Given a #251 w/ a 1.016mm cutting depth:
and a V carving toolpath which is to cut 2.5mm deep:
using a 60 degree V tool:
Raises the possibility that one could define a V tool with an angle of:
58.91 degrees
which would result in 2 passes with a #251 and leaving a thickness less than the 0.762mm Depth per Pass of an Amana #46200-K .125" 2 flute down-cut
The question of course, is what regions the larger tool cannot reach in a given V carving and how the smaller tool rapiding through that uncut material would affect cut quality, or even the tool.
It should be possible to arrange the toolpath depths so as to get an idea of what regions would be left uncut — possibly with the addition of some inset geometry…