If you have a progressive error, your steps per unit will probably wrong.

You do not say what machine you are using, or how you have set it up.

We will assume it is up and working.

You now must calibrate it accurately, and then first thing to do is set the steps per unit - see Config/Motor tuning, bottom left hand corner. Whatever your units are, inches or millimeters, you must calculate how many steps your motors need to move your axis I inch (or mm)

This is a round figure. My Gecko drives have 10 microsteps, my motors requie 200 steps per rev, I have a 3 to 1 step down gear to my leadscrew, and my leadscrew turns 10 times per inch. My steps per unit is therefore 10 x 200 x 3 x 10 = 60,000 steps per inch.

Art included a system for the machine to calculate this, but it involved measuring, so it is flawed, since you cannot measure accurately. It is alright to check your figure with this and see that you are not out by some rediculous amount, but the steps per unit is the calculated figure, not the measured one.

You can then run your machine to 1 inch, 2 inches, 3 inches - in fact as far as you can measure. I am not saying you will get a precisely accurate 1 inch measurement - it might be 0.998 or 1.001 - but over the rest of the measurements the accuracy will stay within these limits, because the errors on the system are not repeatable.

Always remember when taking measurements to move the table right, stop, zero everything, then carry on moving right. Or the other way, move left, stop, zero everything, then start measuring. This will get rid of backlash.

Once you have you steps per unit set, then you can configure backlash.