24-volt steppers aren't too common especially on the surplus market, as
most are 3, 5 or 12 volt -- being takeouts from printers, computers,
audio players, and that sort of thing.
In any case, the usual suspects for surplus motors apply:
...and a whole slew of others. Most sell motors at least up to NEMA 23.
You might also try Web sites of stepper makers for pointers to local
distributors. If you're looking for something specific it can often be
easier just to buy retail! Try www.pacsci.com for starters.
Folks like Dave Rigotti have been selling CNC kits and parts for a
while. His Web still is www.hobbycnc.com. I don't see any 24v steppers,
though...again, this is not too common for steppers (common for DC
motors in automation, though).
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