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Re: [mach1mach2cnc] Re: optical mouse as linear encoder - big encoder

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  • hannu
    Excellent idea ! If you could then calibrate it and add error-mapping, you would have a solution as good as anything out there. I´m very impressed with this
    Message 1 of 22 , Oct 1, 2007
      Excellent idea !
      If you could then calibrate it and add error-mapping, you would have a
      solution
      as good as anything out there.

      I´m very impressed with this as an idea - it would probably work very well,
      maybe some cyclical errors but very good resolution, and absolutely
      repeatable.
      To get a thin beam, you might be able to shine a pen laser onto it,
      maybe at an angle to
      the thread ... you should be able to achieve 0.01 mm ..
      If I had the time, I would go down right now and start trying this, this
      very morning.
      I´ll definitely experiment with this, when my case load goes down a bit.
      A good think ! err ... idea.
      >
      > On Saturday 29 September 2007 19:33, hannu wrote:
      > > Keith - not really
      > > The only real option is rack & pinion, with maybe a floating secondary
      > > axis with a ballscrew for the actual machining.
      > > Thats how i´ve been building my mill, to see it work.
      > >
      > >
      > The idea was to use the threads as optical interrupters, not to move
      > anything.
      > The only thing that would touch the allthread would be light.
      > --
      > Keith Bowers - Thomasville, NC
      >
      >
    • keith
      ... Along the same lines, if you were to sense the rising and falling edges of the output (a-la quadrature encoders) you cold get one transition for the thread
      Message 2 of 22 , Oct 1, 2007
        On Monday 01 October 2007 04:36, hannu wrote:
        > Excellent idea !
        > If you could then calibrate it and add error-mapping, you would have a
        > solution
        > as good as anything out there.
        >
        > I´m very impressed with this as an idea - it would probably work very well,
        > maybe some cyclical errors but very good resolution, and absolutely
        > repeatable.
        > To get a thin beam, you might be able to shine a pen laser onto it,
        > maybe at an angle to
        > the thread ... you should be able to achieve 0.01 mm ..
        > If I had the time, I would go down right now and start trying this, this
        > very morning.
        > I´ll definitely experiment with this, when my case load goes down a bit.
        > A good think ! err ... idea.
        >
        > > On Saturday 29 September 2007 19:33, hannu wrote:
        > > > Keith - not really
        > > > The only real option is rack & pinion, with maybe a floating secondary
        > > > axis with a ballscrew for the actual machining.
        > > > Thats how i´ve been building my mill, to see it work.
        > >
        > > The idea was to use the threads as optical interrupters, not to move
        > > anything.
        > > The only thing that would touch the allthread would be light.
        > > --
        > > Keith Bowers - Thomasville, NC
        >
        >
        Along the same lines, if you were to sense the rising and falling edges of the
        output (a-la quadrature encoders) you cold get one transition for the thread
        and one for the gap. Thus you could get 40 transitions/inch with a 20 TPI
        thread. Acme threads would would probably be easier to work with. In any case
        you may or may not want to angle the light path to match the thread angle. It
        also might help to lay a plate on the thread so the light "peeks" through the
        resulting gaps.
        --
        Keith Bowers - Thomasville, NC
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