[Moondog]

Mr Bean..

It is a 10mm pitch 30 tooth pulley. The belt is attached to the gantry. i.e, the belt moves the gantry. The reduction is 27 to 1.

Using your calcs, would mine be...

10mm pitch * 30T = 300
1mm / 300 = 0.0033333333
0.0033333333 * 27:1 reduction = 0.089999999
0.089999999 * 2000 steps = 179.9999 steps per mm of travel.

OR ?????? per step.

cheers