So the tray drama continues: I get two passes into the tray, then I get skipped steps on the Z, and the tool crashes. I was watching closely, and as close as I can tell, something slipped. I could see the Z-axis drop a bit as it rose out of the tray, then crash, and cut a big gouge in the part.
I double-checked the couplers, and they were tight. It did seem faster, almost like a quick Z move; usually z moves slowly
Check the gcode to see if there’s a Z move speed that’s out of the normal range.
Is there a parameter for height over workpiece? At first glance, I did not find any out-of-spec z movement
There are some z moves where there is no speed defined and no preceding move that sets it
What are you using for CAM, estlcam? If you are using estlcam it is set with your rapids in one of the settings pages. If you are not using esltcam you can do it quick and dirty by adding it to your starting gcode.
What control board?
What steppers?
What is your Z plunge rate, and if you set a ripd what is it set at?
Did you Lube your Z screws, do they move all the way up and down easily with your fingers when the board is powered off? No binding at the bottom?
estlcam
jackpot
V1 steppers
4mm/s plunge
Yes lubed
the one side was a bit tight; I reset that lead screw and rer ran the test it got past the previous spot but the next deep jump it missed.
could not find the estlcam setting
There should be no binding at all, If you have any rough spots fix them. you can flip the leadscrew over if needed.
Values tab, here
Thanks, Ryan. I upgraded without much thought to V13 and lost those settings. I’ll need to try another test.
I see that V12 is still recommended. Are there strong reasons to downgrade?
We have a flood of CAM options now, and it’s getting hard to test them all.
Is there anything in particular in v13 that we should rush to change to?
There is some cool stuff, but in general he switched to this model so he could sell updates yearly that then get all the minor updates for free. There has now been a function to add Arabic text I think. 
I think v13 now has undo.