Good afternoon, how are you?
My name is Sergio and I am from Argentina.
This is my first question, and I clarify that I use Google Translate, in case there is something that is not well translated or is not understood, please ask me and I will try to see how to explain myself better.
I will tell you my problem:
A couple of years ago I built a CNC router which I manage with MACH 3. Initially due to cost issues I bought an inexpensive interface board, of which I found more tutorials on YouTube (#1 in the attached image), sometimes it made me skip steps and it was not always accurate, but it served the purpose I was using it for.
Then I added a laser head to the equipment, and these errors ruined my work, so I decided to invest in a slightly better board (#2 in the attached image).

The 3 axes are moved with Nema 23 motors (57HS112-4004) and DM 556, in all 3 I also use the same flat thread rod with 5 mm pitch.

With this new interface board (MKX-IV), I cannot calibrate the axes.
I did the corresponding calculations for the pulses and steps, with the frequency to be used (USB – 100,000 Hz), but I cannot get the equipment to move the millimeters I want.
I put the theoretical values ​​in Motor Tunning, when I do the test to calibrate the axes in the “Settings (Alt-6)” screen, “Set Steps per Unit” button, it goes through another measurement, I adjust it in the 3 axes.
In the 3 axes the steps vary, it is set to 1850 in “Y” / 1505 in “X” / 1150 in “Z”.
I find it strange because they are the same rods and motors on all 3 axes. Anyway, I save the changes every time I calibrate an axis.

The problem is that after that, I put a “zero” at any point in the work area, move the 3 axes to another side, when I press the button to return to that point, it does NOT return, it always stops before reaching it, and the motor tuning values ​​change again.

Could someone tell me how to fix this? Or why this happens?

Thanks, and sorry if it was long, but I wanted to explain myself as best as possible.

Regards,

Sergio