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Threading hardened shaft

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  • Threading hardened shaft

    Been watching the Clough42 tool post grinder series on YouTube. It’s well done and I’d like to copy it for the most part. Having said that I’m not crazy about his method to retain the spindle, set screws.

    My question is what are the chances of threading a hardened shaft with a carbide insert? How about DOC, speed, lube? It’s a collet extension as shown in the link

    https://www.ebay.ca/itm/302894733149

  • #2
    I've had no problem doing hardened stuff with carbide. Just need to take extra care on the setup making sure everything is tight, and go slower, using less DOC.
    25 miles north of Buffalo NY, USA

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    • #3
      Same here. Don't try to hog it. Nice easy cuts, don't need high RPM just because it's carbide.
      Kansas City area

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      • #4
        I have had no trouble putting spanner flats on the earlier er collet arbors which are medium hard, using solid carbide and would not hesitate to try single pointing with carbide inserts. I always use tapping oil, slow rpm and small cuts down to 0.001" depth towards the finish. Not a job for HSS, even cobalt.

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        • #5
          Most likely only hardened into the Rc 45-50 range anyway, so not that hard. Shouldn't be that difficult.
          It's all mind over matter.
          If you don't mind, it don't matter.

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          • #6
            Originally posted by nickel-city-fab View Post
            I've had no problem doing hardened stuff with carbide. Just need to take extra care on the setup making sure everything is tight, and go slower, using less DOC.
            Only thing to add is feed with the compound rest @ 29.5 ° dont feed straight in with the cross slide. It creates more tool presure that way. Threads on most lathes are progressive. 1st cut .010, 2nd .006 3rd .004- and so on- DOC. Tap magic, moly-Dee or the other lubes will be fine. You can always turn slower on tuff steel, but too fast and your tool may break or dull. If your lathe is small, reduce those DOC in half. As others said....... take it. Slow!

            Built a spindle using that same ER -20 holder 2 yrs ago for spinning wire EDM. Worked well, hope yours does too.
            Last edited by Fasturn; 10-16-2021, 07:33 PM.

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            • #7
              You're talking about the shank, right? Are you sure its even hardened?
              Southwest Utah

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              • #8
                I have bought alot of Chinese tool holders over the years and they seem to be 38 -40 Rc scale. Not a problem for a lot of shops, but my 300lb lathe can be challenged. Right tool and experience Goes a long way.

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                • #9
                  Originally posted by chipmaker4130 View Post
                  You're talking about the shank, right? Are you sure its even hardened?
                  Yes, the shank. No, I’m not.

                  Clough42 believed his was so he didn’t try and thread it. He also has a bench top lathe.

                  I have a Colchester Student. It’s obviously not a huge lathe but should handle this with ease.

                  I will order the shank and report back here with my findings

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                  • #10
                    Reporting my findings. No trouble at all to single point thread the shank. It is from a far away land so of course your results may vary. I don’t believe it was hardened at all, a file cut it no problem

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                    • #11
                      If you do not know the actual material condition it is not possible to predict the outcome.

                      There is a world of difference between 50 and 65 on the Rockwell Scale.

                      That being said, it is unlikely that an ER collet holder is terribly hard so have at it.
                      Also at $18.00 you have little to lose.
                      Last edited by Bented; Yesterday, 08:29 PM.

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                      • #12
                        After watching Clough42 video 24 where he tries out the grinder. I believe he would have got better results if he had been running the lathe in reverse, like you are supposed to run a toolpost grinder.
                        John b. SW Chicago burbs.

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                        • #13
                          Originally posted by Captain K View Post
                          It’s well done and I’d like to copy it for the most part. Having said that I’m not crazy about his method to retain the spindle, se
                          I think you are ok. I did not do the link, I never do.

                          I have turned some hard metals. I never asked for info, didnt need to. Most of my questions were already asked and answered here. Just the way it is. JR

                          They say high grade carbide or whatever needs to tun at so much SFM. I say BS.

                          In a production shop maybe. Wrong Garage folks, mine is a Two Car.. JR

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                          • #14
                            It seems you guys did not read my last post. The spindle arrived and had been threaded with no problem.

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