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Touch probe

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  • msmickelsen
    Does anyone know of a way to detect when two objects touch without there being a mechanical switch closure or a direct electrical connection? I m looking for
    Message 1 of 5 , Oct 7, 2011
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      Does anyone know of a way to detect when two objects touch without there being a mechanical switch closure or a direct electrical connection? I'm looking for a way to make a touch probe for a CNC router that can very accurately detect the position of points on a workpiece even if the workpiece isn't conductive. Switch closure (or opening) can compromise the position information. I'm wondering if anything can be done capacitively or optically.

      Any ideas?

      Thanks,
      Mark
    • Tony Mikolaj
      ... CNC lathes etc must have something along what you are looking for as they have to set the 0 point on the tool each time they change tools or after use to
      Message 2 of 5 , Oct 8, 2011
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        --- In Electronics_101@yahoogroups.com, "msmickelsen" <msmickelsen@...> wrote:
        >
        > Does anyone know of a way to detect when two objects touch without there being a mechanical switch closure or a direct electrical connection? I'm looking for a way to make a touch probe for a CNC router that can very accurately detect the position of points on a workpiece even if the workpiece isn't conductive. Switch closure (or opening) can compromise the position information. I'm wondering if anything can be done capacitively or optically.

        CNC lathes etc must have something along what you are looking for as they have to set the 0 point on the tool each time they change tools or after use to allow for wear on the tip. They have a 0 point near the head and run the tip up to it to get the info. Have a talk to a manufacturer/retailer.

        Tony
      • Mark Mickelsen
        Thanks, Tony. I haven t tried to check with any manufacturer/retailers (it s late at night on the weekend), but I think they accomplish what you re talking
        Message 3 of 5 , Oct 9, 2011
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          Thanks, Tony.
          I haven't tried to check with any manufacturer/retailers (it's late at night
          on the weekend), but I think they accomplish what you're talking about
          by detecting an electrical connection between the tool and the touch plate.
          It's very effective for checking the exact end of a tool (even with wear),
          but it you're trying to measure points directly on the workpiece it doesn't
          work if the workpiece is a non-conductive material.
          Thanks for the idea.
          Mark

          On Sat, Oct 8, 2011 at 8:34 PM, Tony Mikolaj <miktrain@...> wrote:

          > **
          >
          >
          >
          >
          > --- In Electronics_101@yahoogroups.com, "msmickelsen" <msmickelsen@...>
          > wrote:
          > >
          > > Does anyone know of a way to detect when two objects touch without there
          > being a mechanical switch closure or a direct electrical connection? I'm
          > looking for a way to make a touch probe for a CNC router that can very
          > accurately detect the position of points on a workpiece even if the
          > workpiece isn't conductive. Switch closure (or opening) can compromise the
          > position information. I'm wondering if anything can be done capacitively or
          > optically.
          >
          > CNC lathes etc must have something along what you are looking for as they
          > have to set the 0 point on the tool each time they change tools or after use
          > to allow for wear on the tip. They have a 0 point near the head and run the
          > tip up to it to get the info. Have a talk to a manufacturer/retailer.
          >
          > Tony
          >
          >
          >


          [Non-text portions of this message have been removed]
        • George
          Most touch probes are mechanical switches. Their are other ways to do it without a switch, but you probably can t afford them. The switch variety works quite
          Message 4 of 5 , Oct 9, 2011
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            Most touch probes are mechanical switches. Their are other ways to do it without a switch, but you probably can't afford them.

            The switch variety works quite well, even it a dusty shop environment.

            Google: DIY Touch Probe, Two of the better diagrammed:

            <http://www.vinland.com/touch-probe.html>
            <http://www.RoboCNC.nl/?p=1699>(pdf link at bottom)

            - George Lawrence Storm, Maltby, Washington
          • Mark Mickelsen
            Thanks, George. I guess the thing that deters me is that I don t have a metal-working lathe or mill to make those aluminum parts with. I have a small,
            Message 5 of 5 , Oct 9, 2011
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              Thanks, George.
              I guess the thing that deters me is that I don't have a metal-working lathe
              or mill to make those aluminum parts with. I have a small, table-top CNC
              router that can handle plastic or wood but not metal. I don't have any kind
              of lathe. I'm just trying to figure out a way to make something with the
              equipment that I do have.
              Mark

              On Sun, Oct 9, 2011 at 11:03 AM, George <Keencoyote@...> wrote:

              > **
              >
              >
              > Most touch probes are mechanical switches. Their are other ways to do it
              > without a switch, but you probably can't afford them.
              >
              > The switch variety works quite well, even it a dusty shop environment.
              >
              > Google: DIY Touch Probe, Two of the better diagrammed:
              >
              > <http://www.vinland.com/touch-probe.html>
              > <http://www.RoboCNC.nl/?p=1699>(pdf link at bottom)
              >
              > - George Lawrence Storm, Maltby, Washington
              >
              >
              >


              [Non-text portions of this message have been removed]
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