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Re: headstock slack issue

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  • loud3803
    That is normal for this mill. Two things you can do to lessen the effect of the backlash is 1.)Air spring upgrade from LMS helps, there are other options to
    Message 1 of 15 , Jun 15, 2010
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      That is "normal" for this mill. Two things you can do to lessen the effect of the backlash is 1.)Air spring upgrade from LMS helps, there are other options to counterbalance the head as well. 2.)Single axis dro, you can modify a cheap 12" digital caliper or purchase a ready-made solution. I put a digital scale on my z axis a while ago and it made z adjustmens much less stressful.

      Louis


      --- In GrizHFMinimill@yahoogroups.com, "outback_mike" <raindrop-yahoogroups@...> wrote:
      >
      > Interesting. I'll try that next time.
      >
      > The fine feed handwheel seems to have an inordinate amount of slack between backwards and forwards, about half a rotation. I don't know if it's just mine or all of them.
      >
      > --- In GrizHFMinimill@yahoogroups.com, "leonar d bristow" <firstbumper@> wrote:
      > >
      > > Mike
      > > If you put finger pressure on the 3 arm wheel AGAINST the fine feed wheel movement, then lock at the desired height, you wont get head drop, and no chance of the head dropping and causing damage. get into the habit and do it every time.
      > > lennard
      > >
      > >
      > >
      > >
      > >
      > >
      > >
      > > ------------------------------------------------------
      > > Provided by Australis
      > > http://www.australis.com.au/
      > >
      >
    • paul_in_pittsfield
      Go to the Files section of the group s web site, open the folder Paul in Pittsfield s Mill Mods and read Airspring.pdf In it you ll find the solution to
      Message 2 of 15 , Jun 15, 2010
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        Go to the Files section of the group's web site, open the folder "Paul in Pittsfield's Mill Mods" and read "Airspring.pdf"
        In it you'll find the solution to your problem.

        Paul in Pittsfield

        --- In GrizHFMinimill@yahoogroups.com, "outback_mike" <raindrop-yahoogroups@...> wrote:
        >
        > I have the HF MiniMill.
        >
        > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
        >
        > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
        >
        > -Mike
        >
      • John Mattis
        I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand
        Message 3 of 15 , Jun 15, 2010
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          I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
          John

          --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroups@...> wrote:

          From: outback_mike <raindrop-yahoogroups@...>
          Subject: [GrizHFMinimill] headstock slack issue
          To: GrizHFMinimill@yahoogroups.com
          Date: Monday, June 14, 2010, 3:44 PM

           

          I have the HF MiniMill.

          Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.

          Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?

          -Mike

        • ducemailbox@yahoo.com
          What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don t know how many thou it changes but its
          Message 4 of 15 , Jun 15, 2010
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            What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.

            Sent from my Verizon Wireless BlackBerry


            From: John Mattis <jsmattis@...>
            Date: Tue, 15 Jun 2010 07:09:23 -0700 (PDT)
            To: <GrizHFMinimill@yahoogroups.com>
            Subject: Re: [GrizHFMinimill] headstock slack issue

             

            I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
            John

            --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroup s@spamarrest. com> wrote:

            From: outback_mike <raindrop-yahoogroup s@spamarrest. com>
            Subject: [GrizHFMinimill] headstock slack issue
            To: GrizHFMinimill@ yahoogroups. com
            Date: Monday, June 14, 2010, 3:44 PM

             

            I have the HF MiniMill.

            Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.

            Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?

            -Mike

          • redbaron192redbaron192
            One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also
            Message 5 of 15 , Jun 15, 2010
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              One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also aligned the spindle using RDM (rollies dads method) to ensure the spindle is exactly parallel in X and Y directions.

              I found the spindle needed adjusting in both X & Y for which I used shims between the head and its column fixing (you will find 4 bolts i think it was, and 2 pegs holding those parts together. I had to remove one peg entirely to get enough adjustment to ensure parallism of the spindle. If you do this alignment over say 12" (i used a nice rod out of a printer that is dead straight), then you will be able to drill exact holes from near to far distance without any XY deviation. (typically I use a short piece of printer rod (2" - 3" max) lathed to a point to set up word for drilling, and then a typical drill bit would be say 4" long. When I bring the bit down for drilling the hole, I land exactly on the spot every time.

              I found the sliding faces of the head part a very poor fit - I used emery paper taped to the column and plenty of elbow grease to get a 90% finished surface - a lot better than the approx 25% sliding fit. there is an excellent webpage somewhere that explains how to do this for a mini lathe saddle. One this is done, you can tighten up the gib and get a nice smooth slide - a good test is to put oil on the column slides, and when you traverse the head you'll get a nice flat film of oil like a snail trail - but more satisfying haha.

              The tightened head (and the greater slide surface due to the lapping) also helps to stop head drop and any rocking though I still find I have to lock it when milling.

              I reckon all of the above took me a day or so, but it was worth it.

              So far I am dead impressed with the mills capability on aluminum - and no more electronics blown up (yet).

              --- In GrizHFMinimill@yahoogroups.com, ducemailbox@... wrote:
              >
              > What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.
              > Sent from my Verizon Wireless BlackBerry
              >
              > -----Original Message-----
              > From: John Mattis <jsmattis@...>
              > Date: Tue, 15 Jun 2010 07:09:23
              > To: <GrizHFMinimill@yahoogroups.com>
              > Subject: Re: [GrizHFMinimill] headstock slack issue
              >
              > I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
              > John
              >
              > --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroups@...> wrote:
              >
              > From: outback_mike <raindrop-yahoogroups@...>
              > Subject: [GrizHFMinimill] headstock slack issue
              > To: GrizHFMinimill@yahoogroups.com
              > Date: Monday, June 14, 2010, 3:44 PM
              >
              >
              >
              >
              >
              >
              >
              >  
              >
              >
              >
              >
              >
              >
              >
              >
              >
              > I have the HF MiniMill.
              >
              >
              >
              > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
              >
              >
              >
              > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
              >
              >
              >
              > -Mike
              >
            • ducemailbox@yahoo.com
              Very good info redbaron! I did do the lapping when I got the X2 but I never thought about applying rollie dad to the spindle. It worked ok on my lathe so why
              Message 6 of 15 , Jun 15, 2010
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                Very good info redbaron! I did do the lapping when I got the X2 but I never thought about applying rollie dad to the spindle. It worked ok on my lathe so why not?

                Sent from my Verizon Wireless BlackBerry


                From: "redbaron192redbaron192" <casiobearing@...>
                Date: Tue, 15 Jun 2010 17:36:32 -0000
                To: <GrizHFMinimill@yahoogroups.com>
                Subject: [GrizHFMinimill] Re: headstock slack issue

                 

                One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also aligned the spindle using RDM (rollies dads method) to ensure the spindle is exactly parallel in X and Y directions.

                I found the spindle needed adjusting in both X & Y for which I used shims between the head and its column fixing (you will find 4 bolts i think it was, and 2 pegs holding those parts together. I had to remove one peg entirely to get enough adjustment to ensure parallism of the spindle. If you do this alignment over say 12" (i used a nice rod out of a printer that is dead straight), then you will be able to drill exact holes from near to far distance without any XY deviation. (typically I use a short piece of printer rod (2" - 3" max) lathed to a point to set up word for drilling, and then a typical drill bit would be say 4" long. When I bring the bit down for drilling the hole, I land exactly on the spot every time.

                I found the sliding faces of the head part a very poor fit - I used emery paper taped to the column and plenty of elbow grease to get a 90% finished surface - a lot better than the approx 25% sliding fit. there is an excellent webpage somewhere that explains how to do this for a mini lathe saddle. One this is done, you can tighten up the gib and get a nice smooth slide - a good test is to put oil on the column slides, and when you traverse the head you'll get a nice flat film of oil like a snail trail - but more satisfying haha.

                The tightened head (and the greater slide surface due to the lapping) also helps to stop head drop and any rocking though I still find I have to lock it when milling.

                I reckon all of the above took me a day or so, but it was worth it.

                So far I am dead impressed with the mills capability on aluminum - and no more electronics blown up (yet).

                --- In GrizHFMinimill@yahoogroups.com, ducemailbox@... wrote:
                >
                > What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.
                > Sent from my Verizon Wireless BlackBerry
                >
                > -----Original Message-----
                > From: John Mattis <jsmattis@...>
                > Date: Tue, 15 Jun 2010 07:09:23
                > To: <GrizHFMinimill@yahoogroups.com>
                > Subject: Re: [GrizHFMinimill] headstock slack issue
                >
                > I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
                > John
                >
                > --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroups@...> wrote:
                >
                > From: outback_mike <raindrop-yahoogroups@...>
                > Subject: [GrizHFMinimill] headstock slack issue
                > To: GrizHFMinimill@yahoogroups.com
                > Date: Monday, June 14, 2010, 3:44 PM
                >
                >
                >
                >
                >
                >
                >
                >  
                >
                >
                >
                >
                >
                >
                >
                >
                >
                > I have the HF MiniMill.
                >
                >
                >
                > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
                >
                >
                >
                > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
                >
                >
                >
                > -Mike
                >

              • John Mattis
                I replaced the set screws on the column gibs with Little Machine Shop part 2625 dog point self locking set screw. They are much easier to adjust and they hold
                Message 7 of 15 , Jun 15, 2010
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                  I replaced the set screws on the column gibs with Little Machine Shop part 2625 dog point self locking set screw. They are much easier to adjust and they hold their settings. Did the same thing on the table X and Y axis. I also did the same for my mini lathe.
                  John

                  --- On Tue, 6/15/10, ducemailbox@... <ducemailbox@...> wrote:

                  From: ducemailbox@... <ducemailbox@...>
                  Subject: Re: [GrizHFMinimill] Re: headstock slack issue
                  To: GrizHFMinimill@yahoogroups.com
                  Date: Tuesday, June 15, 2010, 10:56 AM

                   

                  Very good info redbaron! I did do the lapping when I got the X2 but I never thought about applying rollie dad to the spindle. It worked ok on my lathe so why not?

                  Sent from my Verizon Wireless BlackBerry


                  From: "redbaron192redbaro n192" <casiobearing@ googlemail. com>
                  Date: Tue, 15 Jun 2010 17:36:32 -0000
                  To: <GrizHFMinimill@ yahoogroups. com>
                  Subject: [GrizHFMinimill] Re: headstock slack issue

                   

                  One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also aligned the spindle using RDM (rollies dads method) to ensure the spindle is exactly parallel in X and Y directions.

                  I found the spindle needed adjusting in both X & Y for which I used shims between the head and its column fixing (you will find 4 bolts i think it was, and 2 pegs holding those parts together. I had to remove one peg entirely to get enough adjustment to ensure parallism of the spindle. If you do this alignment over say 12" (i used a nice rod out of a printer that is dead straight), then you will be able to drill exact holes from near to far distance without any XY deviation. (typically I use a short piece of printer rod (2" - 3" max) lathed to a point to set up word for drilling, and then a typical drill bit would be say 4" long. When I bring the bit down for drilling the hole, I land exactly on the spot every time.

                  I found the sliding faces of the head part a very poor fit - I used emery paper taped to the column and plenty of elbow grease to get a 90% finished surface - a lot better than the approx 25% sliding fit. there is an excellent webpage somewhere that explains how to do this for a mini lathe saddle. One this is done, you can tighten up the gib and get a nice smooth slide - a good test is to put oil on the column slides, and when you traverse the head you'll get a nice flat film of oil like a snail trail - but more satisfying haha.

                  The tightened head (and the greater slide surface due to the lapping) also helps to stop head drop and any rocking though I still find I have to lock it when milling.

                  I reckon all of the above took me a day or so, but it was worth it.

                  So far I am dead impressed with the mills capability on aluminum - and no more electronics blown up (yet).

                  --- In GrizHFMinimill@ yahoogroups. com, ducemailbox@ ... wrote:
                  >
                  > What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.
                  > Sent from my Verizon Wireless BlackBerry
                  >
                  > -----Original Message-----
                  > From: John Mattis <jsmattis@...>
                  > Date: Tue, 15 Jun 2010 07:09:23
                  > To: <GrizHFMinimill@ yahoogroups. com>
                  > Subject: Re: [GrizHFMinimill] headstock slack issue
                  >
                  > I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
                  > John
                  >
                  > --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroup s@...> wrote:
                  >
                  > From: outback_mike <raindrop-yahoogroup s@...>
                  > Subject: [GrizHFMinimill] headstock slack issue
                  > To: GrizHFMinimill@ yahoogroups. com
                  > Date: Monday, June 14, 2010, 3:44 PM
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >  
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  > I have the HF MiniMill.
                  >
                  >
                  >
                  > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
                  >
                  >
                  >
                  > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
                  >
                  >
                  >
                  > -Mike
                  >

                • leonar d bristow
                  Mike, thats a bit much play. take the cover off just behind the fine feed wheel and see if you can improve the mesh on the gears. lennard ... Provided by
                  Message 8 of 15 , Jun 15, 2010
                  • 0 Attachment
                    Mike, thats a bit much play. take the cover  off just behind the fine feed wheel and see if you can improve the mesh on the gears.
                    lennard
                     
                     
                     
                     
                     
                     

                    ------------------------------------------------------
                    Provided by Australis
                    http://www.australis.com.au/
                  • upand_at_them
                    Did you do this with the column laying flat on the workbench? Does it make a difference if it s not in its normal orientation?
                    Message 9 of 15 , Jun 15, 2010
                    • 0 Attachment
                      Did you do this with the column laying flat on the workbench? Does it make a difference if it's not in its normal orientation?

                      --- In GrizHFMinimill@yahoogroups.com, "redbaron192redbaron192" <casiobearing@...> wrote:
                      >
                      > One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also aligned the spindle using RDM (rollies dads method) to ensure the spindle is exactly parallel in X and Y directions.
                      >
                      > I found the spindle needed adjusting in both X & Y for which I used shims between the head and its column fixing (you will find 4 bolts i think it was, and 2 pegs holding those parts together. I had to remove one peg entirely to get enough adjustment to ensure parallism of the spindle. If you do this alignment over say 12" (i used a nice rod out of a printer that is dead straight), then you will be able to drill exact holes from near to far distance without any XY deviation. (typically I use a short piece of printer rod (2" - 3" max) lathed to a point to set up word for drilling, and then a typical drill bit would be say 4" long. When I bring the bit down for drilling the hole, I land exactly on the spot every time.
                      >
                      > I found the sliding faces of the head part a very poor fit - I used emery paper taped to the column and plenty of elbow grease to get a 90% finished surface - a lot better than the approx 25% sliding fit. there is an excellent webpage somewhere that explains how to do this for a mini lathe saddle. One this is done, you can tighten up the gib and get a nice smooth slide - a good test is to put oil on the column slides, and when you traverse the head you'll get a nice flat film of oil like a snail trail - but more satisfying haha.
                      >
                      > The tightened head (and the greater slide surface due to the lapping) also helps to stop head drop and any rocking though I still find I have to lock it when milling.
                      >
                      > I reckon all of the above took me a day or so, but it was worth it.
                      >
                      > So far I am dead impressed with the mills capability on aluminum - and no more electronics blown up (yet).
                      >
                      > --- In GrizHFMinimill@yahoogroups.com, ducemailbox@ wrote:
                      > >
                      > > What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.
                      > > Sent from my Verizon Wireless BlackBerry
                      > >
                      > > -----Original Message-----
                      > > From: John Mattis <jsmattis@>
                      > > Date: Tue, 15 Jun 2010 07:09:23
                      > > To: <GrizHFMinimill@yahoogroups.com>
                      > > Subject: Re: [GrizHFMinimill] headstock slack issue
                      > >
                      > > I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
                      > > John
                      > >
                      > > --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroups@> wrote:
                      > >
                      > > From: outback_mike <raindrop-yahoogroups@>
                      > > Subject: [GrizHFMinimill] headstock slack issue
                      > > To: GrizHFMinimill@yahoogroups.com
                      > > Date: Monday, June 14, 2010, 3:44 PM
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >  
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > >
                      > > I have the HF MiniMill.
                      > >
                      > >
                      > >
                      > > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
                      > >
                      > >
                      > >
                      > > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
                      > >
                      > >
                      > >
                      > > -Mike
                      > >
                      >
                    • redbaron192redbaron192
                      Yup, I have limited bench space so I did it on the garage floor in the end. Also I guess it depends on what you use for a precision rod. The printer rod I use
                      Message 10 of 15 , Jun 16, 2010
                      • 0 Attachment
                        Yup, I have limited bench space so I did it on the garage floor in the end. Also I guess it depends on what you use for a precision rod. The printer rod I use was about 1cm diameter and reasonably lightweight, so bend due to its own weight would be negligible.

                        I found doing RDM on the mill was actually a lot easier than doing RDM on my mini lathe tailstock... because on the mill you only need to worry about getting parallelism, whereas on the tail-stock you have to remember it needs to achieve absolute position (i.e. height and cross position) as well. Also try and use the full length of the mill column bed to do your measurement as it will maximize the accuracy of the alignment procedure.

                        Taking the mill apart in bits is quite easy as each part is relatively light in weight. Also its a lot easier applying equal pressure when lapping if the unit is on the floor. I used bits of wood to support the column so it was level during the work. I didn't bother fitting the gib during the lapping or RDM procedures.

                        The only real pain is the bolts that fix the head to its column fixing can only be reach with the assembly off the column, so after doing RDM you need to guesstimate the amount of shim you need, then remove the assembly from the column, fit the shims, tighten up the bolts and then put it back on the column to test again. (After 30 or 40 times you'll appreciate the results even more haha).

                        I think I sorted out the vertical alignment first, i.e. measuring the normal from the column face to the test rod. This is adjusted with shims fitted at the top \ bottom faces of the head. After that was sorted out I did the horizontal alignment, i.e. what I would call twist error. As I said earlier, I had to remove one of the metal pins to allow me enough rotation of the head to eliminate the error. Since the twist bit relies on bolting the unit up tight to 'fix' the setting, that's the reason the shim bit was done first (which requires repeated dismantling of the assembly).

                        Shimming the rack was also done since it was all apart anyway - i used aluminum foil folded 4 times behind the rack.

                        The final test is putting it all back together. Note that you tram your mill up as usual (now that you have a dead accurate spindle), and then using a short pointer rod, center it onto a metal plate with a ding in it, then wind the head all the way up, fit a long pointer rod and then pin the tail on the donkey as they say... If you have done well you'll land spot on the ding. hehe.

                        And the results show not only when drilling deep holes, but when milling - i now get a nice patterned finish when milling flat surfaces, whereas before it seemed to be a lop sided pattern even though the mill had been trammed.

                        Perhaps in a years time I'll see if i can get the head slide surfaces 100% smooth, but they'll do for now. I was surprised how scored \ uneven they were, but at least doing it now means the column surfaces won't end up getting worn to the same uneven state.

                        One more bit of advice - i used double sided tape to stick the emery paper to the column slides. don't use a scraper to remove it, instead use some kind of solvent, meths, petrol, white spirit whatever to unglue it. that was was the messiest part of the job.

                        --- In GrizHFMinimill@yahoogroups.com, "upand_at_them" <upand_at_them@...> wrote:
                        >
                        > Did you do this with the column laying flat on the workbench? Does it make a difference if it's not in its normal orientation?
                        >
                        > --- In GrizHFMinimill@yahoogroups.com, "redbaron192redbaron192" <casiobearing@> wrote:
                        > >
                        > > One thing you can try is lapping the fit of the head to the column, and also polishing the gib. After doing that and since the mill was apart anyway I also aligned the spindle using RDM (rollies dads method) to ensure the spindle is exactly parallel in X and Y directions.
                        > >
                        > > I found the spindle needed adjusting in both X & Y for which I used shims between the head and its column fixing (you will find 4 bolts i think it was, and 2 pegs holding those parts together. I had to remove one peg entirely to get enough adjustment to ensure parallism of the spindle. If you do this alignment over say 12" (i used a nice rod out of a printer that is dead straight), then you will be able to drill exact holes from near to far distance without any XY deviation. (typically I use a short piece of printer rod (2" - 3" max) lathed to a point to set up word for drilling, and then a typical drill bit would be say 4" long. When I bring the bit down for drilling the hole, I land exactly on the spot every time.
                        > >
                        > > I found the sliding faces of the head part a very poor fit - I used emery paper taped to the column and plenty of elbow grease to get a 90% finished surface - a lot better than the approx 25% sliding fit. there is an excellent webpage somewhere that explains how to do this for a mini lathe saddle. One this is done, you can tighten up the gib and get a nice smooth slide - a good test is to put oil on the column slides, and when you traverse the head you'll get a nice flat film of oil like a snail trail - but more satisfying haha.
                        > >
                        > > The tightened head (and the greater slide surface due to the lapping) also helps to stop head drop and any rocking though I still find I have to lock it when milling.
                        > >
                        > > I reckon all of the above took me a day or so, but it was worth it.
                        > >
                        > > So far I am dead impressed with the mills capability on aluminum - and no more electronics blown up (yet).
                        > >
                        > > --- In GrizHFMinimill@yahoogroups.com, ducemailbox@ wrote:
                        > > >
                        > > > What we are not really discussing here and what bugs me the most is the head rotation while using the gib lock. I don't know how many thou it changes but its considerable enough that I have to be careful between milling and drilling operations. The longer travel and lighter adjustment for drilling followed by fine feed milling with a tighter gib can result in a lot of head rotation about the x y axis, not just z drop.
                        > > > Sent from my Verizon Wireless BlackBerry
                        > > >
                        > > > -----Original Message-----
                        > > > From: John Mattis <jsmattis@>
                        > > > Date: Tue, 15 Jun 2010 07:09:23
                        > > > To: <GrizHFMinimill@yahoogroups.com>
                        > > > Subject: Re: [GrizHFMinimill] headstock slack issue
                        > > >
                        > > > I noticed the same thing when I got my mini mill seven years ago. I mounted a one inch travel dial indicator on an adjustable slide on the column. The hand wheel is just not accurate. You can see the photos in the folder on the group website "Johns Mini Mill Mods".
                        > > > John
                        > > >
                        > > > --- On Mon, 6/14/10, outback_mike <raindrop-yahoogroups@> wrote:
                        > > >
                        > > > From: outback_mike <raindrop-yahoogroups@>
                        > > > Subject: [GrizHFMinimill] headstock slack issue
                        > > > To: GrizHFMinimill@yahoogroups.com
                        > > > Date: Monday, June 14, 2010, 3:44 PM
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >  
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > >
                        > > > I have the HF MiniMill.
                        > > >
                        > > >
                        > > >
                        > > > Lets say I push the drill handle in to use the milling handwheel. I then set it to a particular height using the hand wheel, then use the lock. (If I don't use the lock it drifts.) When I am finished and I unlock it, the headstock drops like 50 thou and the handwheel is somewhere in its runout. then I have to reset everything again to take another deeper cut.
                        > > >
                        > > >
                        > > >
                        > > > Is there something I can check for tightness to eliminate this problem, or is that just how it is with the mill-drill setup? How can I shore up the runout on the handwheel/milling feed?
                        > > >
                        > > >
                        > > >
                        > > > -Mike
                        > > >
                        > >
                        >
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