Depth changes on cuts

I am having a problem getting a consistent cut depth in my projects. Why would it change as the project progresses? i have checked everything i can find in the troubleshooting area. any help would be greatly appreciated.
When the project starts the cut is a consistent depth around the whole parameter of the project. As the cut progresses it does not cut to the same depth. In the last picture the deepest cut is supposed to be the depth for everything. It is a consistent depth all the way around the parameter of the project. Is my machine somehow loosing steps?

When you set your zero point with a probe I am assuming you must do it in the exact same spot for detail and roughing. Also you could be getting flex in your project depending on how you have it secured to your waste board. As you remove material it can flex. for instance. When I do 24x24 PVC I use the glue and tape method to be sure the entire piece is secured down for the reason above. It will dramatically change how clean your carve is. Steve

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Yes sir, same zero point. For the project in the pictures I used four clamps to secure the project. A piece of maple .875 thick 24 long and 8.75 wide. When the carve starts the depth is good and consistent from end to end and top to bottom. The depth doesn’t change until the first time the z axis moves up and then back down in a different spot. Then it doesn’t drive to the same depth again.

On the previous project I was a attempting a area clear and ran the same “g code” three different times and it cut to three different depth all three times to get to a consistent depth for the whole area. Same issue as this project. About 20 minutes in the depth started to rise to the point it wasn’t even touching the project…

What are the bit types for roughing vs finishing?
What are the cut settings (feed, plunge, depth per pass AND the total depth of cut for the design)?

This issue is very common when either different style bits are used OR a thin finishing pass is not in use.
To achieve a thin finishing pass one could do some math with the total carve depth and the depth per pass to ensure the final pass is very thin, removing very little material.

Also ensuring the wasteboard is not flexing (sometimes this means adding support underneath) AND ensuring the cnc is as rigid as possible by maintaining the Vwheel adjustments as well as the belt tension will have an effect on unevel depths between bits…

You are removing a lot of material and I suspect the wood is warping/flexing as a result as Steve said.

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Good news is, Mountains is spelled wrong so you gotta re-carve it anyways