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X axis backlash problem

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  • Neil Albert
    Please help. I have some critical project I need to complete and I m in a bind. I am having problems with my CNC equipped 2000 mill, where even after replacing
    Message 1 of 5 , Sep 11, 2006
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      Please help. I have some critical project I need to complete and I'm
      in a bind.

      I am having problems with my CNC equipped 2000 mill, where even after
      replacing the X-axis backlash nut, the backlash nut will repeatedly
      push out of its seat in the mill saddle during clockwise leadscrew
      rotation, to the point where the backlash is about 1/2 turn or.025".

      Could I possibly need a new mill saddle? The nut is soft brass and the
      saddle is Anodized aluminim which is much harder.


      I am coming back to using my Sherline mill after having moved and not
      used it for a couple of months I observed the problem and replaced the
      backlash nut. The problem seemed to have been corrected but then
      returned after a couple of hours use. Retightening the lock does not
      fix the problem, However I did not replace the backlash lock.




      Neil Albert
    • KM6VV
      Hi Neil, Take a look at the exploded view of the mill. I believe you ll find a threaded piece (nut) UNDER the X ways (saddle). It should be secured with a
      Message 2 of 5 , Sep 11, 2006
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        Hi Neil,

        Take a look at the exploded view of the mill. I believe you'll find a
        threaded piece (nut) UNDER the X ways (saddle). It should be secured with a
        setscrew if I remember correctly. Oops, I think you've already found it!

        Also check the nut that adds the loading to the bearing pair in the stepper
        motor mount. Although it shouldn't be the cause of the problem you are
        seeing, it's something to check while you're at it.

        Alan KM6VV


        > Behalf Of Neil Albert
        >
        > Please help. I have some critical project I need to complete and I'm
        > in a bind.
        >
        > I am having problems with my CNC equipped 2000 mill, where even after
        > replacing the X-axis backlash nut, the backlash nut will repeatedly
        > push out of its seat in the mill saddle during clockwise leadscrew
        > rotation, to the point where the backlash is about 1/2 turn or.025".
        >
        > Could I possibly need a new mill saddle? The nut is soft brass and the
        > saddle is Anodized aluminim which is much harder.
        >
        >
        > I am coming back to using my Sherline mill after having moved and not
        > used it for a couple of months I observed the problem and replaced the
        > backlash nut. The problem seemed to have been corrected but then
        > returned after a couple of hours use. Retightening the lock does not
        > fix the problem, However I did not replace the backlash lock.
        >
        >
        > Neil Albert
      • Neil Albert
        Alan, Thanks so much for reponding. I just got off the phone with Craig Libuse, and he pointed out that that there is a set screw holding the slide screw
        Message 3 of 5 , Sep 11, 2006
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          Alan,
          Thanks so much for reponding. I just got off the phone with Craig
          Libuse, and he pointed out that that there is a set screw holding the
          "slide screw insert" which needs to have the saddle removed to obtain
          acesss to. Since I was able to remove the slide screw insert without
          loosening that set screw, you would seem to be right on-the-money.


          Thanks again, Alan.


          Neil
          --- In SherlineCNC@yahoogroups.com, "KM6VV" <KM6VV@...> wrote:
          >
          > Hi Neil,
          >
          > Take a look at the exploded view of the mill. I believe you'll find a
          > threaded piece (nut) UNDER the X ways (saddle). It should be
          secured with a
          > setscrew if I remember correctly. Oops, I think you've already
          found it!
          >
          > Also check the nut that adds the loading to the bearing pair in the
          stepper
          > motor mount. Although it shouldn't be the cause of the problem you are
          > seeing, it's something to check while you're at it.
          >
          > Alan KM6VV
          >
          >
          > > Behalf Of Neil Albert
          > >
          > > Please help. I have some critical project I need to complete and I'm
          > > in a bind.
          > >
          > > I am having problems with my CNC equipped 2000 mill, where even after
          > > replacing the X-axis backlash nut, the backlash nut will repeatedly
          > > push out of its seat in the mill saddle during clockwise leadscrew
          > > rotation, to the point where the backlash is about 1/2 turn or.025".
          > >
          > > Could I possibly need a new mill saddle? The nut is soft brass and the
          > > saddle is Anodized aluminim which is much harder.
          > >
          > >
          > > I am coming back to using my Sherline mill after having moved and not
          > > used it for a couple of months I observed the problem and replaced the
          > > backlash nut. The problem seemed to have been corrected but then
          > > returned after a couple of hours use. Retightening the lock does not
          > > fix the problem, However I did not replace the backlash lock.
          > >
          > >
          > > Neil Albert
          >
        • Carol & Jerry Jankura
          Hi, Neil: I m just guessing here, but I doubt that you need a new saddle. The antibacklash nut does not screw into the saddle. Its purpose is to provide an
          Message 4 of 5 , Sep 11, 2006
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            Hi, Neil:

            I'm just guessing here, but I doubt that you need a new saddle. The
            antibacklash nut does not screw into the saddle. Its purpose is to provide
            an adjustment to try to "pull" the leadscrew from the threaded insert in the
            saddle. That way, the leadscrew always rides on the "front" side of the
            thread on the insert and on the "back" side of the thread on the
            antibacklash nut.

            I think it's coming loose because the star nut that's supposed to prevent it
            from rotating when the leadscrew is turned is not doing its job. Can you
            tighten the screw tha holds the star nut to the saddle? If not, the saddle
            thread may be bad.

            I'm thinking that the star nut that is supposed to prevent the antibacklash
            nut from turning is not doing its job. This might happen if the points on
            the star are munged up. You might try making a piece to replace that star
            nut. Think about a "U" with a large base that goes around the leadscrew.
            You'd put a hole in the fat base and use the same threaded hole that holds
            the star nut. I read about this just a few days ago. I think it was on
            Sherline's web site in the area that has all of those tips submitted by
            users.

            -- Jerry Jankura
            Strongsville, Ohio
            So many toys.... So little time....



            > Please help. I have some critical project I need to complete and I'm
            > in a bind.
            >
            > I am having problems with my CNC equipped 2000 mill, where even after
            > replacing the X-axis backlash nut, the backlash nut will repeatedly
            > push out of its seat in the mill saddle during clockwise leadscrew
            > rotation, to the point where the backlash is about 1/2 turn or.025".
            >
            > Could I possibly need a new mill saddle? The nut is soft brass and the
            > saddle is Anodized aluminim which is much harder.
            >
            >
            > I am coming back to using my Sherline mill after having moved and not
            > used it for a couple of months I observed the problem and replaced the
            > backlash nut. The problem seemed to have been corrected but then
            > returned after a couple of hours use. Retightening the lock does not
            > fix the problem, However I did not replace the backlash lock.
            >
            >
            >
            >
            > Neil Albert
            >
            >
            >
            >
            >
            >
            > Yahoo! Groups Links
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            >
            >
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            >
            >
            >
            >
            >
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            > Date: 9/8/2006
            >
            >

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          • jehancocy
            You don t need a new saddle. just to review, there are two nuts, the leadscrew nut under the saddle held with a setscrew and the anti-backlash preload nut that
            Message 5 of 5 , Sep 11, 2006
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              You don't need a new saddle.

              just to review, there are two nuts, the leadscrew nut under the
              saddle held with a setscrew and the anti-backlash preload nut that
              is visible on the leadscrew near the front of the saddle. I've had
              problems with the leadscrew nut coming loose. I used thread lock on
              it and it fixed the problem. When you need to get it out, use an
              old leadscrew or brass punch and tap it out. The setscrew can also
              be locked with thread lock. Heating the setscrew with a soldering
              iron will loosen the thread lock if you need to remove it.

              Take the leadscrew nut out from under the saddle and see if the
              setscrew is dragging along the nut. If so, lock with threadlock or
              super glue.

              If the anit-backlash nut is loose, there should be a star washer as
              mentioned that holds it in place. I've noticed some of the new
              leadscrews coming with a straight knurled anti-backlash nut. There
              must be a new mechanism to hold it.
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