Get your steps/inch (or steps/mm) correct before you try to fine-tune your acceleration and max velocity. The easy do-it-yourself way to determine the actual steps/whatever-units-you-are-using is:

(1) Calculate the hypothetical steps/units based on microstepping mode of your stepper driver and any belt/gear/thread-per-inch ratios of the drive train. For the sake of this example, say that comes out to 2000 steps/inch.

(2) Manually jog an axis to a convenient starting point (near one end of travel).

(3) Click on the "Zero X" button (or "Zero Y" or whatever axis you are using) to zero the DRO

(4) Using MDI mode, move that axis some nice, known distance. For example, move the axis 5 inches with "G0 X5".

**WARNING** This presumes that your max velocity and accel settings are realistic enough that the motors won't "cog" or loose steps during this motion. To be safe, you can set the accel and max velocity to something kinda slow.

(5) Measure the actual distance moved. For our example, say that is 5.5 inches.

(5) Now calculate the actual steps/inch. First calculate the actual number of steps that Mach4 (should have) output:

# of steps = (commanded disatance) * (current "steps/unit" setting)

So for our example, that would be (5 inches) * (2000 steps/inch) = 10,000 steps.

Now calculate actual steps/inch by:

actual steps/inch = (# of steps) / (measured distance)

So the new, supposed actual steps/inch = 10,000 / 5.5 = 1818. Enter that as the new "steps/unit" and then re-run this test to verify the setting.

Bob