Steel Framed Router

[JAZZCNC]

The pulleys I use on steepers are HTD 20T 15mm they measure 25mm wide with 5mm boss. You can either use 4mm set screws thru the boss which leaves the shaft 3-4mm short of being flush.
Or do like I do and drill in the middle of the pulley between the teeth with a larger 5 or 6mm set screws which allows better purchase, just make sure the head of the screw sits below the bottom of the teeth.
This hisn't a problem because of the wider OD of the teeth theres more metal to work with. Then I either machine the boss down less so the pulley sits flush or some times dont bother and just turn the boss to the outside.

Unfortunatly I haven't got any machined to show you but I do have some unmachined pulleys which I've just taken pics of to give an idea of what I mean, also give you some idea of scale against a nema 23 stepper.
The set screws are M5's note the blue tak holding them took me 15 mins before I gave up trying to balance them in those groves.:whistling:

I've never had any problems with slipping doing it this way even with just one set screw, thou I always use at least 2, some times 3 120deg apart.!

Other option if going thru paltes etc is to have some extension shafts machined, thou not too long. Either Jonathan or I could do that for you if no access to lathe.