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digital protractor for rotarty table

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  • ol3_m3
    Any one have suggestions on building a digital protractor for a rotary table. Only need to go 0 deg to 90 deg. saw plans once using a carbon trim pot but
    Message 1 of 6 , Aug 4, 2007
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      Any one have suggestions on building a digital protractor for a rotary
      table. Only need to go 0 deg to 90 deg. saw plans once using a carbon
      trim pot but have not wiring schematic or clue as to how to begin.

      any help would be appreciated.
    • Leon
      ... From: ol3_m3 To: Sent: Saturday, August 04, 2007 4:02 PM Subject: [Electronics_101] digital
      Message 2 of 6 , Aug 4, 2007
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        ----- Original Message -----
        From: "ol3_m3" <ol3_m3@...>
        To: <Electronics_101@yahoogroups.com>
        Sent: Saturday, August 04, 2007 4:02 PM
        Subject: [Electronics_101] digital protractor for rotarty table


        > Any one have suggestions on building a digital protractor for a rotary
        > table. Only need to go 0 deg to 90 deg. saw plans once using a carbon
        > trim pot but have not wiring schematic or clue as to how to begin.
        >
        > any help would be appreciated.

        Something like a pot and suitable microcontroller with an ADC and display
        would work. Or, you could use a rotary encoder instead of the pot and ADC,
        with lower resolution unless you incorporated some form of gearing. There
        are some very expensive transducers for that sort of thing, of course.

        Leon
      • Victor Fraenckel
        You did not specify how accurately you wanted to measure the angle. It is possible to get rotary encoders that can provide a count of 4096 pulses per
        Message 3 of 6 , Aug 5, 2007
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          You did not specify how accurately you wanted to measure the angle. It
          is possible to get rotary encoders that can provide a count of 4096
          pulses per revolution. If you could arrange to gear one to make one
          revolution per 90 degrees of table movement - 4 to 1 reduction - then
          the best you could hope for would be a resolution of 0.022 electronic
          degrees disregarding any gearing slop. This type of rotary encoder is
          fairly inexpensive, but you would need some supporting electronics to
          properly use them.

          Hope this helps!

          Vic
          --

          *____________________________________________________________________________________________*

          *Victor Fraenckel
          KC2GUI
          victorf ATSIGN windreader DOT com**
          *
        • ol3_m3
          looking for 1/10 of a degree. need to know what I need for supporting electronics. Thanks for the reply ... It ... then ... electronic ... is ... to ...
          Message 4 of 6 , Aug 5, 2007
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            looking for 1/10 of a degree. need to know what I need for
            supporting electronics.

            Thanks for the reply

            --- In Electronics_101@yahoogroups.com, Victor Fraenckel
            <victorf@...> wrote:
            >
            > You did not specify how accurately you wanted to measure the angle.
            It
            > is possible to get rotary encoders that can provide a count of 4096
            > pulses per revolution. If you could arrange to gear one to make one
            > revolution per 90 degrees of table movement - 4 to 1 reduction -
            then
            > the best you could hope for would be a resolution of 0.022
            electronic
            > degrees disregarding any gearing slop. This type of rotary encoder
            is
            > fairly inexpensive, but you would need some supporting electronics
            to
            > properly use them.
            >
            > Hope this helps!
            >
            > Vic
            > --
            >
            >
            *_____________________________________________________________________
            _______________________*
            >
            > *Victor Fraenckel
            > KC2GUI
            > victorf ATSIGN windreader DOT com**
            > *
            >
          • rtstofer
            ... Then there is no point in considering any type of potentiometer because you want about 1:3600 resolution. There are rotary encoders around that will give
            Message 5 of 6 , Aug 5, 2007
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              --- In Electronics_101@yahoogroups.com, "ol3_m3" <ol3_m3@...> wrote:
              >
              > looking for 1/10 of a degree. need to know what I need for
              > supporting electronics.
              >
              > Thanks for the reply

              Then there is no point in considering any type of potentiometer
              because you want about 1:3600 resolution.

              There are rotary encoders around that will give you what you need -
              Google for 'rotary encoder'.

              You can also skip over the inexpensive incremental encoders because
              they don't have the resolution http://www.usdigital.com/products/s4/

              You could try one of the low resolution devices and use 4:1 gearing
              but the backlash will probably be a problem. There are anti-backlash
              gear sets around.

              Another possibility would be to try to use a strip encoder like those
              in an ink jet printer. I don't know what kind of resolution they have.

              Richard
            • Leon
              ... From: ol3_m3 To: Sent: Sunday, August 05, 2007 5:17 PM Subject: [Electronics_101] Re: digital
              Message 6 of 6 , Aug 5, 2007
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                ----- Original Message -----
                From: "ol3_m3" <ol3_m3@...>
                To: <Electronics_101@yahoogroups.com>
                Sent: Sunday, August 05, 2007 5:17 PM
                Subject: [Electronics_101] Re: digital protractor for rotarty table


                > looking for 1/10 of a degree. need to know what I need for
                > supporting electronics.

                A suitable MCU and display, as I mentioned previously. Suitable units are
                available cheaply from several suppliers, such as Olimex. You'd just have to
                connect everything up and write the software, or get someone to do it for
                you.

                Leon
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