# Old School Barstock 2 Stroke



## Brian Rupnow (Feb 14, 2016)

In my quest for a simple two stroke engine which I could make from barstock, I looked at many different engines. I didn't want a high rpm screamer with a propellor, nor did I really want to use a design that required me to make rings and figure out how to get them past the ports without breaking them. I also wanted to use spark ignition with Naptha (Coleman fuel) as the fuel, mixed with a bit of 2 stroke oil.--and the potential of maybe experimenting with a glow plug. The 1912 Hubbard Marine engine model seemed to offer up everything I was looking for. It has a 24 mm bore, and a 25 mm stroke, no rings, is water cooled, port induction. and a whopping great compression ratio of 4.45:1. The main body is an aluminum casting with a steel liner. There are videos of this engine running on the internet, and from my research, many have been built and ran successfully. After much messing about, I have come up with a design using barstock which copies all of the Hubbard engines critical dimensions and port dimensions. At first glance, it is uglier than Frankenstein's bulldog, but it does hold a lot of promise.


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## Brian Rupnow (Feb 14, 2016)

I have been able to incorporate adjustable ignition timing, and my old standard Chrysler ignition points. The carb shown is a Traxxas Pro15. The piston and the liner will be machined from cast iron. Almost everything else except the flywheel and crankshaft and crank bearings will be from aluminum. The crankshaft will be "two piece"--that is to say, the main crank, the crank throw, and the rod journal will be 3 parts pressed, pinned, and Loctited together forming one "Piece", which will support the flywheel and be driven by the connecting rod. The other crank throw and shaft which runs out to drive the ignition cam will be pressed, pinned and Loctited together to form the second "piece". This second piece is actually a "follower crankshaft" which is driven by the rod journal fitting with a "slip fit" into the crank throw. This helps greatly with alignment issues between the crankshaft and bearings.


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## Brian Rupnow (Feb 14, 2016)

This shows the overall dimensions of the engine. I will be posting the detail drawings as I make the individual parts. I will not post them before making the parts, because I have found that quite often the machinist at my house has to go back and remind the engineer at my house that "You can't make it this way!!!---Change the damned drawing please!!!


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## canadianhorsepower (Feb 14, 2016)

> This shows the overall dimensions of the engine


. 

Brian those dimension give me .69 cu in not 1.2:wall:

and the location of the carb on your drawing need a rotary valve or 
reed valve and their is no mention of this.??


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## Brian Rupnow (Feb 14, 2016)

Luc--I checked the original drawing file and they list the displacement as being 13 cubic centimeters, which converts to 0.8 cubic inches. My solid modeling program gives me 0.89 cubic inches, and I trust it more than the cubic inches given on the original drawings. The cylinder head is a pretty funky shape, and extends way down into the top of the cylinder, which makes the math somewhat difficult. You're right about the reed valve on the carburetor.--Actually, I had another look at the old drawings, and the carburetor has a 1/4" steel ball valve setting in a vertical tube against a seat. The vacuum in the crankcase lifts the ball and draws air/fuel mixture in thru the carburetor. As soon as the vacuum turns to pressure, the ball is dropped back into the seat by a combination of gravity and pressure from the crankcase side.


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## Brian Rupnow (Feb 14, 2016)

The original plans have an elliptical cam machined on one side of the flywheel, which operates a short stroke piston pump to circulate the water. I don't know right now if I will do the same or not. First thing will be to get the engine to run, with just a plain Jane disc of metal as a flywheel. Then, if I get it to run at all I will worry about refinements like a cam and waterpump. Willy--I'm as confused as you in regards to the glow plug. I have never used a glow plug, but like you I thought they would only work with a "specialty" fuel with a low combustion point. Also, by my understanding, a much higher compression ratio is required to run with a glow plug. The plan set I have says that this engine runs really well with a "glow fuel" and a glow plug, and is very easy to start by hand. It also says that the engine works just fine with a conventional spark ignition system and plain "gasoline" but that it is more difficult to start by hand. I never start my engines by hand anyways. God created variable speed drills to start engines with. As far as a degree plate on my variable timing---No, not likely. I find that the variable ignition timing is wonderful for first start ups. Then, after I find the "sweet spot" where the engine runs best, I lock up the variable timing and probably never use it again. On engines with a wide range of speeds, it is great to have timing that you can advance as you open the throttle. I have seen one of George Britnell's engines that does that, with the ignition advance mechanically linked to the throttle advance.---Sweet!!!. However, this particular engine has a moderate range of throttle induced speed, so I will find the optimum timing setting for a low idle and lock it up there.---Brian


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## barnesrickw (Feb 14, 2016)

This looks like the low RPM two cycle I was looking for.  Please build this so I may watch.


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## Brian Rupnow (Feb 15, 2016)

This is a totally new one on me!!! I have never seen this type of throttle control and one way valve on a carburetor before. There is a needle valve and metering jet directly below the brown 1/4" ball bearing, which "floats" in the vertical passage. When the piston travels upward, it creates a vacuum in the crankcase, which allows atmospheric pressure to lift the ball of it's "seat" against the tube immediately below it and be sucked into the crankcase, picking up a charge of fuel on it's way past the metering jet immediately below the ball. Once the piston has reached the top of it's movement and starts back down the cylinder, pressure builds in the cranckase, and that pressure, helped by gravity push the ball back onto it's "seat" and prevents backflow of pressure thru the carburetor.----And the really neat thing is that the red screw on top of the carburetor is threaded, and screwing it in or out determines how far the ball can lift off the seat, thus giving throttle control!!! this is very old school, and very clever.---I love it!!! Apparently this system works best with the fuel tank ABOVE the carburetor, depending on a gravity feed to the carburetor, and you must have a fuel shut-off valve on the tank for when you are not running the engine.


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## Brian Rupnow (Feb 15, 2016)

Some advice please.--Before I go any farther with this design, I decided it would be smart to see if the main body was going to fit into my 12 x 28" metal lathe and still spin for boring the main bearing hosing. It does---but it's darned close!! In the first picture, you see the body at 1:1 scale mounted and centered in the 4 jaw chuck. The top of the most extended jaw clears the nearest obstruction to the center by a good 1/2". In the second picture, I have rotated the four jaw to the point where you can see how far that same jaw actually sticks out past the chuck. ---Scary stuff indeed!!! That jaw is held by two complete turns of the chuck key so, two turns of thread engagement between "not connected" and "up tight against the part". Balance will be totally out the window--I'm aware of that, but won't be turning at a high speed so it's not that big a deal. The third picture shows the full scale cut-out of the main body laying on the faceplate. It looks like some form of attachment to the faceplate would probably be safer and less apt to fly out and damage the lathe or me. The only thing I can think of right now is that profile of the part is the 'finished" profile. If I started the operation with the part 2" wider, I could put a bolt hole on each side of the part in the "extra" material and bolt it to the faceplate (tap the faceplate if I have to) and finish all the boring, and then after removing the part from the faceplate cut away the extra material and finish the profile. I'm open for reasonable suggestions here.---Brian


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## Cogsy (Feb 15, 2016)

Not sure how big your chuck is in relation to mine, which might make a difference. Last week I had a similar situation in a 5" 4 jaw, although my part was a little wider in comparison with it's length (more square I guess, but not a square). Anyhow, I spun it at around 600 RPM and balance wasn't an issue at all. It was a piece of ali about 3" thick and I couldn't detect any unusual vibration. I didn't feel overly comfortable with the jaw swinging out there like that but it all went well and was a non-event. I'd recommend spinning it up and see how it goes.

Edit to add: It was a through boring operation I was doing as well - step drilled 3 sizes to 20mm then boring bar out to about 7/8", so reasonably heavy machining, not just skim cuts.


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## RonGinger (Feb 15, 2016)

You may find balance to be a bigger deal that you suspect. I would use the face plate and bolt on a couple lumps of steel to balance it.


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## Brian Rupnow (Feb 15, 2016)

The total length of that part shown is 5.009", with 4.019" from the center up to the top of the cylinder. If I start with a piece 8 1/8" long and center it on the faceplate, that will do away with any balance issues. I have to think on the quickest, cheapest, securest way of attaching it to the faceplate yet. The finished  width of that part is only 2.27", so if I buy a piece of 3" stock, that will leave lots of room on each side of the cylinder portion for bolts, and maybe tap the other end of the part on center and bolt thru from the back side of the faceplate thru one of the slots.


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## canadianhorsepower (Feb 16, 2016)

Just curious
you have a rotary table and a mill
why not use that instead


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## Brian Rupnow (Feb 16, 2016)

Luc--I'm not sure how that set-up would look. I think it would mean setting the part up on my rotary table and turning the rotary table by hand as I moved the table left or right into the turning cutter. Very clever.--Had never thought about that method.  At any rate, my 3 jaw chuck is attached to my rotary table, and I don't want to disturb it.  I like the faceplate option.


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## Charles Lamont (Feb 16, 2016)

Brian Rupnow said:


> The total length of that part shown is 5.009", with 4.019" from the center up to the top of the cylinder. If I start with a piece 8 1/8" long and center it on the faceplate, that will do away with any balance issues. I have to think on the quickest, cheapest, securest way of attaching it to the faceplate yet. The finished  width of that part is only 2.27", so if I buy a piece of 3" stock, that will leave lots of room on each side of the cylinder portion for bolts, and maybe tap the other end of the part on center and bolt thru from the back side of the faceplate thru one of the slots.


Just hold it down with a strap, using the two slots near to the head end. Just a bit of mild steel flat with a hole at each end, and some long bolts. That will give you enough room for boring the crankcase. To offer you some more ideas, I show several faceplate setups here:

http://www.charleslamont.me.uk/Seagull/crankcase.html

see also the sump, cylinder barrel and con-rod pages.


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## ICEpeter (Feb 16, 2016)

Brian,
I assume you intend to make the center bore on the lathe. Have you considered doing it on the mill with the part centered under the spindle and using a boring head to make the bore accurately?

Or are you trying to accomplish something different to what I assume?

Peter J.


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## Brian Rupnow (Feb 16, 2016)

ICEpeter said:


> Brian,
> I assume you intend to make the center bore on the lathe. Have you considered doing it on the mill with the part centered under the spindle and using a boring head to make the bore accurately?
> 
> Or are you trying to accomplish something different to what I assume?
> ...



My plan at present is to do the cylinder bore on the lathe. It will be a "second operation" after the crankcase bore for the crankshaft is finished. that way I won't be boring into a blind hole, the drill and boring tool will break thru into the cavity already machined in the first operation. As you can see in some of the model cross sections, the cylinder bore is not a smooth stepless bore all the way through. There is an enlarged area part way down the bore for the water jacket, which again would be difficult to accomplish on the milling machine.


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## Brian Rupnow (Feb 17, 2016)

This quest is taking me in new and different directions than I have ever gone before. The consensus seems to be that what I want to do regarding the piston/cylinder fit with no rings is indeed possible, but I am going to have to learn lapping skills that I currently do not have. So---I have today ordered a 15/16" internal barrel lap (which will easily expand to 0.945" or 24 mm) and a tube of 8 micron to 12 micron "light" diamond lapping compound. I looked at external manual hones, but as they cost upwards of $400 I will probably be making my own external lap, (pending some information from Ramon on HMEM) from a piece of brass with a hole bored thru it and a pinch bolt. Wiser heads than mine are suggesting that I use leaded steel for the liner, and as I have a piece of 12L14 left over from my last engine I will probably use it for the liner with cast iron for the piston.  My course of "step by step" actions will be to first make the cast iron piston, turning the outer diameter of the piston to about .001" to .002" oversize from my desired 24 mm (0.945"). I will then set the piston aside.  I next machine the outside diameter of the piece of material for the liner to ensure it's roundness over the full length, including an inch or more to be held in the chuck jaws. Next I will bore the liner and chucking stub to about .0015" to .0001 undersize and then turn the outer diameter to finished size, turn the "lip" at the top of the liner to finished size, and still leave the liner attached to the "chucking stub" held in the lathe. Then over to the rotary table to cut the ports and sparkplug hole in the sides with the mill. Then back over to the lathe to lap the inside bore to exact size, using a lap mounted in the lathe and the cylinder liner in my hand (I try for a tighter fit at the top of the liner than at the bottom--this is sort of a "by feel" thing.). Now, assuming the cylinder liner is exactly finished to "On size", I put the chucking stub end of it back into the lathe. No farther machining operations will be carried out on the liner, except to part it off from the chucking stub after the piston is fitted. I then use the external lapping tool on the piston by hand, and bring the piston down to a point where it will just begin entering the bottom end of the cylinder liner. At this point I attach a T handle to the piston, using a temporary brass "wrist pin" and using a solution of very little fine diamond paste with a lot of kerosene, lathe not running, I wring the piston in and out of the cylinder by hand, untill I feel it enter freely up as far as the exhaust ports ,then with increasingly more friction as it reaches top dead center in the cylinder. This can be adjusted by just how much lapping I do of the piston into the cylinder. When I am happy with the fit, I then part off the liner from it's chucking stub.---Have I got the sequence right???---Brian


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## canadianhorsepower (Feb 17, 2016)

food for your brane

while your parts come in

enjoy 

View attachment Grinding and Lapping Reprint.pdf


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## Brian Rupnow (Feb 17, 2016)

These two parts are going to be the most critical parts on the engine, in terms of me being able to make them well enough to give sufficient compression for an engine to run, so this is where I am going to start. Contrary to what I said earlier, I haven't made them yet, so don't bother to copy them. They may change. I will post a download link to all the drawings when the engine is finished and running.---Brian


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## Charles Lamont (Feb 17, 2016)

Brian Rupnow said:


> At this point I attach a T handle to the piston, using a temporary brass "wrist pin" and using a solution of very little fine diamond paste with a lot of kerosene, lathe not running, I wring the piston in and out of the cylinder by hand, untill I feel it enter freely up as far as the exhaust ports ,then with increasingly more friction as it reaches top dead center in the cylinder. This can be adjusted by just how much lapping I do of the piston into the cylinder. When I am happy with the fit, I then part off the liner from it's chucking stub.---Have I got the sequence right???---Brian



I am in agreement as far as this bit. I would not myself lap the two parts together, but carry on with the external lap to produce the required fit. I would worry that lapping them together might produce too loose a fit. I think the fit you require may well not allow room for abrasive between the parts. I think if you start as tight as you say, you risk a seize-up in the middle of the job. But, I am not very sure of my ground.


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## Brian Rupnow (Feb 18, 2016)

And so it begins---I hadn't planned on beginning to cut metal so soon. But----For the moment I've ran out of intelligent questions to ask. It is plain that for me, the most difficult part of this build may very well be achieving the proper fit between the piston and liner, and the method used to do so. I have ordered a barrel lap, and some "light" diamond compound, and decided that I could build the piston from cast iron and leave it about .002" oversize from the final 24 MM (0.945") that I want to eventually achieve. I have received a lot of interesting and conflicting information so far. The plan calls for three .005" deep oil grooves, while well meaning advisers have told me not to put any oil grooves in.---I chose to put them in, because if I do achieve the fit I want in the liner, I don't want the engine to "seize up" from friction. The original plan has a drip oiler and oil port in the side of the cylinder, so the original designer must have had the same concerns. I have been advised not to use diamond compound by one highly respected and accomplished engine builder. I have been told it really isn't a problem by another equally respected and knowledgeable builder. I had to buy some compound anyways, because the finest compound I currently have is 600 grit, and I need something along the lines of 1000 grit, so I ordered the diamond. i will clean everything out with solvent and a toothbrush when I am finished fitting everything to my satisfaction. The piston shown here is cast iron, "as machined', with no other prep work yet.


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## Goldflash (Feb 18, 2016)

Brian 
Used to build Multistage Compressors with Bores up to 14 inch. All Cylinders after honing were boiled in soapy water ( special Bath ) 
This opens up the pores of the iron/steel  and lets the honing grit out. Have always done it with old Brit Bikes etc  with Cast Iron Liners etc and it does make a big difference on the running in and life of parts etc. 
Ralph.


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## Brian Rupnow (Feb 19, 2016)

And next, we have something that is almost magic!!!  The piston will have to be mounted somehow in order to lap it externally when I go to fit it to the lapped cylinder liner. In the back of my mind, I was thinking about turning a shaft to fit into the counterbore and locking it in there with Loctite temporarily until the piston was lapped, then heating the shaft to release the Loctite. Thanks to help from Jason and Ramon, I have discovered this method. Turn a shaft to slightly less than the finished piston outside diameter, with a step turned to fit into the counterbore in the bottom of the piston. Drill and tap the end of the shaft (I used  1/2"-13). Make up a part that has a matching thread and cross drill it to accept a pin the size of the wrist pin in the piston, and profile the end of it to fit into the piston slot. Make up a dummy wrist pin, assemble the piston, threaded part and dummy wrist pin, then simply screw them to the shaft. It works so well I am blown away!!!  The piston probably doesn't turn perfectly concentricaly with the shaft, but that's okay---The lapping procedure is done with the piston/shaft assembly in the lathe chuck turning at a very low rpm, and the external lap is held in your hand.


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## Brian Rupnow (Feb 19, 2016)

Since I am breaking new ground here, in terms of fits and tolerances, I decided that I needed a plug gauge to let me know when my cylinder liner was getting close to the magic  0.945" (24 mm) inside diameter. Right now my piston is setting at 0.947" diameter, and the last thing I want to do is to turn the bore of the liner too big and have my piston fall thru the darned thing. So, I have made up a plug gauge, that sets fairly and squarely on 0.942".  I made it from a piece of 1018 steel, which I have come to believe is the most miserable damned thing in the world to get a good finish on. The reduced area has been turned to  0.900" more or less. The polished end was turned to 0.945" and then finessed down to 0.942" with a strip of 220 grit carborundum paper.---And believe me, for a lousy, stinking .003", that is a LOT of finessing!!! So----My plan now is to set up a piece of 1 1/4" diameter 12L14 steel 1" longer than the finished length I need for my liner in the lathe, drill and ream to 7/8" (0.875") then bore in very small increments until my "plug gauge" will just enter the bore. At that point I will use my new barrel lap to enlarge the bore to 0.945" (Maybe I need a second plug gauge to let me know when I have reached there.---Not sure. I will start out lapping with 600 grit carborundum paste, then move up to the "fine" diamond paste. Then, assuming the bore has cleaned up okay, I will make an external lap and bring the piston diameter down until it enters the liner.


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## Brian Rupnow (Feb 20, 2016)

So there we have it--a cylinder liner. I started with a piece of 1 1/4" diameter 12L14 steel. I cut it 1 1/8" longer than the finished length I needed. I chucked it up in the lathe, and had 1" in the jaws and the rest stuck out. I know that is an uncommon amount of stick out, but I wasn't going to be taking any heavy cuts. I drilled out the center all the way through with progressively larger drills until I got to 0.780" diameter, then used the brazed carbide boring bar to take it out to the required diameter. The lathe was running at about 280 rpm.  I don't have any kind of instrument to directly measure the bore, but I do have a set of those expanding inside things (not sure what they are called) that you insert into the bore in a collapsed state, then loosen the handle to make them spring out to both sides, then lock them with the handle and take them out and measure them with a micrometer. I was taking .010" deep radial cuts until I seen that I was closing in on my targeted bore of 0.942", then took many smaller cuts with much measuring until I got to a point where my plug gauge would just start into the hole. (second picture) I then turned the outer diameter to first 1.142" and 1.063", and hit the numbers within 0.001" which is close enough for a Loctited liner. I haven't parted the liner off from the parent material yet, because I need that "stub end" to hold it in the 3 jaw chuck which is bolted to my rotary table while I cut the ports and the sparkplug access hole. The lapping won't begin until after the ports and sparkplug holes are cut and the stub end cut off.


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## Charles Lamont (Feb 20, 2016)

Brian Rupnow said:


> I don't have any kind of instrument to directly measure the bore, but I do have a set of those expanding inside things (not sure what they are called) that you insert into the bore in a collapsed state, then loosen the handle to make them spring out to both sides, then lock them with the handle and take them out and measure them with a micrometer



Telescopic gauges


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## canadianhorsepower (Feb 20, 2016)

Charles Lamont said:


> Telescopic gauges



snap gauge :hDe:


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## 10K Pete (Feb 20, 2016)

canadianhorsepower said:


> snap gauge :hDe:


Telescoping gauge!

Pete


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## canadianhorsepower (Feb 20, 2016)

10K Pete said:


> Telescoping gauge!
> 
> Pete


50/50 snap or telescopic


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## 10K Pete (Feb 20, 2016)

A sales catalog??? Come on!  At least look it up from a solid source.

Here's from one of the oldest, most respected, companies:

http://www.starrett.com/metrology/m...isplayMode=grid&itemsPerPage=24&sortBy=wp/asc


http://www.starrett.com/metrology/m...isplayMode=grid&itemsPerPage=24&sortBy=wp/asc

And here's from Wiki...

https://en.wikipedia.org/wiki/Snap_gage

Just Google it up, you'll find hundreds of citations...

Been using 'em for over 50 years.

Pete


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## canadianhorsepower (Feb 20, 2016)

10K Pete said:


> A sales catalog??? Come on!  At least look it up from a solid source.
> 
> Here's from one of the oldest, most respected, companies:
> 
> ...



If this is all you need to have a good day
print the adds and look at them tomorow 
thing`s have change with age


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## Brian Rupnow (Feb 20, 2016)

Guys--Please--I don't care that much what they are called. I know I use them, and they aren't great but they get the job done. They require a special skill set to use them and get repeatable readings.


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## Swifty (Feb 21, 2016)

Always known to me telescopic gauges, snap gauges are usually a go/ no go gauge.

Paul.


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## deverett (Feb 21, 2016)

Brian Rupnow said:


> Guys--Please--I don't care that much what they are called. I know I use them, and they aren't great but they get the job done. They require a special skill set to use them and get repeatable readings.



I usually put the gauge into the hole at an angle with some friction of the lock.  The gauge will naturally find the largest diameter in the bore.  By swivelling the gauge through the true diameter, the friction is sufficient to allow the gauge to be removed from the bore and the lock tightened before using a mic to measure the bore diameter.

Example. With the bore in the lathe, put the gauge in the bore with the handle pointing down at about 30 degrees.  Have some lock on and lift the handle to 30 degrees upwards.  Withdraw gauge, lock and measure.

Dave
The Emerald Isle


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## canadianhorsepower (Feb 21, 2016)

10K Pete said:


> A sales catalog??? Come on!  At least look it up from a solid source. Been using 'em for over 50 years.Pete



is this a solid source for you

http://headportingsupplies.co.uk/index.php?route=product/product&path=95&product_id=196

I don`t have any problem agreeing that they are known
under BOTH name........ Do you


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## Brian Rupnow (Feb 21, 2016)

I'm waiting for my barrel lap to come in to my tool supplier, but decided I could build a lap for the outer diameter of the piston while I waited.


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## Brian Rupnow (Feb 21, 2016)

This is the finished brass lap for the o.d. of the piston. It is a tight fit. I bored the lap to exactly 0.946", but when I put the saw-cut in it, it closed up to about .942, while the o.d. of the piston is about 0.947".  this doesn't alarm me too much, because the first .001"  or .002" will come off very quickly, as the lapping compound is basically knocking off the high ridges left by machining, not only on the outside of the piston, but also on the inside of the lap itself. I will start the piston with 400 grit, then move up to 600 grit. However, I won't do any of the lapping on the piston until I get the cylinder lapped to size, then I will lap the piston independently until it just slides into the cylinder bore.


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## Roboguy (Feb 21, 2016)

I am watching your progress closely Brian as I am up to this point in my Boll Aero build. 

I have a question I am hoping you or another knowledgeable member can help with. I am about to make a similar external laptop for my piston, but I don't have any suitable brass. Do you think aluminium would work, or would it simply be too soft? 

Loving following along as always! 

Cheers 
James


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## Brian Rupnow (Feb 21, 2016)

Roboguy---I am certainly no authority on this, but I think aluminum would work as well as brass. If you have the aluminum already, give it a try. If it works you've saved some money. If it don't, then you're only out a couple of hours of time.---Brian


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## Brian Rupnow (Feb 21, 2016)

Okay---I think I got lucky. I had to go out of town for a few hours today, so I took the squeeze bolt out of the brass lap and wedged it open with screwdriver, right on center to avoid any taper, and left it wedged open for about 4 hours. When I came home, I took the screwdriver out, and the lap didn't close back up a lot. It is now a snug sliding fit over the piston. I realize that it is probably going to be somewhat of a line contact with the piston now, but the first few minutes spent with lapping compound should knock down the external micro-ridges on the piston and the internal micro ridges on the lap, which are a result of machining, and bring things back to round. The piston and arbor will be turning in the lathe at a slow rpm, and I will hold the lap in my hand. As soon as things loosen up a little, I will use the squeeze bolt to bring the lap back to round.


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## Brian Rupnow (Feb 22, 2016)

The liner has had the slots added for the ports, and the hole added for the sparkplug access, then parted off from it's parent stock, and finally faced to size. I had to go over to my tool supplier and pick up a couple of metric endmills, and my new internal lap was in. The fine diamond lapping compound is on back order, so I may have to make alternate arrangements there. There are a few minor burrs on the inside of the lap from milling the port slots. Should I do anything about that or just let the lap take care of it?--The inside of the bore come up really well from the boring operation.-Brian


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## petertha (Feb 22, 2016)

Looks good. So this is a CI liner right? About how much material have you removed from boring diameter to get to that finish?

Just a word of caution on your brass piston lap. I made a similar one from aluminum. It can become a bit 'grabby' depending on the lapping compound grit + fit tightness + other variables. And by grabby I mean if it decides to stick just a bit, especially on a new incremental clamp setting startup or fresh lapping compound application, it can easily wrench your wrist & draw a nice line across your hand from that external bolt head. Gloves might actually be an added hazard. That's kind of the rub: an easily sliding fit is safer, but isn't really removing much material. You'll see what I mean.

A fine pitch bolt is much better than a coarse because of the tiny squeeze distances between stop & start. I think that's why the American lap tools are designed the way they are. The tool has radial relief holes & slits so its more even (radial) force & less clamping effort. The tool imparts its clamping force to thin, replaceable annular lapping sleeve, not the donut itself. Its easier to make replacement sleeves & keep the tool/ Also the sleeves can be preserved to respective grits.

btw - why do you think the lap decreased in ID once the slit was run through? 

Keep up the documentary, interested to see how things come together.


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## Brian Rupnow (Feb 22, 2016)

Petertha No--that liner is made form 12L14 steel. The bore, as shown, hasn't had any lapping yet. that is just the bored finish.The piston is cast iron. I'm quite aware of the tendency to grab, as I lap all of my normal cylinder barrels for ringed engines using a piece of round aluminum .002" smaller in diameter than the cylinder bores. I chuck it up in the lathe, apply 600 grit lapping paste and run the cylinder back and forth over it by hand while it is turning at a low rpm. It is kind of a scary business, and you have to really be ready to let go in a hurry if it grabs. On a round cylinder letting go in a hurry is not usually a problem. The cylinder for my side valve engine had a large undercut feature on one side for lifter clearance, and it grabbed and tore a chunk of meat out of my hand. Luckily, it was only a small chunk of meat, about the size of a fox bite.--Sure woke me up in a hurry though!!! My plan was to use a fine thread bolt on my home-made brass lap, but as things usually go around here, I didn't have any fine thread bolts, so it got a 1/4"-20 unc thread. Why did the lap close up after the sawcut?--Probably internal stresses being released. I'm fairly sure that 1 1/2" diameter brass is rolled similar to cold rolled steel, and this imparts a denser outer surface than at the center. When I bored the hole in the lap off center and then cut through the side, the stresses in the brass from rolling released and closed up the cut.


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## Brian Rupnow (Feb 23, 2016)

While I wait for my back ordered diamond lapping compound, it is time to move ahead with the next stage of the project. --the main body. Normally, on a casting, the water cooling and transfer port passages would be cast in place. Since I plan on machining the main body from a block of solid aluminum, I have to decide how to get the passages in there. The green represents a 7/16" four flute center cutting endmill, standard length, that can be plunged through the base, then through the internal cavity for the crankshaft, then back into the remaining solid material above the crankcase cavity. Any depth beyond the green endmill can be put in with a standard 7/16" drill, to finish the transfer passage up to the port. I can't use a drill to do the entire hole because the sloping sides of the crankcase cavity would make the drill want to wander off to the side. However, a drill will work fine in the flat bottom left by the endmill. The hole left in the base of the main body will have a plug loctited into place.BUT---, the red represents the cooling water passages up to the cavity around the cylinder liner. The water entrance and exit holes are through the sides of the main body, closer to the other end of the cylinder. These holes will be plugged and sealed directly above the crankcase cavity. and in the base of the main body.---and this presents a problem--because I can't get a 3/16:" endmill long enough to do what I want.
   If I put the holes in before I bore the crankcase cavity, then no problem, I can just drill them and not worry about using an endmill. Only this screws up my planned sequence of operation. I have purchased an aluminum bar 10" long, and had planned to center it for perfect balance on my lathe faceplate to bore the crankcase cavity.  Now I have to think on this for a while!!!


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## canadianhorsepower (Feb 23, 2016)

Brian Rupnow said:


> and this presents a problem--because I can't get a 3/16:" endmill long enough to do what I want.
> 
> 
> How long do you need it ??
> ...


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## Brian Rupnow (Feb 23, 2016)

Luc--I was thinking of doing that. I need to be able to plunge at least 1 3/4". I can use an ordinary drill to go from the bottom into the crankcase cavity. then I could switch to the specially ground drill to just get a "flat" started in the material after I had passed thru the drill cavity, then switch back to a normal drill again. How would I grind the end of the drill? Just grind it flat on my grinder?


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## Charles Lamont (Feb 23, 2016)

1) Cutting off the spare piece of bar so that you can drill the holes from the bottom of the crankcase does not mean you can't still use it as a balance weight.

2) Make a sacrificial crescent of alli to fit inside the bored-out crankcase so you can drill through solid all the way.

3) Drill a hole down the shank of the longest end mill you can get, and Loctite an
extension rod into it (but don't blame me if it comes unstuck).


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## canadianhorsepower (Feb 23, 2016)

Brian Rupnow said:


> How would I grind the end of the drill? Just grind it flat on my grinder?



yep flat  ( not 100%  an end mill is not flat eather if is 100 flat it will walk all over the place )
 on the side of the grinding wheel. when I did this I had promise a part
and I was able to mill in aluminium easy.

What I did : took a small piece of steel shorter then my drill
resurface the end with 2 degree taper the drill it with the drill I was going
to use. Then I put the cutting flute of the drill equal to the outside of my adapter and secure the tail of the drill with vice grip to keep the same length
all the time 
and grind it to match my adapter
good luck


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## Brian Rupnow (Feb 23, 2016)

Charles--due to the shape of the internal crankcase cavity the sacrificial crescent idea won't work, but that would have been my first thought too. I can't really use your third idea either. The hole in the bottom of the crankcase where the 3/16" endmill gets admitted is right up tight against another surface, so there isn't room for the shank of a 3/16" endmill.


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## Brian Rupnow (Feb 23, 2016)

Great call, Rick!!  By putting the water inlet on one side of the cooling water cavity and the water outlet directly opposite from it, I can totally avoid having to drill holes up through from the underside except for the transfer port, and it's not a problem for me.


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## canadianhorsepower (Feb 23, 2016)

Brian Rupnow said:


> Great call, Rick!!



Brian 
where is Rick's post can't see it


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## Brian Rupnow (Feb 23, 2016)

canadianhorsepower said:


> Brian
> where is Rick's post can't see it


On a different forum.


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## Brian Rupnow (Feb 24, 2016)

I went out yesterday and spent a whole $30 on a piece of aluminum bar 2 1/2" x 2" x 1 foot long. Since the finished part I am making is 5.009" overall length and 4.016" from the top of the cylinder down to the crankcase hole, I cut a piece of the bar 10 1/8" long so that I can mount it to my faceplate to turn the crankcase hole on my lathe. That length will allow the bar to be mounted on my faceplate with the hole on the center and an equal amount of bar on each side of the faceplate centerline for balance. I set it up in my mill, cleaned up the right hand end to be square, then measured down the appropriate distance of 4.016" and centered the quill on the bar, then drilled and reamed a 1" diameter centerhole.  The finished bore of the centerhole is 1.063", so when I move my operation over to the lathe I can pick up on a short piece of 1" diameter shaft inserted into the hole to center it exactly on the faceplate and finish the bore. I had to take 0.153" of material off each side and then a farther 0.222" off near the center, so I used an endmill for that, and since most of the material on the other side of the crankcase hole is going to be cut off eventually, I left the material on that section so I will have two areas the same height when I mount it on the faceplate.---This will become clearer as I move along. Now I have to flip the part over in the milling vice and machine the far side the same way.


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## Brian Rupnow (Feb 24, 2016)

Bit by bit, the shape of the main body starts to emerge. Both of the "flat" sides are now machined, and I can't really do anymore now until I have mounted it on my faceplate and turned the center cavity for the crankshaft, otherwise it will throw everything out of balance. The plan for right now is to mount it to the facelate, bore the center cavity, then probably mount it between centers to turn the round section at the top of the cylinder next.


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## modelman1838 (Feb 24, 2016)

I have built a number of hot air engines with lapped cylinders and pistons in mild steel and cast iron, I make the cylinder lap out of brass because it is usually a silver soldered assembly, but always use aluminium for the piston lap and it works just fine, best of luck.
Hugh


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## Charles Lamont (Feb 24, 2016)

Brian Rupnow said:


> then probably mount it between centers to turn the round section at the top of the cylinder next.
> 
> If you did the bottom face and bolt holes next, you could mount it on the faceplate by the base (perhaps on an intermediate plate) and do all the barrel turning at one setting? Alternatively, a chunky angle-plate, if you have one of the type that is machined on the inside faces.


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## Brian Rupnow (Feb 24, 2016)

Charles---there is wisdom in what you say. I haven't totally got my head around what I will do next. The main body is currently up on the faceplate getting the crankcase bore completed. I have finished the 1.063" thru bore, but haven't yet put the larger stepped bores in yet. I have sorted out the boring bar and tool I will use for the job tomorrow. My big concern is that I have the cylinder bore perfectly square to the crankshaft. On a piston with rings, there is a very small bit of "forgiveness" because the piston has about .001" radial clearance in the cylinder. However, on a ringless piston like this will be, I'm sure that any "out of square" will throw some serious binding into the rotation of the crankshaft. I may do exactly what you have suggested---will think about it more tomorrow. There is a certain "sequence" to the machining of this main body, that if not fully thought out, can leave me with nothing to hold onto to finish it.---Brian


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## Brian Rupnow (Feb 25, 2016)

So---An afternoons entertainment, and the chatter marks come free!! What?---You can't see the chattermarks?--Trust me, they're there. I could say something about the length and the strength of my tool, but this is a family forum, right!! It was a "work with what you got" kind of thing, and I really didn't want to get anything on the carriage close to all those things whirling around on the faceplate. Everything seems to have went well, but it was both noisy and tedious with such a long and limber boring tool. Oh well, when it's all buttoned up, nobody will know about the chattermarks but me.---Right!!!----


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## Brian Rupnow (Feb 26, 2016)

As I get deeper into this thing, it becomes apparent pretty quickly why people cast them!! The upper cylindrical portion of the cylinder is turned to size. I still have a lot of material to cut away. However, it's February, it's snowing outside, and right now I've got nothing better to do. I never thought I would say this, but "Thank God for power feed!!!"


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## Brian Rupnow (Feb 26, 2016)

For all of those who wondered why I didn't do the crankcase bore on my mill rather than the lathe, as I explained, on a standard, conventional boring head, you can not advance the boring tool inside a bored cavity. Here is a video of an "automatic" boring head similar to the Waulhopter, that can be advanced while the tool is running.
[ame]https://www.youtube.com/watch?v=I4vbBqV6vsU[/ame]


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## petertha (Feb 26, 2016)

Brian Rupnow said:


> .. boring head similar to the Waulhopter


 
Its spelled "Wohlhaupter". 
And I lust for one


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## ICEpeter (Feb 26, 2016)

ENCO sells / has sold Wohlhaupter style "automatic" boring heads for about $ 250.- when I purchased mine quite a while ago. Works like a charm for planing and internal recess making provided you have the right tool for creating the recess. Has two feed settings: 0.0005 and 0.001 per revolution - you count the clicks for determining the advance / diameter until you reach the desired diameter / clicks counted. Used it for O-Ring grove making and similar.

Peter J.


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## Brian Rupnow (Feb 26, 2016)

ICEpeter said:


> ENCO sells / has sold Wohlhaupter style "automatic" boring heads for about $ 250.- when I purchased mine quite a while ago. Works like a charm for planing and internal recess making provided you have the right tool for creating the recess. Used it for O-Ring grove making and similar.
> 
> Peter J.


Yes, and our Canadian dollar is worth about 37 cents American right now---


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## ICEpeter (Feb 26, 2016)

Yes, Brian that is a very unfortunate fact right now. It puts a damper on the best intentions.

Peter J.


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## petertha (Feb 26, 2016)

ICEpeter said:


> ENCO sells / has sold Wohlhaupter style "automatic" boring heads for about $ 250.- when I purchased mine quite a while ago. Peter J.


 
Hmm.. I was not aware of this. That's about 1/4 the cost of a decent used Wohlhaupter on ebay...which rarely comes with R8 & I'm still not clear if/how they can be converted. Does this look the same as yours Peter? I never know what to make of the clones anymore - is this a bad copy of a semi decent Taiwanese copy of a ... 
http://www.use-enco.com/CGI/INLMPI?PMPANO=0307692&PMKBNO=1123&PMPAGE=56

Sorry for the auto boring head side-bar inquiry.


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## petertha (Feb 26, 2016)

Brian Rupnow said:


> Yes, and our Canadian dollar is worth about 37 cents American right now---


 
1 C$ is worth 0.74 $U. 1 US$ is worth 1.35 $C. But at the rate we are going down the toilet your conversion will probably apply by summer.


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## ICEpeter (Feb 26, 2016)

Peter,
The automatic boring head I purchased quite a while ago is found in the ENCO online catalog page 483, model number 222 - 1100 with two feeds. Its currently listed in the online ENCO catalog for $ 384.89. The boring head I received is of a good quality / finish and works flawlessly although it came without instructions. The advertising at the time stated that it would come without instructions / manual.

Anybody considering a purchase of this item just missed the chance to buy at a 30 percent discount, sorry to bring that up.

Peter J.


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## Swifty (Feb 26, 2016)

I have a similar boring head, it is a Kuroda brand made in Japan. It's an excellent boring head, mine has an R8 shank on it, but it is able to have any type shank fitted to it. I have mainly used the facing facility on it to face the bottom of large counterbores in plates. One difference to the one in the video is that mine only uses the large ring to advance the tool bit, the graduations are marked on the ring, and I can easily split the divisions to take off 0.0127mm (0.0005") off a diameter.

Paul.


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## Brian Rupnow (Feb 26, 2016)

Well, you can tell it didn't start life as a casting, but it's pretty good for "home grown". Now if I don't mess anything up, the main body is getting close to being finished.


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## Brian Rupnow (Feb 26, 2016)

Hooray!!!---Just got a new contract. A bakery is having problems adding blueberries to their muffin mix. If they add the blueberries to the mix too soon, they stain the white dough. There are auto feeds commercially available to feed the berries into the mix at a later stage of the process, but they clump up and either don't add any berries to the mix, or add too many in a "glob". Customer wants me to design a machine to add the right amount of blueberries at the right time in the process. This is the kind of thing I love to do.---and part of the proceeds from this will buy me a set of micro deburring tools and pay for my new lap and diamond lapping paste!!!


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## Cogsy (Feb 26, 2016)

Sounds like a cool job. My mind immediately went to an air powered blow-gun type system, completely unrealistic but imagine the fun it would be to play with!


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## ICEpeter (Feb 26, 2016)

Brian,
That blueberry job sounds very intriguing and I wouldn't underestimate the complexity and problem of adding whole blueberries to the muffin dough and keeping them whole in the dough. 

Have been engineering food ingredient handling systems myself in the past including, for example, automated continuous flake ice making with electronic batch weighing and distribution of the flake ice without melting via pneumatic conveying to its dough making destination. Managed to re-grow my hair after pulling it out on that job.

Peter J.


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## Swifty (Feb 27, 2016)

Plus all the blueberry muffins you can eat as an added bonus 

Paul.


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## RonGinger (Feb 27, 2016)

One of my favorite jobs was the CNC controlled brownie cutter. A shop called Simply Divine Brownies wanted to make them in various shape- hearts, pumpkins, cats, etc mostly for holiday sales. I made 20 cutters for it from stainless steel strips. Nice part was they often paid off in brownies. See it at 
	

	
	
		
		

		
			





 [ame]https://www.youtube.com/watch?v=kPNQI-_AUIA[/ame]


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## canadianhorsepower (Feb 27, 2016)

Brian Rupnow said:


> Customer wants me to design a machine to add the right amount of blueberries at the right time in the process.




are you using PLC's


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## Brian Rupnow (Feb 27, 2016)

canadianhorsepower said:


> are you using PLC's


I'm not sure yet. on little jobs like these, if you go PLC based, the electronics often cost more than the rest of the machine. I have to travel to Toronto and see the existing set up before I know what I'm going to do.


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## Jasonb (Feb 27, 2016)

Just add them frozen that way they don't start to thaw until well mixed in so no risk of staining the mix, well thats the way mu Mum does them


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## Brian Rupnow (Feb 27, 2016)

My next step is going to be cutting off the excess material and milling the bottom (shown in red) perfectly parallel and square to the center of the hole bored through the crankcase. The reason that it is a critical operation, is that the bore for the cylinder sleeve must be perfectly square to the centerline of the crankcase hole. I intend to bolt the engine baseplate to the underside of the "main body", and then clamp it to the faceplate when I bore the cylinder sleeve hole.  It only has to be perfectly "square" in one plain, so that the piston doesn't bind in the sleeve when the crankshaft is rotated. The other plain is not suite so important. To do this milling of the area shown in red, I will make the fixture shown in green and blue. (I have also shown a copy of the fixture with part of it made transparent for clarity.) The blue shaft will be turned to be "on size" with the crankcase bore. The green plate will have a hole bored "on size" with the shaft. The shaft will be Loctited into the green plate. The green plate will also have counterbored holes for the six bolts that fit into the threaded holes in that side of the crankcase. The green plate will be clamped to the bed of my mill, the "main body" aligned with the bed in the X axis. Then I will mill the red colored area with the side of an endmill, taking successive passes and lowering the spindle 0.100" on each pass until the red area is totally milled.


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## Brian Rupnow (Feb 28, 2016)

For those of you who enjoy the different set-up shots of the machining, here are a couple of shots of machining the 45 degree chamfers on the four corners of the main body. I call this my "tilt-a-whirl" vice, because it swivels and can be set up to any desired angle. It's really not a very good vice, as the moveable jaw  kicks up too much to do any precision work, but for jobs like cutting chamfers on rectangular parts, it works just great.----Brian


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## Brian Rupnow (Feb 28, 2016)

I hope I don't hate myself in the morning for this-----But I couldn't be bothered making another fixture!!!


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## Brian Rupnow (Feb 28, 2016)

And that, my friends, is quite enough silliness for today!!!


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## Brian Rupnow (Mar 4, 2016)

Regardless of my best intentions, the base of the main body did not turn out to be parallel with the bore for the crankcase. This gave me some pause, as I couldn't figure out quite what to do to correct it. I thought about it for a few days, and then come up with my standard solution---"When in doubt, make a fixture!!!" So---I turned a piece of steel round bar to be an exact fit into the crankcase bore.Then made up a short piece of steel flat bar with a couple of bolt holes to pick up two of the threaded crankcase holes. I bolted the flatbar to one side of the main body, slid the round shaft thru the hole in the crankcase until it was tight against the steel bar, covered all of my aluminum part with 3 layers of masking tape to avoid weld spatter, then walked it out to the main garage and mig welded the flatbar to the roundbar. Now I had something I could hold in the chuck on my rotary table. this automatically established the centerhole in the crankcase as being truly vertical. Then I indicated the base and played with the rotary table until I had zero runout in the Y axis. Then I machined the base flat with the side of a 1" endmill, taking very light cuts. I had painted the base where I was cutting it with layout dye, and it was out of "true" by a surprising amount. This was okay, because I had delibarately left the main body about .050" longer than it's finished length just in case I had to undertake a further machining operation to square it up.


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## Brian Rupnow (Mar 4, 2016)

I have no clearly defined idea of what on earth I'm doing here, but as usual it hasn't stopped me. I am following posts by Jason and Ramon, hoping I get it mostly right. The lap has been smeared with 320 grit carborundum paste, and "enlarged" by turning the screw in the end of the lap until I felt it begin to "drag" as I held the cylinder liner in my hand and worked it back and forth on the lap, with the lathe running at about 40 rpm. I repeated this "enlarging" of the lap about 3 times as material wore away from the exterior of the lap and the interior of the cylinder liner. At one point, it begin to grab a bit and squeal, so I squirted a bit of cutting oil on it. This loosened things up a bit. I didn't want to turn the liner to an i.d. larger than the piston I already have made, so have taken the lap out and washed it with Varsol and an old paint brush, then blown it clean as I can get it with 100 psi of air pressure. I have also thoroughly washed the liner. My next trick will be to repeat this operation with 600 grit carborundum paste, then finally with my diamond paste which arrived today. The liner has taken on a uniformly "matt" finish on the inside diameter at this stage of the operation.


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## Brian Rupnow (Mar 4, 2016)

My home made external lap seems to work fairly well. I have started with 320 grit carborundum paste, and by running the lathe at about 40 rpm and working the lap back and forth while holding it in my hand (ready to instantly let go if it grabs) the piston has taken on a consistent dull finish. As near as I am able to measure, I have to take about .002" off the diameter of the piston before it fits into the cylinder.--Herein lies the rub---I don't know how much I am taking off as I lap the outer diameter of the piston, so I have to frequently stop and "try for fit" because I don't want to make the piston too small.


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## Brian Rupnow (Mar 4, 2016)

Things  are not going as smoothly as I had hoped---My hands are sore from holding the external lap to lap the outer diameter of the piston. I have lapped it until the surface has a smooth matt finish and I can't measure any difference in diameter from one end of the piston to the other. However---it will only go about 1/3 the length of the piston into the sleeve without binding. I conclude from this, that my pretty brass barrel lap is "bell mouthing" the bore of the sleeve. This doesn't surprise me, as I see now that when you expand this lap, it gets larger in the center, somewhat like a snake which has just swallowed a frog. All is not lost. This cylinder as designed, is 24 mm ( 0.945") bore. My reasoning was that I could buy a 15/16" (0.9375") barrel lap and expand it to the required 0.945". Having no experience with barrel laps, I didn't know it would expand only at the middle, but not at the ends. Oh, stupid me!!! So--tomorrow, I will turn a piece of aluminum to the desired diameter and use it to finish lapping the bore and hopefully get rid of any bell mouth. An actual measurement of the piston informs me that it is currently 0.943" diameter, and to the best of my knowledge is quite parallel from one end to the other. It is not really important that I hit the exact 24 mm (0.945")----It is only important that the piston be a very good fit into the sleeve.


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## petertha (Mar 4, 2016)

I'm not quite following what happened. (I have the exact same lap & size btw). Yes the lap expands in the center so has an enlargement there. But that enlargement must pass through the liner from end to end. If the ID is larger, you hear no cutting action. If its smaller the lapping compound goes to work. I'm no expert. I've done about 3 now testing different liner materials, but at least this aspect is consistent. Once the bore is uniform matt finish on any given grit & it feels the same lapping resistance, they bore check very, very similar from crown to mid to bottom. Something must be 'different' here, but I cant quite tell what.

http://www.homemodelenginemachinist.com/showthread.php?t=25163


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## 10K Pete (Mar 4, 2016)

Having used laps for bores, I want to say that one must operate the lap in a manner
that causes it to cut the area of concern. I hope I'm not preaching to the choir but
I haven't read any thing in these lapping posts about this so I'm going to just say it.
A lap won't automatically make a parallel bore or piston. One must lap and measure,
lap and measure, over and over. Work the tight spots with the lap until the desired size 
and straightness is achieved.
If this is done carefully the laps won't ever get way out of shape but they still
will wear a bit. The worst is the lap for the bore as Brian has found. The best
is the OD lap as it's usually short in comparison to the length of the part it's
working, so one has to just use it to reduce the big spots on the rod/piston which is 
easy to do as they can be felt while lapping.
The lap for the bore has to be manipulated using actual measurement as
a guide to straightness. At least until the last tenth or two which should be
done with a newly turned and parallel lap.
Sorry if I'm providing redundant information, just want to see you all succeed.

Pete


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## Charles Lamont (Mar 5, 2016)

The fact that the lap bulges in the middle should *help you to avoid* bell-mouthing the bore. You should be able to feel the tight spots in the bore as you pass it over the hump, and dwell on those parts until you feel even drag all the way along. I think if it is making your hand sore you may have the lap too tight.


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## 10K Pete (Mar 5, 2016)

Charles Lamont said:


> ........ I think if it is making your hand sore you may have the lap too tight.



Good catch, Charles. Lapping should be more of a gentle operation at this
point than a grinding operation. 

Keep at it Brian, you'll have it soon!

Pete


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## Brian Rupnow (Mar 5, 2016)

I have finished lapping the cylinder. I used 300 grit carborundum to start with, then 600 carborundum, then diamond. The liner has gone from grey matt finish to a lighter silver color. Same with the piston. As I said, the piston is just beginning to enter the bottom of the cylinder. Perhaps I will try as Jason says, and try lapping the piston into the liner with lots of oil.


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## Brian Rupnow (Mar 5, 2016)

I want to make a statement here, and I want you all to pay attention!!  LAPPING PISTONS INTO LINERS ISN'T FOR SISSIES!!!! I didn't make any more laps. I followed Jason's advice, and since the piston would just start into the bottom end of the liner and go no farther, I lapped the piston into the liner.  This was a slow and somewhat tedious procedure, and about every 25 seconds I had to shut off the lathe, remove the piston which was now firmly stuck in the liner, and take both piston and liner out to my shop press and push the piston free with a short section of broom handle. I used a lot of oil, and a little bit of diamond grit during this process. Gradually, the piston would go farther and farther into the liner without binding, until it had entered completely, and then on up to about 0.100" past it's maximum travel into the liner under running conditions. How tight is a "good fit"---well, I'm not sure. With all the oil wiped off, the piston will not fall thru the liner under gravity. However, with only moderately light finger pressure, I can push the piston thru with no problem. When the piston is inserted into the liner, it passes the "Blow your guts out" test.---that is to say, with my fingers closing the ports and one end of the liner in my mouth, I can't blow any air past the piston. My thoughts are, that any remaining interference between piston and liner will sort itself out once the engine is running. I hope that is right.


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## petertha (Mar 5, 2016)

10K Pete said:


> ..done carefully the laps won't ever get way out of shape but they still will wear a bit..
> Pete


My experience was they can wear 'quite a bit'. But I'm sure that's a function of lapping grit, liner material, lapping alloy, removal amount... etc. & everyone's mileage may vary. For example on my cast iron liner (harder material) I was progressively pinching in the screw, lapping away. At some point I decided to change grits...which most experts say is a no-no, probably correct, but moss was starting to grow on my head with impatience. I relaxed the screw, cleaned the brass, re-assembled & just out of curiosity measured the barrel diameter on ends vs. now relaxed/contracted middle bulge area. Sorry don't have numbers in front of me right now, but lets just say 'a lot' relative to thousanths of bore diameter. The laps job is to hold grit, but some barrel consumption seems inevitable. I could see a greasy yellow tinge in the slurry. 

Personally I've concluded the bore has to be as close to bang on within a couple thou of target diameter prior to lapping & of course as straight as possible to begin with. Or, you make up for it in lapping time & related consumables. But I'm also no expert, just an opinion thus far.

What the very first couple lapping passes showed me as the surface started to matt up was, despite my best efforts on the prior boring side, spring passes, locked carriage, changing travers & rpm speeds etc. there is a bit of technique to getting the bore geometry right beforehand. Lapping really hilites that. What could be called bell-mouthing might be an artifact of boring. I'm not saying this is the case in Brian's liner because he looks to be at matt finish stage.

I also did a test of the auto-parts 3-stone brake (deglazing?) hones. It didn't take me long to throw in the towel there. I had a very consistent straight bore to begin with & it turned bell-mouthed in no time. There's probably a technique to that too that I could improve on, but it wasn't for me.


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## Brian Rupnow (Mar 5, 2016)

I guess my next trick will be to suss out a way to hold the main body and baseplate to the faceplate, to bore the hole for the liner.The baseplate is going to have to be clamped to the faceplate, but with enough adjustment that I will be able to move it around a bit to indicate "center" based on the outside diameter of the main body at the round end.


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## canadianhorsepower (Mar 5, 2016)

Brian Rupnow said:


> I guess my next trick will be to suss out a way to hold the main body and baseplate to the faceplate, to bore the hole for the liner.The baseplate is going to have to be clamped to the faceplate, but with enough adjustment that I will be able to move it around a bit to indicate "center" based on the outside diameter of the main body at the round end.



Hi Brian 
I simply not getting it:hDe::hDe:
 why not using your mill and boring head
that's what it's made for

the more mass, the longer you are from your face plate,  
the more tricky the set up is.  

the more doors you are opening to Murphy's law :fan:

good luck


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## Brian Rupnow (Mar 5, 2016)

And now you know how I spent my Saturday!! the instructions say to glue the liner in place with #574 Loctite.  This is a loctite that is not stocked in Canada. The minimum amount I can by if I order it in from USA is a 1.7 fluid ounce bottle for $50---Does anyone know of an alternative that I can buy in Canada, that has the same properties?


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## Brian Rupnow (Mar 5, 2016)

canadianhorsepower said:


> Hi Brian
> I simply not getting it:hDe::hDe:
> why not using your mill and boring head
> that's what it's made for
> ...


Luc--Can't turn an internal water jacket recess with the mill.


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## canadianhorsepower (Mar 5, 2016)

Brian Rupnow said:


> Luc--Can't turn an internal water jacket recess with the mill.



and why not :hDe:

I'm totaly confuse,
 the rotation is OK the length is good enough
the travel is good enough 

please explain I have an 877 Busy bee and I can do it


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## Brian Rupnow (Mar 5, 2016)

Luc---There is a dirty little secret to boring something in the mill. If its a "completely thru" bore, there is no problem. if it is a blind hole, then there is no problem, assuming you can mount it with the open side up. The problem comes when you have something like a hole thru the center of this block where the crankshaft ultimately goes--The hole is larger in diameter in the center of the block than it is on the outsides of the block. In a lathe, that is no problem, because you can wind out the cross slide while the piece is turning, and the boring tool will cut it's way out to the larger diameter . In a mill, unless you have a very specialized boring head, (which I don't) you have to shut the mill off to advance the boring tool. Do you see where I am going with this? You have to advance the tool into a stationary part. Then you have to restart the mill with the tool already jammed into the material.--Not good!!! And every time you want to advance the boring head, you have to stop the mill to do so. It gets really nasty, really quick!!!


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## Brian Rupnow (Mar 6, 2016)

Last night I went to bed, all pleased with myself, and the fact that I had successfully lapped a piston into a liner for the very first time. And then, as I lay thinking about it, a thought struck me!!!--Due to the construction of this engine, the piston with con rod attached has to be lowered down thru the top of the liner, and then the "driver" side of the crankshaft has to be inserted from one side of the crankcase bore so that the rod journal engages the big end of the rod.---AND--I had lapped the piston into the cylinder liner from the bottom until it reached a spot about 0.100" beyond where it would travel in the liner under running conditions.--However, it still wouldn't go all the way thru the liner---which meant I would not be unable to insert the piston/con-rod assembly thru the top of the liner when I went to assemble the engine.---So---This morning I got up, put my "lapper hat" back on, and continued lapping until the piston fits completely thru the liner.


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## Brian Rupnow (Mar 6, 2016)

This is the intake window into the crankcase. Up to this point, there has been no "right" nor "left" side to the main body. Now that the window is cut on one side, I have to pay close attention to any further holes or slots that go into the main body.


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## Brian Rupnow (Mar 6, 2016)

I have a question now, that won't really have any effect on the way things get built, but may ultimately effect the way things get assembled. As you can see in this section view, the slot milled into the side of the crankcase to admit air/fuel mix is on an angle. If the engine rotates in the direction I have shown with the black arrow, it seems to me that there will be a pressure wave built up in front of the revolving crankshaft that will try to force incoming air fuel mix back out of the crankcase. Conversely, if the rotation is opposite to what I show, then there should be an area of low pressure behind the revolving crankshaft that will actually help to pull air/fuel mix into the crankcase. Since the engine is symmetrical about the centerline, I can choose which side I put the flywheel on and thus determine the direction of rotation. I like my engines to revolve clockwise when viewed from the flywheel side, because I use a starter spud in my variable speed drill to start my engines, which engages with a slotted hub attached to the flywheel. If the engine revolves counter-clockwise, then the drill chuck will loosen off. Is what I'm saying valid, or am I over-thinking things??


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## canadianhorsepower (Mar 6, 2016)

Brian Rupnow said:


> I have a question now, that won't really have any effect on the way things get built, but may ultimately effect the way things get assembled. As you can see in this section view, the slot milled into the side of the crankcase to admit air/fuel mix is on an angle. If the engine rotates in the direction I have shown with the black arrow, it seems to me that there will be a pressure wave built up in front of the revolving crankshaft that will try to force incoming air fuel mix back out of the crankcase. Conversely, if the rotation is opposite to what I show, then there should be an area of low pressure behind the revolving crankshaft that will actually help to pull air/fuel mix into the crankcase. Since the engine is symmetrical about the centerline, I can choose which side I put the flywheel on and thus determine the direction of rotation. I like my engines to revolve clockwise when viewed from the flywheel side, because I use a starter spud in my variable speed drill to start my engines, which engages with a slotted hub attached to the flywheel. If the engine revolves counter-clockwise, then the drill chuck will loosen off. Is what I'm saying valid, or am I over-thinking things??
> ]



Brian;
it doesn't matter, a two stroke is like a balloon , apply pressure somewhere  and you will have a result  o the other end 

cheers


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## Brian Rupnow (Mar 6, 2016)

I may have answered my own question here. The pencil stuck thru the slot is pretty well lined up with the center of the crankshaft, so it shouldn't make any difference which way the engine rotates. What I said in my previous post would only hold true if the intake slot came through tangent to one of the crankcase walls.--I'm still confused though, about which direction this engine should rotate.--can anyone tell from the cut away view in my previous post which way this engine should rotate?--My lack of knowledge about two stroke engines is hanging out here---


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## GailInNM (Mar 6, 2016)

Brian,
In the for what it's worth department, all the drill motors that I have seen that have a reverse rotation on them have a locking screw on the chuck to prevent it from unscrewing.  If you open the chuck jaws and look into the chuck between the jaws you will see it.  It is typically a cross point screw and must be removed to loosen or remove the chuck.  If you ever decide to change chucks or salvage a chuck you need to know that this screw has a LEFT hand thread.
Gail in NM


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## RonGinger (Mar 7, 2016)

I think most two strokes run well i n either direction. I had a full size 1908 Gray one cylinder marine engine in a boat- much like the hubbard this project is based on. It ran in either direction, had a direct coupled  prop and the way to reverse rotation was to change the spark timing and hit the switch at the right time. 

I also remember my old glow plug model airplane engines would start in the wrong direction about half the time.


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## Brian Rupnow (Mar 7, 2016)

Thank you Gail and Ron--I am considering using glow fuel and a glow plug for this engine. According the the information sheet I have, it will run quite well on glow fuel. It has a 6.5:1 compression ratio. How do you time an engine running a glow plug? I know how to advance or retard the ignition when it is fired by a sparkplug  running a gasoline based fuel, but since a glow plug (continuous glow is called for), how does it know when to ignite the fuel/air mix?


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## ixb1 (Mar 7, 2016)

CR  6.5:1(at full stroke?) is quite low for glow engine. Running on plain methanol/castor fuel mix will needed Hot (or hotter four stroke) plug.
Ignition timing is set by changing type of plug,amount of nitromethane in fuel,CR and richness of fuel/air mixture.


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## petertha (Mar 7, 2016)

Brian Rupnow said:


> I... there will be a pressure wave built up in front of the revolving crankshaft that will try to force incoming air fuel mix back out of the crankcase. http://s307.photobucket.com/user/Br...ASSY-WITH ROTATION ARROW_zpsnbrbbugr.jpg.html


 
The predominant force that makes the (ambient pressure) fuel intake charge 'move' into the crankcase cavity is caused by the reduced pressure (suction force) created by the piston displacement. I suspect the reciprocating & rotating parts are basically just stirring turbulent gas & probably not real effective at that.

https://www.google.ca/search?q=2+st...LAhUW0GMKHSKqB4oQsAQIIQ#imgrc=kF-C0SBgBYs2ZM:


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## canadianhorsepower (Mar 7, 2016)

Brian,
 why don't you take a few second and read the book that
I posted in the download section

It is well documented and there is graph  explaining everything.

cheers


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## ozzie46 (Mar 8, 2016)

Luc, the downloads section isn't working at the moment. I guess admin is working to fix it.

Ron


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## Brian Rupnow (Mar 8, 2016)

No progress on the engine for the last couple of days. I have one customer in town who periodically has work for me, but insists that it be done on his premises. He keeps an office and a computer for my use only. After spending most of the winter cooped up at home, I'm quite happy to get out of the house for a few days. However, after spending 8 hours over at his plant, I don't have a lot of energy left for machining in the evenings.


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## Brian Rupnow (Mar 12, 2016)

This morning I finished all of the holes, slots, and threaded holes in the main body. All went well, and I'm happy to be done with it. I have been so busy at my "real" job all week that I haven't had time nor energy to do any machining in my home shop. I'm not sure just what part I will make next, but I think those tapered bushing supports on each side of the engine will be a challenge, so I may make them next. I tried to make it easy on myself and redesign them with a series of "steps" to make them easier to machine, but they looked ugly, so I reverted to my original plan.


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## Brian Rupnow (Mar 12, 2016)

I was right!!--They are tricky little rascals to machine. The secret seems to be in the sequence of machining.


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## gocy (Mar 12, 2016)

Brian Rupnow said:


> Since the engine is symmetrical about the centerline, I can choose which side I put the flywheel on and thus determine the direction of rotation.



A reed valve should solve any pressure / fuel return issues.


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## 10K Pete (Mar 13, 2016)

gocy said:


> A reed valve should solve any pressure / fuel return issues.




You haven't read this whole thread, have you??

Pete


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## gocy (Mar 13, 2016)

Ooops. Just read posts no. 7 and 8. 
Anyway, i couldnt agree more with petertha.


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## Brian Rupnow (Mar 13, 2016)

This morning I decreed that today would be a cylinder head day. Why fins, you may ask, on a water cooled engine? Well, the cylinder itself is cooled by a water jacket. The cylinder head depends on heat transfer from it to the cylinder for cooling. Heat transfer only happens when you have metal to metal contact. I have found that on all of the engines that I have built, I end up having to make a head gasket to seal the combustion chamber completely and not lose compression, which is vital to the engine running well.----And---heat will not transfer through a gasket. So---that is part of my reasoning. The other part of my reasoning, is that this is a very plain little slab sided engine, and the cooling fins add a bit of visual excitement to a very "Plain Jane" effort.


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## Brian Rupnow (Mar 13, 2016)

As you can see in the drawing in the last post, this cylinder head actually extends down almost half an inch into the top of the cylinder. This would completely cover the end of the sparkplug, if not for a relief machined into the side of the cylinder head in the sparkplug area. So--I made the cylinder head, bolted it upside down to the main body, and this gave me something to hold onto while the clearance was machined.


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## Brian Rupnow (Mar 13, 2016)

I held the main body in my milling vice with the cylinder head bolted to it, and used a 3/32" slitting saw to put the slots into the head to create "fins". Each machined slot was cut at a depth of 0.120" each pass, got 3 passes in total, and the slitting saw was 3/32" thick x 2 1/2" diameter. and the mill was turning about 320 rpm.--Lots of cutting oil.


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## Brian Rupnow (Mar 13, 2016)

I am very pleased with the way the coned bushing housings that fit on each side of the main body turned out (wasn't nearly as difficult as had imagined) and I really like the way the cylinder head looks.


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## Brian Rupnow (Mar 13, 2016)

Found a treasure under my bench!!!----A nasty, crusty old piece of 660 bronze, 3 1/2" diameter x 1" thick. Bet ya there's a flywheel in there!!!


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## Brian Rupnow (Mar 13, 2016)

The original plans for this engine call for the intake manifold to be Loctited in place. Now don't get me wrong---I think Loctite is just great, and I use it on every engine I build.--However---On an overhung, cantilevered load like the carburetor, I want a couple of bolts holding it on. I just don't think Loctite is up to the task, so I have redesigned the intake manifold to attach with a couple of socket head capscrews. Now I will be able to make whatever carburetor adjustments are deemed necessary without having to worry about the whole thing falling off in my hand!!!


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## Brian Rupnow (Mar 16, 2016)

Finally I finished up the short term contract I was on and got to spend some time in my little shop. I have an intake port cover and an intake manifold. There are some very interesting angles on that intake manifold. I ordered the Loctite 574 flange sealant yesterday. I think I will make up an exhaust flange and a short length of exhaust pipe and then get into the crankshaft bushings, crankshaft, and con rod.


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## Brian Rupnow (Mar 16, 2016)

We have an exhaust flange and pipe!! It may need a bit of polishing, but it's all together and it fits. Damn!!! It looks huge, but it isn't really. That exhaust pipe is only 1/2" diameter, but the engine is so small that the pipe looks huge by comparison. I hate making soldered mitre joints like the one on that pipe. There is just never a good way to hold everything aligned and still have enough hands left to hold the torch and a piece of silver solder. I got it close and used a friendly file to make it straight after the fact.  Tomorrow I can get down to some serious crankshaft stuff!!---Brian


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## Brian Rupnow (Mar 17, 2016)

I had the best of intentions for today----But then we ended up with all four grandkids for half the day.---And, although Grandma kept the little devils all busy and I sneaked away to my shop, I got a distress call from a customer who needed a drawing immediately to send off to China to have something made. By the time I got that sorted out, I had a demand performance from all four grandkids to go with them and Grandma to get ice cream.--Dang, I never could turn down an ice-cream invite. So----all I really accomplished was a redesign of the flywheel. The center is aluminum. The outer rim is 660 bronze. The nifty looking green thing hanging from the front of the flywheel is made of steel, as are the two 1/8" diameter pins. That is the hub which I engage with my "starting tool" in my variable speed drill to start the engine. (The 1/8" diameter pins don't go through the end of the crankshaft, they just set up against it. They are pressed and Loctited into the green ring.)


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## Brian Rupnow (Mar 18, 2016)

A little help please. The picture posted is from the original plan set for this engine. The part with the black dashed line around it is the bushing which fits into the coned crankshaft bushing support, one on each side of the engine. I can see that a groove for oil is asked for---I'm just not sure about how I would make a groove like that, and it also appears to run up the face of the disc which is formed at the inner end of the bushing. The finished bore on my bushings will be only 3/8". It's not inconceivable that I could grind a small tool to fit in my quick change tool holder and hold the bushing stationary in the 3 jaw chuck and "broach" a blind v-groove into the bushing. It couldn't run all the way through, or the crankcase vacuum would pull air in through the groove, which would be a big no-no. As for the groove that appears to run up the face of the disc, would it just be one radial line, or a spiral groove, or does it even need to be there at all? I may just decide not to put the groove in there at all. After all, the fuel has oil mixed with it, and may well be sufficient to lubricate the bushing without any kind of groove there. What do you think?---Brian


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## Charles Lamont (Mar 18, 2016)

With the bush fully turned and bored including the end flange (but not yet lapped*) I would grip it lightly in the milling vice by the ends and cut the groove with a small (1/16") slot drill. This would also form the port in the middle of the bush and the radial connecting channel in the flange as a half-round groove. A centre drill (slocombe bit) would mill the chamfered cup at the edge.

An easier way to get an oil hole might be to drill at an angle after the bush is assembled in the bearing housing, drilling so as to safely not break through the
exterior conical surface.

*


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## Brian Rupnow (Mar 19, 2016)

When I installed the bushings into the cone shaped bushing housings, I reamed them individually to 5/16" diameter. After the coned housings were bolted to the sides of the main body, I set everything up with an angle plate to ensure that the underside of the base-plate was truly square to the center of the spindle. A packer plate underneath the base ensured squareness in the other plane. Then I centered the spindle on the top-most bushing, and drilled thru the entire assembly with a 11/32" drill, then reamed through both bushings to 0.375".  Of course, this then demanded an "assembly shot" with the flywheel in place. The flywheel is 95% finished. That's not really a crankshaft in the engine. It's just a piece of 3/8" round cold rolled.


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## Naiveambition (Mar 19, 2016)

Brian,   Sorry to break off your thread but I seen your slitting saw holder and was wandering. If you can elaborate on it a little.   From the looks you have a small mandrel fitted inside of a normal end mill holder. Is this correct?  

I've been tossing the idea around to build one but have not found too much info on them. I like your approach in that I can gain extra distance vs a collet. On my mill the spindle is very short and I spend most of my time struggling to see the work with collets.
Are their plans or just worked up for what was needed.

Thanks. 
Mike


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## Brian Rupnow (Mar 19, 2016)

Mike--I'm not sure where you are in the world, but I bought my slitting saw arbor at Busy Bee Tools in Barrie, Ontario. They are relatively inexpensive, and will fit two or three different hole sizes. They have a 1/2" shank.---Brian
http://www.busybeetools.com/products/arbor-slitting-saw.html


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## Brian Rupnow (Mar 20, 2016)

At this point the flywheel is finished. I find that my jar of #8 set screws is empty, so for the moment I have a couple of #8 socket head caps stuck in where the set screws would normally go. You can see the steel ring mounted to the face of the flywheel with the two 1/8" dowel pins Loctited into it, and my "starter spud" laying on the bench in the foreground. The starter spud fits into my variable speed drill, and disengages very easily as soon as the engine has started. I came up with this method of starting engines about half an hour after building my first i.c. engine and flipping the flywheel by hand until my wrist was sore. Now I move on to the crankshaft. There is a certain method to my sequence in making these parts. I needed the crankshaft bushings machined and installed for the crankshaft to fit into, and I needed the flywheel so I will have something which I can hold by hand to turn the crankshaft once it is in place to check for clearances.


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## Brian Rupnow (Mar 20, 2016)

I've been very "cranky" this afternoon. The crankshaft is a two piece unit. The end with the rod journal is the end with the flywheel on it. The other end of the crankshaft is "driven".--It gets the ignition cam on it. To install the crankshaft, the two coned bushing supports unbolt from the main housing, and each half of the crankshaft gets pushed through from the inside end of the bushing supports, then they get bolted back onto the main body.--Hopefully, I will soon have a con-rod to assemble there as well.


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## Brian Rupnow (Mar 21, 2016)

Once again I have proven to myself that the size of a part in no way reflects the amount of work required to make it!!! However, we now have a connecting rod. The crankshaft is mounted in the engine, and after much fettling, clearancing, dissasembly and reassembly , it goes round and round and doesn't hit anything. I still have to pull it out of the engine (which pretty well demands complete disassembly) and put the keyway in the end of it, then reassemble it with the piston and con rod and hope that everything still goes round and round and up and down.


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## Brian Rupnow (Mar 21, 2016)

News is not good!! When I pressed the rod journal into my 3 piece "driving" crankshaft, it pressed awful hard. I thought afterward that it looked a little crooked, but decided to move forward with other things. Now that I have the rod finished, I have confirmed my fears. With the crankshaft in my 3 jaw and the lathe on it's lowest speed. and the con rod in place on the journal, the con rod has kind of a snaky, twisting motion as the crankshaft revolves, not a true linear motion like it should have. This is not a major disaster, as the rod journal can be pressed out and a new one turned up and pressed in. The next one will have a much longer "lead" on the side that gets pressed into the crank "throw".


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## Brian Rupnow (Mar 22, 2016)

This post is not meant to show me up as a fool, although some are apt to take it that way. I have had an absolute devil of a time to get the con-rod journal pressed into place in the crankshaft "throw" and get it to press in straight. I finally succeeded, but not without my fair share of frustration. The journal is made from 5/16" diameter cold rolled round stock. The "throw" is made from 5/16" thick cold rolled steel bar. The bad journal on the left, had no lead and was .004" oversize. It did press all the way in, but ended up crooked---it pressed VERY hard. I was using my 4" mechanics bench vise to press things together. The bad journal next to it had a lead at 0.250" diameter and a diameter of 0.253 in the area to be pressed. It pressed in to about 3/4 of the way, and then it too began to go crooked and was VERY  hard to press. The third one on the right had a 0.250" diameter lead and was turned to 0.252" diameter in the press area. It pressed in VERY hard, and hung up and began to go crooked at about 3/4 of the way into place. The final, and successful one was turned to have a lead of about 0.249" diameter, and a diameter of 0.2515 in the area to be pressed. It went in VERY  hard, but it went in straight. the "lead" area was then trimmed off on my bandsaw.


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## Brian Rupnow (Mar 22, 2016)

So---Today we reached a "milestone" event in the development of this engine!! The wrist pin with it's brass end-caps was finished and installed earlier today. The piston with con rod connected was dropped down thru the top of the engine and when the big end of the con-rod was visible in the crankshaft area, the coned bushing housings and both halves of the crankshaft were assembled. Everything goes "round and round and up and down" just as I had hoped for. No, it wasn't really that simple. I kept finding minor interferences, chasing them down, removing them, and reassembling things, until eventually the crankshaft would rotate a full 360 degrees without anything inside going "clunk clunk". I have the Loctite 574 on order for sealing the leaded steel cylinder liner into the main aluminum body. All that is outstanding now is the bracket for attaching the ignition points, the ignition cam, and the carburetor, and of course some kind of fuel tank. I plan on using the gear pump I designed and built last year to circulate cooling water thru the engine, and it will be driven by an o-ring drive belt.


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## canadianhorsepower (Mar 22, 2016)

Brian Rupnow said:


> The bad journal on the left, had no lead and was .004" oversize.
> 
> Brian why go so big all you need for a press fit is .001
> 
> coming along good


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## Brian Rupnow (Mar 22, 2016)

Luc--I don't have a lot of experience with press fits. My big concern is that when the engine fires, if the piece the con-rod is connected to comes lose, the engine will be destroyed. I find that my press fits are dramatically effected by the surface finish on the part being pressed. If the male part has a rough finish, then the press fit won't be too good because of all the micro-ridges on the part (they give a rather false reading on the micrometer.) If the part has a good finish, then it will be a much harder press even though it measures the same diameter as the part with the rough finish. A lot of what I am doing is "learn by experience" machining. Next time I go for a press fit on parts 1/4" in diameter, I will remember this exercise and go for a .001" over nominal size.


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## Brian Rupnow (Mar 22, 2016)

And here's a "quick and nasty" of the engine driving the gear pump to circulate the cooling fluid through the cylinder. I haven't taken the time to re-route the coolant lines, but if the engine runs, this is more or less where I will be going with it.


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## Charles Lamont (Mar 22, 2016)

The material you are using for the crankshaft would appear to be 'bright drawn' bar.* To my mind that has neither the accuracy nor the surface finish to use as-it-comes for a respectable crankshaft. At not much extra cost or difficulty of sourcing, you should be able to get 'precision ground' mild steel bar, which I would recommend as much more suitable.

* (You call it 'cold rolled' but I think that is actually something quite  different, normally meaning strip rolled into sections for things like  garage door rails, office partition framing, light gauge square tube and Armco. OTOH the may be some transatlantic terminological misunderstanding.)


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## Brian Rupnow (Mar 22, 2016)

Charles--I now have 16 running engines, all using what is commonly called "cold rolled" 1018 steel in Canada and United States. I'm not sure whether I ever considered my crankshafts to be respectable or not. I know that they work, and work quite well for model engines.


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## canadianhorsepower (Mar 22, 2016)

Brian Rupnow said:


> If the male part has a rough finish, then the press fit won't be too good because of all the micro-ridges on the part (they give a rather false reading on the micrometer.)




Brian 
if this is the case (parts finish) just go with a slide fit
and then knurl your male part. Those two together works
100% and for security use the green locktite on assembly 

good Luck


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## ICEpeter (Mar 23, 2016)

Hello Brian,
Down here in the USA what you call *cold rolled* we refer to as *cold drawn. *That is what you might have obtained because it is typically dimensionally close to precision ground round stock and has a reasonable smooth surface finish.

Peter J.


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## Brian Rupnow (Mar 23, 2016)

Today I made up the bracket which mounts the ignition points, along with it's handle and the ignition cam. The points bracket allows me to unscrew the handle to loosen up the grip on the end of the coned bushing housing, and lets me adjust the ignition timing while the engine is running. I still have to mill a flat on the ignition cam and put in a set screw.


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## Brian Rupnow (Mar 23, 2016)

Before I start to cut any metal for the carburetor, I thought a bit of redesign was called for. From what I am able to understand of the original design, everything leading into the main carburetor body was soldered into place, with the check ball held captive in the center. That's fine, if the check ball really seals the way it is intended to. However, if the ball doesn't seat just right, there is nothing you can do about it without unsoldering pipes, which isn't a really great option. I decided that I wanted access to the ball, so I enlarged the main body enough to get four #40 socket head capscrews in there to hold the top on. I will add a gasket in there too under the top plate, but I haven't shown it in the model.


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## Brian Rupnow (Mar 24, 2016)

I've spent a large part of today doing what I call "Hold your breath machining!!"
Before I make the two large parts of the carburetor (and remember, "large" is a relative thing here) I had to first see if I could make the small parts that make the carburetor work. That longest brass piece has a 1 mm (0.039") diameter hole drilled half the length of it, a 0.056" diameter hole through the remaining half, and a 1 mm cross hole drilled in it. The o.d. is threaded #6-32, and the needle valve top (the brass part with the split in it) has a 0.045"  hole completely through it and a #6-32 internal thread. The needle which will become the other part of my needle valve, is a sewing needle. The steel part with the knurled top and the #5-40 thread on it is what holds the check valve down in place, and effectively becomes the throttle. Everything seems to have went okay, so the two larger parts of the carburetor will come next.


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## Brian Rupnow (Mar 25, 2016)

In the time honored tradition of "making do with what you got", this is a prime example of making round stuff into square stuff.--An added benefit is that I was able to turn the two diameters in the 3 jaw on the lathe before starting to square things up. This is going to end up being the main body and cap of the carburetor.


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## Brian Rupnow (Mar 25, 2016)

We're close.--Very, very close. It's been a long day, but I've managed to squeak out a carburetor. An hours work should see it finished.


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## Brian Rupnow (Mar 26, 2016)

We are carbureted!! Just MIGHT have a runner later this week!!!


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## Brian Rupnow (Mar 27, 2016)

You may remember from "section views" taken thru the main body, that I had to drill holes up thru the inside of the main body from the bottom to provide an air passage from the crankcase up to the intake ports, and for rod clearance at the 3:00 position. Now it is time to plug and seal these access holes in the bottom of the main body to ensure an air tight crankcase. Aluminum plugs were turned to the correct diameter, coated in Loctite, and inserted into the holes. Then the entire engine is turned upside down, and a bit more Loctite poured onto the top of the plugs and the surrounding engine base. After 24 to 48 hours, I will file the area flat and clean, and reinstall the baseplate.


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## Brian Rupnow (Mar 27, 2016)

I'm getting awfully close to "showtime" here-----If there's going to be a "showtime."!!  I really don't know what to expect. I made all the gaskets today while the Loctite was drying on the plugs in the bottom, and installed them about an hour ago. The only thing remaining to be done to the engine is to apply the Loctite #574 to the liner to seal the water-cooled area and the sparkplug entrance hole, which is tapped into the aluminum housing but is a small clearance fit thru the side of the liner. I'm not going to bother doing anything with the waterpump until I know if the engine is going to run. With my usual 4 stroke engines running a Viton ring and hand lapped valves, I am always quite confident they will run---but this 2 cycle business is so new to me I don't know what to expect.The loctite is in transit from somewhere in the USA to my local Brafasco dealer and should be here this week. Keep your fingers crossed for me.---Brian


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## Brian Rupnow (Mar 28, 2016)

There may be a clue here to which way my engine will rotate. This old engine has the almost exact same physical layout as the engine I am currently building. When he starts the engine, you can see that he flips the engine counterclockwise when facing the flywheel. This of course is exactly opposite of what I was hoping for, but it's not really a big deal. the engine certainly runs nice.---EDIT EDIT--after carefully watching the entire video, I can see that when he moves the timing lever far enough in one direction, the engine slows, then kicks back and reverses direction and runs equally as well in the other direction!!-Brian
[ame]https://www.youtube.com/watch?v=1FbLzBkH4Ic&feature=player_embedded[/ame]


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## Niels Abildgaard (Mar 28, 2016)

Starting a  two stroke engine:

[ame]https://www.youtube.com/watch?v=66t2Zl6w-Ic[/ame]


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## canadianhorsepower (Mar 28, 2016)

Brian Rupnow said:


> I can see that when he moves the timing lever far enough in one direction, the engine slows, then kicks back and reverses direction and runs equally as well in the other direction!!-Brian
> https://www.youtube.com/watch?v=1FbLzBkH4Ic&feature=player_embedded




Hi Brian,
you can do that with your's  also 

this is how the get reverse to work on ski-doo with 2 strokes engine.

the only difference is the ski-doo have 2 ignition system,
it's easier togle the switch and you are in reverse 


as you can see he stops the ignition system when changing from one side to the other
and it's done at low RPM

BTW  a single cylinder diesel can be started in both Rotation also CW and CCW  

enjoy


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## Brian Rupnow (Mar 28, 2016)

Yes Luc, I can remember back in the day, when everybody was running 12.3 Skidoo's. One of the first things to break was the starter rewind system, so people just threw the rewind away and filed a notch for the starter rope like an old Evinrude outboard. If you wound the rope wrong way round, you wouldn't know it was running backwards until you hit the throttle. More than a few teeth were lost on windshields because of that one!!


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## RonGinger (Mar 28, 2016)

I had a 1908 Gray 3hp one cylinder in a boat. It had to much compression to turn through so you started it by bouncing it off compression, in the opposite way you wanted it to run. if you had the timing right  it ran the way you wanted, which was nice because the prop was directly connected- there was no neutral or reverse, you were moving in the way the engine was running.  It did take some learning, but actually was fairly reliable.


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## Brian Rupnow (Mar 28, 2016)

Ron---When I was a kid, I had an old Evinrude or Johnston, (can't remember which) that had dual opposed cylinders and no cowling. The sparkplug on one cylinder bank was exactly in the same spot your elbow had to be to steer the boat by turning the engine. Every time I went out in the boat, I managed to get my elbow into that sparkplug. People around the lake knew me as "That kid with the old boat motor that curses a lot!!!"


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## Brian Rupnow (Mar 30, 2016)

This morning I completed the last 3 things which had to be done to the engine. I milled a keyseat in the drive side crankshaft where the flywheel connects to it, built a small brass shim to remove excess end-play from the crankshaft, and used a small 3 cornered file to put the oil-slots partway through the crankshaft bushings. Now it's just a matter of waiting for my Loctite 574 to come in.


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## Brian Rupnow (Mar 30, 2016)

I was just told the Loctite 574 I have on order won't be in until the 7th of April. That's okay. I do need a break.


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## Brian Rupnow (Apr 4, 2016)

Having nothing better to do today, I decided to go ahead with a gas tank for this engine. The pipe cap  and two short nipples are 0.840" o.d. black iron pipe. The bigger rusty piece is 1.67" o.d. black iron pipe. Brass would have been much prettier, but it is also much spendier as well!!!


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## Brian Rupnow (Apr 4, 2016)

First, a skim off the outside and a couple of passes through the inside with my boring bar gets rid of most of the rust--


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## Brian Rupnow (Apr 4, 2016)

Here you can see the finished tank body setting on one of the ways, and the pipe cap screwed onto a nipple and held in the three jaw.


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## Brian Rupnow (Apr 4, 2016)

And "Hey Presto" we have a screw on gas cap.


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## Brian Rupnow (Apr 4, 2016)

Now, with a little creative brazing on the filler neck to body I should have the start on a nice little gas tank. You will see that I have one of the pipe nipples left over. I will throw it in my drawer of "spare stuff". I haven't decided at this point whether to Loctite round discs of 3/8" thick aluminum or possibly brass into the tank to form ends. I have to suss out an adjustable height tank support, and I have to go buy a small shut-off valve and determine just how to attach it. Aluminum is great stuff to machine and work with, but I can't weld or silver solder aluminum, so I have to go carefully now so as not to paint myself into a corner.


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## Brian Rupnow (Apr 4, 2016)

I went down to Canadian tire (Canada's generic hardware store) and purchased a shut-off valve that is close to the size I need. It is one that you tie into a cold water line in your plumbing to provide water to your humidifier or refrigerator. I will throw most of these parts away and just use the valve portion. Fortunately for me, I have a 1/8"-27 npt pipe tap which seems to be the correct size. It is part of an old tap and die set that I bought way back when dinosaurs still roamed the earth, and I don't think the pipe taps have ever been used. I have disassembled the valve to ensure that there there isn't a nylon seat or anything in there that the Coleman fuel would dissolve, and there isn't---just a steel needle acting on a brass seat. This will let me make tank ends out of aluminum, which will be "glued" into the ends of the main body with J.B. Weld. I was going to use Loctite, but the J.B. Weld is thicker bodied and will be less apt to leak.


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## Brian Rupnow (Apr 4, 2016)

This gives a pretty good overview of what the finished tank will look like. I still have to apply the J B Weld to the end caps but I stuck things together long enough to "pose" them for a picture. The 1/2" diameter round stock brazed to the bottom of the tank body will fit into a "receiver" with a set-screw to let me adjust the height of the tank to give the best running characteristics to the engine.


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## Brian Rupnow (Apr 5, 2016)

There has been some controversy about how well J B Weld stands up to gasoline or naptha gas. this is a test. Picture #1 shows a batch of J.B. Weld that I mixed up 24 hours ago. It is set up harder than the devil's horn. Picture #2 shows the end cut off the "mixing jar" and submerged in a container of Naptha (Coleman fuel) with a piece of metal setting on it to keep it submerged. I will check it after 24,48, and 120 hours and let you know what happens to it. Does it go soft and sludgy, or stay hard. Time will tell, and I will keep you posted. The container is now covered with a piece of heavy cardboard to keep the Naptha from evaporating.


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## Brian Rupnow (Apr 5, 2016)

Regardless of how well the J B Weld stands up to gasoline, here is a little trick worth knowing. Any time you are using epoxy around a part which has a threaded hole in it, plug the hole full of Plasticene (Childrens modeling clay) before-hand. The plasticene will keep the epoxy from running into the threads and making life miserable.


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## Brian Rupnow (Apr 6, 2016)

This mornings nifty trick has been to modify the outlet of the gas tank valve to get it headed in the right direction.


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## Brian Rupnow (Apr 6, 2016)

After 24 hours submerged in Naptha gas, (Coleman fuel) the J.B. Weld is completely unaffected. I took the 'sample' out and tried to scratch it with a scriber. I can see no difference in it after 24 hours submersion, so I put it back into the container of gas. I will report again tomorrow on what is happening with it.


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## canadianhorsepower (Apr 6, 2016)

Brian Rupnow said:


> After 24 hours submerged in Naptha gas, (Coleman fuel) the J.B. Weld is completely unaffected.  so I put it back into the container of gas.



Hi Brian 
it will not be affected eather.
Many years ago I was doing lumberjack event
and I was using JB WELD as build up material
for external transfer ports.
I was using Alcool and Nitro Mix  to run
and would flush them with gas and oil mixe
never faille once


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## Brian Rupnow (Apr 6, 2016)

Luc--I didn't think it would be, but somebody on another forum said it would go all soft and gooey from gasoline, and I wasn't 100% sure. Better to have a test and make sure than have the end fall out of a full gas tank while test running an engine.---Brian


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## canadianhorsepower (Apr 6, 2016)

Brian Rupnow said:


> Luc--I didn't think it would be, but somebody on another forum said it would go all soft and gooey from gasoline, and I wasn't 100% sure. Better to have a test and make sure than have the end fall out of a full gas tank while test running an engine.---Brian



Brian 
Totally agree with you 
better be safe then sorry
but some peoples only read 1/2 of the
instruction :wall::wall:

cheers


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## Brian Rupnow (Apr 7, 2016)

Sometimes you just have to put everything together and see what it all looks like assembled. I'm pretty pleased with this. My o-ring drive-belt is actually thicker than the one which will ultimately be used, but it was the right length for a mock-up. The gas line running from the gas tank to the carburetor is pretty well horizontal. The tank sets higher than the carb jet, so it needs the shut off valve I have mounted on the tank. The large vertical tube is a water coolant reservoir. Water runs from the bottom of it over to the gear pump. The gear pump pumps water out the top, thru the tube to the engine cooling passage around the cylinder, out the other side of the engine, and then back thru that overhead tube and is discharged back into the top of the cooling reservoir. I will make something a bit more "pleasing to the eye" than that long tube which returns water to the coolant reservoir from the engine. I'm still waiting for my Loctite 574 so I can re-assemble the engine and see if it will run.


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## Brian Rupnow (Apr 7, 2016)

The gas tank has been leak-tested by filling it with Naptha and letting it set 15 minutes with the valve closed. Nothing leaked. My Loctite 574 has just arrived, and it smells pretty benign but is covered with all kinds of dire warnings about skin reactions, etcetera. It is the same color as orange soda pop and perhaps a bit thicker than Loctite 638 which I use all the time. I may go up to the drugstore and buy a pair of light rubber gloves to wear when applying it. I'd like to get the liner installed tonight so it can set up overnight before I start to reassemble the engine. While I was out picking up the loctite, I stopped at the auto parts store and picked up a 3/16" o.d. metal brakeline to replace that big loop of cooling hose that sticks up above the engine.


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## Brian Rupnow (Apr 7, 2016)

Well, for better or worse, the liner is Loctited in place. I decided to risk a finger and save a trip to the drugstore to get rubber gloves. I had a good wash with lots of soap and hot water after the deed was done and my finger doesn't seem any worse for the experience. Now if the Loctite just sets up properly overnight, and the water jacket is sealed so it don't leak cooling water into the crankcase I MAY soon have a runner!!!


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## Brian Rupnow (Apr 8, 2016)

We've got a lot of snapping and popping going on!!! Engine has good compression, and is trying hard to run. It almost runs in either direction!! I'm having a hard time finding that "sweet spot" where the engine takes hold and begins to rev up faster than the drill is turning it. My waterpump is leaking somewhere, and I will have to address that sooner or later, but I want the engine running first.


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## Brian Rupnow (Apr 8, 2016)

Enough for today. I still don't have a runner. Lots of compression, lots of firing, but no real runs. I must say, I'm not too impressed with this business of having the gas tank higher than the carburetor. All the time that I'm trying to start the engine, there is fuel dripping out the intake side of the carb, and yet the engine is acting like it's starving for fuel. I'm afraid of the fire hazard. I took off the belt that was driving the waterpump, thinking perhaps it was putting too much load on the engine (it shouldn't) but it made no difference. I have tried many different ignition timing settings and found where it seems to work best as indicated by engine firing. This is a quandary!! If the engine was a four stroke, it would have ran by now. I don't even have any leaking valves to blame. The only thing I can think of at the moment that I have left to mess with is the height of the gas tank in relationship to the carburetor. Maybe tomorrow I'll lower the tank and see what happens.


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## Charles Lamont (Apr 8, 2016)

Brian, what is your fuel mix? (Just curious, I don't have anything to suggest.)


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## Brian Rupnow (Apr 8, 2016)

Charles Lamont said:


> Brian, what is your fuel mix? (Just curious, I don't have anything to suggest.)


Running a 20:1 mix which is a bit oil heavy, but shouldn't keep the engine from firing and running.


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## canadianhorsepower (Apr 8, 2016)

Brian Rupnow said:


> Running a 20:1 mix which is a bit oil heavy, but shouldn't keep the engine from firing and running.



WAY to much oil.. this is not a diesel Rof}Rof}
not lest then 50:1 
 a small trick install a bull horn pipe on your intake
and try it then


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## Brian Rupnow (Apr 8, 2016)

What on earth is a "bull horn pipe"?


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## canadianhorsepower (Apr 9, 2016)

Brian Rupnow said:


> What on earth is a "bull horn pipe"?



OUPS I mean a boost tube
in your case a small co2 cartridge from a air pistol would be good enough
The bottle MUST be upward parralel to your cylinder
it serve as a mixture reservoir


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## Brian Rupnow (Apr 9, 2016)

There are no leaks in the crankcase. However, that being said, there are no shaft seals on this engine. I am completely out of tricks that I would normally use to start an engine.---tried them all yesterday.  The engine fires, and fires very consistently when turned by the drill motor, but won't keep running on it's own. I have tried the ignition timing on every setting, and although it makes a difference, it doesn't make enough difference for the engine to catch and "take off". Likewise, I have tried every possible needle valve setting. This engine seems to fire more consistently on what I would deem a very rich mix if it was a four cycle engine.  Today I will do the "easy" stuff---I will start by lowering the gas tank to see what effect that has. I will try and feel for carburetor suction, and may put a piece of clear plastic tube from the intake pipe to a glass of water to see if it is blowing bubbles when I turn the engine over by hand to see if the round ball in the carburetor is sealing the way it is supposed to. If that fails, i may try glow fuel and a glow plug, which are recommended for this engine by the original designer. (He claims that though the engine will run on gasoline, it starts much easier on a glow plug set-up.) What do people generally do for crankshaft seals on an engine like this, where the crankshaft is only 3/8" diameter?----Brian


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## canadianhorsepower (Apr 9, 2016)

Brian Rupnow said:


> However, that being said, there are no shaft seals on this engine. engine like this, where the crankshaft is only 3/8" diameter?----Brian



Brian,
a 2 stroke engine is like a balloon ANY leak will turn into a disaster.
 make an adapter to seal close your exhaust and intake port (after the carb)
apply a pressure small 10 lbs in the spark plug hole and dip it into water
any bubble means trouble. Then apply 10 hg of vacuum  and it should hold 
steady .

As for the 3/8 id seal it's pretty common on chain saws and boat.

I would doubt that it will ever start and run properly without seal 
on the crank
good luck

http://www.timken.com/en-us/products/documents/seal-specification-guide.pdf

page 17 has all you need


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## ixb1 (Apr 9, 2016)

Methanol/oil mix works well with spark ignition.Put some glow fuel directly into the cylinder through exhaust port and turn crank quickly.


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## Brian Rupnow (Apr 9, 2016)

Today I have my detective hat on, and I have found a clue!! I removed the carburetor and holding it in the same position as when it is mounted, I blew air up the intake pipe. Okay, good--air passes thru just like it is supposed to. Then I sucked, expecting to not be able to get any air-(the needle valve was fully closed) -the check ball should have stopped any air going in the opposite direction, however----it didn't!!! WHAT---IT ISN'T SUPPOSED TO DO THAT!!! This called for disassembly of the carburetor, and inspection of the seat against which the ball should set to stop reverse air flow. the seat should have some kind of mark indicating that the ball was seating fully against it.---it didn't. I could just make out what looked like a mark on top of the fuel jet tube which sets directly below the ball seat. A careful measuring of the ball I have in there shows that it isn't 0.250" diameter as I thought. It is only 0.235" diameter. If you look at the drawing, the ball is colored red. You can see that with any decrease in diameter, the ball is going to rest on top of the fuel jet and not seal on the seat.--and that is exactly what has been happening. Now I have to see if I have a .250" diameter ball, or decide to wait until Monday and hope that Canadian Bearings in Barrie has the 1/4" balls in stock.


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## Brian Rupnow (Apr 9, 2016)

For the princely sum of $5.25, I am now the proud owner of 250 steel balls, 1/4" diameter, purchased from Canadian Tire (slingshot ammunition). Thank you to Wagonmaker in Lindsay, Ontario for the suggestion. I don't think these are bearing quality balls, but for a ball poppet valve they should work just fine.--And yes, I have already tried the "Suck and blow test" with one in the carburetor body, and they work fine.


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## Brian Rupnow (Apr 9, 2016)

The larger check ball done the trick!! I dropped the gas tank about 1 1/4", reassembled everything, and away it went. This makes me feel really good. One of the things that can not be stressed strongly enough, is that with these little engines you have to become an expert trouble-shooter. If it doesn't fire up after the first two hours of tinkering with it, then you have to have enough experience to figure out the reason and correct it. Thank you very much to all of you who have followed this build thread.---Brian Rupnow
[ame]https://www.youtube.com/watch?v=BjNhVsfEDMI&feature=youtu.be[/ame]


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## Herbiev (Apr 9, 2016)

Beautiful build as usual Brian. A great sounding engine.


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## Brian Rupnow (Apr 10, 2016)

After much playing with this engine this morning--(which in itself is a problem, because it's still below freezing outside, and I'm running this thing in my office with the door propped open to keep from gassing myself, and my arse is freezing off) I have determined that the top end speed is in the 1800 to 2000 rpm range with my laser tachometer. The bottom speed that I am able to obtain is about 850 rpm, which is a far cry from the supposed 400 rpm figure that was given with the casting set drawings. I'm running Coleman fuel (Naptha gas) with 10% synthetic oil added. The throttle response is not great, and it goes from high speed to low speed all within one turn of that threaded adjustment which bears against the top of the ball in the carburetor to limit how far the ball can lift off it's seat. The thread on that part is 40 TPI.  I guess that on these old original marine engines, there wasn't a lot of requirement for a real wide range of speeds.   When turning the flywheel by hand, it feels far different than turning a four cycle over by hand. It not only has excellent compression as the piston is going up in the cylinder, but what feels really strange is that you can also really feel the compression when the cylinder is going down in the cylinder as it compresses the fuel/air mix in the crankcase. The engine doesn't have any problems driving the gear pump, and as you can see in the video I am getting a good flow of cooling water with the pump running at 1/2 the engine rpm.


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## canadianhorsepower (Apr 10, 2016)

Brian Rupnow said:


> .   . It not only has excellent compression as the piston is going up in the cylinder, but what feels really strange is that you can also really feel the compression when the cylinder is going down in the cylinder as it compresses the fuel/air mix in the crankcase. .



Brian,
you probably feel the vacuum forming when you are going down,
it sur as hell not compression.
you should try one of those tube I talk to you about 
it would help cause you have a very short intake track 

good luck
nice work BTW


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## Brian Rupnow (Apr 10, 2016)

Luc--You were right. It was suction on the piston I was feeling. I tried it with the spark-plug removed, and there is no compression at all.---Brian


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## Brian Rupnow (Apr 10, 2016)

Guys--If the weather ever warms up and if it ever quits snowing here, I will move my act out to the main garage where I can open both the big doors and do a real video. I will show this engine at it's lowest rpm and it's top rpm, and maybe get a shot from the other side where the drive pulleys are set up to drive the waterpump. We got our April weather in March and set record high temperatures, but now we're getting out March weather in April, and believe me, nobody's enjoying it very much.


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## Brian Rupnow (Apr 11, 2016)

And Oh yes, just to set the record straight--I opened the container with my sample of j.b. weld submerged in Naptha gas this morning and checked it out. Naptha gas (Coleman fuel) has absolutely no effect on the j.b. weld.


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## GailInNM (Apr 11, 2016)

Not that you need any further confirmation but:
http://www.jbweld.com/pages/faqs
"When fully cured, J-B Weld is completely resistant to water,
 gasoline, and about every other petroleum product or
 automotive chemical."

Also other useful info about JB weld on that page.
Gail in NM


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## Brian Rupnow (Apr 11, 2016)

Gail--I only conducted that series of tests because some "knowledgeable person"over on another forum posted that the j.b. weld would go all "gooey and turn to mush" in the presence of gasoline".  I get so tired of "expert opinions" from people who don't really know what they are talking about, I decided to do the little experiment thing to set the record straight. Old guys like me have a pretty good knowledge of what works and what doesn't work. The problem arises when  a lot of young people new to the hobby follow my posts and see a statement like that from a "senior member" and take it as truth.


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## Brian Rupnow (Apr 11, 2016)

I'm bored this morning, and since the Devil finds work for idle hands (as my Grandma used to say), here's a video of the two cycle engine running my lighting plant.
[ame]https://www.youtube.com/watch?v=Cn8reNH8mBM&feature=youtu.be[/ame]


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## Brian Rupnow (Apr 12, 2016)

Today I moved the adjustable ignition point lever in the opposite direction to where it had been set, reversed my electric drill, and started the engine running in the opposite direction. It runs as good , possibly even better when turning counter-clockwise. All previous runs have been with the engine turning clockwise, although it doesn't look like that in the videos. My water-pump only works in one direction, so I had to cross the o-ring belt drive to achieve this.


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## deverett (Apr 12, 2016)

Great build thread and engine, Brian.  You have inspired me!

Dave
The Emerald Isle


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## Brian Rupnow (Apr 13, 2016)

When I built this engine, my biggest concern was lapping the piston into the cylinder so that it would run without rings. This was something I had never done before, and it was a totally new learning experience for me. As far as porting is concerned, I copied a proven design, so I assumed it would run if my piston lapping experience was a success. It runs!! Hooray!!! I have ran the engine for about 3 hours now, and have discovered a flaw. When I made the bushings which the crankshaft runs in ( the green one on the left), I made them from brass. Now after 3 hours of running, the crankshaft is very loose and "wobbly" in these bushings. This means that no doubt the crankcase is sucking air thru the clearance around the crankshaft. I know that it is blowing oil out around the crankshaft, because I have the tracks on my desktop on both sides of the engine to prove it. My goal was to not only have a running engine, but to have an engine which would operate at a much lower rpm than this engine is capable of. The lowest sustainable speed I have been able to achieve is about 850 to 900 rpm, and the longer I've ran the engine, the faster it needs to run to keep from stalling. This is a sure sign of leaking air around the crankshaft. Today I went to Canadian Bearings and after searching thru their bearing catalogue, I discovered that a #1610 ball bearing  was 3/8" i.d. x .910" o.d. x .312" thick. I also discovered that they have triple lip rubber shaft seals that are 3/8" i.d.  x 3/4" o.d. x unknown thickness. I ordered 4 bearings and two shaft seals, which cost a total of $49.00. I will make two new bearing housings, which will each get two ball bearings and one seal (which I haven't shown yet). My design on the right is not complete yet, because  #1--I don't know the thickness of the seals yet, and #2 --the bearings are sealed units, and depending on the old "blow your guts out" test may not even require the use of a separate shaft seal. Each bearing housing needs two bearings because of the fact that the crankshaft is a "two-piece" configuration and will not act as a 'bridge" to allow use of one bearing in each housing. I will keep you posted as things develop.----Brian


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## RonGinger (Apr 14, 2016)

Model engines always run fast. Its part of the problem that you cannot scale physics. The flywheels are just to small. Maybe you could make one from depleted uranium to get more weight?


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## Brian Rupnow (Apr 14, 2016)

Ron--I have already tried the heavier flywheel route. It helps, but it only helps some. Luckily, there was enough room between the existing flywheel and the side of the main aluminum body that I was able to add 3/8 inches more of brass to the side of the existing flywheel, which increases the flywheel mass by about 50%---Brian


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## Brian Rupnow (Apr 15, 2016)

This is getting very interesting indeed. I picked up my bearings and seals today, and was able to create a 3D model of the seal. The outer diameter of the 3/8" shaft seal is 3/4", which means that I will have to machine an adapter ring (yellow) to mount the seal. I will remove the seals from the bearings so they get their lubrication from the 2 cycle oil mixed with the fuel. I can make new housings the same length as the existing housings which means that I won't have to modify my crankshaft, and they should bolt right onto the main engine housing.


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## Brian Rupnow (Apr 15, 2016)

And just for the fun of it, here is a cross section thru the engine----Nothing has been changed except that the coned bushing housings and bushings have been exchanged for the new housings with ball bearings and seals. I also show the 3/8" wide addition I made to the side of the flywheel to give it a bit more weight.-----I will have to make a new ignition points mounting bracket.


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## Brian Rupnow (Apr 17, 2016)

The new bearing housings are finished and trial fitted in this picture. I use ordinate measurements for all my hole patterns using the DRO's on my mill. and things always seem to fit, but it still seems a bit like black magic to me. i always trial fit things just to be really sure they fit together properly before final assembly. I am having second thoughts about removing the seals from the bearings. They don't seem that stiff to me, even when they are brand new, and they will certainly loosen up with a few thousand revolutions on them. I will hopefully stick everything back together tomorrow and see what happens.


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## Brian Rupnow (Apr 19, 2016)

As things keep moving moving ahead I keep adding to my own knowledge base. I ended up leaving the grease seals in the ball bearings, and installing a plain 3/8" dummy crankshaft in the engine with a 3" v-pulley on it and driving it for an hour with an 1800 rpm electric motor just to remove any "new bearing seal stiction" . What I have discovered is that after an hours running, the bearings with grease seals rotate very freely. However---the separate shaft seals, even though they have only a thin rubber lip in contact with the shaft add a surprising amount of "stiction". (rolling friction) to the shaft. I am going to try these assemblies in the engine to see what happens. I know they won't leak any crankcase compression or suction. If they add too much stiffness to the rotating crankshaft, I will simply take an exacto knife and cut the lip out of the shaft seals.


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## Brian Rupnow (Apr 30, 2016)

Okay, one final post to finish off this thread. I had to raise the gas tank back up 1" to get the engine to run successfully. (I had lowered it about 1" previously). The engine will clip way all day quite comfortably at the speed shown, but really isn't too crazy about running faster or slower. That carburetor is pretty hokey, but it gets the job done. The speed control screw on top of the carburetor does have some effect, but with an engine this small it is only about half a turn from the speed shown to a speed lower than the engine will run, and consequently stalls out. I did end up making the flywheel about 3/8" wider than the original plans call for. I am going to say this thread is well and truly finished now, and that I have successfully built and ran my first two cycle engine. This is the first i.c. engine I have ever made with no rings, where the piston was lapped into the cylinder with diamond lapping paste for an air tight fit. With each engine I build I learn some new skill, and that pleases me a great deal.----Brian
[ame]https://www.youtube.com/watch?v=4Agy4Lf97-I&feature=youtu.be[/ame]


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## Cogsy (Apr 30, 2016)

Sounds great Brian, like it's making lots of power and I'm surprised it doesn't want to rev. Still, I'm sure you'll find something for it to drive that uses up all that available power.


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## deverett (May 1, 2016)

I've really enjoyed your build of this engine, Brian.

Dave
The Emerald Isle


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## Brian Rupnow (May 4, 2016)

After running the engine for about 20 minutes with the new ball bearings, I noticed that the flywheel was beginning to wobble. I shut the motor off, and sure enough, the crankshaft end with the flywheel on it was quite "wobbly" in the bearings. If I hadn't seen it myself, I would have said that was impossible. They were good quality name brand ball bearings, but after the grease shields wore in a bit, there was enough clearance in the bearings that with two bearings setting side by side like I had them, they allowed the shaft to wobble quite noticeably. So----I took a page from Jason's book. I had already determined on my first go-round with this engine that brass was simply too soft a material for a bushing, as the brass bushings wore out very rapidly. I don't know if this had anything to do with lack of lubrication or not, although I doubt it. So---this time on the crankshaft side only, I made up a new aluminum housing with an insert of 7/8" diameter #660 bronze, which I bored .001" undersize, then lapped the crankshaft into it with #600 carborundum paste. I added an oiler that I had made way back when I built my Kerzel engine, and a steel tube which supports the oiler and runs to the center of the bronze bushing. Time will tell if this was a good idea or not!!


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## mecanotrain (Jun 28, 2019)

Brian Rupnow said:


> This shows the overall dimensions of the engine. I will be posting the detail drawings as I make the individual parts. I will not post them before making the parts, because I have found that quite often the machinist at my house has to go back and remind the engineer at my house that "You can't make it this way!!!---Change the damned drawing please!!!


Hello Brian,
My name is Roger; I live in France.
I am interested in manufacturing this engine. Where can I buy the plan? Thanks for your help.


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## Brian Rupnow (Jun 28, 2019)

Roger--I'm sorry, but I no longer have the plans for that engine.---Brian


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## Bowtie41 (Jun 29, 2019)

RonGinger said:


> Model engines always run fast. Its part of the problem that you cannot scale physics. The flywheels are just to small. Maybe you could make one from depleted uranium to get more weight?


Check with 'ol Doc Brown,he may have some left from the Delorean,lol.


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## Mainer (Jun 30, 2019)

You also need to scale time. Do this by considering  the period of a pendulum. If a model is, say, 1/8 scale, time should pass about 2.8 times faster. Or, to put it another way, if your engine is 1/8 scale, 950 rpm represents a full-scale speed of about 340 rpm.


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## IC-man (Jun 30, 2019)

Hi Brian,
I'm surprised you lapped the crankshaft into a bronze sleeve. I was told that if you did this,the carborundum paste would embed itself into the Bronze making itself into a lap permanently, thereby wearing the crankshaft in no time.
Of course as always I stand to be corrected.
Good engine though and well documented.
All the best


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## Brian Rupnow (Jun 30, 2019)

Roger--Do you have any kind of 3D cad software? If you have Solidworks, I can give you all the drawings and solid models. This engine was not one of the engines I intended to sell plans for, so the drawings were never saved as pdf files.---Brian


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