Z axis going crazy

The Shapeoko Pro is my first experience with any type of CNC, 3D printer, laser engraver, etc, so I may be making some dumb mistakes. My first attempt to cut anything out was a simple Deathly Hallows design on plywood.

Almost the entire process went smoothly until the end during the cutout. The Shapeoko started in the bottom left corner and started cutting the bottom. It did not go all the way through but I expected that since it usually made two passes for all the pockets in the design and a full cutout is even deeper. Then it started cutting the right side, but since my workpiece was a bit too small, it only skimmed the edge rather than actually cut out, which again, is fine. However, for the top, it started out looking okay but near the top left corner, the Shapeoko suddenly plunged deep into the MDF wasteboard and even hit/shaved away at the metal tracks. After I stopped the machine and removed the workpiece, I noticed that the entire top cut went through the entire piece of wood, unlike the bottom cut. The two tabs I added were also missing.

I checked to make sure my bit was tight and didn’t slip and it was all the way in and was actually kind of hard to wiggle out after loosening the nut, and the router was as low as it could be in the mount so I don’t think either of those could be the cause. I’m not too sure what else it could be I am not too sure if I’m making much sense but I added pictures to help clarify (as a new user I can only upload one picture so I stuck multiple together and uploaded them as one).

Thank you

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Hi @Ali,

Can you upload the G-code file you were running for a look ?

Deathly_Hollows_First_Test (1).nc (53.3 KB) Deathly_Hollows_First_Test (1).nc (53.3 KB)

Here it is

G-code is all clean

Strange. It looks the Z reference got lost for some reason, but I can’t see why from what you describe.
I would…just try re-running the same file. But to make it safe, rerun this as an air job first (artifically setting Z0 higher than it should be), and watch the toolpath being followed, with your hand on the switch.

If the air job goes ok, you could retry cutting the same piece again, placing the stock in the exact same position as the first time. Since the file is clean, it would most probably just work this time.

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@Ali I did not want to jump in the middle of your thread but I’m experiencing a similar issue. How I determined something was wrong is by using the bitzero for x, y, and z. After that, I jogged z down to the surface and used a piece of paper to get my z height. As you can see in my thread, the reading is .125" above 0.

I’m curious if you are seeing similar behavior.

I don’t have a bitzero, so I’m not sure if I can test it out. Or maybe I can and I’m just misunderstanding something hahaha.

I have the pro and the bitzero. I have not yet finished setting up the machine, what with it being new year and all its been a busy time- I will give it a go tonight and let you know if I have similar results.

Hey, I saw from the other thread that you seem to have sorted your issues.

for anyone reading - Z axis off using bitsetter

Just curious, is the problem still happening?

Also, what program was used to generate the gcode (the contents of the .nc file)? I ask because I use Fusion360 to generate the gcode I use and I notice formatting differences for the code you have and something like a code I get from F360 (‘humanized’ for easier human parsing of code)…

I have put 2 of my gcodes made through F360, one is for a 1/16" flat single flute endmill (a bunch of pilot holes), and the other is a v-bit (for my website lettering), for you to compare if you want…

MB1_ATP5_MB_2p15Holes_T476_AA20.nc (161.2 KB)

Pne91c_Vbit_AtherisEngrave_T896_AA59.nc (26.6 KB)

I had a simular issue. Doing a 20 circle cutout my z started plunging on the last pass. going into the wasteboard then the track breaking the bit. I think it was caused by EMF from a usb hub I had just put in. Had no problems before or after I installed then removed.

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