"Lloyd E. Sponenburgh" lloydspinsidemindspring.com fired this volley in
. 4.170:

where you'd
have to rotate the cutter in the anvil, and get a "feel" for when it was
properly seated at the 120-degree points.


To clarify that, the wings are cut with relief, but also are not parallel
to the axis of the cutter shaft. So 'fiddling' it to a proper fit in a
micrometer would be a bit troublesome (about like measuring a dovetail
slotter). Even with the mic', it would require some sort of fixturing...

L