Hmmm...in the beginning of entry no doubt...

Yet, to actually implement a true "wedging force" I think the "wood element" being driven...whether square, rectangular, round, or having some other general geometric shape...must be forming an ever increasing "inclined plane"...(i.e. a wedge)

We know that a "screw" is a type of wedge as it maintains all those elements of having multiple "inclined plane" within its helix.

So...is a drawbore peg/trunnel actually a wedge??

There is wedging in the beginning, yet after that it seems to me to act more like a "spring shaft" or perhaps even a "cam" of sorts...not a wedge because the sides of the trunnel are typically of a consistent geometry...

I have seen "square wedging pegs" that also "draw bore" yet those seem uncommon for the most part...

Interesting observation Tim...