Z top plate zero point erratic

Love the machine!!! Randomly when the tip goes to touch the plate for a zero reference, the z cable keeps over slacking at touch and when it finally lifts the tip it changes the Z ref to about .200" negative. With a .200 cut height, it then puts the tip at about zero height…
it does this on hand drawn pendant files and files made on fusion 360.
Thanks for any help in advance

Make sure your workpiece is firmly supported. If it flexes or moves any when the torch tip contacts it the cut height is affected. I have experienced your problem.

plates are flat without bows

Just make sure it isn’t teetering from uneven support from the cutting table.
There is also a known issue with some of the Z axis lead screw nuts not being to spec. There is another thread on this.

Problem solved…
I had ty trapped a 2 wire harness to the entire Z cable housing to run the trigger. Turns out my harness added weight the cable housing caused it to sag at 0.00 and would change the make the 0 offset -.200
Thanks for you help

Ahhh yep attaching anything to the Z cable is a no-no

Glad you got yourself sorted though!