This might be very basic, but I'll ask anyway.

What's the standard fit for a pulley on a shaft? got some pulleys from beltingonline and the one which fits on the motor shaft, which has a 5mm keyway and two grub screws looks like an tight fit, ie. I have to push down really hard on the pulley to get it on the shaft and even then it doesn't go all the way. I'm a bit reluctant to use more force as:

a) not sure what the shaft can take

b) not sure I'll be able to pull it off later

I think it gets a bit tight around the key, which seems pressed into the keyway on the shaft. Is it a good idea to grab some super fine sandpaper and run it around the sides of the key to take a tiny bit off and make fitting easier? if I'm talking crazy feel free to hit me.

Regards,
dsc.