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Re: Mini Mill Head Drop

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  • albertobarreiro171
    Mike, thank for the tip ,i would follow your instructions and a let you know how my problem is solved . Alberto ... me. I installed a digital scale on the
    Message 1 of 13 , Feb 8, 2013
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      Mike, thank for the tip ,i would follow your instructions and a let you know how 
      my problem is solved .      Alberto
      --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
      >
      > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
      > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
      > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
      > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
      > mike
      >
      >
      >
      > >________________________________
      > > From: albertobarreiro171
      > >To: GrizHFMinimill@yahoogroups.com
      > >Sent: Thursday, February 7, 2013 10:28 PM
      > >Subject: [GrizHFMinimill] Mini Mill Head Drop
      > >
      > >
      > > 
      > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
      > >
      > >
      > >Alberto
      > >
      > >
      > >
      > >
      > >
      >
    • a rien
      The easiest way I ve found to greatly reduce head drop was to install a LMS Air Spring Kit. I also have a DRO scale on the Z to be sure the head is where it is
      Message 2 of 13 , Feb 8, 2013
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        The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
        I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
        HTH
        Anthony

        --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

        From: albertobarreiro171 <albertobarreiro171@...>
        Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
        To: GrizHFMinimill@yahoogroups.com
        Date: Friday, February 8, 2013, 3:22 PM



        Mike, thank for the tip ,i would follow your instructions and a let you know how 
        my problem is solved .      Alberto
        --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
        >
        > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
        > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
        > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
        > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
        > mike
        >
        >
        >
        > >________________________________
        > > From: albertobarreiro171
        > >To: GrizHFMinimill@yahoogroups.com
        > >Sent: Thursday, February 7, 2013 10:28 PM
        > >Subject: [GrizHFMinimill] Mini Mill Head Drop
        > >
        > >
        > > 
        > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
        > >
        > >
        > >Alberto
        > >
        > >
        > >
        > >
        > >
        >


      • michael kolchins
        Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me
        Message 3 of 13 , Feb 8, 2013
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          Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.
          I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.
          mike


          From: a rien <amriensr@...>
          To: GrizHFMinimill@yahoogroups.com
          Sent: Friday, February 8, 2013 7:32 PM
          Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

           
          The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
          I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
          HTH
          Anthony

          --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

          From: albertobarreiro171 <albertobarreiro171@...>
          Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
          To: GrizHFMinimill@yahoogroups.com
          Date: Friday, February 8, 2013, 3:22 PM



          Mike, thank for the tip ,i would follow your instructions and a let you know how 
          my problem is solved .      Alberto
          --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
          >
          > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
          > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
          > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
          > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
          > mike
          >
          >
          >
          > >________________________________
          > > From: albertobarreiro171
          > >To: GrizHFMinimill@yahoogroups.com
          > >Sent: Thursday, February 7, 2013 10:28 PM
          > >Subject: [GrizHFMinimill] Mini Mill Head Drop
          > >
          > >
          > > 
          > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
          > >
          > >
          > >Alberto
          > >
          > >
          > >
          > >
          > >
          >




        • a rien
          Hmmm...The only other thing I did was lap the gibb, and keep them just a bit tight. Once I get the setting that I want, I lock up and it holds until I unlock
          Message 4 of 13 , Feb 9, 2013
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            Hmmm...The only other thing I did was lap the gibb, and keep them just a bit tight.
            Once I get the setting that I want, I lock up and it holds until I unlock and re-set for next cut. Have you spoken to Chris at LMS? He may have something to suggest.

            --- On Sat, 2/9/13, michael kolchins <kwoodhands@...> wrote:

            From: michael kolchins <kwoodhands@...>
            Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop
            To: "GrizHFMinimill@yahoogroups.com" <GrizHFMinimill@yahoogroups.com>
            Date: Saturday, February 9, 2013, 1:33 AM



            Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.
            I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.
            mike


            From: a rien <amriensr@...>
            To: GrizHFMinimill@yahoogroups.com
            Sent: Friday, February 8, 2013 7:32 PM
            Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

             
            The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
            I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
            HTH
            Anthony

            --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

            From: albertobarreiro171 <albertobarreiro171@...>
            Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
            To: GrizHFMinimill@yahoogroups.com
            Date: Friday, February 8, 2013, 3:22 PM



            Mike, thank for the tip ,i would follow your instructions and a let you know how 
            my problem is solved .      Alberto
            --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
            >
            > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
            > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
            > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
            > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
            > mike
            >
            >
            >
            > >________________________________
            > > From: albertobarreiro171
            > >To: GrizHFMinimill@yahoogroups.com
            > >Sent: Thursday, February 7, 2013 10:28 PM
            > >Subject: [GrizHFMinimill] Mini Mill Head Drop
            > >
            > >
            > > 
            > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
            > >
            > >
            > >Alberto
            > >
            > >
            > >
            > >
            > >
            >






          • gerry waclawiak
            Mike, the real easy answer to head drop is to use proper technique and lock the z axis using the lock lever provided. If the head is locked to the column you
            Message 5 of 13 , Feb 9, 2013
            • 0 Attachment
              Mike,

              the real easy answer to head drop is to use proper technique and lock the z axis  using the lock lever provided. If the head is locked to the column you cannot have head drop (you may get a little spindle drop if the spindle is poorly adjusted). It also helps if you always drive the head downward to the required reading before locking the z  to compensate for any backlash as you would with the x and y or the axis on a lathe.

              The "fine feed" is very poorly implemented as not only does it utilise the relatively crude rack and pinion of the main lever feed but then introduces further inaccuracy and backlash through the castellated nut disconnect (radial play), the worm and pinion drive (+ axial movement of the worm), the universal joint (radial + axial play) and the fine feed knob (axial play). You can improve things somewhat by shimming the knob and worm to reduce axial play, peen the universal joint spider and some have peened the castellated nut but even doing all this still leaves a  poor fine feed system.

              It is far easier to fit a DRO to the z, drive the head/cutter tip down to the required point and lock the head to prevent movement in any direction.


              I have used this technique for several years and can cut to <0.001" with no problem. Furthermore I was able to fly cut to that accuracy for several yearswithout smashing the plastic drive gears, a fairly common occurrence without the head locked (I have now fitted a belt drive (home made) which dispenses with that particular fault and has other benefits)

              Gerry W
              Leeds UK




              To: GrizHFMinimill@yahoogroups.com
              From: kwoodhands@...
              Date: Fri, 8 Feb 2013 22:33:11 -0800
              Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

               

              Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.
              I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.
              mike


              From: a rien <amriensr@...>
              To: GrizHFMinimill@yahoogroups.com
              Sent: Friday, February 8, 2013 7:32 PM
              Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

               
              The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
              I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
              HTH
              Anthony

              --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

              From: albertobarreiro171 <albertobarreiro171@...>
              Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
              To: GrizHFMinimill@yahoogroups.com
              Date: Friday, February 8, 2013, 3:22 PM



              Mike, thank for the tip ,i would follow your instructions and a let you know how 
              my problem is solved .      Alberto
              --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
              >
              > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
              > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
              > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
              > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
              > mike
              >
              >
              >
              > >________________________________
              > > From: albertobarreiro171
              > >To: GrizHFMinimill@yahoogroups.com
              > >Sent: Thursday, February 7, 2013 10:28 PM
              > >Subject: [GrizHFMinimill] Mini Mill Head Drop
              > >
              > >
              > > 
              > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
              > >
              > >
              > >Alberto
              > >
              > >
              > >
              > >
              > >
              >





            • michael kolchins
              Actually the first thing I did was lap the jibs,then even made new ones. The problem was the head hangs up at a certain height .I did not notice it when the
              Message 6 of 13 , Feb 9, 2013
              • 0 Attachment
                Actually the first thing I did was lap the jibs,then even made new ones. The problem was the head hangs up at a certain height .I did not notice it when the swivel base was on my vice because the milling was done above the area that hangs up. After making new jibs I found that the head hung up in the same spot again. As I posted before I took the fine feed off and found nothing that stood out that caused the problem.
                I solved the problem by tapping the drawbar as it runs and checking against a digital scale. 
                Maybe someone else can help Alberto in the original post,if there is a modification to the mill that works better than mine I would certainly do it.
                mike


                From: a rien <amriensr@...>
                To: GrizHFMinimill@yahoogroups.com
                Sent: Saturday, February 9, 2013 1:23 PM
                Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

                 
                Hmmm...The only other thing I did was lap the gibb, and keep them just a bit tight.
                Once I get the setting that I want, I lock up and it holds until I unlock and re-set for next cut. Have you spoken to Chris at LMS? He may have something to suggest.

                --- On Sat, 2/9/13, michael kolchins <kwoodhands@...> wrote:

                From: michael kolchins <kwoodhands@...>
                Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop
                To: "GrizHFMinimill@yahoogroups.com" <GrizHFMinimill@yahoogroups.com>
                Date: Saturday, February 9, 2013, 1:33 AM



                Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.
                I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.
                mike


                From: a rien <amriensr@...>
                To: GrizHFMinimill@yahoogroups.com
                Sent: Friday, February 8, 2013 7:32 PM
                Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

                 
                The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
                I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
                HTH
                Anthony

                --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

                From: albertobarreiro171 <albertobarreiro171@...>
                Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
                To: GrizHFMinimill@yahoogroups.com
                Date: Friday, February 8, 2013, 3:22 PM



                Mike, thank for the tip ,i would follow your instructions and a let you know how 
                my problem is solved .      Alberto
                --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
                >
                > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
                > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
                > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
                > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
                > mike
                >
                >
                >
                > >________________________________
                > > From: albertobarreiro171
                > >To: GrizHFMinimill@yahoogroups.com
                > >Sent: Thursday, February 7, 2013 10:28 PM
                > >Subject: [GrizHFMinimill] Mini Mill Head Drop
                > >
                > >
                > > 
                > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
                > >
                > >
                > >Alberto
                > >
                > >
                > >
                > >
                > >
                >








              • Leo Reed
                I solved (improved) the problem of head-drop on my Grizzly Mini-mill. First, I modified the Z range by making the modification that AAA (i believe that was
                Message 7 of 13 , Feb 10, 2013
                • 0 Attachment
                  I solved (improved) the problem of head-drop on my Grizzly Mini-mill.  First, I modified the Z range by making the modification that AAA (i believe that was his handle on this site) designed. This increased the range by a considerable amount.
                   
                   Secondly, I mounted a pulley on a mast mounted on the top of the column. This pulley was located about 12" above the top of the column. A nylon rope attached to the head was looped over the pulley and had lead weights attached to the rope behind the column.  the secret is to have enough counter-weight so that the head rises (like the spindle on a drill press) if it is free to move. This allows the Z feed to overcome the upward pressure of the counter-weight.  The backlash problem is minimized with this setup. As has been stated, always apply the Z lock when milling.  The exception would be with plunge cuts.
                   
                  My 2-cents,
                  Leo (pearland, tx)
                   
                   
                  ----- Original Message -----
                  Sent: 2/9/2013 3:34:54 PM
                  Subject: RE: [GrizHFMinimill] Re: Mini Mill Head Drop

                   

                  Mike,

                  the real easy answer to head drop is to use proper technique and lock the z axis  using the lock lever provided. If the head is locked to the column you cannot have head drop (you may get a little spindle drop if the spindle is poorly adjusted). It also helps if you always drive the head downward to the required reading before locking the z  to compensate for any backlash as you would with the x and y or the axis on a lathe.

                  The "fine feed" is very poorly implemented as not only does it utilise the relatively crude rack and pinion of the main lever feed but then introduces further inaccuracy and backlash through the castellated nut disconnect (radial play), the worm and pinion drive (+ axial movement of the worm), the universal joint (radial + axial play) and the fine feed knob (axial play). You can improve things somewhat by shimming the knob and worm to reduce axial play, peen the universal joint spider and some have peened the castellated nut but even doing all this still leaves a  poor fine feed system.

                  It is far easier to fit a DRO to the z, drive the head/cutter tip down to the required point and lock the head to prevent movement in any direction.


                  I have used this technique for several years and can cut to <0.001" with no problem. Furthermore I was able to fly cut to that accuracy for several yearswithout smashing the plastic drive gears, a fairly common occurrence without the head locked (I have now fitted a belt drive (home made) which dispenses with that particular fault and has other benefits)

                  Gerry W
                  Leeds UK




                  To: GrizHFMinimill@yahoogroups.com
                  From: kwoodhands@...
                  Date: Fri, 8 Feb 2013 22:33:11 -0800
                  Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

                   

                  Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.
                  I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.
                  mike


                  From: a rien <amriensr@...>
                  To: GrizHFMinimill@yahoogroups.com
                  Sent: Friday, February 8, 2013 7:32 PM
                  Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop

                   
                  The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
                  I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
                  HTH
                  Anthony

                  --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:

                  From: albertobarreiro171 <albertobarreiro171@...>
                  Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
                  To: GrizHFMinimill@yahoogroups.com
                  Date: Friday, February 8, 2013, 3:22 PM



                  Mike, thank for the tip ,i would follow your instructions and a let you know how 
                  my problem is solved .      Alberto
                  --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
                  >
                  > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
                  > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
                  > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
                  > I had tried taking the fine feed off and looking to see what causes the problem.I did not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
                  > mike
                  >
                  >
                  >
                  > >________________________________
                  > > From: albertobarreiro171
                  > >To: GrizHFMinimill@yahoogroups.com
                  > >Sent: Thursday, February 7, 2013 10:28 PM
                  > >Subject: [GrizHFMinimill] Mini Mill Head Drop
                  > >
                  > >
                  > >� 
                  > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
                  > >
                  > >
                  > >Alberto
                  > >
                  > >
                  > >
                  > >
                  > >
                  >





                • a3sigma
                  For my implimentation of a pulley and counerweight see my document in Files D.C. Clark stuff X2 Counterweight.pdf
                  Message 8 of 13 , Feb 10, 2013
                  • 0 Attachment
                    For my implimentation of a pulley and counerweight see my document in

                    Files > D.C. Clark stuff > X2 Counterweight.pdf

                    http://groups.yahoo.com/group/GrizHFMinimill/files/D.C.%20Clark%20stuff/

                    David Clark in Southern Maryland, USA

                    --- In GrizHFMinimill@yahoogroups.com, "Leo Reed" wrote:
                    >
                    > I solved (improved) the problem of head-drop on my Grizzly Mini-mill. First, I modified the Z range by making the modification that AAA (i believe that was his handle on this site) designed. This increased the range by a considerable amount.
                    >
                    > Secondly, I mounted a pulley on a mast mounted on the top of the column. This pulley was located about 12" above the top of the column. A nylon rope attached to the head was looped over the pulley and had lead weights attached to the rope behind the column. the secret is to have enough counter-weight so that the head rises (like the spindle on a drill press) if it is free to move. This allows the Z feed to overcome the upward pressure of the counter-weight. The backlash problem is minimized with this setup. As has been stated, always apply the Z lock when milling. The exception would be with plunge cuts.
                    >
                    > My 2-cents,
                    > Leo (pearland, tx)
                    >
                    >
                    >
                  • a3sigma
                    PS, I need to do a supliment to that document. I ve since switched to a solid comlumn, and hold the weight with more webbing instead of the bag. DC
                    Message 9 of 13 , Feb 10, 2013
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                      PS, I need to do a supliment to that document. I've since switched to a solid comlumn, and hold the weight with more webbing instead of the bag.

                      DC

                      --- In GrizHFMinimill@yahoogroups.com, "a3sigma" wrote:
                      >
                      > For my implimentation of a pulley and counerweight see my document in
                      >
                      > Files > D.C. Clark stuff > X2 Counterweight.pdf
                      >
                      > http://groups.yahoo.com/group/GrizHFMinimill/files/D.C.%20Clark%20stuff/
                      >
                      > David Clark in Southern Maryland, USA
                      >
                      > --- In GrizHFMinimill@yahoogroups.com, "Leo Reed" wrote:
                      > >
                      > > I solved (improved) the problem of head-drop on my Grizzly Mini-mill. First, I modified the Z range by making the modification that AAA (i believe that was his handle on this site) designed. This increased the range by a considerable amount.
                      > >
                      > > Secondly, I mounted a pulley on a mast mounted on the top of the column. This pulley was located about 12" above the top of the column. A nylon rope attached to the head was looped over the pulley and had lead weights attached to the rope behind the column. the secret is to have enough counter-weight so that the head rises (like the spindle on a drill press) if it is free to move. This allows the Z feed to overcome the upward pressure of the counter-weight. The backlash problem is minimized with this setup. As has been stated, always apply the Z lock when milling. The exception would be with plunge cuts.
                      > >
                      > > My 2-cents,
                      > > Leo (pearland, tx)
                      > >
                      > >
                      > >
                      >
                    • Leo Reed
                      Wow! Your setup is really professional! For my mast to hold the pulley, I found an old 2x4 pine stick. I whittled one end so it would fit inside the hollow
                      Message 10 of 13 , Feb 10, 2013
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                        Wow!  Your setup is really professional!  For my mast to hold the pulley, I found an old 2x4 pine stick. I whittled one end so it would fit inside the hollow column.
                         
                        Leo (pearland, tx)
                         
                         
                        ----- Original Message -----
                        From: a3sigma
                        Sent: 2/10/2013 12:20:29 PM
                        Subject: [GrizHFMinimill] Re: Mini Mill Head Drop

                         

                        PS, I need to do a supliment to that document. I've since switched to a solid comlumn, and hold the weight with more webbing instead of the bag.

                        DC

                        --- In GrizHFMinimill@yahoogroups.com, "a3sigma" wrote:
                        >
                        > For my implimentation of a pulley and counerweight see my document in
                        >
                        > Files > D.C. Clark stuff > X2 Counterweight.pdf
                        >
                        > http://groups.yahoo.com/group/GrizHFMinimill/files/D.C.%20Clark%20stuff/
                        >
                        > David Clark in Southern Maryland, USA
                        >
                        > --- In GrizHFMinimill@yahoogroups.com, "Leo Reed" wrote:
                        > >
                        > > I solved (improved) the problem of head-drop on my Grizzly Mini-mill. First, I modified the Z range by making the modification that AAA (i believe that was his handle on this site) designed. This increased the range by a considerable amount.
                        > >
                        > > Secondly, I mounted a pulley on a mast mounted on the top of the column. This pulley was located about 12" above the top of the column. A nylon rope attached to the head was looped over the pulley and had lead weights attached to the rope behind the column. the secret is to have enough counter-weight so that the head rises (like the spindle on a drill press) if it is free to move. This allows the Z feed to overcome the upward pressure of the counter-weight. The backlash problem is minimized with this setup. As has been stated, always apply the Z lock when milling. The exception would be with plunge cuts.
                        > >
                        > > My 2-cents,
                        > > Leo (pearland, tx)
                        > >
                        > >
                        > >
                        >

                      • jnormgagnon
                        If you are using the mill to bore a hole you need the fine feed and can not lock the z-axis. I have added the counterweight solution to mine. My ctrwgt is
                        Message 11 of 13 , Feb 16, 2013
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                          If you are using the mill to bore a hole you need the fine feed and can not lock the z-axis. I have added the counterweight solution to mine. My ctrwgt is about 40 - 45 pounds. Now the ctrwgt does not eliminate the backlash; but the milling head is held up against rack and pinion. There are area in the z travel of my mill in which if the fine feed is disengage the milling head move upward by itself. Since I've installed the ctgwgt, I have not had had the milling head pulled into the work. You might want to revisit your counterweight modification and add more weight.

                          --- In GrizHFMinimill@yahoogroups.com, gerry waclawiak <gerrywac@...> wrote:
                          >
                          > Mike,
                          >
                          > the real easy answer to head drop is to use proper technique and lock the z axis using the lock lever provided. If the head is locked to the column you cannot have head drop (you may get a little spindle drop if the spindle is poorly adjusted). It also helps if you always drive the head downward to the required reading before locking the z to compensate for any backlash as you would with the x and y or the axis on a lathe.
                          >
                          > The "fine feed" is very poorly implemented as not only does it utilise the relatively crude rack and pinion of the main lever feed but then introduces further inaccuracy and backlash through the castellated nut disconnect (radial play), the worm and pinion drive (+ axial movement of the worm), the universal joint (radial + axial play) and the fine feed knob (axial play). You can improve things somewhat by shimming the knob and worm to reduce axial play, peen the universal joint spider and some have peened the castellated nut but even doing all this still leaves a poor fine feed system.
                          >
                          > It is far easier to fit a DRO to the z, drive the head/cutter tip down to the required point and lock the head to prevent movement in any direction.
                          >
                          >
                          > I have used this technique for several years and can cut to <0.001" with no problem. Furthermore I was able to fly cut to that accuracy for several yearswithout smashing the plastic drive gears, a fairly common occurrence without the head locked (I have now fitted a belt drive (home made) which dispenses with that particular fault and has other benefits)
                          >
                          > Gerry W
                          > Leeds UK
                          >
                          > To: GrizHFMinimill@yahoogroups.com
                          > From: kwoodhands@...
                          > Date: Fri, 8 Feb 2013 22:33:11 -0800
                          > Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop
                          >
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                          > Anthony, I did install the air spring,did not help.Removed the air spring and set up a counter weight on a pulley that helped some. The only sure way for me was the tapping with a wooden mallet until the reading on a digital scale stabilized. Something in a small range on the fine feed or possibly the rack seems to hold up the head,then it drops when the endmill pulls it into the work.I wanted to eliminate the head drop as it will ruin the work ,the tapping method along with a digital scale does this.mike
                          > From: a rien <amriensr@...>
                          > To: GrizHFMinimill@yahoogroups.com
                          > Sent: Friday, February 8, 2013 7:32 PM
                          > Subject: Re: [GrizHFMinimill] Re: Mini Mill Head Drop
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                          > The easiest way I've found to greatly reduce head drop was to install a LMS Air Spring Kit.
                          > I also have a DRO scale on the Z to be sure the head is where it is suppose to be.
                          > HTH
                          > Anthony
                          >
                          > --- On Fri, 2/8/13, albertobarreiro171 <albertobarreiro171@...> wrote:
                          >
                          > From: albertobarreiro171 <albertobarreiro171@...>
                          > Subject: [GrizHFMinimill] Re: Mini Mill Head Drop
                          > To: GrizHFMinimill@yahoogroups.com
                          > Date: Friday, February 8, 2013, 3:22 PM
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                          > Mike, thank for the tip ,i would follow your instructions and a let you know how my problem is solved . Alberto
                          > --- In GrizHFMinimill@yahoogroups.com, michael kolchins wrote:
                          > >
                          > > Alberto, as far as the head drop I found one solution that works for me. I installed a digital scale on the column first. Cost about $35.00 from Grizzly if I recall.
                          > > Then with the mill running and the scale set to 0 , I tap the drawbolt lightly with a small wooden mallet until the reading stabilizes. After I turn the fine feed screw a bit I tap again until the reading stabilizes.I made the mallet, probably weighs less than 3 lbs.
                          > > The head drop on my mill is usually in a 1" range.Of course it is the range I use the most.I never noticed a head drop until I removed the swivel from the vice. The rest of column range seems okay.
                          > > I had tried taking the fine feed off and looking to see what causes the problem.I did
                          > not see any excessive wear in the fine feed or the column rack.Sorry I can't help you with Barney's instructions,I have not seen them myself.
                          > > mike
                          > >
                          > >
                          > >
                          > > >________________________________
                          > > > From: albertobarreiro171
                          > > >To: GrizHFMinimill@yahoogroups.com
                          > > >Sent: Thursday, February 7, 2013 10:28 PM
                          > > >Subject: [GrizHFMinimill] Mini Mill Head Drop
                          > > >
                          > > >
                          > > >Â
                          > > >On feb 2 2013 BARNEY did a replay article on how to fix some of the problems that machine has,he mentioned that those instructions and pictures would be under the name " barney g1fak'' I"m in yahoo mill group and cannot find them. Any help would be appreciated Thank You
                          > > >
                          > > >
                          > > >Alberto
                          > > >
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                          >
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