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Re: [GrizHFMinimill] Re: Mini-Mill Adjusting the Z axis Gibs

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  • Kevin Jones
    Found the root cause of my problem. The locking nuts on the Gib screws were loose. The screws have been working their way out over the last few weeks. As I
    Message 1 of 12 , Mar 11, 2004
      Found the root cause of my problem. The locking nuts on the Gib screws were
      loose. The screws have been working their way out over the last few weeks.
      As I suspecting the "deforming" of the head was just a perception issue. I
      checked with the DI and its definitely not bending. However, I manage to
      strip the "teeth" in the between the locking lever and locking screw. Does
      anyone out there have a better home built design for this lever ? I guess I
      can always use a cap screw and hex wrench if I get desperate.

      Regards,
      Kevin Jones

      >
      >Thanks, I will look for a crack this evening. The unit is still under
      >warranty so if that is the issue I'm ok, just annoying that I will have to
      >drag the thing back to HF store to get them to replace it. I think it just
      >may be that the way (term for the little piece of metal in the dovetail
      >right?) may be so loose that I'm seeing too much movement. I'll put a dial
      >indicator on it and see if it is actually deflecting relative to the head.
      >By your description the head is way to loose on the dovetails.
    • dudeair
      I ve had similar issues with my mini-mill, and have done a few things to it that help. 1st issue: setting the gib adjusting screws tight enough to stop head
      Message 2 of 12 , Mar 15, 2004
        I've had similar issues with my mini-mill, and have done a few things
        to it that help.

        1st issue: setting the gib adjusting screws tight enough to stop
        head flop also prevents movement. Partial cure: lap the gib strip.
        (See mini-lathe.com for the procedure.) After doing so, the gibs can
        be adjusted to a closer fit without preventing head movement.

        2nd issue: The fine-feed adjustment was binding. Cure: I
        disassembled the fine-feed. (Remove circlip from shaft of vertical
        feed on the right side of the head. Remove four allen-head screws,
        and two phillips head screws. The whole unit comes right off then.
        The shaft of the vertical feed can then be removed.) It was totally
        unlubricated, so I lubed it. It was still binding. After some
        examination, I realized that there was a slight misalignment of the
        shaft leading back from the fine-feed knob to the housing around the
        vertical feed shaft. I tried shimming the housing a couple of
        different ways an finally found a shim setupt that completely cured
        the binding.

        3rd issue: Like you, I also have stripped the inside of the gib lock
        lever for the vertical feed. It is a very poor design. I replaced
        it with a allen-head screw. This works very well, but is
        inconvenient. I plan to fabricate a better lever that it permanently
        attached to the head of an allen screw.

        This solution is not as straightforward as it seems, though, because
        there is not enough clearance between the vertical feed shaft and the
        gib lock screw hole to allow a screw with a permanently attached
        handle to be threaded in. It will be necessary to remove the
        vertical feed mechanism to insert the new screw and lever. No big
        deal - about 10 minutes work to remove, thread in new lever and
        remount the vertical feed mechanism.

        The other consideration in developing a gib locking screw and lever
        setup is that one can't just mount the handle in any old orientation,
        or it may not be possible to completely tighten or completely loosen
        it. There are two workarounds for this that occur to me. The first
        is to simply find and mark the correct orientation on the allen screw
        head before mounting the handle. The other would be to mount it at
        any orientation, then adjust the length of the screw by grinding and
        refitting until the proper orientation is found.

        One more suggestion: The gib locking screws should all be rounded on
        the tips with your grinder. If they are square or sharp on the end,
        they will keep digging into the gibs (which are soft cast iron). A
        nice, rounded end is much gentler on the gibs.

        HTH,
        David
      • Kevin Jones
        ... It took me a while to come up with it, but all you really need is a set screw in the stripped handle. That way you can adjust the angle of the handle at
        Message 3 of 12 , Mar 15, 2004
          >3rd issue: Like you, I also have stripped the inside of the gib lock
          >lever for the vertical feed. It is a very poor design. I replaced
          >it with a allen-head screw. This works very well, but is
          >inconvenient. I plan to fabricate a better lever that it permanently
          >attached to the head of an allen screw.

          It took me a while to come up with it, but all you really need is a set
          screw in the stripped handle.
          That way you can adjust the angle of the handle at any time.

          Regards,
          Kevin Jones
        • Kevin Jones
          ... I ve been hesitant to take the machine apart to do this for fear of not being able to put it back together. However, I ve learned enough from the groups
          Message 4 of 12 , Mar 15, 2004
            >
            >1st issue: setting the gib adjusting screws tight enough to stop
            >head flop also prevents movement. Partial cure: lap the gib strip.

            I've been hesitant to take the machine apart to do this for fear of not
            being able to put it back together. However, I've learned enough from the
            groups and the web that I don't think its going to be that big of an
            ordeal. One question I still have is what happens with the spring arm once
            I remove it ? It obviously must be removed once the head is at the top of
            the column or else the head is not going to come off. Its not going to whip
            around on me when I try to remove it, is it ?

            I have pretty much given up on the dial indicator on the fine feed having
            any meaning. That system has so many points of slop I don't see how is
            could be correct. There is slop in the little universal in the shaft. There
            is a lot of end play in the worm. There is play in the "teeth" that engage
            the fine feed to the corse feed. Then there is that slop between the rack
            and pinion, just to add to the fun I found that the rack was loose and
            moving up and down on the column. I'm installing a DRO on the Z axes as
            soon as I get up the nerve to take it apart. Does anyone have a lead screw
            conversion for the Z axes ?

            Regards,
            Kevin Jones
          • Harvey White
            ... Mine did not, but I removed the bolt at the top of the head s travel, just as you plan to. I d move the mounting bolt up an inch or so on the head, gives
            Message 5 of 12 , Mar 15, 2004
              On Mon, 15 Mar 2004 14:09:08 -0500, you wrote:

              >
              >>
              >>1st issue: setting the gib adjusting screws tight enough to stop
              >>head flop also prevents movement. Partial cure: lap the gib strip.
              >
              >I've been hesitant to take the machine apart to do this for fear of not
              >being able to put it back together. However, I've learned enough from the
              >groups and the web that I don't think its going to be that big of an
              >ordeal. One question I still have is what happens with the spring arm once
              >I remove it ? It obviously must be removed once the head is at the top of
              >the column or else the head is not going to come off. Its not going to whip
              >around on me when I try to remove it, is it ?

              Mine did not, but I removed the bolt at the top of the head's travel,
              just as you plan to. I'd move the mounting bolt up an inch or so on
              the head, gives you longer reach.

              >
              >I have pretty much given up on the dial indicator on the fine feed having
              >any meaning. That system has so many points of slop I don't see how is
              >could be correct. There is slop in the little universal in the shaft. There
              >is a lot of end play in the worm. There is play in the "teeth" that engage
              >the fine feed to the corse feed. Then there is that slop between the rack
              >and pinion, just to add to the fun I found that the rack was loose and
              >moving up and down on the column. I'm installing a DRO on the Z axes as
              >soon as I get up the nerve to take it apart. Does anyone have a lead screw
              >conversion for the Z axes ?

              I put a DRO on the z axis. Think that it's documented on the website.
              Clearances are a bit tight the way I did it, but details are at
              http://home.netcom.com/~madyn and go to metalworking. There's also
              some machining stuff in the electronics section as well.

              Harvey


              >
              >Regards,
              >Kevin Jones
              >
              >
              >
              >
              >
              >Yahoo! Groups Links
              >
              >
              >
              >
              >
            • dudeair
              You don t need to take the head apart to lap the z-axis gib strip. Just loosen the adjusting screws and slide it out. The head will be floppy loose on the
              Message 6 of 12 , Mar 16, 2004
                You don't need to take the head apart to lap the z-axis gib strip.
                Just loosen the adjusting screws and slide it out. The head will be
                floppy loose on the column while the gib is out, but it will not fall
                off. After you lap the gib, just slide it back in, center it under
                the adjusting screws, and readjust the screws. Depending on how
                rough the gib was before this procedure, it can make a large
                difference.

                Do the same for the x- and y-axis gibs, too.

                Good luck,
                David



                --- In GrizHFMinimill@yahoogroups.com, Kevin Jones <krjone01@a...>
                wrote:
                >
                > >
                > >1st issue: setting the gib adjusting screws tight enough to stop
                > >head flop also prevents movement. Partial cure: lap the gib
                strip.
                >
                > I've been hesitant to take the machine apart to do this for fear of
                not
                > being able to put it back together. However, I've learned enough
                from the
                > groups and the web that I don't think its going to be that big of
                an
                > ordeal. One question I still have is what happens with the spring
                arm once
                > I remove it ?
              • Kevin Jones
                ... Thanks for the tip. Sometimes the simplest solution is not always the obvious one :) Regards, Kevin Jones
                Message 7 of 12 , Mar 16, 2004
                  >You don't need to take the head apart to lap the z-axis gib strip.
                  >Just loosen the adjusting screws and slide it out.

                  Thanks for the tip. Sometimes the simplest solution is not always the
                  obvious one :)

                  Regards,
                  Kevin Jones
                • accuraman1
                  I am using a 3/8-16 lead screw and drive it with a servo motor. Right through the middle of the head. Works great! Accuram.com ... strip. ... of not ... from
                  Message 8 of 12 , Mar 23, 2004
                    I am using a 3/8-16 lead screw and drive it with a servo motor.
                    Right through the middle of the head. Works great!
                    Accuram.com
                    --- In GrizHFMinimill@yahoogroups.com, Harvey White <madyn@i...>
                    wrote:
                    > On Mon, 15 Mar 2004 14:09:08 -0500, you wrote:
                    >
                    > >
                    > >>
                    > >>1st issue: setting the gib adjusting screws tight enough to stop
                    > >>head flop also prevents movement. Partial cure: lap the gib
                    strip.
                    > >
                    > >I've been hesitant to take the machine apart to do this for fear
                    of not
                    > >being able to put it back together. However, I've learned enough
                    from the
                    > >groups and the web that I don't think its going to be that big of
                    an
                    > >ordeal. One question I still have is what happens with the spring
                    arm once
                    > >I remove it ? It obviously must be removed once the head is at
                    the top of
                    > >the column or else the head is not going to come off. Its not
                    going to whip
                    > >around on me when I try to remove it, is it ?
                    >
                    > Mine did not, but I removed the bolt at the top of the head's
                    travel,
                    > just as you plan to. I'd move the mounting bolt up an inch or so
                    on
                    > the head, gives you longer reach.
                    >
                    > >
                    > >I have pretty much given up on the dial indicator on the fine
                    feed having
                    > >any meaning. That system has so many points of slop I don't see
                    how is
                    > >could be correct. There is slop in the little universal in the
                    shaft. There
                    > >is a lot of end play in the worm. There is play in the "teeth"
                    that engage
                    > >the fine feed to the corse feed. Then there is that slop between
                    the rack
                    > >and pinion, just to add to the fun I found that the rack was
                    loose and
                    > >moving up and down on the column. I'm installing a DRO on the Z
                    axes as
                    > >soon as I get up the nerve to take it apart. Does anyone have a
                    lead screw
                    > >conversion for the Z axes ?
                    >
                    > I put a DRO on the z axis. Think that it's documented on the
                    website.
                    > Clearances are a bit tight the way I did it, but details are at
                    > http://home.netcom.com/~madyn and go to metalworking. There's also
                    > some machining stuff in the electronics section as well.
                    >
                    > Harvey
                    >
                    >
                    > >
                    > >Regards,
                    > >Kevin Jones
                    > >
                    > >
                    > >
                    > >
                    > >
                    > >Yahoo! Groups Links
                    > >
                    > >
                    > >
                    > >
                    > >
                  • h12721
                    ... Can You send a picture??? Hilmar
                    Message 9 of 12 , Apr 1, 2004
                      --- In GrizHFMinimill@yahoogroups.com, "accuraman1" <accuraman1@y...>
                      wrote:
                      > I am using a 3/8-16 lead screw and drive it with a servo motor.
                      > Right through the middle of the head. Works great!
                      > Accuram.com
                      >

                      Can You send a picture???
                      Hilmar
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