Z Axis Resets / Won't Save Zero

I’m working on cutting the final sled to finish up assembly of my Maslow and I’m having a problem with Ground Control. It seems that, despite setting the zero and saving, as soon as I start the process the zero resets to around +.3". I double checked the GCode and it shows “Sending: G1 Z-0.8 F30,” which is the correct Z Depth for that cut, but for some reason the cut is only achieving a depth of around -.5". Any help, or a point in the right direction, would be great. Thanks!

Sounds strange. What does the z-report in GC show? The actual Z or the desired one?
G90 and G20 in the top of the file?

Oh, and welcome to the Forum!

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Sending: G90
Sending: G00 Z0.196

Is G90 some sort of offset built into the GCode?

GCode G90 absolute positioning and G91 incremental.
G90 G00 Z-5 will send Z -5 from where 0 is defined, while G91 will send Z -5 from where it is.
If you watch the happening if the arrow keys, the set to G91 to move from where they are and send a G90 and the amount to move and set the system back to G90.

Edit: What router is it and how is the Z-motor mounted? Did you take a look for a ‘backlash’ between up/down moves is noticeable?

I’m using the RIDGID R22002 mounted with the MakerMade kit, thoroughly bungee’d down to keep the router bottomed in it’s sleeve. One of the first things I noticed is the slack in the height adjustment, but I don’t think that slack was more than a quarter of an inch.

I just noticed I was running GC 1.25 with 1.26 firmware on the controller. Going to run another test to see if that was the issue.

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Edit: Looking at my last post, i discovered a un-sync between brain, fingers and keyboard.
Guess what i tried to say with the pictures is, that there where no changes that could relate to the error you are seeing. Good n8. See you soon.

Kind regards, Gero

A few questions…

When it is at the -.5 when it is supposed to be at -.8, what does the z-axis readout say in GC? Meaning, does GC think it is at -.8?

Also, are you trying to plunge directly to -.8"? When the z-axis retracts, does it retract to the correct height?

I am trying to ascertain if the axis thinks it is plunging, but actually isn’t for some reason (like the locking tab popping out of the threads)

You’re totally right. I dind’t think it was the case at first because it was hitting the same depth every time, but basically it seems like I had the tension too high on the cylinder clasp thing, so it was causing the orange button to skip and essentially re-zeroing the Z Height. By the time I figured that out, the orange button was already completely fubar’d, so I returned it to HD and got a new one. Seems to be working okay now. There’s still more slack in the system than I’d like (plunge to .745 instead of .8), so I’ll definitely be putting together the Meticulous Z kit asap.

Thanks for all the help!

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Sorry for the trouble. Glad it is figured out.