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OT: Why would anybody need a stepper this slow???

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  • OT: Why would anybody need a stepper this slow???

    http://cgi.ebay.com/Crouzet-Synchron...QQcmdZViewItem

    21 revolution per YEAR stepper motor!!!
    You never learn anything by doing it right.

  • #2
    slow turnings

    So that the house you build can ALWAYS be syncronized/ and oriented with Jupiter and the planat Urainus!

    mark61

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    • #3
      They're not steppers, they're synchronous motors.
      Hey, you could build an orrery
      Just got my head together
      now my body's falling apart

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      • #4
        The stepper drive on my scope only runs about 15 steps per second.

        Free software for calculating bolt circles and similar: Click Here

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        • #5
          "The stepper drive on my scope only runs about 15 steps per second."



          Hmmm....this brings up a question. I'm working on a very slowly rotating device driven 1:1 with a 200 steps/rev motor. At how slow a stepping rate do you suppose the motor ceases to have smooth motion, but more of noticeable ratcheting motion?
          Last edited by DR; 03-31-2007, 11:17 AM.

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          • #6
            My article, The Quartz Movement, in the Digital Machinist was about this:

            Electronics and mechanics to produce 1 RPM. Perfect for driving a second hand on a clock. The rest of the clock will appear in the next issue of the Digital Machinist.

            The rotor moves in distinct 1 second steps.
            Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
            ~Practitioner of the Electromechanical Arts~

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            • #7
              Smooth motion to the naked eye? Probably right about 15 steps/second. Film or video (or flip books!) frame rates slower than this are perceived as jerky.
              Todd

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              • #8
                Film is 24 frames per second, video is 30 (in the US).

                Joe

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                • #9
                  The 8mm film format was available in 24 fps for professional work, but far more popular was the 18 fps for amateur/home movies.
                  Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                  ~Practitioner of the Electromechanical Arts~

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                  • #10
                    These motors were used in process control before the integrated circuit solid state timer became more widely available.
                    I used to use a 1 rev per 24hrs to control a liquid nitrogen supply for amass spectrometer. I believe there were 14 day per rev motors used in heating controllers in public buildings again now superceeded by solid state.
                    The Crouzet were a simple cheap solution and would last several years before needing replacement.
                    Peter
                    I have tools I don't know how to use!!

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                    • #11
                      Originally posted by Optics Curmudgeon
                      Film is 24 frames per second, video is 30 (in the US).

                      Joe
                      But that is not the whole story. 24 or 30 frames per second will show flicker.

                      Film projectors, at least the professional ones, will indeed run at 24 frames per second, but the projectors will chop the light several times during each of those frames so the flicker rate is actually much higher, perhaps 96 or even 120 actual flashes of light per second.

                      Video (standard NTSC video as transmitted by all TV stations for over 50 years) does have 30 frames per second but that is composed of 60 fields, due to interlace. Even at that, some people say they can see flicker so it perhaps is not enough.

                      I would guess that the flicker rate needs to be at least 75 and perhaps 90 or 100 images per second before the majority of viewers would not see the flicker.
                      Paul A.
                      SE Texas

                      Make it fit.
                      You can't win and there IS a penalty for trying!

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                      • #12
                        For a telescope drive it isn't the flicker or "jerk" rate that matters. The step rate is calculated so that the size of one step moves the scope at least 50% less than the theoretical maximum resolution of the scope in arc seconds. That is determined by the aperture of the scope. The larger the aperture the higher the required step rate since the rotation of the Earth is relatively constant.
                        Free software for calculating bolt circles and similar: Click Here

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