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Looking for source of lead screw nut

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  • Looking for source of lead screw nut

    need flanged 7/8" 5tpi (.2 lead) nut

    My lathe won't do anything under 9 ..

    The only thing I found was one at roton .. but .. its $60 min order

    any help

    Mike A
    John Titor, when are you.

  • #2
    That's unusual, the standard coarse is 9 tpi for 7/8". You may have to make it, McMaster doesn't carry it, and that means in general that it will be rare and hard to find.

    Your lathe WILL do 5, but you need the right gears.

    And if you do get the gears, it may be that the step-up ratio to the leadscrew is so high that you are better off driving the leadscrew instead of the spindle, to avoid a large strain on the gears. It's been done, though.

    Keep eye on ball.
    Hashim Khan


    • #3
      I get the impression that the OP may be looking for an Acme lead screw, given the pitch.


      • #4
        Greenbay Mfg. sells Acme leadscrew Nuts. You may have do some machining to make it work, but they give you extra material so you can do that.

        They don't make machine specific nuts or lead-screws. It is a block with a threaded hole and you machine the outside to fit the application. :-) Rich


        • #5
          If you need to cut 5 tpi with 2 starts,
          you need a lathe to cut 2-1/2 tpi.

          And don't be so sure that his lathe can can
          cut a lead this coarse. Some smaller lathes
          have a fine leadscrew, like 20 tpi. Making
          a lead screw like this mean overdriving the
          heck out of it (ratio wise) and it will require
          more torque to do this than the gear train
          can physically handle. One solution is to
          rig a motor drive to the leadscrew and
          have the gear train back drive the spindle
          in reduction mode rather than the standard
          method of driving the leadscrew in over
          drive. This is why toolroom lathes typically
          have a coarse lead screw, like 6 or 4 tpi.
          This is so the the drive ratio to cut coarse
          threads is not so extreme, which would mean
          the torque required to drive such a gear
          train would me more within the limits
          of the strength of the gears.

          Last edited by Doozer; 01-20-2014, 09:43 AM.


          • #6
            He means .200" lead,not double start.
            I just need one more tool,just one!


            • #7
              yea .. terminology is everything and I don't quite have it yet .. still learning ..
              here are some pics to clear it up.

              while looking for nuts .. they kept giving "lead" size. Finally found out that
              on a single thread, lead IS pitch. Hence the .2 for 5 tpi

              this one is usable but just a little sloppy ..

              I really wish I did have some change gears .. but .. I don't

              hope this cleared my question up.
              John Titor, when are you.


              • #8
                Hi mikeamick
                I'm probably counting it incorrectly, but that looks like it's 4.5TPI.


                • #9
                  The measurement range isn't over an integral number of threads, so it hard to say for sure what the pitch is, but it looks to me like it is less than 5 and slightly more than 4.5. Given the lathe and it's origin I'd guess on it being metric.

                  Although it would not be a long term fix, the threads could be repaired with Turcite or Moglice. There is a some chance that you could get a new part from Emco.
                  Last edited by jlevie; 01-20-2014, 03:23 PM.


                  • #10
                    Damnit .. I knew I shouldn't have used that pic .. its some kind of barrel effect from the
                    camera. The lines really do line right up. Here is a different pic.

                    John Titor, when are you.


                    • #11
                      I had a real odd ball thread on a lathe of mine, an old Artisan. 1/2" lead, 2 start, left hand. It would have cost a couple hundred to have a local machine shop make a new one. Instead I used Moglice:



                      • #12
                        Originally posted by mikeamick View Post
                        Damnit .. I knew I shouldn't have used that pic .. its some kind of barrel effect from the
                        camera. The lines really do line right up. Here is a different pic.
                        Now that looks like 5tpi.


                        • #13
                          you need to measure that better... Both pictures don't look like 5tpi.. If I would have to guess - I would say it might be 5mm...



                          • #14

                            To my eyes it looks like it might be plausible...though it may turn out not to be the case since I don't know how much room there is on the machine going back from the "inner" edge of the current nuts flange.

                            If there is room, I can envision how the Evanut would work in terms of supporting it and including features the current nut has but its a bit tough to explain (and maybe long).


                            • #15
                              It's not five. The 2" mark is at the beginning edge of the thread and the 3" mark is at the end of the thread.