[CNGBiFuel]

How the Steppers Got its Heatsink
Oh best beloved your stepper needs a heatsink. We shall begin.

See the piccy. You are lucky. My background is electronics so I was aware small motor can sizes are to one industry standard. Our friends with Radio Control cars, boats, and aircraft have come to our rescue. Their DC motors have the same can-size as a Necam stepper motor. See? I said you were lucky.

Dirt cheap, you'd be a fool not to fit one. You want a 540.
But again, pulling from my background, I suggest you bring heatsink-paste to the party. Used on heatsinks in your laptop etc, heatsink paste gives a vastly improved surface-areas to the bond. The fan you hear on your laptop will be blowing over the heatsink. This heatsink will be fixed to the processor-chip using a paste. Also dirt-cheap, this paste can be used to glue the heatsink to your stepper. Electronics must be kept cool. Borrow this lesson from the electronics industry.

These heatsinks are almost always Chinese made, hence the colours of these things are definitely last season, but this is no concours-parade. I repeat, I would advise you follow what one of customers did, fit the heatsink, and get your old vacuum-cleaner hose force-cooling the stepper by letting it act as a scoop fitted somewhere in the grill. Hence a nice cool stepper.

Heatsink paste/grease
You'll find these pastes easily enough. See pix, you need the tiniest squirt. You'll do the whole job for under £10 (Euro15). Far cheaper than a cooked steppper.