Small clarification. If you don't set a flat depth, then the depth of cut is, in fact, set by the distance between the sides of the closed vector and the angle of the tool, as Mark noted. However, you can set a flat depth for a v-carve toolpath, in which case the depth will be limited to whatever you set. This means that if there are areas where the flat depth is shallower than the depth would be without it, those areas will be cut flat and will not have a "V" shape in the bottom.
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