your pre-polished ring on the steel stick, heating till the same color as the factory ring is achieved. Then your ring will spring and wear the cylinder into a proper fit.

It takes a break-in period you know. Some times the compression developes immediately, but usually it requires turning an engine over for a few minutes to start break-in. They use to show shots at Ford where they spun model T engines for breakin. Some of that was burning in the babbitt too. But new cast iron rings need spun over for a period of time before being fired up for the first time. Always oil well too.

  One of the reasons they use crome molly, (I think that the material) rings is they require no breakin time.


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## Nerd1000 (Jun 16, 2021)

Gordon said:


> I am not sure but is ductile iron a better choice for piston rings instead of grey iron? I think that Meehanite is a trade name as opposed to a type of cast iron.


Ductile iron will be stronger and stiffer than grey iron but its 'nodular' graphite inclusions provide less self-lubrication than grey iron's flake graphite.

Ductile iron is commonly used for the top ring in full sized engines that run high compression ratios or forced induction that could break a grey iron ring. Such rings are usually coated to improve their friction properties so they don't gall up the cylinder walls.

 For a model engine I think grey iron would be superior as no coating is required, plus continuous cast grey iron is usually slightly harder than the ductile iron equivalent.


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## Gordon (Jun 17, 2021)

I certainly do not agree that this thread should end. Many of us have learned a lot. Many of us who have built engines have had very erratic results when making rings. Brian did not have 6 or 8 failures, he found 6 or 8 ways that do not work. It just amazes me that some folks seem to use rather crude methods and seem to have success and others who try to do everything right cannot find the magic combination. I am sure that some things were done correctly and had offsetting incorrect operations. It is like getting an engine to run the first time. Nothing seems to work and suddenly we get ignition, valves, carburation, and compression right and everything takes off and runs but we do not know which adjustment finally made the difference.   

Carry on Brian.

Gordon


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## ozzie46 (Jun 17, 2021)

No body sys you have to keep reading this thread. those of us that want t keep up with it can and those that don't can just stop.


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## minh-thanh (Jun 17, 2021)

Gordon said:


> I certainly do not agree that this thread should end. Many of us have learned a lot. Many of us who have built engines have had very erratic results when making rings. . It just amazes me that some folks seem to use rather crude methods and seem to have success and others who try to do everything right cannot find the magic combination. I am sure that some things were done correctly and had offsetting incorrect operations.
> 
> Carry on Brian.
> 
> Gordon



With a little bit of my experience : When I make cylinders and rings , of course the cylinders and rings they are not perfectly round and straight , but they can combine to create compression .
  I think the important thing is that the cylinder is not   the ring !


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## clintonntilla (Jun 20, 2021)

Hello all, I've been reading with interest the many ways of producing piston rings for model engines. My experience with making rings started in 1967, I was a spring chicken of about 18 years when I decided to build a model diesel four stroke from scratch. I had a few scribbles for plans, but mostly the plans or ideas were in my head. I lived on my Fathers farm and bought an old lathe as old as the hills, but it served its purpose. I had about two years experience working on a centre lathe at a local engineering firm. Finding scrap aluminium, cast iron from old machinery etc was no problem.
I melted the aluminium in my mothers rayburn "much to her annoyance" but she put up with me. I made everything except the ball races for the crankshaft and valve springs. I had it running on commercial diesel fuel blended with a small amount of model diesel fuel. It was stored for some 53 years until 2020.  when I had renewed interest. Improving the fuel pump and injector and had it running again on 8 parts diesel to 1 part model diesel fuel. It would probably run on 100% diesel fuel when hot. I want to improve the fuel injection system more when I have a chance. I have a small recollection of making the piston rings. Made of cast iron, outside diameter turned to within a few thou of the required size. Cut them and bolted them to a mandrel with a centre screw to grip them and machined them to size with the required gaps preset to whatever size I came up with. Perhaps I should have posted this to general engine building. Hope you enjoy it.&


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## Gordon (Jun 20, 2021)

Interesting that you have five rings. The bottom ring below the wrist pin would not be for compression. What would it do?


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## clintonntilla (Jun 20, 2021)

Gordon said:


> Interesting that you have five rings. The bottom ring below the wrist pin would not be for compression. What would it do?


It's an oil control ring, it originally had two oil control rings, but the original aluminium con rod broke catching the piston. I left it as it is. 
P.S The sump has oil just like most engines and lubricated by the crank splashing in the oil. The oil control ring prevents the oil from migrating past the piston although it also allows the piston to be lubricated.
Regards Paul.


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## Brian Rupnow (Jun 22, 2021)

It's summer time and the livings easy--Kinda sounds like a song, doesn't it. Wife and I have both had our second shots, and we are enjoying summer. My desire to work in my shop is at a very low ebb, but that's okay. We have a visiting grandson this morning who is doing his schoolwork on my wife's computer, so I have found a bit of time to sneak down to my shop. First order of the day was to design something, so I started with Trimble's ring splitter. I am still waiting for my "fine india stone" to arrive, but decided to design the ring splitter in 3D cad. The two square red sections are made from 01 steel, hardened. The rectangular body is aluminum, and the #6 set screws are 3/4" long. The ring shown is 1" o.d. x 0.038" x 0.038".


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## IC-man (Jun 22, 2021)

I can't believe how much effort people go to cleaving thier rings. I've said this before, but just hold the ring with 2 pairs of pliers( close together) and tweek. I've made literally dozens of ring and never had a "duff" one.
Just try it people.
Graham


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## Gordon (Jun 22, 2021)

I just use an end cutter/wire cutter. I cannot believe that a homemade cleaver is going to be any better than a good quality end cutter. Just make sure that the cutting jaws are lined up.


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## IC-man (Jun 22, 2021)

Hi Gordon,
Yep, that would do it. And save a few hours in the workshop.


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## Gordon (Jun 22, 2021)

It has to be an end cutter. Diagonal cutters would not cut evenly.


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## Steamchick (Jun 22, 2021)

I didn't know these methods (above) as I was taught to use a piece of gauge plate on a machine bed (flat and strong) and a gentle tap with a hammer on a sharp chisel. But can't say I have ever done it... that was 55 years ago and I don't  remember everything. Most rings back then came from the Hepworth and Grandage agent's  shop. Collected by muggings using a push bike....
K2


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## Brian Rupnow (Jun 22, 2021)

That 3D mode I showed is made exactly to Trimble's drawing. It seems like a case of overkill to me, but since none of my attempts at ring making have yielded good results I am going to follow Trimble's method as closely as I can.


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## Steamchick (Jun 23, 2021)

Hi Brian. I think you are following the right way. You can prove the cut of the machine with many pieces from a broken ring. I suspect the material will make a difference though. The major factor is probaly the accuracy of the cutting edges aligning... 
I made a device (My job at the time) when developing the method of cutting glass fibres on fibre-optic cables. This was 1976... The first fibre optic cable had been made in USA, and my factory (telephone cable manufacturer) wanted a device for accurately cutting the ends of the fibre optic "glass conductors" for making joints in long cables - as the traditional "silver soldering of copper conductors" was to become partly obsolete.
They had a device, Very accurate, with microscope to see the cut of the carbide tool and fibre against an anvil. But is wasn't robust and "simple" for the factory use, or down a hole in the road or pavement for joining cables "on-site" during installation/repair. I made a machine that applied just a tad of pressure as the blade rocked across the fibre. It cut the glass fibre (which was encased in three materials of polymers as a coating for strength). But not perfectly. However it was used for training purposes, until the "proper" tool became available, about a year later. The first cable made was an experimental 2-pair cable. The first production cable was a 6-pair, to carry the same number of telephones as the existing largest with 1012 pairs of copper wires! Round Glass fibre is different from square cast iron, and you must ensure high accuracy of the blades for opposite alignment. I suggest 2 blades clamped together and ground in a single setting on your tool and cutter grinder? A tad of loctite can hold them together until you have finished grinding.
Anyway, do let us know how you get on.
Enjoying reading your stuff!
K2


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## Richard Hed (Jun 23, 2021)

IC-man said:


> I can't believe how much effort people go to cleaving thier rings. I've said this before, but just hold the ring with 2 pairs of pliers( close together) and tweek. I've made literally dozens of ring and never had a "duff" one.
> Just try it people.
> Graham


before you tweek them, do you score it where you want it to break?


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## IC-man (Jun 23, 2021)

Hi Richard,
No scoring needed, I just use 2 pairs of flat nose pliers right next to each other and twist. It's surprising how little you need to twist. In fact once you hear it break, it can be difficult trying to find where the break is.
Graham


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## Tim1974 (Jun 23, 2021)

All I use is a new bit of hss square about 3/8 I think in the mill in a drill chuck ( yes your chuck will grip it ) it’s not turning so it’s all good and use the quill to put slight pressure on ring in a position in the middle of a t slot or could set your vice jaws to about right I found it so easy no need for fancy tool I think about .034 wide 1 inch dia I did maybe 30 in a batch and maybe 3 or 4 broke on a angle I didn’t like so no reel loss


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## johwen (Jun 23, 2021)

I just push the ring down a Morse taper sleeve easy does it.


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## Jasonb (Jun 23, 2021)

Old pair of end cutters works for me too, gives a nice straight "cut". Can't remember if these were 3/32" or 1/8" wide


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## dsage (Jun 23, 2021)

Yeah. Yeah. We've heard it all before. I do it like this.... I do it like that......
But is there anything wrong with Brian making the dedicated tool to do the job?
BTW there is something to using the proper cleaving method. A similar method is used in cleaving fibre optic cables before the connectors are applied and the ends are polished. Nobody ever told us (at work) to just whack the end off the fibre with a pair of side (or end) cutters. That can crush and fracture the glass.
Continue on Brian.

BTW make sure the two cutter ends meet dead on in all axis' in your fixture. When you lightly tighten the tips against each other they should not shift.


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## awake (Jun 23, 2021)

I think the bottom line is that it is really cleaver to use a clever.

Wait ... maybe I got that backwards ...


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## Henry K (Jun 23, 2021)

Just last night I was watching a "History" program on TV. It turns out that Mr Soichiro Honda, of Honda motors, started his entry into the auto business making piston rings for Toyota. He had lots of problems at first but was then VERY successful in the auto business.


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## Brian Rupnow (Jun 23, 2021)

So, here we have Mr. Trimble's ring cleaver.---does it work? Well yes, I "cleaved" one ring and I already see room for improvement. When you tighten the screws to push the hardened 01 "cleavers" into contact with the ring, they pop up out of the slots, just as I kind of figured they would. I will add my version of a "hold down" and then we will try this again.


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## Brian Rupnow (Jun 23, 2021)

Okay, next step is to add the "Rupnow hold down" to the "Trimble cleaver".


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## yavuzfoz (Jun 24, 2021)

Dear Brian,
I was following topic for a while and few some suggestions about design.
I think you can split the holding profile in the middle and place a slot on A point. So you can adjust it to your thickness. While supporting from B screw you can press from C to split.
Just an idea.




Yavuz


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## Brian Rupnow (Jun 24, 2021)

So, here we have a Trimble ring cleaver, with a Rupnow add-on. The "add on" keeps the cleaver knives from trying to kick upward out of the guide slots when the screws are tightened. In a perfect world, I would have had a ring to "pose" in the picture, but I'm out of rings now until I make some more. I did "cleave" one piece of a ring, just to assure myself that this thing works, and it does (I don't see any difference from the rings that I broke in the vice with my fingers).


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## Brian Rupnow (Jun 24, 2021)

Found something out today. Two weeks ago I ordered a "Fine India Stone" from Sharpening Supplies .com on the internet. Today I went searching for it because two weeks should get it from anywhere in the USA. I phoned Canada Post with the tracking number supplied by Sharpening Supplies. Canada Post informs me that the stone shipped out of Sweden a week ago. What???---Sweden?? Okay, maybe I've been had.  Of course, Sharpening Supplies never indicated that the stone was coming from Sweden. It doesn't really matter, I don't have any urge to do much machining right now, but still----


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## Brian Rupnow (Jun 25, 2021)

It's raining here today. I am fully vaccinated and bored, so I went out this morning and made a tour thru my tool shops. Came home and had a sleep.--And now it's time to move a little farther along with my pursuit of making cast iron rings. This time I wanted to modify the piston on an engine which needs no (or very little) disassembly to access the piston. I've decided that my air cooled side-shaft engine is a prime candidate. It runs very well, and by simply removing the two con rod bolts I can pull the con rod and piston out of the engine without doing anything else. The new piston will be aluminum instead of cast iron (mainly because aluminum is cheaper and I have some here). The new piston will be nominally 0.002" less in diameter than the bore of the cylinder. The rings will be 1 mm (0.039") x 1 mm (0.039") in cross section. The rings will be made following the Trimble method as much as I am able to.


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## Gordon (Jun 25, 2021)

If you make the rings.039 thick you not following the Trimble method. He says thickness should be .043 to .045 x bore. .039 makes wall pressure below 30PSI which he says is too low.


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## Brian Rupnow (Jun 25, 2021)

This is a video made today showing the side-valve engine running. I had to mess around with fuel tanks, but other than that the engine runs very well. Next step will be to make the new piston and rings and install them on the engine without changing any of the engine settings.


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## Brian Rupnow (Jun 25, 2021)

Gordon---I hear you. As I said previously, I am going to follow the Trimble method as closely as I can.


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## Brian Rupnow (Jun 26, 2021)

This mornings work was to machine a new piston with grooves for cast iron rings, setting alongside the old cast iron piston with a Viton ring. The old piston was 1.006" diameter and was almost an air-tight fit in the cylinder. The new piston is 1.005" diameter.  Now I wait until my "fine India stone" arrives from Sweden so I can make the rings.


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## petertha (Jun 26, 2021)

FWIW I've bought a few stones over the years for model engineering purposes. I think India stone is shorthand for aluminum oxide and fine is ?? whatever grit meets your definition. Some I grudgingly bought as singles through the machinery supply places like KBC or Travers due to price. Others from typical sharpening suppliers maybe like you went through. More recently I've been pleasantly surprised at what I've received through AliExpress/Ebay which all come from Asia. It would not surprise me if its the classic middleman / markup game. Equally important is some means to lap them back to flat because they obviously wear with use. Which is yet another stone. Tom Lipton, Rob Renzetti & Stefan Gotteswinter have some good video content on this subject. Anyways good luck on the next ring making chapter. I hope this saves you some money you can invest in a dial bore gauge one day.


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## Brian Rupnow (Jun 26, 2021)

Tomorrow, if it's still raining I will make the Trimble heat treat fixture. It will be made of the same material as the ring itself, so I don't get into problems with differential expansion factors during heat treat. I only show one ring on there, however it will accept up to six rings at once. The round red rod is the "spreader", and if the heat treat is done correctly the red rod should pull out of the fixture very easily. If the rings are still "gripping" the red rod, then the heat treat hasn't done it's job.


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## Jasonb (Jun 27, 2021)

Hopefully you will see this before cutting metal

That does not look right to me Brian, the spacer rod usually ends up needing to be partly cut into the side of the spigot that the rings fir round. Also the rings are a closer fit on the spigot. If you look closely at Trimble's article you will see that at 0.497 from the ctr his 0.150" dia pin hole will need clearance on the 0.941" spigot. As you have it the rings can move about while tightening the top cap which will affect the gap.


What were the figures you used to arrive at those sizes in your drawing?


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## dsage (Jun 27, 2021)

Jasonb is correct. Check your figures Brian.


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## stevehuckss396 (Jun 27, 2021)

Hello Brian!

I am going to assume from your post that your bore is 1.006.

Trimble says your ring should be .043 X .0225.

From your drawing i assumed your groove is already cut to .039 wide so I made actual width of the ring .0375 for a .039 wide groove.

Dowel diameter should be .151. I would use a #24 hardened drill blank at .152

Mandrel diameter should be .950-.951

Dowel should be drilled in at .502 off center.

I agree with JasonB that something in your model looks incorrect. The dowel pin is typically embedded into the mandrel suggesting that in the model, the pin is drilled too far off centerline or the diameter of the mandrel is too small in diameter.


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## Brian Rupnow (Jun 27, 2021)

I was all prepared to begin machining the heat treat fixture this morning, but it appears that I am lost in space. My cylinder bore is 1.006". My rings are going to be .038" x 0.038" (square cross section). The grooves in my piston are 0.039" wide x 0.042" deep.  I had decided to make that red spreader rod 0.150" diameter, but since I haven't made the heat treat fixture yet, I can use a 0.152" diameter. Steve--I don't know where you got that chart from, but I don't have it. Can you please plug my figures into the chart and see what you come up with.---Brian


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## Gordon (Jun 27, 2021)

When the rings are on the fixture should they be a tight fit of the ring id to the fixture od? I may have done something wrong but I have always had a slight gap between the ring and the fixture. I have placed this gap opposite the ring groove. I seem to remember Trimble saying that was normal but I cannot find that now. 

Gordon


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## Jasonb (Jun 27, 2021)

Couple of thou clearance. See text just before and after fig 10 in SIC #7


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## stevehuckss396 (Jun 27, 2021)

The sheet is a little thing I wrote based on the Trimble math. Here it is with the .038 X .038 rings. Notice how that simple changed made for a completely different fixture as for as mandrel diameter and dowel offset. If you are wondering about any further changes I have attached the little ring utility.

Type in the cylinder bore and the utility will give the Trimble numbers for width and thickness. The actual width and thickness can be changed and I do it often. I have a .027 parting tool so I would retain the thickness at .043 but change the width to .0255 mostly because it's easier to groove the pistons and of course I'm lazy. When you enter in what the "real"/ actual thickness and width the rind is going to be, the correct numbers for the fixture and ring groove are calculated. If you go back and edit the actual numbers the dimensions for the fixture are updated automatically. I don't remember but I think I put this in the downloadable files section years ago but I could be wrong.


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## Brian Rupnow (Jun 27, 2021)

I have put in the figures for my application on the left hand side of the columns in pencil, but the resulting mandrel and offset dimensions I arrive at don't look right to me. The ring isn't going to fit down properly on the mandrel using the numbers I have arrived at. My given features that can't be changed are a ring of 1.006" outside diameter x 0.038" square cross section. Can somebody please take a look at this and see where I've gone wrong.----Brian


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## Jasonb (Jun 27, 2021)

Dowel offset in pencil is wrong, you have .484 and Steve has it at .504

So is the mandrel dia, you have it as .954, Steve .960


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## stevehuckss396 (Jun 27, 2021)

When the ring is cracked and sprung open it will be held in a way that the pressure will be evenly distributed around it.

Imagine if you spring open a ring and stick a piece of flat bar in the gap. Almost all the stress will be transferred to the point across from the gap. During the stress relieving process a flat spot will be created directly across from the gap and when sprung closed, that spot will not touch the cylinder wall.

The fixture will hold the rings as best to avoid the deformation of the ring so when sprung closed, it will return to being round again at the correct diameter. 

That's the best I can describe it. Once you build the fixture and get your rings in it tighten it up and heat. I have never had 100 percent good ones so if you need 2 do 5. 2 you need, 2 spares and the last one in case of a bad one.


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## Jasonb (Jun 27, 2021)

using Steves figures I get it to look something like this.

I have clicked on the inner edge of the ring highlighted with the blue line and that is showing a measurement of 2.923"

Pi x inner ring diameter = 3.142 x 0.930 = 0.922"

Thats close enough to the same circumference for me.


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## Vixen (Jun 27, 2021)

Brian,
You appear to have drawn the ring as some sort of oval. The expanded ring will be a *circle* whose diameter will be the circumference of 1.006" plus the distance across the dowel (diameter). 

Mike


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## Brian Rupnow (Jun 27, 2021)

Okay, I've redone the two dimensions for the offset and the mandrel diameter, and redrawn the ring as being circular, tangent to the left side of the mandrel and up against the two sides of the red spacer rod. I think I'm getting pretty close to what Trimble intended. I can go ahead and make the fixtures based on that. When I split my rings (which I haven't made yet), I will have to see if they fit the way this model shows them. If I have to, I can always monkey about with the mandrel diameter after the fact. Thank you Jason and Steve.---Brian


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## Henry K (Jun 27, 2021)

This dialog is very interesting. It also shows why drawings in larger companies often have "drawn By", Designed by", and "approved by".
We (hobbiests) are lucky to have the internet and friends to help check our designs.


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## Brian Rupnow (Jun 27, 2021)

Henry--You are absolutely right. It is nice to have some help once in a while. I appreciate it very much.---Brian


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## Gordon (Jun 27, 2021)

Henry K said:


> This dialog is very interesting. It also shows why drawings in larger companies often have "drawn By", Designed by", and "approved by".
> We (hobbiests) are lucky to have the internet and friends to help check our designs.


I have tried to understand the Trimble method and I understand some of what he is doing but I have never been able to figure out where he comes up with some of his numbers. I can plug in the values and come up with the numbers but I have never been able to figure out where he comes up with something like 1.0072 + .1569 etc. 

You are correct that it is very helpful to have a group like this where we can ask a question and receive input from like minded individuals. For instance last week I asked if there was a way to make custom decals for out engines and I received several answers within a very short time. Frequently it is not even the answer but the information on where to obtain the information.


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## Jasonb (Jun 28, 2021)

I'm not quite sure where he gets those numbers from either.

The spread ring *won't be a true circle*, as Steve said there is a bit more bending going on opposite the split and gradually decreasing to nothing at the split but hard to draw  and certainly not the shape Brian had in his earlier image (mine is not actually completely right either).


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## Jasonb (Jun 28, 2021)

I tweaked my drawing a bit more to have the variable change in radius that Trimble gives where it is more opposite the split than at the split using the internal radius as the one to change but should possibly be along teh neutral axis and eyeballed the 30degree increments so not perfect but good enough for this example.

First sketch shows the dimensions taking radius increase from his chart.

Second is the actual ring from that shape laid onto the fixture. Few gaps are my imperfect sketch.


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## bobden72 (Jun 28, 2021)

stevehuckss396 said:


> The sheet is a little thing I wrote based on the Trimble math. Here it is with the .038 X .038 rings. Notice how that simple changed made for a completely different fixture as for as mandrel diameter and dowel offset. If you are wondering about any further changes I have attached the little ring utility.
> 
> Type in the cylinder bore and the utility will give the Trimble numbers for width and thickness. The actual width and thickness can be changed and I do it often. I have a .027 parting tool so I would retain the thickness at .043 but change the width to .0255 mostly because it's easier to groove the pistons and of course I'm lazy. When you enter in what the "real"/ actual thickness and width the rind is going to be, the correct numbers for the fixture and ring groove are calculated. If you go back and edit the actual numbers the dimensions for the fixture are updated automatically. I don't remember but I think I put this in the downloadable files section years ago but I could be wrong.
> 
> View attachment 126824


Hi do you know of a ring math calculator for mac


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## stevehuckss396 (Jun 28, 2021)

I do not. This one I made for myself but do give it away if it can help others.


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## Gordon (Jun 28, 2021)

stevehuckss396 said:


> The sheet is a little thing I wrote based on the Trimble math. Here it is with the .038 X .038 rings. Notice how that simple changed made for a completely different fixture as for as mandrel diameter and dowel offset. If you are wondering about any further changes I have attached the little ring utility.
> 
> Type in the cylinder bore and the utility will give the Trimble numbers for width and thickness. The actual width and thickness can be changed and I do it often. I have a .027 parting tool so I would retain the thickness at .043 but change the width to .0255 mostly because it's easier to groove the pistons and of course I'm lazy. When you enter in what the "real"/ actual thickness and width the rind is going to be, the correct numbers for the fixture and ring groove are calculated. If you go back and edit the actual numbers the dimensions for the fixture are updated automatically. I don't remember but I think I put this in the downloadable files section years ago but I could be wrong.
> 
> View attachment 126824


It is interesting that your calculator gives a different result than what I come up with using my spreadsheet calculator. I entered a 1.25 dia ring and my spreadsheet and I come up with M=1.1804 and Offset = .6232. Your calculator gives M = 1.1607 O = .625. 

Petertha also shows his spreadsheet in 
piston-rings-trimble.32899/ 
and his calculations and formulas are the same as mine.

I am not saying that your calculator is wrong. I may have done something wrong. I would be happy to send you my spreadsheet if you are interested. Lots of different opinions here.

Gordon


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## stevehuckss396 (Jun 28, 2021)

I can go back and see what I did. How many decimal points did you go when calculating. You got me curious. I'll check it out when I get home from work


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## Gordon (Jun 28, 2021)

Steve: I sent you a copy of my spreadsheet.


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## stevehuckss396 (Jun 28, 2021)

I cant check my stuff. I was forced into a windows 10 computer when the old one quit. It wont let me install my Visual Basic 6.0. Says it wont run.


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## Brian Rupnow (Jun 28, 2021)

Today I made the Trimble heat treat fixtures. I managed to hit the numbers "right on", so if my cleaved rings fit, the fixture and the rings go into my new heat treat oven for 3 hours at 1100 degrees F. 
I decided at the last minute to make the fixtures from mild steel instead of cast iron, but I don't think it will make any difference.  Why is the head turned on that 5/16" cap screw?---I really don't know, but that is the only 5/16" cap screw that I could find around here.


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## Ghosty (Jun 28, 2021)

stevehuckss396 said:


> I cant check my stuff. I was forced into a windows 10 computer when the old one quit. It wont let me install my Visual Basic 6.0. Says it wont run.


Steve, just set up another computer as a stand alone( not connected to the web) and load the older windows system, I have one set up with XP to run my old film scanning progs and I also run Autocad 14 on it.
Cheers
Andrew


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## stevehuckss396 (Jun 28, 2021)

Yeah I dont have another computer or I would consider that. Right now the plan is to try to find a  newer version of visual basic


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## doc1955 (Jun 28, 2021)

Steve you should be able to run it just click on it and go to properties and set it to run with xp capabilities I know that worked for me in windows 7 for a program I used. I would think 10 would still have that option.


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## stevehuckss396 (Jun 28, 2021)

I cant even install it. Windows wont allow it


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## doc1955 (Jun 28, 2021)

You could also create a virtual box and try that to install.


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## petertha (Jun 28, 2021)

I'm curious about the Trimble bolt selection. Actually he says _5/16-32 TPI_. He used the same (cast iron) material for fixture but says (among other things) '_I doubt that this is very important_'. Then _'the dowel & bolt are stainless steel so they wont lose all their strength as the cast iron does at its annealing temperature_' and '_I think the material for the dowel and bolt is important_' and '_there is no reason to to tighten the bolt more than finger tight_'. 

So how this collectively converges on a choosing a 5/16-32 TPI stainless bolt torqued to finger tight is above my pay grade, especially considering he wasn't fussy about the fixture material.


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## Brian Rupnow (Jun 28, 2021)

I read somewhere in all of my junk that Trimble got the thread pitch wrong. Fine threads don't like to turn after heat treat. He also contradicted himself on the type of material to use on the heat treat fixture.


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## petertha (Jun 28, 2021)

Right you are - under the infamous SIC Errata. "_Should read 5/16-8_", "_George would have used a coarser thread if there was one readily available_".


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## petertha (Jun 28, 2021)

It appears stainless has higher thermal coefficient of expansion (E-6 in/in). Which would infer... the bolt is growing slightly = loosening. But the dowel pin is growing = expanding (ever so slightly) at elevated temp??
303 stainless = 10.9
Cast iron = 5.8
4140 = 6.8
A36 = 6.5

table here, different units




__





						Thermal Expansion            - Rolled Alloys, Inc.
					





					www.rolledalloys.com


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## Brian Rupnow (Jun 28, 2021)

Trimble used numbers in his calculations that are of unknown origin. They may be "constants", but if they are, I don't know what they refer to. If you have a spread sheet to do the calculations, where you just plug in the known values and the spread sheet kicks out the answers, then that's great. If you try and do it on a calculator, it's pretty iffy because you don't know what his numbers are referring to.


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## Gordon (Jun 29, 2021)

I am sure that a lot of folks would love to get Trimble on a forum like this and ask some questions. Primarily they would like to know what is critical and what is open to modifications. Things like how critical is dowel dimeter if other parts are changed accordingly, how critical is material, and how did he arrive at some of his calculations.


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## Brian Rupnow (Jun 29, 2021)

This is my interpretation of the Trimble deburring station. One side of the ring is chamfered and deburred before the ring is parted from the parent stock. The other side of the ring, after parting off will need deburring and chamfering. This is the station that allows you to do that. The good side of the ring is butted up tight to the shoulder on the blue piece, the the bolt is tightened to pull the yellow piece into the blue, causing it to expand and grip the ring, leaving the second side of the ring exposed so it can be deburred and chamfered.


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## awake (Jun 29, 2021)

doc1955 said:


> You could also create a virtual box and try that to install.


That was going to be my suggestion if no one else suggested it. I have a Windows XP virtual machine (and a Windows 10 virtual machine) available on my Linux laptop - I use these on the rare occasions when I need to access something that is only available on Windows or on an old Windows platform.


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## Sprocket (Jun 29, 2021)

As I read the Trimble articles, and he talked about all the rings he made and tested in the V8, I had to wonder if he  ever finished that engine....
I never saw anything about it running, other than external power, but maybe I missed that.
Doug


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## Brian Rupnow (Jun 30, 2021)

Here we have the internal expanding mandrel, which holds the ring while the "bad" side of the ring is deburred and chamfered. (The other side of the ring was chamfered and deburred before it was parted off from the parent stock). I even have a ring shown on the end of it, although that ring isn't the right ring, it's just one of the old rings I had around. You will notice that the main body of this tool is much, much longer than the solid model.---This is why---My 3 jaw chuck never can grip something twice in a row, without grabbing it a little differently. This shows up with a dial indicator, even if it's hard to see with the naked eye. So, my thoughts were, if I want to use this tool more than once, I should do something to guarantee that I always grip it the same way, in the same place. My lathe spindle is 1 1/2" thru the bore, so on the far end of this 1 1/4" diameter main body I have a ring of material 1.499" in diameter, and have the other end stamped 1, 2, and 3 to correspond with the chuck jaws. When installed, the ring of material is flush with the far end of the spindle. This brings me to a point where there are no more fixtures to build. All I need now is that damned fine India stone which is somewhere between Sweden and here. I am going to call "Terra Nova Steel and Iron inc. in Mississauga this afternoon and see if they will sell me a 12" length of Durabar to make rings from. I doubt very much that I need to do that, but I am not leaving any stone unturned in my quest to make working cast iron rings.


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## dsage (Jul 1, 2021)

There is one more fixture that is not covered by Trimble but is pretty handy to have. After annealing, the sides of the rings need to be polished and possibly to bring the rings exact thickness to fit in your piston ring grooves. It's a puck of metal with a shallow pocket machined into the end - shallower than your ring is thick.
It's used as a handle to hold a ring while you polish the sides of the ring by hand pushing it around on a flat surface with wet/dry paper.


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## Brian Rupnow (Jul 1, 2021)

Dsage--I have that fixture already, left over from previous ring making adventures.


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## Brian Rupnow (Jul 2, 2021)

Today my "fine India stone" arrived in the mail. If it had been holding me up on a project I could get really ugly about how long it took to get here. However, it hasn't held me up, as I had three fixtures and a new piston to make before it would be needed anyways, and I just finished the third fixture yesterday. Now all that is left is to make the rings. Wish me luck!!!---Brian


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## GreenTwin (Jul 2, 2021)

I tried making cast iron rings, and found that it is not that difficult to do.
After a few practice rings, I was able to easily make some nice cast iron rings.
I have seen various methods for parting the rings.
The method I used was to place flat-nosed pliers immediately adjacent to each other on the ring, and rock them ever so slightly back and forth until the cast iron fatigues and breaks.
Then I lightly cleaned up the ends at the break.
Worked fine.

For low-rpm steam engine work, it is not much of a problem to get the correct ring clearances.
For a high-rpm model airplane engine with very tight tolerances, I guess a lot more care would need to be paid.

I leave a slight amount of clearance to allow for expansion due to steam.
I prefer cast iron rings because "they wear like iron", LOL, they are iron, but also because as a model builder, I love the challenge of trying to make the engines like they were made in the day, not that there is anything wrong with the modern materials.
Its like standing in front of Everest; do you ride the cable car up to the top, or get out the ropes and carabiners and start climbing?

Edit:
For now, I turn my rings to the same size as the bore (actually slightly smaller for expansion), and then expand the ring and heat it, to spring it out.
I have dabbled with making oversized rings that are sprung inwards and turned to final size, but that takes quite a bit more work, and I have not mastered that technique yet.

.


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## Brian Rupnow (Jul 2, 2021)

Second oldest grandkid just graduated from public school. She's a pretty girl.


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## Brian Rupnow (Jul 2, 2021)

So-----------Here we are again. A new batch of rings, made from fine grain grey cast iron. I used my "special grind" HSS grooving tool to part these rings off. Each ring is 0.044" wide, which leaves a small bit on each side for "clean up" on a sheet of 600 grit paper. I hit the numbers perfectly on the o.d. and the i.d. and made 8 rings, of which I only need two. My opinion on the "Fine India Stone" that I bought---It doesn't do anything that a piece of 220 grit paper held against a flat file won't do. I may have wasted my money buying it 
 but I'm trying to follow everything that Trimble suggests. Next step will be to mount each ring on the Trimble fixture and deburr/chamfer the side which was not deburred/chamfered before it was cut off from the parent stock. If these rings don't work, there is enough turned material on the "parent stock" to make new rings 0.045" thick, same as Trimble did.


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## GreenTwin (Jul 2, 2021)

There is nothing like the smell of freshly parted piston rings in the morning.........
A beautiful sight for sure.

.


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## Ghosty (Jul 2, 2021)

Brian, I don't use a file, I use a piece of alloy flat bar 1" wide and 3/8" thick to hold the emery paper, files have bumps on them the alloy flat bar does not.

Cheers
Andrew


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## Brian Rupnow (Jul 2, 2021)

The rings have been sanded on both sides with 600 grit paper on a flat cast iron surface plate to 0.038" thick, and tried for fit into the grooves on the piston. This picture is the Trimble deburring fixture that "sorta kinda" works. Ring is placed on end of fixture in a "step" machined in the end of the fixture and then the cone is pulled in by the bolt to expand the fixture and hold the ring for deburring. I don't think I would dare to use a cutting tool on the ring because I'm sure it would fly off. However, it does seem to hold the ring secure enough that I can get in there with a piece of 240 grit emery paper and knock off any burrs, both on the o.d. and the i.d. of the exposed side of the ring.


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## Jasonb (Jul 3, 2021)

You have not followed the Trimble method again. The idea of the fixture to hold the rings is that you can face them all to correct size (0.038") in your case and ensure they are parallel, rubbing that amount off the rings is unlikely to give an even section. It's only after annealing that Trimble says rub them if any are a bit oversize.

I believe he also faced the exposed end of each ring before parting off from the "tube" as it gives a better finish than parting, looks like you just sliced a stack off.

As Andrew says I always use a bit of flat back to back up abrasives not a file as did Trimble in the text.


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## Brian Rupnow (Jul 3, 2021)

Out of 8 rings, 4 survived the polishing, deburring, and gapping. The four that didn't was because of a mistake on my part. I have a 1.006" hole thru that round piece of cast iron (same as the cylinder bore) and I used it as a guide for gapping the rings to a 0.004" end gap when squarely inserted into the hole. Surprisingly, Trimble doesn't cover this gapping procedure at all. He just says to run a piece of fine emery paper between the cleaved ends of the ring. The surviving four which are on the heat treat fixture will now go into my heat treat oven at 1100 degrees F for three hours.


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## petertha (Jul 3, 2021)

(page 8) '_before putting the ring on the mandrel, give it a swipe on 400 grit paper on the side already faced, in case there is a burr lurking somewhere. Put the ring on the mandrel.._.'

My interpretation is this is very light precautionary cleanup, but not altering the cleaved ring part line in order for the heat set to work. The gapping occurs
after heat set. If you are gapping now & putting on the fixture it will surely heat set differently, no?

**edit** Jasonb pointed out in #484 that I grabbed the wrong text above. Thanks for correction. The relevant verbiage is :
_..cut them with a cleaver. After cutting the first one, find the split - it where the tiny shiny spots are that are left by the knives. Pull the gap apart a little and look through it against a bright background with a low power magnifier. You will see that the cast iron has separate along grain boundaries and the grains stick out into the gap beyond the knife marks. If you put that ring on the spreader, the neutral axis will be too long. Allow the rings to close and the grains will interlock so that you cannot move the gap faces sideways with respect to each other. So pull a piece of 400 grit through the gap gap two or three times until the interlocking disappears_...


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## Jasonb (Jul 3, 2021)

Peter, that quote is before he even splits the rings. This just removes any micro burr from the internal chamfer cut.

Brian you don't gap the rings until after heat treat, Trimble jays just pull a bit of folded 400g paper through the split a couple of times to flatten the "grain" of the Cast iron. As Peter says your rings won't be opened up as much now that you have prematurely gapped them See last couple of paragraphs page 8

Trimble describes gaping the rings in part 3


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## Jasonb (Jul 3, 2021)

Brian, why the change of diameter of the pin, the top ring is not going to get opened as much as the others?


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## petertha (Jul 3, 2021)

Jasonb said:


> Peter, that quote is before he even splits the rings. This just removes any micro burr from the internal chamfer cut.



Good catch, thanks Jasonb. I had one foot out the door & was hoping to mention before Brian gapped and/or heat set them. My eye saw '400 grit paper' but of course he uses same for different steps. I corrected my post #483.


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## Brian Rupnow (Jul 3, 2021)

Must be camera angle. That pin really is 0.150" diameter over it's full length.


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## Brian Rupnow (Jul 3, 2021)

These are the rings about two hours after heat treat. Lots of black crud on both rings and fixture, but it seems to brush off very easily. Tomorrow I will take the heat treat fixture apart to free up the rings and clean them individually.


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## stevehuckss396 (Jul 3, 2021)

Just rub them down with a scotchbrite pad to clean them up. Then remeasure and polish on your.new stone if they have grown in width.


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## Brian Rupnow (Jul 3, 2021)

All of the black crud came off very easily with a brass bristled brush. The rings have "taken a set" at the required gap (0.150").


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## Brian Rupnow (Jul 3, 2021)

Rings are installed on piston (lots of 30 weight oil and very deft fingers). Piston is installed in cylinder, rod cap bolts are back on, and engine has excellent compression. I'm not going to try and start the engine tonight. I have trouble sleeping as it is, and if I start this engine tonight I will be too revved up to sleep. This is all looking very positive, and tomorrow morning we will see if the engine runs.---Brian


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## 926wolf (Jul 4, 2021)

I have learnt so much in such a short time keep up the good work


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## Brian Rupnow (Jul 4, 2021)

Ladies and Gentlemen--I have a thrilling announcement to make. My engine runs with my own home brewed cast iron rings. This is the first time ever for me to successfully make my own cast iron rings to run in one of my engines. I followed about 80% of the Trimble method of making rings. This makes me feel very good.---Happy Dance-Happy Dance!!!!----Brian


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## lee webster (Jul 4, 2021)

If I ever make an engine that sounds that good I will be a happy man!


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## propclock (Jul 4, 2021)

Fantastic!!! On the 4th of July no less, now you can declare independence from  purchased
or un obtainable rings.  Now that is sticking with it!   Congratulations.


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## dnalot (Jul 4, 2021)

I would like to see video of your happy dance. 

Mark T


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## petertha (Jul 4, 2021)

Great to hear, congrats.


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## Vixen (Jul 4, 2021)

Well done Brian,

You got the result you wanted, despite the stream of rude and offensive comments from one particular person on this and other forums

Mike


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## kuhncw (Jul 4, 2021)

Congratulations, Brian.

Chuck


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## minh-thanh (Jul 4, 2021)

Brian !
Patience pays off .
Congratulations !
And thanks for sharing .


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## GreenTwin (Jul 4, 2021)

Those rings will last a very long time, and will hold up under load too.
Congrats.  Very nice.
.


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## Steamchick (Jul 4, 2021)

Well done Brian. An excellent result!
K2


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## stevehuckss396 (Jul 4, 2021)

As long as your bore still has a decent cross hatch that can retain a little lube, your rings will actually get a little better.

Congrats sir!


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## stevehuckss396 (Jul 4, 2021)

As long as


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## GRAYHIL (Jul 4, 2021)

I have been reading your post with admiration for your perseverance  and patience.
Congratulations
Grayhil


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## Ghosty (Jul 4, 2021)

Brian,
Congrats on moving to cast iron rings, it sounds like it is running better than when it was running on an "o"ring
Again, great work to see it through, lots of info came forward as well.
Cheers
Andrew


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## doc1955 (Jul 4, 2021)

Way to stick with it Brian as you run it, it should get better and better congrats!


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## Nerd1000 (Jul 4, 2021)

Fantastic, I knew you could do it!


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## Brian Rupnow (Jul 4, 2021)

This post is not so much about rings, but it does show something very important. I am always amazed at how much a difference in gas tank height affects an engine. When I built this engine a few years ago, I had made a gas tank to fit underneath the cylinder, with a 3/32" diameter check valve in the discharge. This year when I went to start it, I couldn't get it to draw fuel up from the tank. Okay, when these engines set around on the shelf for years, check valves have a tendency to freeze up. That wasn't a big deal, I just grabbed a spare gas tank I had and mounted it on a block of wood. This allowed me to start the engine and see that it actually did run. After putting the cast iron rings in, the engine would run good for four or five minutes and then die, as if it were running out of fuel. When everything else is set at "optimum" and the engine dies for no good reason, I always suspect the gas tank height. In this picture you see a 1.6" tall aluminum spacer under the tank. That fixed it!! Now the engine will run until I turn it off with the switch in the electrical system.


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## Tim1974 (Jul 5, 2021)

Nice work it’s been interesting  reading with a good ending thanks for hanging in there and well dun


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## ShopShoe (Jul 5, 2021)

Congratulations Brian. I am doing a mental happy dance for you this morning. I follow all your adventures and I have to say again that you get the stick-to-it-iveness award again for seeing this through. 

Take a well-deserved break and be assured that I will be watching whatever you do next.

--ShopShoe


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## Badhippie (Jul 5, 2021)

Brian 
Nice job why to work through a problem


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## Brian Rupnow (Jul 5, 2021)

-Every once in a while, I run into something that I don't think I'm going to be able to do.---and that worries the Hell out of me. I've always been the man who can do anything, and I hate to think that there is something that has defeated me. I'm happy that I was able to finally get some workable rings and a "process". Not bad for a "geezer". I'll be 75 this Wednesday.


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## Gordon (Jul 5, 2021)

I am not sure that it is a "process". Looking at some of the replies it appears to be a religion or perhaps even more serious.

75 is not geezerhood. I will be 81 at the end of the month and I still learn new things. Well perhaps I am just relearning things that I forgot. I am finding it very easy to forget things. I can pick up a part, set it down and spend the next 15 minutes trying to remember where I set it down. That is frequently without even moving away from the spot.


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## awake (Jul 6, 2021)

Well done and congratulations, Brian!


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## oldengineguy (Jul 6, 2021)

Hey Brian .I turned 75  end of April  and I am NOT a Geezer, Opinionated old fart  yes  but to be a Geezer youv'e got to be OLD. Great job on the rings by the way. You are an inspiration.   Colin


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## Bentwings (Jul 6, 2021)

johwen said:


> Hi Brian,
> I'm sorry I did not know you had no access to Trimble articles, so having a full copy of SIC I have copied all the article and put them on 2 PDFs for you.
> Hope this helps you overcome your difficulties with the rings. Frances Washburn was suppling copies but the web site is not working so maybe she is no longer able to continue. If you have any questions give me a shout. Cheers John. These files are the basic Trimble method that I follow however the full Trimble description is more detailed in many issues. J.
> 
> ...



thank you I’ll have more reading material. Better than Netflix.
Model rings are quite different from full size top fuel engines. Even bore finish is different.   A supercharged engine can lift the top of the piston off in a heart beat. Then burn the top of the aluminum rod ubtilit fails. Then you have a big mess. I’ve always been a fan of plenty of top ring clearance. We leak tested our engines years ago and found no real advantage in tight end gaps. Plenty of disadvantages. Our old Briggs engines had plenty of clearance too. Fuel spark and correct timing and they ran great. My current mower has got to be 20 yrs old still runs fine smokes a little but runs every time. .004” per inch of bore was good for about everything except blown top fuel. Then more was better.LOL
I think it was early 60’s when rings went to moly filled . That took care of most issues. My dodge diesel truck has 42k on it doesn’t use oil doesn’t smoke.but it’s diesel so much better lived. My Streetrod was super charged an tan fine after 34k miles. Never used oil it did have more top ring gap but never changed leak down or compression test.  Got 15 mpg about as good as any unbloen cars I cruised with.


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## johwen (Jul 7, 2021)

Brian Rupnow said:


> -Every once in a while, I run into something that I don't think I'm going to be able to do.---and that worries the Hell out of me. I've always been the man who can do anything, and I hate to think that there is something that has defeated me. I'm happy that I was able to finally get some workable rings and a "process". Not bad for a "geezer". I'll be 75 this Wednesday.


"Happy Birthday" Brian your now as young as you will ever be so have a great one. John


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## Brian Rupnow (Jul 7, 2021)

And today we get to see how slow the engine will run. I've got about an hours continuous run time on it now, and as those cast iron rings "bed in" the compression gets higher and higher, and consequently the idle speed can become less and less. I'm pretty impressed with this.


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## dsage (Jul 8, 2021)

YES. Very impressive low RPM running. Good work.


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## OscarII (Jul 9, 2021)

Brian Rupnow said:


> This post is not so much about rings, but it does show something very important. I am always amazed at how much a difference in gas tank height affects an engine. When I built this engine a few years ago, I had made a gas tank to fit underneath the cylinder, with a 3/32" diameter check valve in the discharge. This year when I went to start it, I couldn't get it to draw fuel up from the tank. Okay, when these engines set around on the shelf for years, check valves have a tendency to freeze up. That wasn't a big deal, I just grabbed a spare gas tank I had and mounted it on a block of wood. This allowed me to start the engine and see that it actually did run. After putting the cast iron rings in, the engine would run good for four or five minutes and then die, as if it were running out of fuel. When everything else is set at "optimum" and the engine dies for no good reason, I always suspect the gas tank height. In this picture you see a 1.6" tall aluminum spacer under the tank. That fixed it!! Now the engine will run until I turn it off with the switch in the electrical system.


As another old fart engineer I would like to add by 2 bobs worth to the discussion. . I have now idea of Brian's experiences except he produces some damn fine models and his posts have helped me in the past. To the problem of fuel feed and raising the tank it sound to me to be about basic fluid flow. This type of problem is found all through the world of pumps and pipes.  An easy fix is to increase the fuel pipe ID and that of the check valve. I have had these problems in water supply to boiler pumps. Each small elevation of the fuel tank has the equivalent of enlarging the pipe ID. Every fitting or bend in the fuel line has the equivalent of lowering the pipe ID.  Apologies to those who already know all this, Peter


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## Steamchick (Jul 9, 2021)

What a good engine to celebrate your birthday with.
Happy Birthday young man! (I am still 37 in my head - I have been for 30 years.... How old do you feel?). Bodies and minds measure time differently. Keep the brain busy and stay young.
K2


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## Badhippie (Jul 9, 2021)

Brian 
I missed your birthday sorry about that. 
Happy Birthday Late. Lol my Dad always told me I would be late for my own funeral lol which by the way I don’t think that is a bad thing lol.
Thanks 
Tom


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## Brian Rupnow (Jul 9, 2021)

The curious thing about being old, is that unless my arthritis is killing me, I feel like a young man. I would say that overall, I feel more like forty or fifty, but with 25 years more experience. I always used to think that when I got old, I would only be able to do old man things. it really isn't like that.---Brian


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## Badhippie (Jul 9, 2021)

The old saying is your only as young as you feel 
Tom


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## Charles Lamont (Jul 9, 2021)

OscarII said:


> ...] To the problem of fuel feed and raising the tank it sound to me to be about basic fluid flow. [...] Each small elevation of the fuel tank has the equivalent of enlarging the pipe ID. Every fitting or bend in the fuel line has the equivalent of lowering the pipe ID. [...



Well, yes OK, but In the case of fuel flow to a model engine, the flow velocity is so tiny that bends, fittings, and pipe resistance are going to be insignificant. This is why you can get away with banjo fittings in fuel lines. Without a float chamber, and with any reasonable pipework, the flow restriction is overwhelmingly at the jet needle. Given a particular setting of the needle, what affects fuel flow is (a) the ability of the carburettor to create a vacuum, and (b) the head, i.e. the distance the fuel surface is above or below the jet. As the fuel level drops, the available vacuum becomes insufficient to lift fuel to the jet.


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## IC-man (Jul 10, 2021)

Well I feel like a 18 yr old.....anyone know where I can find one.


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## Badhippie (Jul 10, 2021)

They are smart enough to stay away from us ic-man lol
Tom


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## Gordon (Jul 11, 2021)

I have a question about ring grooves in the piston. Trimble says the width of the groove should be .0015 wider than the ring width. I have a note that says the groove depth should be .003 deeper than the ring thickness. I cannot seem to find that in the Trimble article even though I thought that is where I got that dimension. I seem to keep having a problem with the installed ring bottoming out and jamming when installed in the cylinder. I suspect that at least part of the problem is that the bottom of the groove does not have a perfectly square corner. Any idea where that dimension came from and is it correct? Would another few thousands make a big difference. It would seem like the width would be much more important.

Gordon


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## cds4byu (Jul 11, 2021)

Bob Shores suggests to make rings from the same bit of cast iron as the piston.  It starts with the diameter .003 oversize, and ring grooves cut .003 "deeper than specified".  I don't think that is describing the depth of the ring groove to be .003 less than the ID of the compressed ring, but rather recognizing that you are working on an oversize workpiece.

Trimble does not give a specification for the difference between the ID of the ring and the OD of the ring groove.

Walshaw suggests that the clearance behind the rings (I interpret this to be the radial clearance between the installed ring and the OD of the ring groove) should be .004 for compression rings and .010 for oil control rings.

Personally, I don't think a few thousandths extra is a huge problem.  But I would be looking at (1) the corners of the ring groove (make sure your grooving tool has sharp corners) and (2) the internal corners of the ring (make sure there are chamfers on the ring).

Carl


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## petertha (Jul 11, 2021)

On page 7 (Apr/May-1989) Trimble says his objective groove clearance gap was 0.0005 - 0.001". This is the vertical distance viewing the piston from the side with the ring resting on one side of the ring gap.

Terry.M has provided a sketch for several of his successful builds. I believe he follows a similar recipe each time - Trimble ring math for the ring design & ring fixture and 0.001" vertical ring groove clearance. Post #453 has the sketch & Trimble equations all nicely laid out. 270 Offy


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## Brian Rupnow (Jul 11, 2021)

Your numbers are right. 0.0015" side clearance and 0.003" greater groove depth than the rings radial thickness. If you don't have a specially ground tool to cut the grooves in the piston, the grooves will have a radius in the bottom.  You have to do a really good "sand and chamfer" operation on the inside corners of the ring or it will hang up on those radii.


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## Gordon (Jul 11, 2021)

petertha said:


> On page 7 (Apr/May-1989) Trimble says his objective groove clearance gap was 0.0005 - 0.001". This is the vertical distance viewing the piston from the side with the ring resting on one side of the ring gap.
> 
> Terry.M has provided a sketch for several of his successful builds. I believe he follows a similar recipe each time - Trimble ring math for the ring design & fixture and 0.001" vertical ring groove clearance. Post #453 has the sketch & Trimble equations all nicely laid out. 270 Offy


That is interesting. He is showing .0065 clearance behind the ring which is over twice what I have been using,


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## mayhugh1 (Jul 11, 2021)

Gordon said:


> That is interesting. He is showing .0065 clearance behind the ring which is over twice what I have been using,


I do that to compensate for the non-zero radius of my grooving tool so the ring doesn't bottom out on a radius left behind in the groove. I can't see how the actual distance between the back of the ring and the facing wall of the piston is critical so long as there's space for compressed gas to flow between them and force the ring against the wall of the cylinder during combustion. - Terry


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## stevehuckss396 (Jul 12, 2021)

Unless the tool is perfectly on center you are not cutting as deep as you think. I cut my grooves .005 to compensate.


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## mayhugh1 (Jul 12, 2021)

stevehuckss396 said:


> Unless the tool is perfectly on center you are not cutting as deep as you think. I cut my grooves .005 to compensate.


good point ...


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## Gordon (Jul 12, 2021)

It appears that I have been overly concerned over the groove depth. There is no such thing as a perfectly square corner and if the chamfer is not big enough there is interference. 

I am presently working on an engine which was marginal running on CI rings and to proceed I put in an O ring and the engine ran well except that the only O ring I had was Butyl and after a short time of running it hardened up and was not sealing. I always intended to go back and get the CI rings right and that is what I am doing now.


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## Henry K (Jul 12, 2021)

Congratulations. Really impressive.


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## LorenOtto (Jul 12, 2021)

Brian Rupnow said:


> The curious thing about being old, is that unless my arthritis is killing me, I feel like a young man. I would say that overall, I feel more like forty or fifty, but with 25 years more experience. I always used to think that when I got old, I would only be able to do old man things. it really isn't like that.---Brian


At 78 I can second that.


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## petertha (Jul 12, 2021)

I think piston ring grooves & retaining ring grooves are the few times I used my blade micrometer. It cant accurately measure corner radius at these widths of course, but they are handy for similar applications. I initially tried to take the groove measurement using conventional mic & little slivers of gage block in the groove but it was pretty fiddly. Mind you, I am also not very good at 3 wire method measuring threads and I have a soft spot for tools.

I will dig up my notes but I seem to recall the commercial (O.S.-56) piston/ring I used as a guide for my radial was pretty close to the gaps being discussed here. The inner corners of the ring had no appreciable chamfer so I think they are similarly relying on the groove depth to not cause interference problems.


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