Im not sure but mine dropped about 4 thou mid cut in a 500$ sheet of aluminum thankfully on the backside last night. What version of CM and CC are you using?
Since the tool aligned with the correct Z afer initialization, that would seem to rule out slippage.
So check the Z bearings - lubrication, dirt, corrosion.
Check Z motor wiring - every connector, check for loose wires, corrosion or evidence of arcing (heat / discoloration).
You could set up a Quick Action that raises and lowers the Z repeatedly - you can then run it when everything is quiet, see if there is any evidence of binding. You can also manipulate each connector as it is running, to see if there is a dodgy connection.
I upgraded recently but didn’t know the exact build of CM. I know it was from 2023 though. My guess would be build 639. I’m now on build 640 the latest as of now and running it again.
I did a full internal cleaning before this happened and tightened down the Z motor.
Tomorrow I’ll check out the wiring. I feel like it’s not a mechanical thing, but probably hardware/wiring/software. The quick action to test Z might trigger it or maybe I’ll mess around with the jogging to trigger something abnormal.
Almost certainly Z bearings/rails need cleaning/lubing so it skips steps on retraction.
I really wish CM would measure the tools at the end of the cycle to warn of skipped
steps of slipped cutter.
Figured out the issue after ruining so many damn parts and wasting time with this. The top of Z stepper motor was completely detached and the rails were the only thing holding it in place.
Closer inspection of this I see that the housing here has top and bottom screws which share the same thread insert (the top screws go all through the motor, the bottom hex screws hold the motor in place).
I think what happened is that the bottom hex screws which attach the motor to the z carriage were over tightened and force stripped the 4 philips screws that hold the motor case together.
I tried screwing the philips, all 4 simply spun. when I lowered the z to the ground, it simply fell apart like pictures.
OK, so at this point there is literally nothing you could do to make this worse - the alternative at this point is getting a replacement from C3D.
It looks like the motor is attached to the mount from below, so if you could get the motor together permanently, you could still remove it if you had to.
I would first clean things out to make sure that there are no metal shavings inside. I would get some epoxy (NOT the 5 minute stuff - it sets up too quickly), and put a small amount in each hole, and a small amount on the flats around the screw holes. You don’t want a lot of squeeze-out, so in this case you want to be conservative. Push everything together with some weight, and let it cure.
Yea, I’m really hoping to salvage what I can from this piece. Thanks for the ideas @mhotchin I’m going to clean and fix it up best I can for the short term. I also reached out to support and looks like I’ll be able to buy a new stepper to replace this one with but it won’t arrive soon enough cuz I need to finish this prototype for a kickstarter I’m working on. Your ideas should help with that.
Here’s how I got things working — went to lowes and got some #6 zinc hardware, expanded the hole size, and cleaned everything up. Zinc won’t last, but I think it’ll be enough to get me through a few more jobs.
I’m just gonna sell this nomad, disclosing the issue here of course, and find something else with an ATC and more power instead of getting the motor.