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View Full Version : Turns per inch to metric conversion

sixpence
08-28-2004, 02:33 AM
We use the metric system here and I have now gotten so used to imperial due to having to order all the parts in inches. I have done the calculation but am not going to post it here just in case I have done someting really stupid whch is very likely. How do I convert 10 tpi to steps per mm. I am using 1.8 degree motors.
Maybe I should start with checking if my imperial calculation is correct.
1.It takes 200 steps to turn the motor 360 deg.
2. multiply number of steps to turn shaft 360 by number of tpi:200x10tpi=2000
to get steps per inch
Any help for the mathematically challenged?
I am using KCam at the moment to try and set up the machine I have entered the steps per inch but when I click on imperial this value of 2000 stays the same and when I enter the value for steps per mm it alters the value on the imperial side?
What am I doing wrong and anyway I don't know if I have calculated the metric version correctly.

ESjaavik
08-28-2004, 03:19 AM
10 TPI is the same as 2,54mm pitch.
So the movement will be 2,54mm for each turn of the motor, or 2,54/200=0,0127mm/step. That's for full step of course. If doing 1/4step, multiply your value by that. 0,0127*1/4=0,003175. Or simply 0,0127/4=0,003175, it's the same.

If you have a gearing, multiply by your gearing ratio.