[holger jurgens]

I am trying to replace the motors and electronics of my cnc. I have the motors, steppers and control board all wired up. The motors turn fine, but the digital readout doesn’t match the DRO. I am using a single start .5 inch acme screw to drive the z axis. It takes 10 turns to move the axis 1 inch. 10 turns times 200 full steps times 2 micro steps equals 4000 steps per inch. That is the number I entered under motor tuning in mach3. So when I turn the motor about one revolution, the digital readout should change by about .1 inch. However, it changes by about 5 inches. That is 50 times too much. How can I fix this?

[ger21]

Are your native units set to inches?
Is Mach3 in Inch mode (G20)
Are you sure the drives are set to 1/2 step?

[holger jurgens]

Are your native units set to inches?
Is Mach3 in Inch mode (G20)
Are you sure the drives are set to 1/2 step?

I set the units to inches and the dip switches are correctly set to half step. I was not running a program with a G20 command. I was just turning the motor shaft about one revolution with the jog key and I noticed that the numbers on the DRO changed by about 5 inches instead of .1 inch. So this is completely off. I have no idea what I am doing wrong. Perhaps the control board is defective. I just ordered another one. I have been using KCAM for many years. It always worked flawlessly. But it is getting difficult finding old computers to run KCAM. I wished there was another control software as simple and reliable as Kcam. I have not paid for Mach3 yet. And I am not going to until I see that it works.

[ger21]

Look at the status bar, and make sure it says G20.
And go to Config > Native Units, and make sure it says inches.

This is a configuration problem, not a Mach3 problem.

[holger jurgens]

Thank you for your reply. The native units are definitely set to inches, but I don't see G20 on the status bar. How can I fix that?

[ger21]

Enter G20 in the MDI.