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Parting off relatively large diameter stock

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  • #16
    Water jet cut them to 30 thou over, then push against 3 jaw with a bushing and your revolving center to finish OD.
    Parting them would be easy on my 16 inch lathe with 3mm Seco inserts...
    More like 1.8 stickout, I parted 5 inch or more with mine but I cheat , cut to the 2 inch or 1.5 diameters then cut in the WorldsWurstBandsaw..... it actually works on smaller stuff.

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    • #17
      Coincidentally, just yesterday my copy of the latest edition of HSM arrived containing an article describing the use of appropriately sized short sections of PVC pipe as handy spacers. Just the thing for such thin facing tasks as needed here.

      To attain the right size, in some instances the author would remove a small longitudinal section of the pipe, permitting it to be squished down as the chuck jaws are tightened. I thought it was a clever solution.
      Last edited by lynnl; 10-24-2017, 01:56 PM.
      Lynn (Huntsville, AL)

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      • #18
        Robin Renzetti's chuck stop video is worth mentioning for this kind of like work:
        https://youtu.be/W7jZO3ZTd0Q
        Location: Helsinki, Finland, Europe

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        • #19
          Another Joe Pieczynski video--Machining ultra thin shaft spacers and precision washer

          Originally posted by Yondering View Post
          I stumbled across this video that details mounting spacers to the chuck face for the same effect. I like the idea, seems like it would be very versatile, and should work perfectly for the OP's needs.

          https://www.youtube.com/watch?v=U3x8H1Xb-jg
          Cut a bunch of larger discs from 1/4" sheet and use his method of pressure turning.

          https://www.youtube.com/watch?v=lGsA_q4guwM

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          • #20
            Originally posted by DR View Post
            "the stick-out will need to be nearly 2in. I also know that with this much stick-out parting tools like to "bow", creating a convex or concave cut, depending on your perspective."

            If you were to look up recommended blade thickness versus diameter in a book on automatic screw machines I bet you'd find 1/4" blade or thicker would be about right.

            (I'd look it up myself if I hadn't got ridden of my B&S books.)
            I was thinking that a wider tool would be required too. And with that much round bar turning into chips it further supports the idea of picking up some 5/16 or 3/8 plate metal and cutting circles from that then machine the blanks as required.
            Chilliwack BC, Canada

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            • #21
              Just throwing it out there, we had to cut slices off 250 MM extrusion billots for micro analysis, (back end defect on the press) we parted on a big old lathe, the parting tool was made from a circular saw blade fixed to an angle plate on the cross slide, I thought sawing them on the billot saw would be easier but according to the metallurgist at the time it affected the crystal structure, I still don't get that as the blade was cooled but I'd just started work and was in no position to argue, besides the metallurgist was a head case with a chip on his shoulder, I did learn to like him after a fashion.
              Besides I did like standing in front of a lathe anyway, it was a new thing for me then!
              Mark

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              • #22
                I read recently on this forum that it is better to part off in a four jaw chuck, and it made perfect sense to me.

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                • #23
                  Y, MJ & 9--thanks for the interesting links.
                  12" x 35" Logan 2557V lathe
                  Index "Super 55" mill
                  18" Vectrax vertical bandsaw
                  7" x 10" Vectrax mitering bandsaw
                  24" State disc sander

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                  • #24
                    Depending how many i wouldnt bother parting off, buy in cut to size to face off, done thousands.

                    Depends on grade of aluminium though the free cutting stuff is glorious to use. 6082 you wont stop it picking up coolant or not and have 2 seconds top whack warning. That said have parted 6" dia 6082 with 1/8" wide tip, trick is feed blade out the deeper you go in.

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                    • #25
                      You guys seem to have trouble with blades..
                      2.5 inches stick out with a 3 mm cutter is everyday scenario..
                      I bought the Seco system after watching them repeatedly cut thin slices of railroad rail off in the lathe.. 4 jaw chuck.. it was at a trade show.

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                      • #26
                        Originally posted by 754 View Post
                        I bought the Seco system after watching them repeatedly cut thin slices of railroad rail off in the lathe.. 4 jaw chuck.. it was at a trade show.
                        Now that's a REAL man's interrupted cut!
                        Which way was the rail oriented?
                        Lynn (Huntsville, AL)

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                        • #27
                          It was held in a 4 jaw on a 16 or 20 inch lathe.
                          I I think pieces about 10 inches long.
                          The rail was about 5 inches high, they would part off thin slices..
                          I looked at it, watched a few cuts, and thought that will do ANYTHING I will try cutting..
                          Last edited by 754; 10-25-2017, 02:10 AM.

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                          • #28
                            Both Iscar and Corocut have videos out of cutting rail, mine is Seco as was the demo I saw.
                            It sounds pretty horrible for most of the cut..

                            On my turret late I usually cut around 800 pc's per insert, I think 1200 at least once

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                            • #29
                              Here's parting railroad track.

                              https://www.youtube.com/watch?v=EZ-cqhGUHAA
                              12" x 35" Logan 2557V lathe
                              Index "Super 55" mill
                              18" Vectrax vertical bandsaw
                              7" x 10" Vectrax mitering bandsaw
                              24" State disc sander

                              Comment


                              • #30
                                Originally posted by 754 View Post
                                You guys seem to have trouble with blades..
                                2.5 inches stick out with a 3 mm cutter is everyday scenario..
                                I bought the Seco system after watching them repeatedly cut thin slices of railroad rail off in the lathe.. 4 jaw chuck.. it was at a trade show.
                                That what I was also thinking. 2.5" aluminium is not any fun on my small lathe but I have done it with 3mm parting blade couple of times.

                                Not exactly railroad track but when I'm lazy to walk out to bandsaw I cut rectangular key stock also with the cheappo MGMN200 insert tool.
                                ~HRC55-60 hex stock was pretty brutal for parting tools tough...
                                Location: Helsinki, Finland, Europe

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