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A new attempt at making piston rings

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  • Whats going on Brian? Off hunting down some cast iron? All the different types out there make it pretty confusing.

    Make up the Trimble fixtures yet?

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    • Enjoying summer.--staying out of my machine shop.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • Originally posted by brian Rupnow View Post
        Enjoying summer.--staying out of my machine shop.
        I can relate to that, helps one preserve any sanity left.

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        • Over here the shop puts some sanity back in. Before We were retired the Wife was jealous of My shop time, now some days I can't seem to get there fast enough to suit Her.
          mark costello-Low speed steel

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          • [QUOTE=Mcostello, now some days I can't seem to get there fast enough to suit Her.[/QUOTE]


            Just the way you want it. Well done!

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

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              • If I might make a suggestion for an improvement: make the main body adjustable also, so you can vary that groove width and use it with different ring thicknesses. I might also make the wedges narrower so the ring isn't unsupported for such a large distance. That could also be accomplished by not leaving the end of the wedge slot open, such as by using an endmill to make the slots separately and leaving a round captured end instead of milling all the way through, just leaving a wide enough opening for the wedge ends to almost meet.
                Last edited by eKretz; 06-22-2021, 04:49 PM.

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                • Originally posted by eKretz View Post
                  . . . I might also make the wedges narrower so the ring isn't unsupported for such a large distance.
                  I don't see how this matters. The two wedge edges will each be trying to start a crack at opposite surfaces of the ring. Will there be two cracks, meeting in the middle? I suspect there will be only one crack, starting at whichever wedge edge abuts a weaker section of the crystalline ring material. That crack could go straight across the width of the ring, emerging at the opposite surface close to the other wedge edge. But the shape and direction of a developing crack surface is unpredictable; it will be interesting to see what happens!
                  Allan Ostling

                  Phoenix, Arizona

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

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                    • Originally posted by aostling View Post

                      I don't see how this matters. The two wedge edges will each be trying to start a crack at opposite surfaces of the ring. Will there be two cracks, meeting in the middle? I suspect there will be only one crack, starting at whichever wedge edge abuts a weaker section of the crystalline ring material. That crack could go straight across the width of the ring, emerging at the opposite surface close to the other wedge edge. But the shape and direction of a developing crack surface is unpredictable; it will be interesting to see what happens!
                      For one, it would appear that the wedges tighten individually in this design. One could easily push the ring over if it's tightened further and bend it. I don't like this design. Better would be a single wedge pushing the ring against a solid backing, or dual wedges that float so that they self-center.

                      These types of things can almost always be made better with a little critical thinking. Even great men can have their designs improved. One can't always see things as clearly as one might like when working alone. Collaboration is good.
                      Last edited by eKretz; 06-22-2021, 07:39 PM.

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                      • I'd be inclined to just saw them with a little jewelers saw.

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                        • Originally posted by brian Rupnow View Post
                          That 3D mode I showed is made exactly to Trimble's drawing. It seems like a case of overkill to me, but since none of my attempts at ring making have yielded good results I am going to follow Trimble's method as closely as I can.
                          Excellent plan, one that has worked for the vast majority. I can't recall reading of any failures using Trimbles method exactly.

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

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                            • Okay, next step is to add the "Rupnow hold down" to the "Trimble cleaver".
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

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

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