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Re: [CNC_Toolkit] 4th & 5th Axis Unit

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  • Tom Benedict
    I was able to track down that part at All Electronics Corp. here in the US. Here s the URL for the item:
    Message 1 of 6 , Jun 25, 2003
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      I was able to track down that part at All Electronics Corp. here in the
      US. Here's the URL for the item:

      http://www.allelectronics.com/cgi-bin/category.cgi?item=DCM-178

      $31.95 each. Not bad considering it's weatherproofed (won't suck up
      coolant.)

      As far as backlash goes, do you think this would respond well to replacing
      the large gear with a loaded pair? Or is that just asking for your tool
      to spring during machining?



      On Wed, 25 Jun 2003, rainnea wrote:

      > I've uploaded some photos with close-ups of the 4th & 5th Axis unit.
      >
      > Basically what it is are two satellite dish-positioning units mounted
      > at right angles (thanks to Alan for originally pointing these out to
      > me)
      >
      > The units are made by Globe Motors and the motor code is 409A582
      > rated at 12V. A quick Google search will bring up some links.
      >
      > I removed the brake and tach sensor and replaced them with a US
      > Digital encoder disc and pickup and drive them with Gecko 340 servo
      > controllers. I had to make up some differential transmitter /
      > receiver circuits for the encoders as they were picking up noise over
      > the cable run. (see http://www.geckodrive.com and
      > http://www.usdigital.com )
      >
      > The units have a flange that I machined off and I mounted them at 90
      > degrees to each other using some 8mm aluminium angle (this bracket
      > should probably be beefed up)
      >
      > There is an amount of backlash in these units, some more than others,
      > but then they are very cheap. The motor / encoder assembly is quite
      > long and sticks out beyond the unit a bit too much. You also need
      > quite a bit extra clearance to allow the tool to rotate and your work
      > area will be smaller than for an equivalent size 3-axis machine.
      > If I could find a low weight / low backlash / reasonable cost, etc.
      > alternative then I `d use that.
      > I used a Sherline CNC-ready rotary unit for the 5th axis on my Taig
      > mill, but these are too heavy for the router. An alternative set-up
      > with timing belts and pullies could be constructed. I'm also looking
      > at some parallel kinematics design ideas for tilting the tool angle
      > as an alternative to rotary units.
      > I can quickly change out the Z-axis on my router from the 4/5 axis
      > unit to just a simple, but larger router if I'm doing a job that only
      > requires 3-axes, or indeed a vinyl cutting knife.
      >
      > There's a very informative free download at Thermwood, although I
      > think if I'd read that first then I'd have been put off trying to do
      > this at all, as it discusses a lot of the inherent problems with
      > accuracy.
      > http://www.thermwood.com/twood_site/pages/books_and_multimedia/three_d
      > _trim_and_machine.htm
      >
      > I'd certainly encourage anyone thinking about it to have a go at a 5-
      > axis machine, just remember that it wasn't all that long ago that a
      > 4th axis was thought to be exotic!
      >
      > Rab
      >
      >
      >
      >
      >
      > To unsubscribe from this group, send an email to:
      > CNC_Toolkit-unsubscribe@yahoogroups.com
      >
      >
      >
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      >
      >
    • rainnea
      Tom, A lot of the backlash is in the gearbox before it gets to the large gear, so the split gear would nt help very much, Rab ... the ... 178 ... replacing ...
      Message 2 of 6 , Jun 25, 2003
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        Tom,

        A lot of the backlash is in the gearbox before it gets to the large
        gear, so the split gear would'nt help very much,

        Rab

        --- In CNC_Toolkit@yahoogroups.com, Tom Benedict <benedict@h...>
        wrote:
        > I was able to track down that part at All Electronics Corp. here in
        the
        > US. Here's the URL for the item:
        >
        > http://www.allelectronics.com/cgi-bin/category.cgi?item=DCM-
        178
        >
        > $31.95 each. Not bad considering it's weatherproofed (won't suck up
        > coolant.)
        >
        > As far as backlash goes, do you think this would respond well to
        replacing
        > the large gear with a loaded pair? Or is that just asking for your
        tool
        > to spring during machining?
      • bgriggstwcny
        Rab, I was wondering if you have any 3D close ups of how the two axis were mounted together? Or perhaps some photos from the construction process. I think it
        Message 3 of 6 , Sep 1, 2003
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          Rab,

          I was wondering if you have any 3D close ups of how the two axis
          were mounted together? Or perhaps some photos from the construction
          process. I think it is probably a simple thing but a picture is
          worth a thousand words.


          --- In CNC_Toolkit@yahoogroups.com, "rainnea" <rainnea@b...> wrote:
          > Tom,
          >
          > A lot of the backlash is in the gearbox before it gets to the
          large
          > gear, so the split gear would'nt help very much,
          >
          > Rab
          >
          > --- In CNC_Toolkit@yahoogroups.com, Tom Benedict <benedict@h...>
          > wrote:
          > > I was able to track down that part at All Electronics Corp. here
          in
          > the
          > > US. Here's the URL for the item:
          > >
          > > http://www.allelectronics.com/cgi-bin/category.cgi?item=DCM-
          > 178
          > >
          > > $31.95 each. Not bad considering it's weatherproofed (won't
          suck up
          > > coolant.)
          > >
          > > As far as backlash goes, do you think this would respond well to
          > replacing
          > > the large gear with a loaded pair? Or is that just asking for
          your
          > tool
          > > to spring during machining?
        • rainnea
          There s a couple of pictures under 4th & 5th Axis Unit in the photos section. I just used some 80 x 80 x 8mm L-bracket and bolted this to the backs of the
          Message 4 of 6 , Sep 2, 2003
          • 0 Attachment
            There's a couple of pictures under "4th & 5th Axis Unit" in the
            photos section. I just used some 80 x 80 x 8mm L-bracket and bolted
            this to the backs of the rotary units although a more solid
            arrangement would be preferrable.

            Rab


            --- In CNC_Toolkit@yahoogroups.com, "bgriggstwcny" <bgriggs@t...>
            wrote:
            > Rab,
            >
            > I was wondering if you have any 3D close ups of how the two axis
            > were mounted together? Or perhaps some photos from the construction
            > process. I think it is probably a simple thing but a picture is
            > worth a thousand words.
            >
          • nattyone960
            Thanks for this! While cutting a part and needing to kill some time, I decided to dig around here. Came up with this beauty. I have already gone a little way
            Message 5 of 6 , May 31, 2006
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              Thanks for this!

              While cutting a part and needing to kill some time, I decided to dig
              around here.
              Came up with this beauty.

              I have already gone a little way past this stage although not 5th
              Axis that would be able to utilize these drives, this discussion
              might still help others who might not have seen it and who may be
              planning a similar setup(s).


              --- In CNC_Toolkit@yahoogroups.com, "rainnea" <rainnea@...> wrote:
              >
              > I've uploaded some photos with close-ups of the 4th & 5th Axis unit.
              >
              > Basically what it is are two satellite dish-positioning units
              mounted
              > at right angles (thanks to Alan for originally pointing these out
              to
              > me)
              >
              > The units are made by Globe Motors and the motor code is 409A582
              > rated at 12V. A quick Google search will bring up some links.
              >
              > I removed the brake and tach sensor and replaced them with a US
              > Digital encoder disc and pickup and drive them with Gecko 340 servo
              > controllers. I had to make up some differential transmitter /
              > receiver circuits for the encoders as they were picking up noise
              over
              > the cable run. (see http://www.geckodrive.com and
              > http://www.usdigital.com )
              >
              > The units have a flange that I machined off and I mounted them at
              90
              > degrees to each other using some 8mm aluminium angle (this bracket
              > should probably be beefed up)
              >
              > There is an amount of backlash in these units, some more than
              others,
              > but then they are very cheap. The motor / encoder assembly is quite
              > long and sticks out beyond the unit a bit too much. You also need
              > quite a bit extra clearance to allow the tool to rotate and your
              work
              > area will be smaller than for an equivalent size 3-axis machine.
              > If I could find a low weight / low backlash / reasonable cost, etc.
              > alternative then I `d use that.
              > I used a Sherline CNC-ready rotary unit for the 5th axis on my Taig
              > mill, but these are too heavy for the router. An alternative set-up
              > with timing belts and pullies could be constructed. I'm also
              looking
              > at some parallel kinematics design ideas for tilting the tool angle
              > as an alternative to rotary units.
              > I can quickly change out the Z-axis on my router from the 4/5 axis
              > unit to just a simple, but larger router if I'm doing a job that
              only
              > requires 3-axes, or indeed a vinyl cutting knife.
              >
              > There's a very informative free download at Thermwood, although I
              > think if I'd read that first then I'd have been put off trying to
              do
              > this at all, as it discusses a lot of the inherent problems with
              > accuracy.
              >
              http://www.thermwood.com/twood_site/pages/books_and_multimedia/three_d
              > _trim_and_machine.htm
              >
              > I'd certainly encourage anyone thinking about it to have a go at a
              5-
              > axis machine, just remember that it wasn't all that long ago that a
              > 4th axis was thought to be exotic!
              >
              > Rab
              >
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