I used a 1 inch wide belt, 5mm pitch, for my X axis. The belt rides on 26T pulleys. It is geared down 3.6:1 at the motor.
This gives a resolution of:
5mm*26t = 130
1mm/130 = 0.0077
motor is 200 step and gearing 3.6:1 so:
0.0077*200steps = 1.54
1.54*3.6 = 5.544 motor steps to move 1mm
1/5.544 = 0.18mm is the minimum movement. Or .007"
When I build my all belt drive machine I'll use smaller pulleys on the movement belt to give more resolution. And aim for a 4:1 reduction also for more resolution.
Speed is no problem. My 110 OZ motors are running at 65% of rated current and I'm getting rapids of 800 IPM. So can afford to trade off some speed for extra resolution.
I hope that helps you make your choice of what pitch and pulleys to go with.
Regards Terry.....
http://www.terry-is.f2s.com/