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Re: B&C axis spindle head

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  • Graham Stabler
    ... other than engraving I can t see a satalite drive based head being used with stainless or normal steel regardless of the spindle. Graham
    Message 1 of 10 , Jul 5, 2006
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      --- In CNC_Toolkit@yahoogroups.com, "jamesvand25" <krymis@...> wrote:
      >
      > Thanks for the help. What should be used for the actual spindle for
      > cutting the different materials? I want to cut mainly high density
      > foam and aluminum, but a few projects call for some SS and regular
      > 1018 steel engraving and such.
      >

      other than engraving I can't see a satalite drive based head being
      used with stainless or normal steel regardless of the spindle.

      Graham
    • Steve Blackmore
      ... Why not? Steve Blackmore --
      Message 2 of 10 , Jul 5, 2006
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        On Wed, 05 Jul 2006 09:19:57 -0000, you wrote:

        >other than engraving I can't see a satalite drive based head being
        >used with stainless or normal steel regardless of the spindle.

        Why not?

        Steve Blackmore
        --
      • Graham Stabler
        ... rigidity, you have two rotary joints (that s always bad) with gears and the associated backlash, you also have relatively low torque because the gear ratio
        Message 3 of 10 , Jul 5, 2006
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          --- In CNC_Toolkit@yahoogroups.com, Steve Blackmore <steve@...> wrote:
          >
          > On Wed, 05 Jul 2006 09:19:57 -0000, you wrote:
          >
          > >other than engraving I can't see a satalite drive based head being
          > >used with stainless or normal steel regardless of the spindle.
          >
          > Why not?
          >
          > Steve Blackmore
          > --
          >

          rigidity, you have two rotary joints (that's always bad) with gears
          and the associated backlash, you also have relatively low torque
          because the gear ratio is not all that high. The bearings I can't say
          much about but they are for revolving dishes not milling loads. I'm
          guessing the spindle would be quite a bit less stiff than a Taig for
          example and that is ignoring the large distance from z-axis bearings
          to the tool tip inherent in all 5-axis machines of that type.

          I guess I should have expanded on my answer somewhat, you could mill
          steel of course but I wouldn't want to try and make a cavity mould for
          example unless I was prepared to take a long time over it with very
          light cuts, you know if you engrave for long enough you can make
          anything :)

          Its just my gut feeling, I could be wrong but I assume no one is
          taking my word as law (I don't).

          Graham
        • Steve Blackmore
          ... Got to disagree, I just stripped one of mine. Removing the existing 12V motors and their gearboxes, there is a high quality and very substantial steel ring
          Message 4 of 10 , Jul 6, 2006
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            On Wed, 05 Jul 2006 22:58:31 -0000, you wrote:

            >> Why not?

            >rigidity, you have two rotary joints (that's always bad) with gears
            >and the associated backlash, you also have relatively low torque
            >because the gear ratio is not all that high. The bearings I can't say
            >much about but they are for revolving dishes not milling loads. I'm
            >guessing the spindle would be quite a bit less stiff than a Taig for
            >example and that is ignoring the large distance from z-axis bearings
            >to the tool tip inherent in all 5-axis machines of that type.

            Got to disagree, I just stripped one of mine. Removing the existing 12V
            motors and their gearboxes, there is a high quality and very substantial
            steel ring gear and steel spur at 5.5:1 ratio, so even with typical Nema
            23 steppers at 250 oz/in, that gives a good amount of available torque.
            There is also a useful 24V brake that could easily be fitted to a double
            ended stepper if required. I couldn't feel any backlash BTW.

            There are two bearings on the ring gear assembly, the larger one is
            100mm dia x11mm thick, the smaller bearing is 42mm x 8mm, again no play
            in them.

            >I guess I should have expanded on my answer somewhat, you could mill
            >steel of course but I wouldn't want to try and make a cavity mould for
            >example unless I was prepared to take a long time over it with very
            >light cuts, you know if you engrave for long enough you can make
            >anything :)

            I think they will do far better than just engraving cuts. I wouldn't
            hang them on a Taig though, too much bending moment on the column.
            However I've got enough ballscrews and linear slides to make a nice
            12'x6' router table, just haven't got any space :)

            I could however squeeze a 4'x3' in at work <G>. Just missing some
            structural aluminium to make the table if anybody in the UK has any
            going cheap!

            >Its just my gut feeling, I could be wrong but I assume no one is
            >taking my word as law (I don't).

            Neither did I <G>.

            Steve Blackmore
            --
          • Graham Stabler
            ... Compared to sticking the same motor on a ballscrew the mechanical advantage will be tiny, your 250oz-in motor on the ballscrew then tries to push the
            Message 5 of 10 , Jul 6, 2006
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              --- In CNC_Toolkit@yahoogroups.com, Steve Blackmore <steve@...> wrote:
              >at 5.5:1 ratio, so even with typical Nema 23 steppers at 250 oz/in,
              >that gives a good amount of available torque.

              Compared to sticking the same motor on a ballscrew the mechanical
              advantage will be tiny, your 250oz-in motor on the ballscrew then
              tries to push the cutter through some steel and which gives up?
              Typical worm drive might be up to 100:1 ratio, quite a difference.

              >I couldn't feel any backlash BTW.

              Then you can't be trying hard enough, surely all gears must have some :)

              > There are two bearings on the ring gear assembly, the larger one is
              > 100mm dia x11mm thick, the smaller bearing is 42mm x 8mm, again no
              >play in them.

              The bearings sound promising, when testing for play did you have any
              leverage? What about end float?

              >I wouldn't hang them on a Taig though, too much bending moment on the
              >column.

              Neither would I, my point was just that you might consider the taig to
              be the smallest machine you might happily machine steel on, my thought
              was that two sat drives might give you less rigidity than on a taig.

              I guess all of this is just a little pointless, best thing might be to
              bolt one to something and try and ram a spindle through some steel :)
              It all just goes against everything you expect from a machine that
              will machine steel effectively but perhaps it is just me being scared
              of steel or perhaps we have not defined exactly how good a steel
              machine machine is.

              Perhaps Rab, the only guy who has used these things in anger can put
              in a few words.

              Graham


              p.s. If you think I haven't machined much steel don't even go there.
              I spent more hours than I care to mention operating a manual Boko and
              have the mental scars to prove it. Now that has a tilting head, and a
              suitable spindle! :)
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