The pictures show clearly the 45 deg location of the cutting
edge, the 40 deg clearance behind the cutting edge is visible but less
obvious.

Interesting. I'd always pictured skiving tools angled
the other way, so that they cut the chip off to the right.
And I want to say that some of them are angled even more,
so that they're nearly perpendicular to the lathe axis...?

--Glenn Lyford