[QUOTE=2e0poz;22816]I played around with the ratio tonight and set it to 5.35 which brings it almost correct after some trial and error adjustment.

4.5*173.5/150=5.20 which is close to 5.35 ... doesn't make sense to me at this time of night though.

With 3200 steps per rev, and using 26.66mm per revolution as worked out in my last post that's 120 steps per mm.

Oh just notices, 5.35/4.5 is 1.188 ... i.e. very very close to 1.2, which is the factor the 24T pulley adds in. 1.2*4.5=5.4

So in conclusion try 5.4 and I bet it will be right...I'm not going to bet much though as it's getting late