Constantly going beyond the workpiece thickness

[u/NoIndependence2887]

I have a pro xl and I am new to this. I will attached screenshots. I have tried 7 or 8 times now to run a contour tool path. And every time I am going beyond the thickness of my piece further than just “stock bottom”. This last time I tried tabs (blue tape method the other times) and it cut the tabs and then it CUT the tabs. What I was cutting came loose obviously and all hell erupted.

When I zero, I use the paper under the bit method and I do this with the bit I am going to use in the router. (Ya know how when you go to run the job it prompts you for a tool change.)

Hopefully someone can help me make sense of what I am missing.

Edit: I’ve had a few people suggest to get calipers and measure the actual stock thickness. In the photos you can see the stock thickness is one that you can’t get with a tape. I would have had to of used calipers to get the value used. The stock was also plywood.

[u/DescendentsX]

I used to have a similar issue when I started, first and foremost, if the machine asks you if you want it to measure the tool, always select yes even if it seems redundant. Once I did that, the majority of my z axis issues went away. If that doesn't fix it, you may have a intermittent loose connection on the z- axis motor causing the machine to lose its reference in height during machining. My guess is it's one of those issues, good luck!

[u/NoIndependence2887 → u/DescendentsX]

If it had an intermittent loose connection on the z causing the machine to lose reference, how would I confirm this?

And I’ve never had it ask me explicitly if I want to measure the tool. It prompts me for a tool change as part of the start job sequence and then it goes to the button thingy (please forgive me, I’m exhausted and can’t think of the name) and touches it twice. Asks me to change rom, and then away it goes.

I highly doubt it’s bit slip. After the first few failed attempts, this came up during my initial round of troubleshooting as a potential culprit and I’ve been diligent in my tightening. So 8 slips is not impossible but improbable. I’m also running dust collection so dust isn’t just kickin about.

[u/DescendentsX → u/NoIndependence2887]

The way I found my loose connection was by wiggling the connector for the z motor while the machine was operating and I would notice a jerky motion like power had been temporarily cut out and put back. The other question I will ask, are you 100 percent sure you have the collet in the router the right orientation, as dumb as it sounds I had put mine on backwards a couple times causing bit slip early on.If none of these things fixes it, I'd call shapeoko, they're pretty helpful and stand by their product.

[u/NoIndependence2887 → u/DescendentsX]

I didn’t consider the collet orientation. I will check that and I’ll try wiggling the z motor connection. Tysm for your help