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A new attempt at making piston rings

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  • So........... Why the "cleaver"? Why break the ring to get the gap?

    Is it supposed to fit closely together again? just like broken rod big ends? That does not sound as if it could expand to fit, so that can't be the idea.

    What is wrong with just cutting the ring?
    2730

    Keep eye on ball.
    Hashim Khan

    Everything not impossible is compulsory

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    • Originally posted by J Tiers View Post
      So........... Why the "cleaver"? Why break the ring to get the gap?

      Is it supposed to fit closely together again? just like broken rod big ends? That does not sound as if it could expand to fit, so that can't be the idea.

      What is wrong with just cutting the ring?
      I think it has to do with distorting the shape of the ring while splitting it. George Trimble uses a fixture with a sharp vee and a mating half, somewhat like a die, so there is no force or stress except at the exact spot of the split. Other methods "may" work, his methods are hailed as the best out there. Until a proven set of rings is made, I wouldn't deviate from his methods.

      And no, it is not supposed to fit together again similar to rod big ends, the gap is filed to obtain the proper gap after breaking. Again, I think its about not distorting the shape.

      Comment


      • Why would using a saw cause more distortion?
        2730

        Keep eye on ball.
        Hashim Khan

        Everything not impossible is compulsory

        Comment


        • My assumption is (without rereading the prior posts) - if the rings are already on size prior to splitting, one would need to cut them with a kerf <= to the gap. I have no .004 blades of any kind. 'Breaking' them eliminates this problem.
          Location: North Central Texas

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          • Originally posted by J Tiers View Post
            Why would using a saw cause more distortion?
            Might, might not.... depending how fine the teeth and how well the ring is clamped both sides of the cut. The only other thing I can think of is that breaking it does not remove any material, unlike a saw. If the ring is turned to exact bore diameter as Brian said, the kerf of the saw would be the minimum gap obtainable, if you wanted a 2 to 4 thou gap that would be a might thin saw.
            Last edited by Sparky_NY; 06-07-2021, 04:20 PM. Reason: LOL Just read Joel's post after I typed mine. Oh well, great minds think alike.

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            • Today I had one of those wonderful, drop in, 8 hour jobs from an old customer. Design fixtures in the morning, send off to customer for approval, get immediate approval, make detail drawings, then machine like a fiend until suppertime. I don't want any "big" jobs, but I love those one day deals. I'm having a grooving tool ground for me at a local shop to make piston grooves, and todays work will pay for that with money left over.
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

              Comment


              • That would be 1100 degrees F with a 3 hour soak time. I have tons of input on this one, and everybody is recommending something different. This is why I bought a heat treat oven. I am hoping that I can make working rings, and that I can set up a standard and repeatable process for doing so.
                Brian Rupnow
                Design engineer
                Barrie, Ontario, Canada

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                • Knowing you Brian I know you'll get there and we'll all learn something along the way.
                  Home, down in the valley behind the Red Angus
                  Bad Decisions Make Good Stories​

                  Location: British Columbia

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                  • A local milling machine cutter sharpening service is currently making this tool for me to groove aluminum pistons for 0.038" wide rings. Actually, his price for a tool as shown here was $60, but a lot of that must have been set-up, because he also quoted me on a double ended tool for 75$. I ordered the double ended tool and will have it sometime this week.
                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • Ouch!!
                      Are they EDMing it?

                      Comment


                      • Does that tool have any side clearance? Sure doesn't look like it in the drawing.

                        Comment


                        • No, it doesn't have side clearance. It only extends 0.050" into the aluminum.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

                          Comment


                          • Originally posted by sid pileski View Post
                            Ouch!!
                            Are they EDMing it?
                            Come on up to Canada and live for a while. We'll make you an honorary Canadian for a while and you can find out what it costs to live in the land of the free. It is machined from a 1/4" hss blank.

                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • Originally posted by brian Rupnow View Post

                              Come on up to Canada and live for a while. We'll make you an honorary Canadian for a while and you can find out what it costs to live in the land of the free. It is machined from a 1/4" hss blank.
                              I think the costs are about right. I'm just north of Buffalo (an hour or two away from Brian) and local shop rates are between 60 and 120 per hour. I would have thought they were using a surface grinder to do your job? It should work OK either way.
                              25 miles north of Buffalo NY, USA

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                              • I called the toolmaker this afternoon about the cutting tool he is making me and asked about side clearance. He was out, but I left a message. He emailed me back and this is what he had to say.

                                "Hi Brian
                                Sorry I missed your call. I was driving.
                                I intend to put side clearance on the tool. Probably only 2-3 degrees per side. I would put more because it’s aluminum but it’s pretty small. I will also make the tool narrower at the base. Only by .001/.002 but it will give you a cleaner cut. Both clearances will stop the aluminum from smearing and give you a better cutting action. I should have them ready tomorrow and I’ll let you know. Thanks"



                                Okay--I never claimed to be a tool designer. This guy is good. He has sharpened cutters for me before, and I was impressed by his background and knowledge.



                                Brian Rupnow
                                Design engineer
                                Barrie, Ontario, Canada

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