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A new attempt at making piston rings

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  • This is the first time ever for me to successfully make my own cast iron rings to run in one of my engines. I followed about 80% of the Trimble method of making rings. This makes me feel very good.---Happy Dance-Happy Dance!!!!----Brian
    https://www.youtube.com/watch?v=cupLhD2bC3I
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

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    • Yay Brian!! Maybe now you can solve all your troubles!
      25 miles north of Buffalo NY, USA

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      • Congratulations, Brian. It has been an interesting run. Thanks for sharing.
        Glenn Bird

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        • Good job!

          Engine sounds/looks great.
          2730

          Keep eye on ball.
          Hashim Khan

          Everything not impossible is compulsory

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          • I knew you didn't need luck Brian.
            Happy dance indeed!
            Congratulations, the little engine sounds very healthy.
            I'll bet you are one happy camper getting that piston ring monkey off of your back.
            Home, down in the valley behind the Red Angus
            Bad Decisions Make Good Stories​

            Location: British Columbia

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            • Great job! Much learned by everyone.
              olf20 / Bob

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              • Willy---the diameter of that round rod is arrived at by a formula provided by Trimble. In this case it worked out to 0.150" diameter.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

                Comment


                • Originally posted by brian Rupnow View Post
                  This is the first time ever for me to successfully make my own cast iron rings to run in one of my engines. I followed about 80% of the Trimble method of making rings. This makes me feel very good.---Happy Dance-Happy Dance!!!!----Brian
                  https://www.youtube.com/watch?v=cupLhD2bC3I
                  You are a tease ! What is the 20% of the Trimble method that you did NOT follow?

                  Great to see the rings working so well ! I must say I was a bit concerned about the crud all over the rings after the heat treat and if it might hurt the surface finish enough to not seal well, but that question is answered now.

                  Suggestion, make a few more rings for another engine, just to prove you can !!! After that I bet your O ring days are over.

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                  • Sparky--Trimble's rings were 0.045" thick, while mine were only 0.038". Trimble didn't advocate rubbing the rings on a flat piece of 600 grit paper to make a final adjustment of the thickness. Instead, he wanted to adjust the final thickness of the rings using what I call his "expanding mandrel". Other than that, I followed Trimble.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • Originally posted by brian Rupnow View Post
                      Sparky--Trimble's rings were 0.045" thick, while mine were only 0.038". Trimble didn't advocate rubbing the rings on a flat piece of 600 grit paper to make a final adjustment of the thickness. Instead, he wanted to adjust the final thickness of the rings using what I call his "expanding mandrel". Other than that, I followed Trimble.
                      Ok, extremely minor deviations. I think the majority of the miniature engines only use one piston ring, the thickness would change the sealing area and having two rings your dimension is reasonable and gives less friction. As for adjusting the thickness, its the end dimension that counts and critical that it be consistent. IF you find you can part them off closer to the final dimension so less sanding is required that would be a preferred technique. All tiny details of course, your rings work well which is what really counts.

                      Care to take a stab at why the trimble rings worked well and your other trials did not? My guesses: hard to believe its chamfering or deburring, maybe the breaking process distorted the geometry?, the heat treat fixture preventing any movement is a decent bet, better piston ring groove finish with the new tool is also a decent bet. More than likely, its a mix of a few things. Be interesting to hear your thoughts, you were the guy hands-on that would notice any differences best.
                      Last edited by Sparky_NY; 07-04-2021, 01:18 PM.

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                      • I think the biggest part of my failed ring attempts were because it is very hard to get the heat treating uniformly done with a torch. The Trimble heat treat fixture and the heat treat oven are probably the biggest factors in creating good rings.
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • Originally posted by brian Rupnow View Post
                          I think the biggest part of my failed ring attempts were because it is very hard to get the heat treating uniformly done with a torch. The Trimble heat treat fixture and the heat treat oven are probably the biggest factors in creating good rings.
                          I think most of the guys that successfully used the Trimble method did not use a oven. That said, the fixture mass would help to evenly distribute the heat even with a torch. Hard to beat a oven tough, no guessing on the temperature, temp is steady and even too, no guesswork. The fixture clamping action insures no distortion which is very common in any heat treat operation if precautions are not taken.

                          SO... are the viton O rings something from a former Rupnow life now? (your builds, others building from your plans may not want to tackle making rings)

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                          • I hope to not use anymore Viton rings. Everything is subject to change though. I wanted to prove to myself that I could make cast iron rings that would work, and I have proved that. On any further plans that I publish I may detail two pistons and let the buyer choose whichever type of ring he wants.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • I think you are probably correct on why your earlier iterations failed. It is very difficult to get even heat with a torch, which means when you expanded those rings over the piston they may have had spots with differing hardness that bent a little and in random places due to added stress. Congrats on your success! I bet it feels great.
                              Last edited by eKretz; 07-04-2021, 04:25 PM.

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                              • eKretz---It does feel really good!!! When I started building engines in 2008, I made a couple of attempts at making cast iron rings, but I never got much happiness using them. Viton o-rings are so cheap and work so well, that I never got serious about cast iron rings again. I promised myself that I would take the summer off from engine building, but time hangs heavy on my hands, and I decided to tackle the one thing that I never had success with. I am very happy with the outcome.
                                Brian Rupnow
                                Design engineer
                                Barrie, Ontario, Canada

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