by cvoinescu » Tue Oct 29, 2013 10:17 am
Help us help you. There is no one "the" kit -- there are several, from different companies, and I'm sure they have changed over time too. So, which kit do you have, and, ideally, what motor are you looking to replace? Almost all have part numbers on them, so give us that, and the name of the manufacturer, if known.
That said, there are only a few sizes of NEMA17 motors. They all have the same footprint, 42 mm square (1.7", thus NEMA17), M3 holes on a 31 mm square, and a 22 mm diameter boss raised 1.6 mm. Most have 5 mm diameter shafts, about 24 mm long (but watch out for more exotic shaft sizes, and for dual-shaft motors -- you don't want one of those). What differs is the length of the body of the motor, with 40 mm and 48 mm being very common. If you get a NEMA17 motor of the same length, same rated current (or close), and the same step size (either 0.9 or 1.8 degree), it should work.