Your maximum depth is always going to be limited to the length of bit that extends from the spindle and the rigidity of same..
Sorry, disagree. I have cut with the collet well below the top surface of the material as have many others. It depends on what you are cutting and how the model was designed. Things like draft angle on the model can allow the cut to be deeper than the length of the tool protruding from the spindle.
My max depth of cut has been 3.5 inches, roughly 88mm. IIRC the longest length of tool was 2 inches. The model height was 3.5 and had drafted sides. It is a flag with an eagle that I posted a month or so ago.
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