Thanks,guys. I checked the Sopko site and found the specs on the taper. The Delta uses a 3" per foot taper as do many of the other machines, but the Delta is slightly smaller - .87" at the large end vs.
1" for the others. I pulled the adapter off and confirmed the spindle measurement.
Making the puller was a whole lot of fun - I started with a piece of snowplow cutting edge from one of the big town trucks. It wasn't hardened, but it sure did work harden when I drilled one of the holes in it. Tried a few different bits - some cut it, some didn't. Even one of the cobalt bits had a tough time. Tapped OK, though, with carbon steel serial taps. Glad I had them in that size - I don't know if I could have done it with a single-pass tap. I should have known that was tough stuff - another piece I got had Kennametal stamped on it and had an inserted edge of carbide or something similar. Although the steel was relatively soft.
The puller was probably a waste of time, as now that the adapter is off it'll probably never stick again, but it meant I didn't have to bang on the spindle with a hammer. Which I really didn't want to do.
John Martin