Steps per Inch / mm

[themonster]

Hi i'm trying to calculate my steps per mm for mach 3.

I am using an 8mm threaded rod at 1.25mm pitch for the lead screw.
I have the FL57STH76-2808B-1 Motors: 1.8degree

how do i calculate the steps per mm for mach 3. Also do i put the input in as steps per mm or inch. (i am using mm as the native units)

Thanks

[High Seas]

Welcome to the CNCZone. I assume you've checked the MACH3 manual pages 5-10 through 5-13 and found them a bit confusing? (http://www.machsupport.com/docs/Mach3Mill_1.84.pdf)

Maybe this will be helpful: (maybe not - but gives you something to think about)
(STEPS per REV)*(THREADS per unit)*(1/(Controller Stepping FACTOR))

STEPS per REV for your 1.8 degree motor this is 200 (A most common setting for many Stepper Motors)

THREADS per unit For Imperial threads: pitch is 1/TPI -Threads per Inch. But in the above solution you'd use TPI. Your mileage may vary with the mms.

Controller Stepping FACTOR for Full Step = 1; 1/2 Step = 2, 1/4 Step = 4; etc

Then, MACH 3 also has a means to calibrate the axis to fine tune your system - see page 5-13.

Hope thats helpful - Jim

ger21 has a nice answer of two here on the site - too. You'd need to wait for his response - or do a search