Hi Ty. It's not as difficult as people make out. Larger sizes are easier. My Kawasaki generator rings lasted a long time. Not worth spending much money on some old equipment, that's if you can even get the spares. Cheers Rob
Glad you found it useful. If I had moved the ring in closer to the bricks it would have heated up a bit quicker - but it worked OK as shown. To tension a really big ring (eg. out of a vintage stationary engine) you may need to consider heating it on a metal plate in a forge to red hot, while applying light tension to pull the round metal slug forming the set out of the gap when the cast iron reacts - basically the reverse of what's shown in the video. Or you could use oxy acet.
I like the simple way you use to make basic piston rings, I'll have to give it a try sometime. the most important thing to make rings seal and last is the finish of the cylinder bore, proper honing pattern and grit of stone are necessary to make the rings "seat" .Also ring side clearance and depth of ring groove are critical to keep the ring from vibrating as it moves up and down the bore at high speed. Vibration will let compression gasses slip past the rings into the crankcase
The original method I use says to air cool the ring, but I understand what you are saying about oil tempering, and it's worth a try. The only difference is that the ring is cast iron and not steel. Still an interesting suggestion. The only question is whether quenching (fast cooling) would make it more brittle. Cheers Rob
Excellent. Have wanted to make some for years and now I have the need. An old boy I used to work with used to make them for his daily transport a 1937 Coventry Eagle. Put new ones in every spring. Well it was works time and material ! His method was much more complicated than yours, multiple operations. Like the idea of a plate in a forge to set them. I haven't got a forge but I have got a Barbie and an air blower !!! Cheers from the UK near Earles Court.
Rob Lane Making a compression ring for a two stroke is relatively easy. Where it gets tricky is making an oil scraper/ring, especially if it's a small size. But all do-able. I guess it must be getting a bit cool over your way about now. Cheers from down under. Rob
If you did that you wouldn't be able to use this simple method. This video isn't about making the perfect piston ring, it's about making a usable piston ring simply without a lot of effort. These rings work perfectly OK - as can be seen in the video where they are fitted to my Kawasaki generator. Three or four years later they are still working perfectly. Cheers Rob.
Hi Rob, Great video. As you are going to split the ring, do you calculate the desired end gap and then over size the ring diameter to allow the amount of material removed? Also do you simply split it with a cut off wheel? Thanks
Glenn MacGregor Hi Glenn. All is explained in my web page on this subject: users.tpg.com.au/agnet/make%20piston%20rings.html I intend to do a video of the full process at some stage - just waiting for a suitable engine candidate needing a replacement ring to come along. Cheers Rob
To ensure uniform stress relieving around the circumference you need to clamp the expanded ring between two plates in order to fix the stress at that postion while the ring is heated.
@@Xynudu I made a ring that is flatter with no effect. Then I made a ring with 50% bigger inner diameter. So I have a narrower ring and it's way more bendable. You might be right about the type of cast iron...
I've mainly made replacement rings, so I have used the existing measurements for expansion gap/thickness/width/ diameters successfully. Most compression rings are roughly two or three times as wide as the depth, but not all. Some slow reving motors/compressors and many two strokes run almost square rings in cross section. The only rings I've had break when expanding/fitting were for very small piston sizes/two strokes which really need a specialised type of cast iron I think. Smaller means more fragile.
Hi there, I've got a vintage Briggs and stratton engine I'm tidying up while on look down, she's a smoker, I removed the piston and found the oil ring stuck no big deal, I find a tin can, stick the piston in the can and cover it with oil, then I head inside a stick it in the old girls oven for a couple hours. I've used this method a number of times and find it very effective. Then I carefully work the ring loose but I broke it. I have oodles of new old stock ring sets but nothing the correct size. The question I'd like to ask is... If I used a ring slightly larger and trimmed the ends, is it possible to gently heat it up and compress it to fit the bore? Kind regards from new zealand.
Hi Michele, it's not something I've ever attempted. I would expect the ring to compress in an elliptical shape and put uneven pressure/wear on the cylinder walls. It would probably only seal in a few places. It depends how oversized the ring is. I think it's a bit risky. You would have to heat the ring red hot to get any benefit when compressing it. Your call ;) Cheers Rob
Piston rings don't have to be polished. Some are, but many commercial rings have a matt finish. I couldn't understand the last question. Please clarify it and I will do my best to answer it. Rob.
Can you go the other way and make it smaller? If so, how would on go about it? I'm unable to find rings for my old chainsaw but can buy slightly larger rings. could you turn a 52mm ring into a 48mm ring?
Hi Walt. Not really. Even if you could grind the external ring diameter back (in a compressed state), the amount to remove would be as much as the ring width. Cheers Rob
@@Xynudu I was thinking more on the lines of compressing the ring to the desired size by suspending it between 4 metal rods on the od and then heating it until it drops. Wouldn't work?
Hmmm. Not such a bad idea Walt. Some good lateral thinking going on there. Of course you would have to grind the ring gap a lot wider to be able to compress the ring down to the smaller diameter/size. I like it. Definitely worth a try. The ring may not actually drop with four pegs, but should hold the set when it cools anyway, so you could even try re-shaping it in a cylinder the bore size. Just get everything red hot and then air cool. Once it gains the correct shape and diameter through your process, you would then have to re-do it with an expansion peg (as I do) to spread the ring (as it won't have any tension at just the nominal bore size). So in escence you will redimension the ring first and then spread it separately for the tension. Very interesting approach. I'd be interested to hear how you get on. Cheers Rob
You will have to grind open the existing ring gap to allow the ring to compress and fit in the four pegs, and have a small (normal) amount of gap to allow for heat expansion. That then should be the correct running gap and just needs opening by my method to add spring tension. Cheers Rob
When making watchmaker parts, we drop red hot steel part in oil, this creates perfect tempering (blue) as sometimes parts are soo small that air cool causes crystallization and then annealing (softening) is needed. The ideal color is blue as it is the strongest. But super heat (dull red hot) must always be established before metal can transform. When crystalized cooled, metal needs to be shined up and then heated to 500 degrees to establish blue. Dropping red hot into oil is simpler.
I use ordinary fine grain grey cast iron (as in a metal pulley). I believe spun cast iron has a different graphite content/structure. That ring cross section is tiny. I would have expected the ring to have a thicker one. ie. more than the ring thickness. Cheers Rob
Hi I managed to machine some piston rings for my Blackstone OPH they are 7 1/4 inch dia but I did not use your method for heating the rings to expand them. I just opened them with a piece of steel packing in the gap and put them flat on a brick and heated them I am afraid that your method will damage/distort the ring when it falls:-)) Thanks for the info!
Hi John, Your method should work quite OK provided the brick is flat - or you can get twist distortion that way. The ring only has to drop a small amount, and I've not had any distortion issues. But do whatever floats your boat. If it works OK then that's all that matters. It's a good tensioning method, far simpler than all the others out there, and the rings in my Kawasaki generator running at 3000 rpm are still running fine after many years of use. Glad you found it helpful Cheers Rob
I am making some at the moment for a 53mm bore I turn them in a jig which is .005 over size from the bore, after slitting. and measure the inside Dia of the piston ring "where it will sit " on the piston and give and bore of the ring .005 clearance ,then I remove it and do the next one , question is , because the bore is only 53mm will I have to put them on an arbour and turn the outside then heat treat them or will they be ok PM if you like for discussion
If I understand correctly, you have sized the external diameter slightly oversize prior to cutting. I don't see any reason to turn the outside down with that measurement. I think they will be OK. I can't advise on the ring gap for that diameter. Use one of the ring gap calculators on the web. Rob
xynudu . thanks rob, you have understood correctly . I have been thinking about it and would agree the amount oversize it has been turned will be enough I think now because as you said it must expand against the wall and with heat treating as in your video it will be enough , because it has been turned .005 oversize at the start it should make a "seal" , thanks for you video's they are easy to follow and explain things easily adrian
Once you expand the ring, it will seal regardless of the amount of oversize. The only benefit from a very slight oversize is to allow for wear in - according to what I have been told. Glad to share what I have learnt. Cheers Rob.
I reread this reply again. I think .001 oversize would be plenty for that diameter. I hope you are not thinking that the sealing action is caused by the oversize effect. This is NOT the way it's supposed to work. The ring should be the nominal size of the bore and THEN expanded to give sealing/compression effect against the cylinder wall. I know you can avoid expansion by going oversize, and it will work for a while, but that is definitely not the way to do it. Cheers Rob
hi rob i have a old chainsaw needing piston rings the piston measures 52.35 so i would like to make some rings for this project any advice you can give would be great thanks
***** Hi Stephen. You make the ring to the minimum internal diameter of the cylinder bore. The width of the ring must allow the ring to compress without contacting the bottom of the piston ring grooves. I intend to do a video when I replace the ring in my very old McCulloch yard blower (Airstream) but it refuses to die, even though compression is low. Not too far away though. Two stroke engines are good to re-ring as you don't have an oil ring to contend with. Being high reving engines, the quality of the cast iron is pretty important to avoid possible ring breakage. Keep the revs low initially to let everything bed in. Cheers Rob
trouble is you need to heat uniformly otherwise all the stress relieving takes place at one point only which means you have only modified the curvature in that location.
Hi Jose, I've never worked very much with stainless steel. SS is fairly heat resistant. You can only try it and see if they tension. They should, as the tension loss/gain effect will be the same in both cases. Cast iron rings work well - the set I made for my little Kawasaki generator are still going strong after quite a lot of work. Cheers Rob
I was lucky enough to watch a navy trained machinist make some for some obsolete engine. That was 1965 . I remember him using a torch. Great skill. Ty
Hi Ty. It's not as difficult as people make out. Larger sizes are easier. My Kawasaki generator rings lasted a long time. Not worth spending much money on some old equipment, that's if you can even get the spares. Cheers Rob
Glad you found it useful. If I had moved the ring in closer to the bricks it would have heated up a bit quicker - but it worked OK as shown.
To tension a really big ring (eg. out of a vintage stationary engine) you may need to consider heating it on a metal plate in a forge to red hot, while applying light tension to pull the round metal slug forming the set out of the gap when the cast iron reacts - basically the reverse of what's shown in the video.
Or you could use oxy acet.
I like the simple way you use to make basic piston rings, I'll have to give it a try sometime.
the most important thing to make rings seal and last is the finish of the cylinder bore, proper honing pattern and grit of stone are necessary to make the rings "seat" .Also ring side clearance and depth of ring groove are critical to keep the ring from vibrating as it moves up and down the bore at high speed. Vibration will let compression gasses slip past the rings into the crankcase
The original method I use says to air cool the ring, but I understand what you are saying about oil tempering, and it's worth a try. The only difference is that the ring is cast iron and not steel. Still an interesting suggestion. The only question is whether quenching (fast cooling) would make it more brittle. Cheers Rob
Excellent. Have wanted to make some for years and now I have the need. An old boy I used to work with used to make them for his daily transport a 1937 Coventry Eagle. Put new ones in every spring. Well it was works time and material ! His method was much more complicated than yours, multiple operations. Like the idea of a plate in a forge to set them. I haven't got a forge but I have got a Barbie and an air blower !!! Cheers from the UK near Earles Court.
Rob Lane Making a compression ring for a two stroke is relatively easy. Where it gets tricky is making an oil scraper/ring, especially if it's a small size. But all do-able. I guess it must be getting a bit cool over your way about now. Cheers from down under. Rob
Fantastic, just used your method to make some 30mm piston rings
Hi Roy,
Glad it worked out OK.
The ones in my Kawasaki generator I made/replaced years ago are still working :)
Cheers Rob
Your idea is good.Thanks you sir.But ring should be polished again isnt it?Is there any inner portion moving piston ring used yet?
If you did that you wouldn't be able to use this simple method. This video isn't about making the perfect piston ring, it's about making a usable piston ring simply without a lot of effort. These rings work perfectly OK - as can be seen in the video where they are fitted to my Kawasaki generator. Three or four years later they are still working perfectly. Cheers Rob.
Hi Rob,
Great video.
As you are going to split the ring, do you calculate the desired end gap and then over size the ring diameter to allow the amount of material removed? Also do you simply split it with a cut off wheel? Thanks
Glenn MacGregor Hi Glenn. All is explained in my web page on this subject: users.tpg.com.au/agnet/make%20piston%20rings.html
I intend to do a video of the full process at some stage - just waiting for a suitable engine candidate needing a replacement ring to come along.
Cheers Rob
To ensure uniform stress relieving around the circumference you need to clamp the expanded ring between two plates in order to fix the stress at that postion while the ring is heated.
What if i need to do the opposite? Lower ring tension like when trying to install oversized ring in std piston?
That won't work as the ring will no longer be cylidrical and will not seal.
Any tips on getting the rings on the piston? They keep breaking before I even get half way.
If the rings have been expanded enough they should go on OK. The cast iron used may be incorrect as well.
@@Xynudu I made a ring that is flatter with no effect. Then I made a ring with 50% bigger inner diameter. So I have a narrower ring and it's way more bendable. You might be right about the type of cast iron...
I've mainly made replacement rings, so I have used the existing measurements for expansion gap/thickness/width/ diameters successfully. Most compression rings are roughly two or three times as wide as the depth, but not all. Some slow reving motors/compressors and many two strokes run almost square rings in cross section. The only rings I've had break when expanding/fitting were for very small piston sizes/two strokes which really need a specialised type of cast iron I think. Smaller means more fragile.
Another good, informative video. Thanks appreciated and keep em coming!
Hi there, I've got a vintage Briggs and stratton engine I'm tidying up while on look down, she's a smoker, I removed the piston and found the oil ring stuck no big deal, I find a tin can, stick the piston in the can and cover it with oil, then I head inside a stick it in the old girls oven for a couple hours. I've used this method a number of times and find it very effective. Then I carefully work the ring loose but I broke it. I have oodles of new old stock ring sets but nothing the correct size. The question I'd like to ask is... If I used a ring slightly larger and trimmed the ends, is it possible to gently heat it up and compress it to fit the bore? Kind regards from new zealand.
Hi Michele, it's not something I've ever attempted. I would expect the ring to compress in an elliptical shape and put uneven pressure/wear on the cylinder walls. It would probably only seal in a few places.
It depends how oversized the ring is. I think it's a bit risky. You would have to heat the ring red hot to get any benefit when compressing it.
Your call ;)
Cheers Rob
Piston rings don't have to be polished. Some are, but many commercial rings have a matt finish. I couldn't understand the last question. Please clarify it and I will do my best to answer it. Rob.
Can you go the other way and make it smaller? If so, how would on go about it? I'm unable to find rings for my old chainsaw but can buy slightly larger rings. could you turn a 52mm ring into a 48mm ring?
Hi Walt. Not really. Even if you could grind the external ring diameter back (in a compressed state), the amount to remove would be as much as the ring width. Cheers Rob
@@Xynudu I was thinking more on the lines of compressing the ring to the desired size by suspending it between 4 metal rods on the od and then heating it until it drops.
Wouldn't work?
Hmmm. Not such a bad idea Walt. Some good lateral thinking going on there.
Of course you would have to grind the ring gap a lot wider to be able to compress the ring down to the smaller diameter/size. I like it. Definitely worth a try.
The ring may not actually drop with four pegs, but should hold the set when it cools anyway, so you could even try re-shaping it in a cylinder the bore size. Just get everything red hot and then air cool.
Once it gains the correct shape and diameter through your process, you would then have to re-do it with an expansion peg (as I do) to spread the ring (as it won't have any tension at just the nominal bore size). So in escence you will redimension the ring first and then spread it separately for the tension.
Very interesting approach. I'd be interested to hear how you get on.
Cheers Rob
@@Xynudu Calculating the ring gap. I'm assuming you measure the diameter of the ring in it's expanded form and take 15% of that?
You will have to grind open the existing ring gap to allow the ring to compress and fit in the four pegs, and have a small (normal) amount of gap to allow for heat expansion. That then should be the correct running gap and just needs opening by my method to add spring tension. Cheers Rob
When making watchmaker parts, we drop red hot steel part in oil, this creates perfect tempering (blue) as sometimes parts are soo small that air cool causes crystallization and then annealing (softening) is needed. The ideal color is blue as it is the strongest. But super heat (dull red hot) must always be established before metal can transform. When crystalized cooled, metal needs to be shined up and then heated to 500 degrees to establish blue. Dropping red hot into oil is simpler.
I've try it once on my stihl ms381 ring..and it works😁
Right on
Can you please give the material details used for making this piston rings.
It is fine grain plain cast iron used in an electric motor drive pulley.
do you use spun cast iron, or normal cast iron
made soem today, 1/8" x 1/8" x 2.25 diameter.
broke every single one
I use ordinary fine grain grey cast iron (as in a metal pulley). I believe spun cast iron has a different graphite content/structure. That ring cross section is tiny. I would have expected the ring to have a thicker one. ie. more than the ring thickness. Cheers Rob
Hi I managed to machine some piston rings for my Blackstone OPH they are 7 1/4 inch dia but I did not use your method for heating the rings to expand them. I just opened them with a piece of steel packing in the gap and put them flat on a brick and heated them I am afraid that your method will damage/distort the ring when it falls:-)) Thanks for the info!
Hi John,
Your method should work quite OK provided the brick is flat - or you can get twist distortion that way.
The ring only has to drop a small amount, and I've not had any distortion issues.
But do whatever floats your boat. If it works OK then that's all that matters.
It's a good tensioning method, far simpler than all the others out there, and the rings in my Kawasaki generator running at 3000 rpm are still running fine after many years of use.
Glad you found it helpful
Cheers Rob
Do you use Iron for the ring material?
Fine grain cast iron. Nodular would probably work best and be less likely to break. Cheers Rob
Great explanation, just what I need.
I am making some at the moment for a 53mm bore I turn them in a jig which is .005 over size from the bore, after slitting. and measure the inside Dia of the piston ring "where it will sit " on the piston and give and bore of the ring .005 clearance ,then I remove it and do the next one , question is , because the bore is only 53mm will I have to put them on an arbour and turn the outside then heat treat them or will they be ok PM if you like for discussion
If I understand correctly, you have sized the external diameter slightly oversize prior to cutting. I don't see any reason to turn the outside down with that measurement. I think they will be OK. I can't advise on the ring gap for that diameter. Use one of the ring gap calculators on the web. Rob
xynudu . thanks rob, you have understood correctly . I have been thinking about it and would agree the amount oversize it has been turned will be enough I think now because as you said it must expand against the wall and with heat treating as in your video it will be enough , because it has been turned .005 oversize at the start it should make a "seal" , thanks for you video's they are easy to follow and explain things easily adrian
Once you expand the ring, it will seal regardless of the amount of oversize. The only benefit from a very slight oversize is to allow for wear in - according to what I have been told. Glad to share what I have learnt. Cheers Rob.
I reread this reply again. I think .001 oversize would be plenty for that diameter. I hope you are not thinking that the sealing action is caused by the oversize effect. This is NOT the way it's supposed to work. The ring should be the nominal size of the bore and THEN expanded to give sealing/compression effect against the cylinder wall. I know you can avoid expansion by going oversize, and it will work for a while, but that is definitely not the way to do it. Cheers Rob
thanks rob much appreciated
hi rob
i have a old chainsaw needing piston rings the piston measures 52.35 so i would like to make some rings for this project any advice you can give would be great
thanks
***** Hi Stephen. You make the ring to the minimum internal diameter of the cylinder bore. The width of the ring must allow the ring to compress without contacting the bottom of the piston ring grooves.
I intend to do a video when I replace the ring in my very old McCulloch yard blower (Airstream) but it refuses to die, even though compression is low. Not too far away though.
Two stroke engines are good to re-ring as you don't have an oil ring to contend with. Being high reving engines, the quality of the cast iron is pretty important to avoid possible ring breakage.
Keep the revs low initially to let everything bed in.
Cheers Rob
Thank you
trouble is you need to heat uniformly otherwise all the stress relieving takes place at one point only which means you have only modified the curvature in that location.
What do you say about stainless steel rings for a cast iron sleeve? Nice work by the way.
Hi Jose,
I've never worked very much with stainless steel. SS is fairly heat resistant.
You can only try it and see if they tension. They should, as the tension loss/gain effect will be the same in both cases.
Cast iron rings work well - the set I made for my little Kawasaki generator are still going strong after quite a lot of work.
Cheers Rob
The bigger issue i´m having about making them is at the snap, since i cant snap the gap on stailess steel. Regards!
That's a non issue.
Just cut the ring with a thin friction disc in a small air die grinder.
Cheers Rob
thank you.going to make one now
Nicely done!
Thermal forming is not suitable. Due to loss of tangential force in working condition. It should be oval turning or cam coiling.
Awesome thanks for sharing!
Cool