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A new attempt at making piston rings

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  • Originally posted by J Tiers View Post
    Would it be fair to assume that the grade Brian has now is at least "reasonable", since it passes the "spring it over the piston" test without either breaking or deforming?

    Grades that one may not want to use quite likely would not pass that test. Not all of the possible grades, but many.
    You are probably correct Jerry. I was just curious if he verified what he had or is going going to roll the dice. His silence probably answers that.

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    • Tomorrow, if it's still raining I will make the Trimble heat treat fixture. It will be made of the same material as the ring itself, so I don't get into problems with differential expansion factors during heat treat. I only show one ring on there, however it will accept up to six rings at once. The round red rod is the "spreader", and if the heat treat is done correctly the red rod should pull out of the fixture very easily. If the rings are still "gripping" the red rod, then the heat treat hasn't done it's job.
      Brian Rupnow
      Design engineer
      Barrie, Ontario, Canada

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      • Today I made the Trimble heat treat fixtures. I managed to hit the numbers "right on", so if my cleaved rings fit, the fixture and the rings go into my new heat treat oven for 3 hours at 1100 degrees F.
        I decided at the last minute to make the fixtures from mild steel instead of cast iron, but I don't think it will make any difference. Why is the head turned on that 5/16" cap screw?---I really don't know, but that is the only 5/16" cap screw that I could find around here.
        Brian Rupnow
        Design engineer
        Barrie, Ontario, Canada

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        • This is my interpretation of the Trimble deburring station. One side of the ring is chamfered and deburred before the ring is parted from the parent stock. The other side of the ring, after parting off will need deburring and chamfering. This is the station that allows you to do that. The good side of the ring is butted up tight to the shoulder on the blue piece, the the bolt is tightened to pull the yellow piece into the blue, causing it to expand and grip the ring, leaving the second side of the ring exposed so it can be deburred and chamfered.
          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

          Comment


          • That would be, before the ring is split, correct? Neat use of what is basically an expanding mandrel.
            25 miles north of Buffalo NY, USA

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            • Yes, that would be before the ring is split.----Brian
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

              Comment


              • Brian, what is the formula or criteria for determining the diameter of the expander or spreader rod. As I suspect it's dimension is dependent on the intended bore size. Not having read all of Trimble's notes I thought you could shed some light on this aspect.
                Home, down in the valley behind the Red Angus
                Bad Decisions Make Good Stories​

                Location: British Columbia

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                • The shoulder on which the ring sets is equal to ring outside diameter minus twice the ring radial thickness. The ring will have an o.d. equal to the cylinder bore. My cylinder is 1.006" diameter, so the inside diameter of the ring will be 1.006-(0.038+0.038)=0.930", so that will be the o.d. of the fixture the ring sets on.
                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

                  Comment


                  • Here we have the internal expanding mandrel, which holds the ring while the "bad" side of the ring is deburred and chamfered. (The other side of the ring was chamfered and deburred before it was parted off from the parent stock). I even have a ring shown on the end of it, although that ring isn't the right ring, it's just one of the old rings I had around. You will notice that the main body of this tool is much, much longer than the solid model.---This is why---My 3 jaw chuck never can grip something twice in a row, without grabbing it a little differently. This shows up with a dial indicator, even if it's hard to see with the naked eye. So, my thoughts were, if I want to use this tool more than once, I should do something to guarantee that I always grip it the same way, in the same place. My lathe spindle is 1 1/2" thru the bore, so on the far end of this 1 1/4" diameter main body I have a ring of material 1.499" in diameter, and have the other end stamped 1, 2, and 3 to correspond with the chuck jaws. When installed, the ring of material is flush with the far end of the spindle. This brings me to a point where there are no more fixtures to build. All I need now is that damned fine India stone which is somewhere between Sweden and here. I am going to call "Terra Nova Steel and Iron inc. in Mississauga this afternoon and see if they will sell me a 12" length of Durabar to make rings from. I doubt very much that I need to do that, but I am not leaving any stone unturned in my quest to make working cast iron rings.

                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

                    Comment


                    • Be advised, Durabar is another trade name, they have many different grades of Durabar.

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                      • Today my "fine India stone" arrived in the mail. If it had been holding me up on a project I could get really ugly about how long it took to get here. However, it hasn't held me up, as I had three fixtures and a new piston to make before it would be needed anyways, and I just finished the third fixture yesterday. Now all that is left is to make the rings. Wish me luck!!!---Brian
                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

                        Comment


                        • You don't need luck Brian, you've got skills and experience to help guide down this path.
                          Home, down in the valley behind the Red Angus
                          Bad Decisions Make Good Stories​

                          Location: British Columbia

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                          • Thanks for the vote of confidence Willy. Second oldest grandkid just graduated from public school. She's a pretty girl.
                            Brian Rupnow
                            Design engineer
                            Barrie, Ontario, Canada

                            Comment


                            • She looks like a sweetheart. Congrats to her and your family!
                              Kansas City area

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                              • So-----------Here we are again. A new batch of rings, made from fine grain grey cast iron. I used my "special grind" HSS grooving tool to part these rings off. Each ring is 0.044" wide, which leaves a small bit on each side for "clean up" on a sheet of 600 grit paper. I hit the numbers perfectly on the o.d. and the i.d. and made 8 rings, of which I only need two. My opinion on the "Fine India Stone" that I bought---It doesn't do anything that a piece of 220 grit paper held against a flat file won't do. I may have wasted my money buying it
                                but I'm trying to follow everything that Trimble suggests. Next step will be to mount each ring on the Trimble fixture and deburr/chamfer the side which was not deburred/chamfered before it was cut off from the parent stock. If these rings don't work, there is enough turned material on the "parent stock" to make new rings 0.045" thick, same as Trimble did.
                                Brian Rupnow
                                Design engineer
                                Barrie, Ontario, Canada

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