# The great O ring discussion



## gbritnell (Feb 14, 2021)

Gentlemen,
I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings. 
To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings. 
gbritnell


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## Vietti (Feb 14, 2021)

George,

100% agree with your comments re valves.

0 rings are perhaps the easy way out but may have some advantages beyond ease.  In my last two engines I first fitted shop made cast iron rings.  They worked, but when I switched to 0 rings I felt the compression was better and there was better oil control. On one engine I had added 4 rings/piston with drain holes around the bottom ring for oil control, the 0 ring still out performed it.  I do kind of think running regular rings followed by 0 rings had the benefit of a nicely polished bore.

I think too that in a hit and miss engine, 0 rings may be superior because, if loosely fitted, there is no friction when coasting unlike a regular ring 

Cast iron rings are attractive to some extent because they are prototypical.  But we all take liberties when it come to originality, take ignition systems as an example. All most all our ignition systems are hardly prototypical using a large battery and coil or CDI.  That's why I spend time making magnetos, both high and low tension.  I admit to using CDI on smaller engines.  We all decide how close we are going to follow original practice in our models.  Keeps things interesting plus no one sees the rings!  

Enjoying the discussion and not trying to be contrary.

John


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## petertha (Feb 14, 2021)

gbritnell said:


> Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture....gbritnell



Good post, George. I've already committed that the next engine will be self made rings. I'm using OS-56 rings for my radial, but its actually more work to hit 5 bore diameters exactly with right finish vs lapping 5 bore diameters the same (whatever that size may be in the end) & sizing the rings a/p Trimble's method.

I'm reasonably clear on the Trimble method & fixtures, but its the scale issue that I'm still fuzzy on. I think the original article had some sacrificial paper which burned in the enclosed clamping fixture? Anyways, can you show a pic of your fixture? Is the boron more about scale prevention or potential loss of carbon? (or are these kind of inter-related). I've seen pictures of rings being heated bare with propane torch until they fell off the gapping pin, but of course, is that the best way?


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## chrsbrbnk (Feb 14, 2021)

the o ring solution does kinda defeat the whole point of model making


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## lantain1982 (Feb 14, 2021)

I fully support gbritnell`s comments on fitting CI  rings.  If you have lived through all the problems of your engine construction why not go the extra mile and tackle a sealing medium which will eliminate the above concerns.    CI rings will introduce you to a possible range of unfamiliar processes, but this what we are all about.   As an aside, if you are concerned about scaling, there is a ring manufacturing  process that, by machining the ring to finished size after the stress relieving process effectively removes the scale.
lantain1982


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## vederstein (Feb 14, 2021)

Oh hell, not again.  This hobby is dying.  Why make the barrier to entry more difficult by criticizing how people make their engines?  The whole "you're doing it wrong" does nothing but push people away.  So what if someone wants to use sealing method over another?  Give it up.


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## gbritnell (Feb 14, 2021)

HI Vederstein,
When I wrote this piece i chose my words very carefully. In the text there was mention of newcomers to the hobby and then the rest of us. If making piston rings is going to prevent someone from building an engine then I'm afraid they will never get passed the valve and seat process.
Regards, 
gbritnell


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## kiwi2 (Feb 15, 2021)

Hi,
     Speaking of making CI piston rings, I came across this on YouTube:

Regards,
Alan


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## Charles Lamont (Feb 15, 2021)

I really don't think George is trying to put anyone off, and I do think it unfair to accuse him of that. (He just wants to encourage them to try doing it properly. )

I also assume he is only talking about IC engines. Model steam locomotives have been running successfully with O-ringed pistons for decades, including club workhorses that in the UK may run several hundred (full size) miles a year.

Personally, if I made a steam engine with gunmetal cylinders I would use them. I have a very back-burner loco with iron cylinders, and for them I would always use iron rings. IC engines: iron.

In the video pointed to by kiwi2, I think his ring splitting tool is brilliant, but those rings are far, far too thick. I am no expert on the Trimble method (I prefer Chaddock) but Mr Crispin's heat treatment jig seems to misunderstand the geometric principles of the method.

By-the-way, but perhaps of interest, I have seen numerous full size steam loco piston rings being made. They are turned to size and expanded (after splitting) by running through a swageing tool that has two rollers. The inside roller has edged teeth which crush a series of indents on the inside surface of the ring, thereby stretching it.


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## tornitore45 (Feb 15, 2021)

George where did you get Boron powder?    I find sources as dietary supplement witch may not be pure boron but just a biological source of boron like iron pill for example are not iron.


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## IanN (Feb 15, 2021)

Hi Group,

So many issues!

Personally, I machine cast iron piston rings (or use graphite yarn for steam) because it gives me pleasure - if others want to use o-rings, that is their choice, there is no right or wrong

Regarding Vederstein’s comments about discouraging people from engineering as a hobby:  There are far greater issues than a comment about differing techniques at play....

Finally, sources of knowledge: O-ring manufactures publish extensive data on the use of their products and operate technical advice and support lines.  Of course accessing these resources requires spending time reading texts and understanding the engineering principles - unfortunately we live in a world where many people are reluctant to make that investment and would prefer to re-invent the wheel through trial and error

I would suggest that most group members can stop reading this post at this point - the bits that follow are simply my opinions on the encroachment of “alternative technologies” in to established practices and these issues cannot be discussed with out causing offence to someone somewhere.  Those of a nervous disposition or delicate nature read no further.


I am dangerously near my allotted three score and ten years on the planet and my initial reaction (a good number of years ago) to the use of synthetic O rings as piston rings was “Oh no! Not another new technology to master!”

It was the same with Loctite.  I had been making press-fit interfaces for a couple of decades and then they introduce this idea of gluing stuff in place - what is the world coming to?

There is a thing called “progress” - I didn’t vote for it myself, we are just stuck with it.

I have a day job (retirement is for wimps) teaching engineering apprentices and lecturing in engineering.  My last job in industry was as Head of Electronics at the European R and D centre of a global corporation that nobody has ever heard of.  I spent my time working on time plans, spreadsheets, budgets, while in the labs just down the corridor talented engineers were doing the job I originally signed up for in my youth - hands on engineering research

I left industry when I accepted that if the brilliant young engineers leaving university and college did NOT have better ideas, better imaginations and better visions of the future than I had, then there is something very, very wrong with our education system.

So I teach my students to embrace the opportunities provided by exciting new technological developments, use CAD/CAM, 3D printing, CNC (or at least DROs) while in my hobby I still machine press-fits, turn by hand, and (to my lasting shame) know that I can file a part flat and true to with in a few thou in less time that it would take me to wrestle with the set-up of the part on my mill and rummage through a jumbled box of cutters in my disorganised home workshop.  It is a case of “Do as I say, not as I do”

This means I now fall in to the category of “miserable old git”, I have my own chair in the corner of the pub where I can bang my fist on the table, moan about “young people” and start everything I say with the words “Well back in my day .....” (or at least I could do all of that before this virus thingy took off)

I’ll stop now - I have to “FaceTime” my sons so they can listen to me moan about the Six Nations (England has been at war with France for the last thousand years so it rankles to see them at the top of the table) and then we can get on to discuss the cricket umpiring in India....


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## ozzie46 (Feb 15, 2021)

vederstein said:


> Deleted post was quoted here.


This is totally uncalled for. George has been nothing but helpful to people in the hobby for years.
Ron


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## cds4byu (Feb 15, 2021)

tornitore45 said:


> George where did you get Boron powder?    I find sources as dietary supplement witch may not be pure boron but just a biological source of boron like iron pill for example are not iron.


I believe it is Borax powder, not Boron powder, that is referemoved.  Borax powder is a flux. Borax is readily available as a cleaning product, at least in the US.

Carl


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## gbritnell (Feb 15, 2021)

Actually the powder I was referring to does contain Boron. I purchased mine from an American gun supplier named Brownells. This particular powder is PBC although they carrry several anti-scaling types.
There are several methods for heat treating piston rings. Probably the simplest, which it tried once or twice, is to make the ring, split it then hang it on a piece of steel that is wide enough to create the expanded shape. This is then held in front of a backstop created by using a couple of fire bricks. Heat is bounced against the fire bricks but not directly on the ring itself. When the ring has absorbed enough heat to become plastic it will drop from the piece of steel. I have to admit it has worked for me but only when making one or two rings at a time. For multiple rings the process I use was described in my original posting. The last method or third method for this discussion is the use of a kiln or heat treat furnace that has a temperature control. The rings are made as described and mounted on the expanding fixture. The whole affair is then wrapped in stainless foil (which is also available from Brownells) Before finally folding the foil shut to create a chamber a piece of heavy paper is inserted along with the fixture. The purpose of the paper is to catch fire when the heat has reached the burning point and therefore burn off the oxygen from the chamber. This method has to be used with a temperature controlled oven because there is no way of ascertaining the internal heat if one was to use an open flame.
The controversy in the second two methods is what amount of heat to apply. Mr. Trimble's method calls for a higher heat than some others have recommended. Having never used the oven method I have only heated my ring fixture to a dull red and held it there for several minutes to ensure a complete heat soak. I have engines with many hours on them with no visible oil smoke so the process I used I would consider successful.
gbritnell
The Boron based powder is very toxic and the safety instructions should be followed to the letter.


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## dnalot (Feb 15, 2021)

I recently made rings using the Trimble method. An interesting observation was that where I used celo-tape to hold the several wraps of heavy paper  around the rings, the rings had no scale at all. The area that was covered with paper but had no tape the rings had some scale. 

Mark T


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## minh-thanh (Feb 15, 2021)

I totally agree with  *gbritnell !*
With me, making a piston ring is a lot simpler than make a valve and  valve seat are airtight
And with my little experience, for a novice, making a ringless piston is enough, not necessarily using o rings.


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## Cymro77 (Feb 15, 2021)

Fascinating stuff -  obviously there are more ways than one to skin a cat!  Keep it cool and enjoy the hobby.


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## Longboy (Feb 15, 2021)

chrsbrbnk said:


> the o ring solution does kinda defeat the whole point of model making


Well....no it does not.  Simple, effective, durable and available components enhance and grow interest in modeling engines as in many other hobbies. If carburetors, gears, design software, ignitions, casting kits were not available, this hobby would revert back to the exclusivity of retired journeymen tinkering for months/years on outstanding but obscure projects. The easy, a shortcut, a purchased item incorporated in your model is not a disgrace nor considered improper.  One can always try traditional methods buying the tooling and materials to make components and evaluate the outcomes. This gives one another notch in skill level.....but not necessary in building a quality item. Not everyone building engines can spend hours a day in the shop and many youngsters with an interest in machining can feel intimidated self engineering some of these finer engine parts and never invest in our corner of making model engines.


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## coulsea (Feb 15, 2021)

A very enjoyable thread. I recently had a comment to one of my posts about my way being unnecessary ( no i am not offended) and it made me think about the right and wrong ways of doing things. model building is generally just a way for people to enjoy themselves so if you are having fun you are doing it right. if you are not interested in ignitions buy one, if you don't want to make rings buy them, any kind. I buy all my steel because I don't have an iron ore mine
Please keep sharing the way you do things because I might want to do it that way next.


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## el gringo (Feb 15, 2021)

gbritnell said:


> Gentlemen,
> I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings.
> To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings.
> gbritnell





gbritnell said:


> Gentlemen,
> I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings.
> To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings.
> gbritnell





gbritnell said:


> Gentlemen,
> I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings.
> To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings.
> gbritnell


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## el gringo (Feb 15, 2021)

Well said gbritnell. I have many similar thoughts regarding the 'real deal'. that is a very us-full and thoughtful posting.
I have averaged ~ one IC engine a year since 1991 and never tried o-rings for pistons, even when self learning to be a model machinist in 1991. [my first IC was Bob Shores 'little angel']. I did use viton on the Rudenow's Henry Ford engine and it ran as designed.

I posted some pics on another thread ( raym/rupinow vert hit & miss) related to my way of going about it, that method of the flame not touching the rings leaves very little oxidation to be removed with a swipe of 600 grit.
Tis a good thing to see the almost mirror finish on the rings and cylinder wall after a brief pre run


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## stevehuckss396 (Feb 15, 2021)

One thing to think about is the o-rings do wear faster than CI rings. One of my pals had a complete loss of compression and of course it happened at a show. Thank god it was a hit miss engine and that made it easy to pull the piston and replace the o-ring. Due to fuel and oil being in the cylinder, heat and friction also a factor, they do have to be replaced from time to time. My first IC engine ran for the first time in 2010 and has not needed that kind of maintenance. They are easier to make (just buy one) but in the long term are a little more work. Both work equally well if executed properly.


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## Nerd1000 (Feb 15, 2021)

I suspect that there is an element of 'horses for courses' here. O rings appear (to my total newbie eyes) to be a route to simple and reliable compression in a 'demonstration' engine, but given that much of the heat that goes into the piston of an ICE is conducted to the cylinder walls by the rings, I suspect that a polymer O-ring (with its intrinsically lower thermal conductivity and heat resistance) is unsuitable for engines that are expected to operate under significant load.


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## Donleybill (Feb 16, 2021)

gbritnell said:


> Gentlemen,
> I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings.
> To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings.
> gbritnell



I found a consistent simple way to break the piston ring.   I held the piston ring in my mill vise.  With a 1/2” dia pin or anything stiff in the collet I side load the piston ring until it snapped. Lots of control, easy to do,  broke clean every time. I made extra rings thinking I was doing this with a bench vice and hammer.  Didn’t need them using this approach.


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## johwen (Feb 16, 2021)

Folks
Following the "Trimble Method" is the way to go. Just a few extra operations but is worth while. However I deviate slightly by halving the width of the ring and put two rings in each groove with the gaps set 180 degrees apart. Making sure you have the correct clearance around the ring in the groove. A couple of strokes in the bore and you should have full compression ready to run. Just make sure that the RING OD is the same as the Cylinder bore and push the ring over a tapered bore to split. Have patience and give it a go Cheers. John Auto Engineer.


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## gbritnell (Feb 16, 2021)

Gentlemen,
I had been following the ongoing thread relative to the use of O rings for model engines. It is now 3 pages long and contains a multitude of thoughts and ideas about O ring application for model engines. The ideas range from fit, type, clearance, longevity etc. Some have stated that they have many hours of running time on their engines with absolutely no issues while others say they just couldn't get them to work. In my reading of that thread I came to the conclusion that there were so many variables at work that I would start a new thread relative to the use of metal piston rings. 

If one reads my original post nowhere in there did I say that O rings wouldn't work nor did I say that anyone who uses them is trying to subvert the model engine hobby.  If you're happy using O rings God bless you. In further reading of my text my suggestion was that as accomplished engine builders why not try metal piston rings. 

I started in this hobby building model steam engines. Some of the Stuarts I built had metal piston rings and others only required a graphite string packing. If a steam engine loses a little piston seal it will still operate. If the valve, D or piston, is a little leaky it will still operate. If the valve is a little out of time it will still operate. They are very forgiving engines when it comes to operating. On the other hand when building an internal combustion engine so many elements need to be exact or the engine will not function properly. The bore needs to be straight and concentric with the proper surface finish. The valves need to seal both at the valve seat and the valve stem. The engine has to have compression which falls back to the bore and valve conditions. Now you advance to the ignition. An I.C. engine needs a spark plug, a triggering device, points or Hall sensor, and in the case of a multi-cylinder engine a distributor. An I.C. engine needs a carburetor that will supply the proper amount of fuel. 
We who have built running I.C. engines have accomplished all of the aforementioned things but yet in some cases (IN SOME CASES) struggle with the use of O rings so why not try metal piston rings. 

These forums are about learning and passing on learned information and that is what I have always tried to do. 
gbritnell


----------



## ajoeiam (Feb 16, 2021)

IanN said:


> Hi Group,
> 
> So many issues!
> 
> ...


Hmmmm - - - - I, for one, would love to know that CAD/CAM, or even just CAD programs you use, recommend or whatever combination of that you care to offer. 
3D printing - - - I'll start simple - - - - I would like to get such a system but - - - -which one?
Purchasing in north america drives the costs too high (imo) but purchasing in the far east significantly ups the risk. 
Ideas, suggestions etc please.


----------



## Richard Hed (Feb 16, 2021)

IanN said:


> Hi Group,
> 
> So many issues!
> 
> ...


Ah, gads, what a complainer!  you know, the snow was whiter when I was a kid (last week).  the Six Nations, BTW FYI IMNSHO, r the MOhauk, Iroquois, Huron, Seneca and I forgets the other two who made a peace instead of constantly warring against each other.  Yeah, yeah, kidz, how will the humanity survive?


----------



## Tim Wescott (Feb 21, 2021)

My question, which was sorta kinda touched on a bit above here, but only qualitatively, is how long will O-rings last vs. cast iron rings?  In the event that I wanted to bolt it to a model airplane and go fly it, how many hours can I put on an O-ring engine vs. how many hours on a cast-iron ringed engine?


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## Aerostar55 (Feb 24, 2021)

gbritnell said:


> Gentlemen,
> I have been following the O ring discussion in another thread and have read several others in the past. Most of the builders on this forum have been machining and making engines for quite some time. That being said I have trouble understanding why there is such an aversion to making actual piston rings. If one follows the discussions about O ring use there seems to be more negatives than positives in their use. It seems everyone has their own guidelines for using them, type, O ring, X ring, material, Viton, neoprene, piston fit, loose, tight, cylinder wall fit, tight versus loose.  When using piston rings there are hard numbers and data for their use. I feel that using O rings is taking the easy way out. Granted for a novice builder who would just like to build his first engine and hear it run I understand their thoughts but for the rest of us that have two or more engines under our belt I don't understand the aversion to making and using piston rings. Having built many engines over the years and following other's builds the biggest challenge in getting an engine running, bar none, is getting the valves to seat and seal properly. Hours can be spent machining the valves, seat cutting, lapping and pressure testing but yet we all accomplish this task one way or another. In building an engine there's so many somewhat complicated parts that need to be made, gears, cams, valves and crankshafts to name but a few and yet here again we are all able to do this but mention the word piston ring and some people get cold chills. To me making rings is one of the easier machining exercises connected with building an engine. You turn a piece of iron (very easy to machine) to a given I.D. and O.D. You then part it off to a given thickness. You break the edges then split the ring. If using the Trimble method a fixture needs to be made for heat treating. This is just another simple machining project. Now the heat treating. I don't have a kiln or heat treating furnace, I just use a standard propane torch. When making my fixture I hollow out the bottom so when heating there's not a lot of mass to heat up. Long ago i purchased a jar of Boron powder from a gun supply shop and after multitudes  of piston rings I still have enough to last my engine building career. The rings are mounted on the fixture. The fixture is heated up then coated with the powder. The powder turns to a somewhat liquid coating much like silver solder flux. I then place the flame of the torch into the pocket in the bottom of the fixture so that I'm not applying the heat directly on the rings. I then hold the torch until the whole fixture and rings are brought up to a dull red color and once obtained hold it there for 2-3 minutes. The fixture is then allowed to cool and then the Boron coating is washed of with tap water. The rings are then unmounted, cleaned. fitted to the bore and gapped. Trimbles method and several other can be found on the internet for free and give a more thorough explanation in the making of piston rings.
> To sum up my dissertation, why not give piston rings a try. It's really not that hard of a job and then you don't have to worry about all the issues of fitting and using O rings.
> gbritnell


I agree, piston rings aren't that terribly difficult.  I was once anxious to see my new project run so I just left the rings out !  After some success running, I went ahead and made some rings for it.  NP  (no problem)


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## Aerostar55 (Feb 24, 2021)

dnalot said:


> I recently made rings using the Trimble method. An interesting observation was that where I used celo-tape to hold the several wraps of heavy paper  around the rings, the rings had no scale at all. The area that was covered with paper but had no tape the rings had some scale.
> 
> Mark T


I read the Strictly IC article "The Trimble Method" on piston ring, and its a great article.  When I make rings I use a very similar method, but I cut out a couple of detailed steps.  I never made the heat treating cup fixture.  I just heat treat the rings on a steel plate in the vise.  Also I use a slitting saw to cut the gap instead of the cleaver method.  I find this saves filing time.


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## popnrattle (Mar 26, 2021)

O-rings are the way to go for me cuz I like the easy way to do things, causes no wear on cyl., they last over a year and by that time it's ready to be taken apart to clean carbon and gunk from valves anyway. The hardest part for me is lapping the valves to seal well enough to run(half-hour or so). Here are my latest couple of examples. Later, RT.


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## awake (Mar 27, 2021)

ajoeiam said:


> Hmmmm - - - - I, for one, would love to know that CAD/CAM, or even just CAD programs you use, recommend or whatever combination of that you care to offer.
> 3D printing - - - I'll start simple - - - - I would like to get such a system but - - - -which one?
> Purchasing in north america drives the costs too high (imo) but purchasing in the far east significantly ups the risk.
> Ideas, suggestions etc please.


ajoeiam, I missed this question earlier, and it looks like it didn't get answered, at least not on this thread.

There are several YouTube channels that focus on 3d printing, which include reviews. Two that I tend to trust the most are Tom Sanladerer and Maker's Muse. Based on their reviews, my sense is that for a basic machine, it is hard to beat the price & performance of the Ender 3, though they may require a little bit of tuning up (making sure the rollers and belts are properly tensioned). If you want to get rock-solid reliability, absolute best performance vs. price, it is hard to beat the Prusa - but now you're talking 4x the money.

Just to be clear, I have no stake in and no personal experience with either of these. My 3d printer is my own home-brewed design, based on commonly available components - it works very well, and at the time it saved some money compared to commercially available units. With the Ender 3 and similar machines, however, that last point is no longer true.


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## ajoeiam (Mar 28, 2021)

awake said:


> ajoeiam, I missed this question earlier, and it looks like it didn't get answered, at least not on this thread.
> 
> There are several YouTube channels that focus on 3d printing, which include reviews. Two that I tend to trust the most are Tom Sanladerer and Maker's Muse. Based on their reviews, my sense is that for a basic machine, it is hard to beat the price & performance of the Ender 3, though they may require a little bit of tuning up (making sure the rollers and belts are properly tensioned). If you want to get rock-solid reliability, absolute best performance vs. price, it is hard to beat the Prusa - but now you're talking 4x the money.
> 
> Just to be clear, I have no stake in and no personal experience with either of these. My 3d printer is my own home-brewed design, based on commonly available components - it works very well, and at the time it saved some money compared to commercially available units. With the Ender 3 and similar machines, however, that last point is no longer true.



Why - - - thank you for your response sir!

If you might take a stab at the CAD and CAD/CAM question too please?

AISI CAM is quite necessary for 3D printing - - - - at least it would seem so. (grin)


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## awake (Mar 28, 2021)

Sure, happy to address CAD and CAM for 3d printing:

A form of CAM is necessary, but in the 3d printing world, that is called a "slicer," and there are some excellent free & open source slicers available - I think the best is PrusaSlicer, but some people like Cura better. Either one will come with a large number of presets to suit different machines, but you can also adjust the parameters to suit your particular machine - that is what I have done with PrusaSlicer to use with my homebrew machine.

The slicer needs a 3d model file. The most common is an .stl file, which has the benefit of being near-universal. It also has the deficit of lacking any units of measurement - when it sees that something is "1" long, it doesn't know if that's 1 inch, 1mm, or 1 cubit. However, pretty much every system I know of defaults to mm as far as the .stl file and as far as what the 3d printer expects, even if the actual design is done in inches.

You don't actually have to do any CAD to start 3d printing. There are repositories with hundreds of thousands of .stl files that people have shared. Thingiverse is probably the best known such repository, but there are others. Just download the .stl file, slice it (feed it to PrusaSlicer or Cura, possibly scaling it as needed), and send the generated gcode to your printer.

If you want to create your own .stl file, then you do need some sort of 3d CAD system. A bit of searching on this forum will show you lots of discussion of the relative merits of different software, but in terms of software that is free to the hobbyist, the main choices (IMO) are Fusion 360, FreeCAD, or OpenSCAD. The latter two are free and open source; the former is a commercial package that has a somewhat limited free license for hobbyists.

Fusion 360 and FreeCAD both have enormous range of what they can do, and are suited for just about any design work - model up your parts, attach them together to see how it all fits, make up a set of technical drawings, generate g-code for a CNC mill, generate .stl files to print 3d models ... and the lists go on. They offer several different ways to build up a model (different ways may suit different problems), but the most common process for both is to start with a 2d sketch that is then "extruded" into a 3d part. From there, additional features are added or subtracted as needed, often by sketching the feature and creating an extrusion or a pocket, or by adding fillets or chamfers, or by repeating features across or around the part. (That may not make much sense without seeing it in action ....)

OpenSCAD is a _very_ different approach, being essentially a programming script that tells the software how to put the model together. It is really only suited to creating .stl files for 3d printing, and not much of anything else - but there are times when it is the cat's meow for that purpose, and I often find myself choosing it for 3d printing designs. For the most part, this approach uses "constructive solid geometry," in which you tell it to create basic shapes such as cubes or spheres or cones or so on, then add these together or "subtract" one from another or take the intersection. (Again, hard to describe without actually seeing it in action ....)

Any of this software has some learning curve, but there are tons of tutorials. Just be aware that for FreeCAD and Fusion 360 in particular, you will usually want to limit yourself to more recently produced tutorials, because both programs continue to evolve - it is frustrating when the tutorial says to "click on this button," and that button no longer exists in the latest version.


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## Kasey (Mar 29, 2021)

In a 2 stroke engine, is there any possibility that an O ring could replace the second ring and survive passing either the transfer or exhaust ports for very long? (even with a very tight fitting O ring on the piston)


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## Brian Rupnow (Apr 10, 2021)

Where can I get a full explanation of the Trimble method of ring making, along with fixtures required? I have no plans for making another engine until fall, but I might try the Trimble method of making rings if I can find a good write up on it. I have tried the method of machining the rings to size, breaking a gap in the ring, and hanging them on a wedge and heating them until they dropped off.--I was not very successful with that. I have read about the Trimble method in the past, and have vague memories of needing two different fixtures. Any help would be appreciated.---Brian


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## Tim Wescott (Apr 10, 2021)

__





						How To Make Piston Rings
					





					modelenginenews.org


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## jtb11711 (Apr 11, 2021)

Brian,
Additionally, the George Trimble article referenced in the previously linked page is available for purchase from the Strictly IC website, for a price:


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


John

[Edit: I should have known that my post would be delayed because it needed to be moderated, but there is the link if that is helpful.]


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## AndrewW (Apr 11, 2021)

Brian Rupnow said:


> Where can I get a full explanation of the Trimble method of ring making, along with fixtures required? I have no plans for making another engine until fall, but I might try the Trimble method of making rings if I can find a good write up on it. I have tried the method of machining the rings to size, breaking a gap in the ring, and hanging them on a wedge and heating them until they dropped off.--I was not very successful with that. I have read about the Trimble method in the past, and have vague memories of needing two different fixtures. Any help would be appreciated.---Brian


Hi Brian
Strictly IC website suggests that they sell back issues. I enquired regarding the three issues featuring the Trimble method. Unfortunately Strictly IC said they only accept cheques or bank transfers in US$ which was too restrictive for me in the UK. A contact of mine in the US is in the process of trying to purchase them.
I've just made some piston rings based on your previous approach and they appear to have turned out well. Check my video out at:

Cheers
Andrew


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## Brian Rupnow (Apr 11, 2021)

I have made piston rings in the past, but they were failures. It's been a while, but as I remember I turned the o.d of the rings to some pre-established diameter based on the cylinder diameter, turned the i.d. to a diameter based on some calculated formula, then split the rings by holding one side in the vice and pushing on the ring with my fingers. After "splitting" the rings were wedged open around a piece of bar stock and then heated until they fell off. The sides of the rings were then cleaned up by rubbing on a piece of glass with some 600 grit compound to remove any scale that had formed. When pushed into the cylinder and held up to a light, I could see visible gaps between the outside diameter of the ring and the inside of the cylinder. It seemed to me at the time that if I could have refixtured the rings and turned the outside diameter to be truly round, they would have worked for me. I remember that some time after making these rings that I seen a good write up on the Trimble method of making rings, which did include using a fixture to turn the outer diameter of the rings to be perfectly round, but by that time I had moved on and didn't pursue any more ring making. I have spent the morning Googling and watching Youtube videos about ring making using the Trimble method, and I can't find the article that I seen eight or ten years ago. Trimble wrote a 16 page paper on "Design and Fabrication of Piston Rings" but I haven't been able to find it anywhere.


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## Tim Wescott (Apr 11, 2021)

That link that I posted for you links to two or three different methods of making rings, at least one (and I think two) of which have you compressing the split rings, clamping them into an arbor, then turning (and maybe lapping -- it's what I recall, but I'm too lazy to go read the articles) the rings to size.

Also in the framing article, Ron mentions that the easier methods do end up with rings that don't have the world's greatest fit at first, but will eventually run in.  Personally, I think I'll start with one of the methods that makes round rings that fit the bore...


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## kuhncw (Apr 11, 2021)

Hi Brian,

Terry Mayhugh's posts, detailing how he makes rings may help you. He uses the Trimble method.
Here are two links:

See  the May 8 post.
Another Knucklehead Build

See Aug 4 post





						Another Radial - this time 18 Cylinders
					

Peter,        My goal was, as you said, to first get the all the cylinders to a consistent bore diameter. I had a lot of time invested in their external features that I didn't want to risk, but I knew I could eventually lap them all to a common diameter even though at the time I didn't know...




					www.homemodelenginemachinist.com
				




Regards,
Chuck


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## Brian Rupnow (Apr 11, 2021)

Chuck and Terry---Thank you for the links. I have read thru them and tried to comprehend everything I read.---Brian


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## Brian Rupnow (Apr 12, 2021)

I'm getting old and kinda dumb---but Damn, I thought I had seen a method of making rings where there were two fixtures involved. One fit inside the stack of rings and clamped them before heat-treat with a torch, and one that fit inside the rings and clamped them for turning  the outer diameter to a perfect roundness. I can not find that method anywhere. I distrust my own memory now.---Brian


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## Brian Rupnow (Apr 12, 2021)

Hah!!--I'm not crazy after all. The method I remember seeing was work by Chaddock and Warsaw. One fixture was used to heat multiple rings at one time for heat treat, and the second fixture was used to turn the ring outside diameter to a perfect roundness, one ring at a time. The only catch is that in that second step, the depth of cut is 0.001" or less to achieve perfect roundness. That is a cut far more suitable to a toolpost grinder than any kind of cutting tool, and I don't have a toolpost grinder.


			Making Piston Rings for Gas Engines


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## Tim Wescott (Apr 12, 2021)

I wonder if you could achieve that second cut by lapping the outside of the rings.  The tool would just be bog-standard outside lap, which you could whip up in an hour.


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## mayhugh1 (Apr 12, 2021)

If you use the Trimble method, the rings come out perfectly round without having to re-turn them in a second fixture after heat treatment. Trimble published two lengthy articles in Strictly IC containing the math he used to develop his method. He did his analysis on a programmable pocket calculator long before home computers were available. His heat treatment fixture is actually a precision device that according to his analysis creates a proper balance of radial forces to insure the rings end up perfectly round after heat treatment. The problem is, many people didn't read the original articles and if they did, don't understand and appreciate the math involved. Many have taken shortcuts with the dimensions, the cleaving, and the machining of the fixture and have been disappointed with the results. Some started combining a look-alike Trimble fixture with yet another method for making rings such as the one requiring a second final turning operation. Jerry Howell in fact recommended a similar technique in the plans for his V-twin, and I successfully used it to make my very first set of rings.

Unfortunately, Trimble also recommended a much higher normalization temperature than many 'experts' felt should be used. This cast some doubt on the credibility of his method in some builders eyes and may be one of the reasons it wasn't strictly adopted.

I've closely followed Trimble's method (except for his excessively high normalization temperature) for well over a hundred rings and light testing showed them to be perfectly round after heat treatment with no further turning required. What I have found tough is that some care is required to turn the initial blanks from which the rings will be parted. Trimble's method assumes distortion-free starting blanks from which the rings will be parted. Even quality cast iron has pent-up stresses that will be unevenly relieved when the blanks are initially turned. Some of this distortion can show up days after the blanks are turned. I've tried different methods for creating blanks with minimum starting distortion during my various builds and was most successful with the one described in my last build - the 270 Offy. In any event, I think it's much easier to tackle the up front problem of creating distortion-free blanks that it is to take a .001" clean-up pass on a finished ring and hope its final circularity is within a tenth or so. - Just my two cents worth - Terry


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## Brian Rupnow (Apr 12, 2021)

Thanks Terry. ---I've read your post, and I keep adding to my knowledge base.---Brian


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## IC-man (Apr 13, 2021)

I too have used the Trimble method with good results, making 3-4 rings in a stack
Many seem to worry about the cleaving but I have found by griping the ring with 2 pairs of flat nose pliers (right next to each other) and just bending slightly i get a clean break every time. Clean and gap with needle file after  heat treatment.


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## Brian Rupnow (Apr 17, 2021)

I have spent the last week or so reading everything I can find about making piston rings. I would much rather buy them than make them, they only cost $4 each and I only need two.---But---the guy at Ringspacers.com seems to be very, very busy. I emailed him and got no response, and then after a few days I called him and he said he was so busy he couldn't spit, and it might take him a while to send me a quote. It's been another 3 or 4 days now, and I still haven't heard from him. I'm going to have to buy some grey cast iron and make a new piston to suit the rings. (I don't want to make the piston from aluminum this time, because grey cast iron has much better wear qualities when it's running in a cast iron cylinder.)  I do have lots of short ends of grey cast iron laying around here, big enough to make rings from but not big enough to make a piston from. I used rings from Ringspacers in my vertical hit and miss engine, and they worked very well, and the bore on it was 1", same as my vertical engine-2021---So---I have all of the necessary dimensions to build another piston.  I'm not under any time limitations except for my own impatience, so I'll give it another week and if I haven't heard from Ringspacers I may try making my own rings again.


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## dsage (Apr 18, 2021)

I thought you bought some rings from DeBolt machine in the past and were satisfied?
 Click Products below. 1" is $8




__





						Products
					





					www.deboltmachine.com


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## Brian Rupnow (Apr 18, 2021)

Deboldt and Ringspacers are the same place. EDIT--EDIT---they are not the same place. i was mistaken.


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## dsage (Apr 18, 2021)

Good to know. Thanks


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## Brian Rupnow (Apr 18, 2021)

dsage--I may have been mistaken on that. Debolt has a nice new web page with good information and pricelist. Ringspacers has an old web page which seems to imply that it was once owned by Debolt but may now be owned/used by somebody else. I believe the mans name was Dave Reed, and his rings were $4 each. I contacted him by phone and by email over a week ago, and he said he was overwhelmed by work and would get back to me. I am tired of waiting for him, so will now try to order rings from the link you gave me. If anybody knows what is actually going on with them, please let me know.----Brian


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## Brian Rupnow (Apr 18, 2021)

After a bit of sleuthing I have found the following. Two different companies. Debolt is out of Zanesville, Ohio. Ringspacers is out of Elkton, Maryland. I have dealt with both in the past and consider their products to be first class stuff.


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## Tim Wescott (Apr 18, 2021)

You may also want to try this guy -- he caters to people keeping model airplane engines alive, but he says he makes stock and custom rings.  https://rmjmachineworx.com/online-store

I think if it was me I'd call him with an approximate bore, and see if he's got something in stock that comes close, then machine my cylinder/piston to fit.


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## Brian Rupnow (Apr 18, 2021)

Just placed an order with Debolt for two 1" rings. Rings are $10 each and shipping is $20 so $40 American---which is $52 Canadian. Ouch, ouch, and double ouch!!! Oh well, I've studied so much this week on how to make my own rings that my NEXT set will be made by myself.


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## dsage (Apr 19, 2021)

What !!
Are you saying they charge $20 US PER RING for shipping?
Like it makes any difference if they put one or two (or a dozen) in the same shipping envelope. Robbery. (Sorry).
I've noticed this same approach from a lot of companies. Seems they are taking advantage of charging shipping to increase their profit. It will be interesting to see what the actual shipping charge was on the package. Keep us posted.
Of course there could be another explanation.


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## Tim Wescott (Apr 19, 2021)

dsage said:


> Seems they are taking advantage of charging shipping to increase their profit.



Possibly to to bring it up to $0, even.

Orders take time to fulfill.  Someone has to read them, pack them, make an address label, etc.  Unless you're doing it yourself -- and don't value your time -- someone has to be paid to do the work.  $20 to send you an empty box, from a one-man business, means that someone is paying themselves around $15 an hour, or possibly less.

To a certain extent, big operations (like Amazon) can refine the shipping process to bring that minimum down, but even then "free" shipping is just a come-on, that results in more expensive orders subsidizing the less expensive orders, to reduce competition and lock in your business.

Try running a small mail-order business for a while -- then report back on why shipping should always be free.


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## chrsbrbnk (Apr 19, 2021)

*OTTO GAS ENGINE WORKS* 2167 Blue Ball Rd Elkton Maryland 21921-3330

phone:* 410-398-7340*

E-mail address: [email protected]

Home Page on the web: OTTO GAS ENGINE WORKS

Just about any size and the ones I have work well


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## dsage (Apr 19, 2021)

Tim Wescott said:


> Try running a small mail-order business for a while -- then report back on why shipping should always be free.



I didn't say anything about free shipping. Only reasonable shipping. If it's $20 then so be it. BUT
The fact is whether the order says two or one for pistons rings, it takes the same amount of time and effort to process the order. Except maybe a few tenths of a second to pull two from the drawer instead of one. Shipping is / should be based on package size and weight. There is no need to DOUBLE the shipping based on two piston rings. Maybe so for some other heavy items. That's fine.
In the US there is a flat rate package with US postal service. Put anything you want, any amount and any weight in a certain sized box and it's not a high as $40 (last time I checked). A bubble envelope is all that's required to send a couple of pistons rings. Charge the going rate, but don't double it for two in this case.


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## Brian Rupnow (Apr 19, 2021)

You may have misinterpreted my post. Each ring costs $10 American. The shipping is a total of $20 American to ship both rings in one package. That total of $40 American translates to $52 Canadian because of the differential in the value of a dollar between Canada and USA.


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## dsage (Apr 19, 2021)

Ok. My bad math / interpretation. $20 was enough though. Enough said.


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## ajoeiam (Apr 20, 2021)

Tim Wescott said:


> Possibly to to bring it up to $0, even.
> 
> Orders take time to fulfill.  Someone has to read them, pack them, make an address label, etc.  Unless you're doing it yourself -- and don't value your time -- someone has to be paid to do the work.  $20 to send you an empty box, from a one-man business, means that someone is paying themselves around $15 an hour, or possibly less.
> 
> ...



I would counter that if it takes even a one man shop an hour to fulfill a purchase order - - - - - well - - - - he/she needs to stir their stumps at the minimum or  devise better systems. In fact if you're taking more than 20 minutes do the same. (I'm not sure but I think markups have also increased but am not so sure of that!)

I think we have far too many people who go to work for a paycheck and precious few who go to 'work'.

(I'm looking at a local retirement residence expansion. They've already been at it for 8 months and their expected completion isn't for another year. When I worked in construction in the late 70's that size of project would have been done in some 8 to 10 months. Remember - - - -work expands to fill available space (I think most people today are allergic to work - - - they think they will die if they're faced with such!).)

I just love Amazon's shipping.
First they demand an urban address (sorta tough for us rural folks! but I spend money every month for such). 
Second they complained when there was no one available on Easter Sunday morning at 09.15. 
    Somehow  they haven't ever heard of business hours. 
   That kind of delivery really isn't enhancing service at all. 
   I wonder what Mr Jeff would do if I showed up at his house with an order say on a Tuesday at 06.00 - - - - and my working day starts before that.


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## doc1955 (Apr 20, 2021)

When making 2 or 3 rings I use the method from the book "The Shop Wisdom Of Philip Duclos" This method has not failed me. When I make a larger quantity then I make a fixture for heat treating. Once you have made rings a few times you will say "that was easy" LOL


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## Dragons_fire (Apr 20, 2021)

Question relating to the o-ring debate...  How small can CI rings reliably work? For example, Kelly's Tiny Inline 4 engine uses o-rings, but it's only a 3/8" bore.  He recommends vinton o-rings, and that was my plan, mostly cause I'm having issues finding CI under 2" diameter and I'm not spending my life savings on that to turn it down to 3/8".


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## Tim Wescott (Apr 20, 2021)

If you're in the US (or Canada, and want to spend money on postage) McMaster-Carr has cast iron rods down to 5/8" -- and pretty reasonable on price for the smaller dimensions.


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## Brian Rupnow (Apr 20, 2021)

I'm right in the middle of doing a bunch of research on making my own cast iron rings. What I am seeing is that for cylinders under 5/8" diameter, it is better to go for a lapped fit between piston and cylinder with no rings at all, or one Viton o-ring. That's not to say iron o-rings would be impossible, but at such a small size it would be very difficult.---Brian


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## Nerd1000 (May 11, 2021)

I think at 3/8" your rings would be devilishly thin. Rings for my Webster worked out to 0.8mm thick, and while I found making them to be easier than expected (I thought I'd goof up for sure) that's still a little thinner than i feel comfortable making. Plus the engine is far from finished so I can't speak to whether they'll actually work. 3/8" is a little under half the bore diameter of the Webster, so you'd want something like a 0.4mm ring? Crazy.

I think for such small rings I might try making them from bronze. Much easier to get in small sizes, and it works in steam engines so why not IC? Would need a larger gap to compensate for lower stiffness of the bronze.


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## Steamchick (May 12, 2021)

I think Brian is right. I have owned a bought 1/2"bore Compression ignition engine that had no piston rings. - Just 2 grooves, because the gas dynamics resist blow-by. The clearance of piston to bore was incredibly small - which helped get the compression high enough for auto-ignition.
But a model I made, only ran for a couple of minutes, before the clearance was too big to get enough compression. With cylinder head changed to glow-plug type, I got another couple of minutes running before the piston to bore leaked too much so I had no compression.
However: It may be possible to make wire rings  = wind a coil onto a  shaft and select middle coils, after slitting. Hold coils tight on the shaft while slitting. I have not made any, but that's what the factory does. There is an "end effect" for the tangential load of the ring within about 30 degrees of the split, where the ring, when compressed in the bore, is trying to straighten more at the "ends", so this is compensated by bending-in the coil maybe 1 wire diameter at the ends. Of course, it may not be significant with wire rings in tiny bores? Also, dress ends so there are no sharp edges to score bores. Don't chamfer, just remove burrs and "sharpness" at the cut.
Modern cars have wire rings, not cast iron, (Mostly, as some have Lithium Batteries!).
Enjoy!
K2


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## Nerd1000 (May 12, 2021)

Would you have to straighten the slightly helical shape of a wire ring so it sits flat? Stands to reason you would.


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## Steamchick (May 12, 2021)

HMMM... Assume I am thick, but why does it stand to reason? The ends (gap) don't have to align perfectly, because there is a gap anyway, and as long as the ring contacts all the way around it should be OK if "close", - with my reasoning? The ring groove does that anyway. With 0.5mm wire it only has a pitch of 0.5mm. as wound. The ring clearance will be only 0.025~0.05mm anyway, - which at max is only 1/10th of the wire diameter, so "I Guess" it will be OK? the slight axial force from the "twist" would probably just form a slight contact on one end on the top, and on the other at the bottom. If this prevented rotation then it would be an issue, but if the ends are suitably fettled they should slide, allowing rotation. I don't remember a "flattening" process on Production rings in H & G's factory. - But my not remembering doesn't mean there wasn't one. I can only suggest "try it and see".

K2


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## awake (May 12, 2021)

Nerd1000 said:


> I think at 3/8" your rings would be devilishly thin. Rings for my Webster worked out to 0.8mm thick, and while I found making them to be easier than expected (I thought I'd goof up for sure) that's still a little thinner than i feel comfortable making. Plus the engine is far from finished so I can't speak to whether they'll actually work. 3/8" is a little under half the bore diameter of the Webster, so you'd want something like a 0.4mm ring? Crazy.
> 
> I think for such small rings I might try making them from bronze. Much easier to get in small sizes, and it works in steam engines so why not IC? Would need a larger gap to compensate for lower stiffness of the bronze.



That's mighty thin, but possibly doable. However, keep in mind that when working with models, sometimes the math has to be thrown out in favor of what is practical - most people making the Webster use thicker rings, more like 1.5mm. In my case, I used a Viton o-ring, 1.5mm, and it has worked and continues to work perfectly.


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## Nerd1000 (May 12, 2021)

Steamchick said:


> HMMM... Assume I am thick, but why does it stand to reason? The ends (gap) don't have to align perfectly, because there is a gap anyway, and as long as the ring contacts all the way around it should be OK if "close", - with my reasoning? The ring groove does that anyway. With 0.5mm wire it only has a pitch of 0.5mm. as wound. The ring clearance will be only 0.025~0.05mm anyway, - which at max is only 1/10th of the wire diameter, so "I Guess" it will be OK? the slight axial force from the "twist" would probably just form a slight contact on one end on the top, and on the other at the bottom. If this prevented rotation then it would be an issue, but if the ends are suitably fettled they should slide, allowing rotation. I don't remember a "flattening" process on Production rings in H & G's factory. - But my not remembering doesn't mean there wasn't one. I can only suggest "try it and see".
> 
> K2


It's my understanding that the ring seals against the bottom of the ring groove (on the power stroke) so it must either be flat or get forced down into a flat shape by pressure in order to work. Otherwise the gas could go around it via the ring groove.


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## Steamchick (May 13, 2021)

Good one. I guess you are right. I just don't remember seeing a flattening process in the factory 30 years ago.
K2.


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## timo_gross (May 13, 2021)

vederstein said:


> Oh hell, not again.  This hobby is dying.  Why make the barrier to entry more difficult by criticizing how people make their engines?  The whole "you're doing it wrong" does nothing but push people away.  So what if someone wants to use sealing method over another?  Give it up.



I am fairly new to all this trying to make a first sort of working steam model at some point. ( boiler beeing the problem ) Piston rings beeing an interseting question.
No ring at all works fine so far. ( not beeing combustion, not running on steam, not required to do more than just moving )

I did not read a "you*re doing it wrong" in the original post, rather than a "it is horribly difficult to make an engine anyway, so the rings are not the worst hurdle" and "just go for it, before you tell yourself it cannot be done!"

... continues reading ...

Greetings Timo


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## Steamchick (May 17, 2021)

Timo. I agree with the "just go for it" sentiment. But please can I offer some advice (from my bucket of scrap knowlege from 50 years in Engineering). 
Develop manufacturing methods, techniques and skills by following an existing design. (My first few engines were from drawings).
Try and understand the designs so you can appreciate critical sizes, fits, etc.
Then consider you own "freelance" ideas. 
At each stage gain buckets of knowledge from "teachers"  on this site, books, theory, calculations, etc.
Remember, a machining apprentice would take 4 or 5 years full-time work to become fully proficient. A professional Engineer would take 3 to 5 years of education plus a few years or decade of experience to become reasonably good at Design and Manufacturing. 
Experts have even 50 years experience and are always learning and improving.
So you have picked a hobby that can occupy a long and happy life!
Enjoy!
K2 (just learning, after 50 years!)


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## timo_gross (May 17, 2021)

Steamchick said:


> Timo. I agree with the "just go for it" sentiment. But please can I offer some advice (from my bucket of scrap knowlege from 50 years in Engineering).
> Develop manufacturing methods, techniques and skills by following an existing design. (My first few engines were from drawings).
> Try and understand the designs so you can appreciate critical sizes, fits, etc.


Hello steamchick,

i think I am trying to follow that advice on the one hand and doing some things "freelance" in parallel. Trying to not get too much off topic from the piston rings . So far I started with a myfordboy "compressed air engine", then I found some Elmers engine design on the internet (it is a barstock engine), finally another bar stock one that is called "Gerry Dykstraa beam engine".
They are all somewhat running without any piston ring. The nuts that tighten the packing around the piston rod are also "missing"  ( not all, but some ). All of them have a Brass cylinder with approx. 12 mm diameter and a rattlefitnesium piston.

My assumptions concerning the piston rings

Low friction is better if the engine does not need to really work, but only move, so a little leak in the piston does not harm?
A new piston with rings can still be "retrofitted" or a ring groove can be added at a later stage or is there a reason why it needs to be done right away?
Task at hand for me as beginner converting the "compressed air" engines into steam engines. The piston rings, may become one task during this endeavour.

Greetings Timo


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## Steamchick (May 17, 2021)

There are 2 schools of thought:
1) - the best possible sealing is the most efficient.
2) - Steam engines usually run "wet" - I.E. condensate from the expanding (And cooling) steam condenses and the droplets lubricate the bore and help seal the piston anyway. 
Unless you are running a locomotive or some serious load, then a few grooves acting as a labyrinth seal are usually adequate on most stationary models, that are idling rather than doing any serious work. The major advantage is the low friction of a labyrinth seal so the models run on a minimum of steam and the slow action looks more "real". Unless you have a high speed engine of course!
But making a working piston ring of whatever design is necessary for high compression engines - like infernal combustion engines. And some do it "because they can".... even if it takes hours of labour and experimenting to get it right.
Cheers!
K2


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## timo_gross (May 17, 2021)

Steamchick said:


> "because they can".... even if it takes hours of labour and experimenting to get it right.
> Cheers!
> K2


I guess that brings us back to original post, that I interpreted "Just try if you can!" . So I am pushing my envelope further, but I try if the ring groves in the piston do the job for now. The piston rings are postponed, but not forgotten. 

So do not feel discouraged or "doing it wrong" for now. 

Cheers!

I recently saw some cast iron blanks lying in a pulley and gear shop. The blanks are maybe 2" diameter and 10" long. Would that be worth to try to make a cylinder or pistonrings out of this kind of material? I would guess they sell it for a reasonable price.


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## Charles Lamont (May 17, 2021)

Steamchick said:


> Unless you are running a locomotive or some serious load, then a few grooves acting as a labyrinth seal are usually adequate on most stationary models, that are idling rather than doing any serious work. The major advantage is the low friction of a labyrinth seal so the models run on a minimum of steam and the slow action looks more "real". Unless you have a high speed engine of course!


I have a Stuart Double-10 that I finished in the summer before going up to university (about 50 years ago). It has labyrinth grooves on the pistons, and glands packed with graphited yarn. The glands are good but there is a bit of a bit of blow-by, particularly on one piston. On the other hand, it will run on lung pressure - quite fast if you have plenty of puff, and it will move under the weight of its own parts.


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## Steamchick (May 17, 2021)

Hi Charles: The old ones are the good uns! Graphited yarn olnly served a few centuries before "modern technology" replaced it with Viton seals... Took something REALLY good to replace it!
Timo - I am fascinated by this shop... "some cast iron blanks lying in a pulley and gear shop. " - But wouldn't pay more than scrap price for unknown cast iron. You need the correct "temper" and grain for rings and cylinders. Read around these threads - the Experts will tell you grades to buy. I rely on them. I have made stuff with wrong materials - only to berate myself later for being so stupid - when I had wasted my time making scrap.
K2


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## timo_gross (May 18, 2021)

Haha that is true, 
I am constantly fascinated.  
I think to them it is raw material that they will not sell at scrap price. I will ask. 
The problem is often to find the right source for something, I am getting better at it.


Steamchick said:


> when I had wasted my time making scrap.
> K2


I always though that is called hobby? Making swarf out of perfectly good materials, damaging expensive equipment in the process.
By chance I saw these signs on my morning bike ride on Sunday. It says piston rings on them  . 



Cheers Timo


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## Steamchick (May 18, 2021)

The old adage... "A bad workman blames his tools" - well, it is often the wrong material selection that causes failures. - The "bad workman" just selected the wrong stuff for his parts - usually to save money, but more often because he didn't know what the right stuff was, or how critical it could be. E.G. the Victorian Tay Bridge disaster was caused by the wrong material for the fatigue stress at the base of the bridge piers.  (It took 100 years of technological development to understand why the piers failed). So when you make such a mistake  you are in "good company", just not the company you would really choose to be in!
Some of us (well rarely me...) know the "right stuff" for the job, and I have learned it is worth the extra cost of buying "the right stuff". So if material is "unknown" it is often better left alone than used to waste your money.
Regards,
K2


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## Richard Hed (May 18, 2021)

Steamchick said:


> The old adage... "A bad workman blames his tools" - well, it is often the wrong material selection that causes failures. - The "bad workman" just selected the wrong stuff for his parts - usually to save money, but more often because he didn't know what the right stuff was, or how critical it could be. E.G. the Victorian Tay Bridge disaster was caused by the wrong material for the fatigue stress at the base of the bridge piers.  (It took 100 years of technological development to understand why the piers failed). So when you make such a mistake  you are in "good company", just not the company you would really choose to be in!
> Some of us (well rarely me...) know the "right stuff" for the job, and I have learned it is worth the extra cost of buying "the right stuff". So if material is "unknown" it is often better left alone than used to waste your money.
> Regards,
> K2


Pleez tell us who are ignorant of the Victorian Tay Bridge disaster.  I know nothing of it.  There are some parts, sometimes that are just parts.  Virtually anything could be used.  Knowing the difference, that is, which piece NEEDS aluminum or brass, or steel or cast iron and which piece doesn't matter if it's mild steel, or cast or something out of your metal pile.  I use a LOT of material that I don't know what it is for just average parts.  But there are many that I get a specialized metal.


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## Steamchick (May 18, 2021)

Tay Bridge disaster - Wikipedia
					






					en.wikipedia.org
				



The pier bases were made from Cast Iron instead of wrought iron. Because they didn't know about materials and fatigue cracking failures.....


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## Richard Hed (May 18, 2021)

Ah, very interesting.  Does you know about the infamous "Tacoma Narrows Bridge" disaster?  It was actually filmed during it's collapse.  The man responsible for the insurance had stolen the insurance money.  Very funni.


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## awake (May 18, 2021)

timo_gross said:


> All of them have a Brass cylinder with approx. 12 mm diameter and a rattlefitnesium piston.



Timo, good job obtaining the rattlefitnesium for your pistons - this is a good first material to use. The next step will be to see if you can source some semifitnalese for your next few rounds of model engine making. Ultimately, of course, you want to get hold of some unobtanium, or at the very least costarmandlegium, to make the very best models.


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## awake (May 18, 2021)

timo_gross said:


> Haha that is true,
> I am constantly fascinated.
> I think to them it is raw material that they will not sell at scrap price. I will ask.
> The problem is often to find the right source for something, I am getting better at it.
> ...


Timo, where is home for you? (I grew up in Southeast Asia - Philippines and Singapore - but the sign makes me think maybe East Asia?)


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## Steamchick (May 21, 2021)

I knew a guy (ex. Blacksmith turned welder) who said the hardest welding rods to obtain were woodtrode (Often used in Teak and Lignite structures for strength), the most difficult to use for electric arc welding is nosparkium (used where the arc must be cool enough to avoid heat distortion), and when gas welding he hated welding with flammalobium! - Just too hot!
I haven't found a source of unobtainium yet - anyone found it? - it is supposed to be the best after Hen's teeth enamel? - That is supposed to be the best natural hard material for machining diamond. Also, in the natural world another incredible material is Unicorn Horn, for making musical instruments. One of the few natural materials of which we do not have a man-made substitute. Apparently when you hear a note played on a Unicorn horn you think the sound is Magic!
Oooh look! The flying-pig squadron is passing overhead!
K2


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