Need stepper motor that travels 6 Deg/step.

Discussion in 'The Projects Forum' started by holychachi, Aug 2, 2011.

  1. holychachi

    Thread Starter New Member

    Jul 13, 2010
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    0
    Im looking to build a clock with an arduino and stepper motors. Only problem is I can only find motors that turn at 1.8 or 7.5 or 3.6 deg per step.
    So anyone know of a motor that can go 6 deg per step or 60 steps per rev or 'X' deg per step that can add up to 6?
    I know the first thought is going to be to grab an old clock and rip out the innards, 60 steps per revolution there, but I want to start fresh on this.
    Thanks in advance.
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
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    If you use a microstepping driver (like the LiniStepper; http://www.piclist.com/techref/io/stepper/linistep/index.htm) it can do 1800 steps/rev or 3600 steps/rev.

    Both those divide by 60 units per revolution, good for stepper motor clocks. It also has the benefit of a PIC on board so that can be your entire clock brain and motor driver, like this clock;
    http://www.massmind.org/techref/io/stepper/linistep/LiniClock/index.htm

    Other microstepping stepper drivers will do 800, 1600 or 3200 steps per rev, which you could also use if you can tolerate not getting each minute an exact 60th of a rev.
     
  3. John P

    AAC Fanatic!

    Oct 14, 2008
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    Alternatively, get a 200 step/rev motor and give it a sequence of 3 steps the first second, then 3 steps the second second (!!) then 4 steps the third second, and repeat. After 20 sequences of 3 seconds each (= 1 minute) you'd get (3+3+4) * 20 or 200 steps, i.e. one full revolution. I doubt if the unequal motions per second would be noticeable.
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    I am planning a similar project using a PICAXE and three really cheap 7.5° motors: one each for the hours, minutes, and seconds (three dials side by side). I will have code for the PICAXE that can either full step or half step the motors and will use the following 5 second sequence: full step, half step, full step, half step, full step, and then repeat. Thus, the second hand will move 5 times in 5 seconds and cover 30° (7.5 + 3.75 + 7.5 + 3.75 + 7.5). Granted, the steps won't move the hand the same amount each time, but there will be 5 movements in 5 seconds and the hands will point in exactly the right place every five seconds, which is where the numbers will be.
     
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