I resurfaced the CNC spoilboard today. There were a huge number of excessively deep cuts; people have gotten very careless about this, and I think we really need to reset the culture for the new CNC. In some cases, there were distinct patterns cut very deep in multiple places, which means that someone saw how deep they were over-cutting — more than a tenth of an inch in one case! — and didn’t adjust their cut, which I think is totally unacceptable.
If you measure your piece accurately and adjust your toolpaths or Z zero accordingly, you should leave only a faint shadow of a cut on the apoilboard.