First I had a problem with stepper motor torque which was solved with reduction (this was done by the guy that build my cnc). Before reduction machine was relatively precise but it would never keep zero position. I had to check every time when changing tool or starting a new operation. After reduction was mounted, cnc has enough power for me not to be able to hold axis by hand, it pushes me away. it still doesn't keep zero and it got even worse. I changed linear rails and bearings which made axis move great but it didn't solve my problems. Next I formated the HDD and installed new win 7 32 bit and a fresh Mach3 install. Now it keeps zero but it developed strange behavior and that is the problem I can't solve. Now when I Auto tune a motor it will move perfectly, example: I tell it to move 200 mm and it moves like 150 mm and i give it correction and after that it will move perfectly 200 mm, but when i tell it to move 1400 mm it will move 1422 mm. If i tune it by moving 1400 mm and then tell it to move 20 mm it will move cca. 18 or 17 mm. Consistency is not a problem cause the machine will always move the same 1422 mm when is told 1400 if tuned to 20 mm and will return to 0 after. DRO says 1400 but it is on 1422 or in case of 20 mm it says 20 but it is 17 -18 or something but it is always on the same spot. If it is tune to 1400 it will move 1400 and DRO will say 1400 other dimensions will be more or less than 1400. I don't know what to do. Just can't figure out what is the problem. I have adjusted for backlash as well.
Z axis has Acme rod and it works like charm. What I tell it it does, 10 mm is 10.00 mm. X and Y are the problem.
Problem with tuning motor or maybe something else
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