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Re: [multimachine] Are there any stories and videos of multimachines running?

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  • David G. LeVine
    ... Keith, I have seen that, usually it means the casting into which the lead screw goes is not well machined. Try some few thou at a time facing cuts to
    Message 1 of 14 , Jul 2, 2013
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      On 07/02/2013 01:31 PM, keith gutshall wrote:
      HI Guys
       Maybe the bachlash on a leadscrew is some where besides the threads.
       On my mil-drill table there is clearence where the screw goes thriugh the casting.
       The handle has some slack so you can turn it.
       There is an adjustment nut on the outside, but if you get it to tight the knob will
      not turn.
       
       Keith
       
      Deep Run Portage
      Back Shop
      " The Lizard Works"

      Keith,

      I have seen that, usually it means the casting into which the lead screw goes is not well machined.  Try some "few thou at a time" facing cuts to get the surfaces true.

      Dave  8{)

      --

      "A word to the wise ain't necessary - it's the stupid ones that need the advice."

      Bill Cosby
    • Kobus Van der Walt
      hi a friend of mine and member of www.house4hack.co.za use a masonry drill bit for lead screw- 200 step stepper motor- in 3D printing. Over here we buy it for
      Message 2 of 14 , Jul 2, 2013
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        hi a friend of mine and member of www.house4hack.co.za use a masonry drill bit for lead screw- 200 step stepper motor- in 3D printing. Over here we buy it for $15. I know this has been mentioned before. 

        The nut is made from PLA or ABS plastic. And since it is his Z axis(the one that go up and down?) he use gravity for anti backlash. But i moved the axis - there is very little play on. He senses his printing bed and do levelling with software- so his Z axis move up and down all the time. And in 3D printing the tolerances are very fine as well. So maybe gravity can also be used in machine design for this "problem"? 

        regards
        Kobus

        On Tue, Jul 2, 2013 at 11:23 AM, Steve Wan <stewan@...> wrote:
         

        Hi Guys

        Here's the video of a DIY lathe, not sure the base contains any filled
        cement or at the headstock. Very impressive and easy to build.

        http://www.youtube.com/watch?v=lwmpFI1kDww

        Steve Wan



        On 7/2/13, David G. LeVine <dlevine@...> wrote:
        > On 07/01/2013 11:49 AM, Pat Delany wrote:
        >> IMPORTANT (maybe!) last night it occurred to me that the answer was
        >> staring me in the face. A wooden (or plastic) block like that used on
        >> the thread follower could also be used on the cross slide instead of
        >> the commonly used nut. A wooden block could average out the crossfeed
        >> thread imperfections and it could remove most (or all) backlash. This
        >> would seem pretty cool since I have never seen a cross slide without
        >> considerable backlash.
        >
        > Actually, having seen CNC lathes before with ball screws, I have seen a
        > few with under 0.0005" (yes 1/2 of a thousandth) backlash. It can be
        > done, often is has been done but manually operated lathes where the
        > cutting is only in one direction tend to be less needful of that
        > embellishment.
        >
        > And many inaccurate lathes are both very precise and very repeatable,
        > resulting in quite good work. A lathe with a straight bed and
        > repeatable positioning can do incredible work with the right operator.
        >
        > Dave 8{)
        >
        > --
        >
        > "A word to the wise ain't necessary - it's the stupid ones that need the
        > advice."
        >
        > Bill Cosby
        >
        >
        > ------------------------------------

        >
        > -------------
        > We have a sister site for files and pictures dedicated to concrete machine
        > framed machine tools. You will find a great deal of information about
        > concrete based machines and the inventor of the concrete frame lathe, Lucian
        > Ingraham Yeomans. Go to
        > http://groups.yahoo.com/group/Multimachine-Concrete-Machine-Tools/
        >
        > Also visit the Joseph V. Romig group for even more concrete tool
        > construction, shop notes, stories, and wisdom from the early 20th Century.
        > http://tech.groups.yahoo.com/group/romig_designs/
        > -------------Yahoo! Groups Links
        >
        >
        >
        >


      • Kobus Van der Walt
        Or just do what Pat said. Use gravity, available in abundance and free. And in any bearing nut there have to be play- otherwise it cant work.
        Message 3 of 14 , Jul 2, 2013
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          Or just do what Pat said. Use gravity, available in abundance and free. And in any bearing nut there have to be play- otherwise it cant work.

          On Wed, Jul 3, 2013 at 7:30 AM, Kobus Van der Walt <kvdwalt@...> wrote:
          hi a friend of mine and member of www.house4hack.co.za use a masonry drill bit for lead screw- 200 step stepper motor- in 3D printing. Over here we buy it for $15. I know this has been mentioned before. 

          The nut is made from PLA or ABS plastic. And since it is his Z axis(the one that go up and down?) he use gravity for anti backlash. But i moved the axis - there is very little play on. He senses his printing bed and do levelling with software- so his Z axis move up and down all the time. And in 3D printing the tolerances are very fine as well. So maybe gravity can also be used in machine design for this "problem"? 

          regards
          Kobus


          On Tue, Jul 2, 2013 at 11:23 AM, Steve Wan <stewan@...> wrote:
           

          Hi Guys

          Here's the video of a DIY lathe, not sure the base contains any filled
          cement or at the headstock. Very impressive and easy to build.

          http://www.youtube.com/watch?v=lwmpFI1kDww

          Steve Wan



          On 7/2/13, David G. LeVine <dlevine@...> wrote:
          > On 07/01/2013 11:49 AM, Pat Delany wrote:
          >> IMPORTANT (maybe!) last night it occurred to me that the answer was
          >> staring me in the face. A wooden (or plastic) block like that used on
          >> the thread follower could also be used on the cross slide instead of
          >> the commonly used nut. A wooden block could average out the crossfeed
          >> thread imperfections and it could remove most (or all) backlash. This
          >> would seem pretty cool since I have never seen a cross slide without
          >> considerable backlash.
          >
          > Actually, having seen CNC lathes before with ball screws, I have seen a
          > few with under 0.0005" (yes 1/2 of a thousandth) backlash. It can be
          > done, often is has been done but manually operated lathes where the
          > cutting is only in one direction tend to be less needful of that
          > embellishment.
          >
          > And many inaccurate lathes are both very precise and very repeatable,
          > resulting in quite good work. A lathe with a straight bed and
          > repeatable positioning can do incredible work with the right operator.
          >
          > Dave 8{)
          >
          > --
          >
          > "A word to the wise ain't necessary - it's the stupid ones that need the
          > advice."
          >
          > Bill Cosby
          >
          >
          > ------------------------------------

          >
          > -------------
          > We have a sister site for files and pictures dedicated to concrete machine
          > framed machine tools. You will find a great deal of information about
          > concrete based machines and the inventor of the concrete frame lathe, Lucian
          > Ingraham Yeomans. Go to
          > http://groups.yahoo.com/group/Multimachine-Concrete-Machine-Tools/
          >
          > Also visit the Joseph V. Romig group for even more concrete tool
          > construction, shop notes, stories, and wisdom from the early 20th Century.
          > http://tech.groups.yahoo.com/group/romig_designs/
          > -------------Yahoo! Groups Links
          >
          >
          >
          >



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