Hand Tools Archive
Hmm, I'm not sure what you mean by "taper" (this is definitely one of the cases where a couple of beers and a piece of paper would make the conversation a lot quicker ).
We did use a drawknife to shave a bit off of the top of bottom to get them to a more consistent thickness (this was mostly for shops/chicken coops though so never got to carried away).
The sapwood (and ratty edges) were (if I recall correctly, its been a longish while) were mostly shaved off with a hatchet or split off with a froe (I seem to remember doing both but can't recall why). We might have tapered the bottom of the shingle to be a smidge narrower than the top while doing that as well but I just don't remember.
Prying with the drawknife is sort of a crime, unless its not to bad and enables me to get one on the cheap I have been guilty of hitting a knot a bit to hard and nicking the edge, there's no real valid excuse for that either (and as a youngster I got me ears boxed for it as well).