OVERLOADED - THANKS FOR INTRODUCING ME -
Mr Chips - I fail to see what your problem is, and how you can possibly put all these diffrent numbers into "steps per unit" and hope to get anywhere.
Steps per unit, and we are talking of Config/Motor Tuning - bottom left hand corner, is a finite fixed number. It is not something that can be measured, guessed at, adjusted or anything else. We have covered this many time n this forum - and we still get the same old arguments popping up.
Steps per unit is asking you to say how many pulses the computer has to put out to move the axis by 1 inch (if in inches) or 1mm (if in millimeters). You must calculate this.
The thing most people seem to have difficulty with is the pitch of the leadscrew. I converted my old manual machine and here the pitch was 1/10th inch, i.e. 10 turns per inch - easy. You must find out accurately what the pitch of your leadscrew is. If you don't have a leadscrew - say a belt drive, it still comes down to the same thing - how many turns of the cog wheel produces 1 inch movement. If your leadscrew is in millimeters, then I would set up the whole machine in millimeters, it is easier.
Most motors are 1.8 degree per step these days, so therefore 200 pulses are required to turn them one rev. All drivers do microsteps , and 8 microsteps are the norm - so settle for 8, it gives a good combination of smoothness and power, and is well within the capabilities of the standard P.C. Multiply 8 by 200 = 1,600 steps per 1 rev of the motor.
If you have any gearing between the motor shaft and the leadscrew shaft, then this is added now - mine is 3 to 1 (steel cutting lathe) - so the equation is now 200 x 8 x 3 = 4,800. The only thing left is the leadscrew - I said mine is 10 turns per inch - therefore my result was 200 x 8 x 3 x 10 = 48,000 steps per inch.
This is a fixed number - it cannot be altered - particularly not to adjust your supposed shortfalls - the fault will lie elsewhere.
This is entered in Config/Motor tuning/(select the axis) - bottom left hand corner. Make sure after you have entered it you press the "Save Axis Setting" before you leave that axis, otherwise the figures will revert to the previous entries. Whilst on this page I would also set the speed at a modest 4 inches per minute and acceleration at 0.5. You want accuracy at the moment - not speed.
The way to check this for accuracy, if you must, is not to muck about with squares. Simply move you axis using the MDI line.
Make sure backlash compensation is OFF
With the table central on the machine, zero the axis DRO. Type in G0 X1 and the axis will move 1 inch. Do not try and measure this - it was only to get rid of backlash (and do not believe anybody who says they don't have backlash). Set up your measuring equipment and zero it (I use digital calipers) and then type in G0 X2. The axis will move another inch - and this you should measure and it should be 1 inch. (Give or take a couple of thous either way - because accurate measuring is impossible unless you have really specialist equipment.
If the answer is not 1 inch, then you have a problem - and you will have to come back to us.
While you have the measuring set up, the type in G0 X1, the axis will return 1 inch - only it won't - and if you check your measurement then the shortfall is backlash - make a note of it.
Repeat with the other axis.
You can then enter the backlash into Config/Backlash and switch on Backlash compensation. Set speed at say 50%. Backlash compensation sounds very disconcerting when you first use it, but it is accurate - and adds that little bit extra on each change of direction to take up any movement in the gears etc as the get their shoulders down to pushing the other way.
You could now try your 1 inch square.
You can now try motor tuning !
Gradually increase the speed on each axis. (Dont forget to save axis settings each time) You will reach a point where the motors stall as they start up - back off from this point to your last safe setting. You can try the same with acceleration. Don't try and get to the moon - I need accuracy - not super fast speed.
My motors, at first would not get past 4 inches per minute - 220Ncm motors, wired in series at 24 volts. I wired them in parallel and changed to Gecko drivers - and I can get up to 40 inches per minute (although I have reduced this for accuracy - they keep stalling on a couple of tight spots on my lathe bed) and my latest improvement is using 36 volts for the drivers.
Setting up the "step per" and speed and acceleration and backlash is an exact science - not something you can find by trial and error.
Sorry about the big post - but I had to get that diatribe off my chest (again)