Need Help!- Something HAS to be wrong with my steps per inch....

[kauaicuda]

Hi folks.

Im a total newbie, I'll admit.

Im running a cncrouterparts.com design 80/20 build.

I'm using a Gecko G540, Nema 23 steppers, 5 start 10 tpi leadscews, and of course mach3.

I have seen others using steps per inch at "4000"

200 step motors x 10 microstep drives, x 2 turns per inch on the screws.


But, my steps per is only accurate around "160". Thats right, one-hundred-sixty.


I cant figure out what I'm doing wrong. Any ideas?

[ger21]

You probably have your default units set to mm's. Change to inches and retune the motors.

[kauaicuda]

I did check that, I thought it was correct, but now I'm guessing not.

160 x 25.4 (mm in an inch) = 4064

Will recheck and report back.

[kauaicuda]

Yep. Sure was in "mm"

Here's where it gets really interesting.

I reset my steps per inch with mach loaded up with no G code.

I had to set it to about 100,000 steps per inch to be in the ballpark of 1 inch. I knew this wasnt right, but it worked....sort of....The DRO on mach read 1 inch of movement for 1 inch of travel.

Then I loaded my G code, and the steps per inch was no longer accurate. It changed, with my G code loaded, to where I wanted to be, 4000 steps per inch.

Great, I suppose, but why did my "steps per" change when the G code loaded?

[ger21]

You have a G20 or G21 in your g-code, which is changing the units.

You're steps per unit isn't changing.

Set the default units to inches, set the proper steps per inch, and make sure youre g-code doesn't have a G21 in it, and it should work fine.