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Remember to lock the gibs while tramming the head

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  • Jeremy Winder
    So I just spent the last few hours out attempting to tram the head on my G0704 mill. Just as I had the dial of the test indicator moving a fraction of a
    Message 1 of 10 , Mar 31, 2014
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      So I just spent the last few hours out attempting to tram the head on my G0704 mill. Just as I had the dial of the test indicator moving a fraction of a gradient I had one of those DAH moments.

      I had bumped one of the gib locks and throw my "perfectly trammed" head out 15-20 thousandths. And then discovered I could throw it off an additional 5-10 thousandths, depending on how hard I tighten the lock.

      Now obviously my gibs are way to loose. But I wanted to share hoping to save the next guy his evening.

      Speaking of adjusting the gibs, how do I know they aren't too tight or too loose?

      Thanks,

      --
      Jeremy - Columbus, GA USA
    • Alan Reinhart
      If the axis won t move they are too tight. =A.
      Message 2 of 10 , Apr 1, 2014
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        If the axis won't move they are too tight.

        =A.
        On 3/31/2014 8:03 PM, Jeremy Winder wrote:
         
        So I just spent the last few hours out attempting to tram the head on my G0704 mill. Just as I had the dial of the test indicator moving a fraction of a gradient I had one of those DAH moments.

        I had bumped one of the gib locks and throw my "perfectly trammed" head out 15-20 thousandths. And then discovered I could throw it off an additional 5-10 thousandths, depending on how hard I tighten the lock.

        Now obviously my gibs are way to loose. But I wanted to share hoping to save the next guy his evening.

        Speaking of adjusting the gibs, how do I know they aren't too tight or too loose?

        Thanks,

        --
        Jeremy - Columbus, GA USA

      • Jeremy Winder
        So tighten them down until it is hard to move the hand wheels, then back off a little? ... -- Jeremy - Columbus, GA USA
        Message 3 of 10 , Apr 1, 2014
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          So tighten them down until it is hard to move the hand wheels, then back off a little?


          On Tue, Apr 1, 2014 at 8:01 AM, Alan Reinhart <avr@...> wrote:
           

          If the axis won't move they are too tight.

          =A.

          On 3/31/2014 8:03 PM, Jeremy Winder wrote:
           
          So I just spent the last few hours out attempting to tram the head on my G0704 mill. Just as I had the dial of the test indicator moving a fraction of a gradient I had one of those DAH moments.

          I had bumped one of the gib locks and throw my "perfectly trammed" head out 15-20 thousandths. And then discovered I could throw it off an additional 5-10 thousandths, depending on how hard I tighten the lock.

          Now obviously my gibs are way to loose. But I wanted to share hoping to save the next guy his evening.

          Speaking of adjusting the gibs, how do I know they aren't too tight or too loose?

          Thanks,

          --
          Jeremy - Columbus, GA USA




          --
          Jeremy - Columbus, GA USA
        • markkimball2000
          One approach I ve used is to adjust the gibs to minimize the slop or play in the axis perpendicular to the gib. The other axis is locked in order to keep
          Message 4 of 10 , Apr 1, 2014
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            One approach I've used is to adjust the gibs to minimize the "slop" or play in the axis perpendicular to the gib.  The other axis is locked in order to keep all visible wiggle confined to the axis of interest.  I have done this by eyeball but you can also do it with a mag-base and DTI.  Put the base on the saddle and the point of the DTI on the table.  Push, then pull, and see what you get.  Reducing the play to .001 or less may not be in your best interests -- you do want some room for lube in there!

            Here's a link to a discussion describing various ways to do it:  http://www.cnccookbook.com/CCBacklash2.htm  The "wiggle" method appears partway down.

            Disclaimer:  I have not tried the DTI method yet, eyeballing and "feel" have been good enough for me.  But it's attractive in that it gives you a quantify-able measure of table play.  Next time I'm in the mood for some frustration I'll give it a try

            Mark
          • Jeremy Winder
            Umm. Got some shop time tonight and tried to tighten up the z-axis gib. The screw bottomed out before the gib became tight. And the dovetail on the column
            Message 5 of 10 , Apr 2, 2014
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              Umm. Got some shop time tonight and tried to tighten up the z-axis gib. The screw bottomed out before the gib became tight. And the dovetail on the column doesn't seem to be parallel. After doing some googling it appears I'm not the first with this problem and it is a poorly manufactured column. 


              I have emailed Grizzly; however, I passed the 1 year mark for the warranty last month. Hopefully Grizzly will come through with a solution, if not I'm going to have to hope someone local can recut the dovetails. Bet that is going to be expensive...


              On Tue, Apr 1, 2014 at 11:32 AM, <mark.kimball2@...> wrote:
               

              One approach I've used is to adjust the gibs to minimize the "slop" or play in the axis perpendicular to the gib.  The other axis is locked in order to keep all visible wiggle confined to the axis of interest.  I have done this by eyeball but you can also do it with a mag-base and DTI.  Put the base on the saddle and the point of the DTI on the table.  Push, then pull, and see what you get.  Reducing the play to .001 or less may not be in your best interests -- you do want some room for lube in there!

              Here's a link to a discussion describing various ways to do it:  http://www.cnccookbook.com/CCBacklash2.htm  The "wiggle" method appears partway down.

              Disclaimer:  I have not tried the DTI method yet, eyeballing and "feel" have been good enough for me.  But it's attractive in that it gives you a quantify-able measure of table play.  Next time I'm in the mood for some frustration I'll give it a try

              Mark




              --
              Jeremy - Columbus, GA USA
            • superc_53
              Hi Jeremy. There is of course one small problem with that approach. Specifically Grizzly is just a vendor, not the actual manufacturer of a mill. Complaining
              Message 6 of 10 , Apr 7, 2014
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                Hi Jeremy. 
                There is of course one small problem with that approach.  Specifically Grizzly is just a vendor, not the actual manufacturer of a mill.  Complaining to Grizzly may not accomplish that much to fix the problem.  I would give consideration to finding a longer Z axis gib screw.  The non-parralell dovetail on the bottom of the column sounds like, if correct, a genuine manufacturing problem.  Is not the GO704 a variation of the Sieg SX3 product line?
              • Jeremy Winder
                The G0704 is a clone of the BF-20L. Over the weekend I attempted to shim the gib so it would be tighter; but I could not resolve the problem with the tram.
                Message 7 of 10 , Apr 7, 2014
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                  The G0704 is a clone of the BF-20L. Over the weekend I attempted to shim the gib so it would be tighter; but I could not resolve the problem with the tram. Grizzly asked that I remove the head and take measurements of the dovetails, which I did tonight. Here are the measurements I got:

                  Distance from
                  top of column    measurement
                  1"               3.485
                  4"               3.484
                  7"               3.483
                  10"             3.483
                  13"             3.483 to 3.484
                  15"             3.484 to 3.485

                  So the column's dovetails are bowed. So I see I have two options, either replace the column or pay one of the local machine shops to regrind them. I'm not sure if any of the local shops can regrind dovetails. It is something I'll have to check into.

                  Is there another option I'm missing?

                  Thank you,

                  Jeremy


                  On Mon, Apr 7, 2014 at 12:00 PM, <superc_53@...> wrote:
                   

                  Hi Jeremy. 
                  There is of course one small problem with that approach.  Specifically Grizzly is just a vendor, not the actual manufacturer of a mill.  Complaining to Grizzly may not accomplish that much to fix the problem.  I would give consideration to finding a longer Z axis gib screw.  The non-parralell dovetail on the bottom of the column sounds like, if correct, a genuine manufacturing problem.  Is not the GO704 a variation of the Sieg SX3 product line?




                  --
                  Jeremy - Columbus, GA USA
                • Ian Newman
                  Hi Jeremy, This is probably an aspect you have already addressed, but when measuring the dovetail, I assume you measured over precision ground dowels rather
                  Message 8 of 10 , Apr 8, 2014
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                    Hi Jeremy,

                    This is probably an aspect you have already addressed, but when measuring the dovetail, I assume you measured over precision ground dowels rather than standard silver steel (drill rod) which is usually specified to have a defined diameter but is not necessarily to be cylindrical. It is usually a "shape of constant width" which makes it unsuitable for use as a gauge in situations where the surfaces being referenced are not parallel - see:


                    All the best,
                    Ian



                    On 8 Apr 2014, at 01:14, Jeremy Winder <cptwinder@...> wrote:

                     

                    The G0704 is a clone of the BF-20L. Over the weekend I attempted to shim the gib so it would be tighter; but I could not resolve the problem with the tram. Grizzly asked that I remove the head and take measurements of the dovetails, which I did tonight. Here are the measurements I got:

                    Distance from
                    top of column    measurement
                    1"               3.485
                    4"               3.484
                    7"               3.483
                    10"             3.483
                    13"             3.483 to 3.484
                    15"             3.484 to 3.485

                    So the column's dovetails are bowed. So I see I have two options, either replace the column or pay one of the local machine shops to regrind them. I'm not sure if any of the local shops can regrind dovetails. It is something I'll have to check into.

                    Is there another option I'm missing?

                    Thank you,

                    Jeremy


                    On Mon, Apr 7, 2014 at 12:00 PM, <superc_53@...> wrote:
                     

                    Hi Jeremy. 
                    There is of course one small problem with that approach.  Specifically Grizzly is just a vendor, not the actual manufacturer of a mill.  Complaining to Grizzly may not accomplish that much to fix the problem.  I would give consideration to finding a longer Z axis gib screw.  The non-parralell dovetail on the bottom of the column sounds like, if correct, a genuine manufacturing problem.  Is not the GO704 a variation of the Sieg SX3 product line?




                    --
                    Jeremy - Columbus, GA USA

                  • Jeremy Winder
                    Ian, That explains what I m seeing with another issue altogether where I thought I would have better results with silver steel. For measuring the dovetails, I
                    Message 9 of 10 , Apr 8, 2014
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                      Ian,

                      That explains what I'm seeing with another issue altogether where I thought I would have better results with silver steel. For measuring the dovetails, I didn't have any dowel pins large enough so I used the 3/8" shanks of a couple broken smaller end mills. They are the best I had access to last night. If they are precision enough, please let me know, and I'll order pins today.

                      Also, what would be the best way of measuring the tapered gib to ensure it is the correct taper?

                      Thanks again,

                      Jeremy


                      On Tue, Apr 8, 2014 at 8:28 AM, Ian Newman <ian_new@...> wrote:
                       

                      Hi Jeremy,

                      This is probably an aspect you have already addressed, but when measuring the dovetail, I assume you measured over precision ground dowels rather than standard silver steel (drill rod) which is usually specified to have a defined diameter but is not necessarily to be cylindrical. It is usually a "shape of constant width" which makes it unsuitable for use as a gauge in situations where the surfaces being referenced are not parallel - see:


                      All the best,
                      Ian



                      On 8 Apr 2014, at 01:14, Jeremy Winder <cptwinder@...> wrote:

                       

                      The G0704 is a clone of the BF-20L. Over the weekend I attempted to shim the gib so it would be tighter; but I could not resolve the problem with the tram. Grizzly asked that I remove the head and take measurements of the dovetails, which I did tonight. Here are the measurements I got:

                      Distance from
                      top of column    measurement
                      1"               3.485
                      4"               3.484
                      7"               3.483
                      10"             3.483
                      13"             3.483 to 3.484
                      15"             3.484 to 3.485

                      So the column's dovetails are bowed. So I see I have two options, either replace the column or pay one of the local machine shops to regrind them. I'm not sure if any of the local shops can regrind dovetails. It is something I'll have to check into.

                      Is there another option I'm missing?

                      Thank you,

                      Jeremy


                      On Mon, Apr 7, 2014 at 12:00 PM, <superc_53@...> wrote:
                       

                      Hi Jeremy. 
                      There is of course one small problem with that approach.  Specifically Grizzly is just a vendor, not the actual manufacturer of a mill.  Complaining to Grizzly may not accomplish that much to fix the problem.  I would give consideration to finding a longer Z axis gib screw.  The non-parralell dovetail on the bottom of the column sounds like, if correct, a genuine manufacturing problem.  Is not the GO704 a variation of the Sieg SX3 product line?




                      --
                      Jeremy - Columbus, GA USA




                      --
                      Jeremy - Columbus, GA USA
                    • Jeremy Winder
                      So I heard back from Grizzly regarding my g0704. The tech doesn t think the bow in my column is enough to cause the head to be pulled out of alignment by .015
                      Message 10 of 10 , Apr 10, 2014
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                        So I heard back from Grizzly regarding my g0704. The tech doesn't think the bow in my column is enough to cause the head to be pulled out of alignment by .015 to .020 when the gib lock is tightened. My dovetails measurements are:

                        Distance from
                        top of column    measurement
                        1"               3.485
                        4"               3.484
                        7"               3.483
                        10"             3.483
                        13"             3.483 to 3.484
                        15"             3.484 to 3.485

                        The tech has offered me a new blank gib, which will need to be machines and lapped to fit. After shimming the gib and having the same issue, I'm not sure a new gib is going to fix the problem unless my current gib's taper is all wrong.

                        So, my questions are:
                        1) What is everyone else's thoughts on the new gib fixing the issue?
                        2) How would I check my current gib to see if the taper is wrong?

                        Thanks again,

                        Jeremy


                        On Tue, Apr 8, 2014 at 8:59 AM, Jeremy Winder <cptwinder@...> wrote:
                        Ian,

                        That explains what I'm seeing with another issue altogether where I thought I would have better results with silver steel. For measuring the dovetails, I didn't have any dowel pins large enough so I used the 3/8" shanks of a couple broken smaller end mills. They are the best I had access to last night. If they are precision enough, please let me know, and I'll order pins today.

                        Also, what would be the best way of measuring the tapered gib to ensure it is the correct taper?

                        Thanks again,

                        Jeremy


                        On Tue, Apr 8, 2014 at 8:28 AM, Ian Newman <ian_new@...> wrote:
                         

                        Hi Jeremy,

                        This is probably an aspect you have already addressed, but when measuring the dovetail, I assume you measured over precision ground dowels rather than standard silver steel (drill rod) which is usually specified to have a defined diameter but is not necessarily to be cylindrical. It is usually a "shape of constant width" which makes it unsuitable for use as a gauge in situations where the surfaces being referenced are not parallel - see:


                        All the best,
                        Ian



                        On 8 Apr 2014, at 01:14, Jeremy Winder <cptwinder@...> wrote:

                         

                        The G0704 is a clone of the BF-20L. Over the weekend I attempted to shim the gib so it would be tighter; but I could not resolve the problem with the tram. Grizzly asked that I remove the head and take measurements of the dovetails, which I did tonight. Here are the measurements I got:

                        Distance from
                        top of column    measurement
                        1"               3.485
                        4"               3.484
                        7"               3.483
                        10"             3.483
                        13"             3.483 to 3.484
                        15"             3.484 to 3.485

                        So the column's dovetails are bowed. So I see I have two options, either replace the column or pay one of the local machine shops to regrind them. I'm not sure if any of the local shops can regrind dovetails. It is something I'll have to check into.

                        Is there another option I'm missing?

                        Thank you,

                        Jeremy


                        On Mon, Apr 7, 2014 at 12:00 PM, <superc_53@...> wrote:
                         

                        Hi Jeremy. 
                        There is of course one small problem with that approach.  Specifically Grizzly is just a vendor, not the actual manufacturer of a mill.  Complaining to Grizzly may not accomplish that much to fix the problem.  I would give consideration to finding a longer Z axis gib screw.  The non-parralell dovetail on the bottom of the column sounds like, if correct, a genuine manufacturing problem.  Is not the GO704 a variation of the Sieg SX3 product line?




                        --
                        Jeremy - Columbus, GA USA




                        --
                        Jeremy - Columbus, GA USA



                        --
                        Jeremy - Columbus, GA USA
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