positioning problems

[mohsen7]

hi guy
I have problem with my cnc
when i move the X and Y axis in (+) it miss the zero point by 1 mm
but when i move it in (-) the X and Y it go back in zero point with no problem
can anyone help me

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[jones]

Sounds like your machine has backlash. You could check if the screws are moving axially or if they turn a small amount before the table starts moving.

[wizard]

I’d most certainly be looking for backlash also. It could be in the leadscrew nuts or in the leadscrew thrust bearings. Don’t dismiss other things though like loose serscrews, software settings issues, or issues with the linear bearings that you are using. Too much slop in the linear bearings can lead to the saddles rocking as the direction changes leading to displacements that look like bachlash.