Does anyone have a test block that would help me diagnose a drifting Z error. I have a 40mm x 40mm milling area and 5mm blocks woule be good.

I have this drifting z and I am trying to tell if it is geometry dependent, a failure of the cam software to interpret the stl file, or if the mill is drifting for some odd reason.

Any and all help will be appreciated.

Regards,
James