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  1. #1
    Join Date
    Mar 2004
    Posts
    204

    Calculating "steps per unit" for rotary axis?

    What formulas do you use to calculate "steps per unit" for the motor settings in regards to the A - axis (rotary)? I have gone through the Mach2 manual and I can't quite figure out if you use the same formula used to calculate linear axises or some variant of it. For some reason I am just drawing a blank.
    I am going to be using a stepper motor directly mounted to a gearhead which has a 50/1 ratio and I will be using a Xylotex driver in 1/8th micro-stepping mode.

    Anyone know what the proper formulas I need to use?

    Thanks

  2. #2
    Join Date
    Dec 2003
    Posts
    24220
    I would assume you want to program pulses/degree? If it is a rotary axis.
    First, how many motor pulses for one rev of the motor?, say 1600 micro steps/rev so one revolution on output of the 50:1 reducer will require 50x1600 = 80,000, so to get the pulses/degree will be 80,000/360 = 222.2222
    Thats what it looks like to me.
    Al
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
    Join Date
    Mar 2004
    Posts
    204
    Yes it would be 1600 pulses for 1 rev. of the motor. I got as far as the 80,000 value but I wasn't sure if that was the value I had to enter into the "steps per units" box in Mach2 or if there was more calculations. It seemed way too high a value to be entered. Guess I was really missing an important part of the formula. I think part of the problem as I see now by how you figured that out is I kept on thinking in the way of, "steps per unit" when I should have been looking at it as "pulses per unit" or better yet "pulses per degree".

    Thank you Al.

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