Can not get CENTER to be equal to HOME

As you can see from the pictures Ground Control believes my center point is about 19 inches higher on the axis but my Maslow has the rig dead center on the ply. I can not figure out how to get these to point to align. I have retried calibration many times but when I hit “center” Ground Control moves my rig 19 inches lower on the ply. I’m on version 1.26 any thoughts?

There are a few parameters that get optimized during the calibration and one is the height of the motors above the worksurface. It’s called “Motor Offset Height in MM” in the Maslow Settings. What value do you have for that? If its really low, then that’s going to result in center being high and if really high, then that’s going to result in center being low (I think I got that correct).

The most common cause for a bad value is entering bad measurements during calibration. Double and triple check your measurements, record them, and post them here.

I saw that one, I am sitting at 444.2 mm. Well within range to have a reasonable center point. It’s hard for me to understand that the center of the 8 by 4 ply isn’t what the computer believes is center because of slight differences. But when I originally calibrated the machine my center point was less then 1 inch off on x and y access, plenty close for my needs. Now after letting it sit for 3 months it has the center about 4 inches from the top of the ply… Very odd. I have spent 6 hours with it today…no luck.

Have you reset the chain lengths?

I did and that seems to have helped, I wonder why that would have changed to drastically? I never messed with the setting. Still not in the dead center of the ply but close enough. Thanks!

Dead center (left and right) will only happen if the motors are perfectly spaced apart centered on the plywood. You have to be very precise in construction of the frame and installation of the motors to achieve that.
Dead center (up and down) is entirely the result of getting lucky with calibration… but note, a bad calibration may result in a vertical center whereas a better calibration might be off-center as the formulae used in the kinematics are not a perfect representation of the machine.