View Full Version : Calculating "steps per unit" for rotary axis?

11-28-2004, 02:45 PM
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 :)

11-28-2004, 03:44 PM
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.

11-28-2004, 04:31 PM
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. ;)