Jonathan,
the y axis motor shaft was not long enough to got through the motor mount to take the pulley. I had looked at making a different mount for the motor but it was working out to be rather thin material to get the pulley fully on the shaft so I decided to go this way. I could have made it a bit shorter but I dont think it will make too much difference.
The pulleys I had at the time so went with them rather than buying new ones. If the belt does give problems and runs off I can always change them for castle ones later.
The motors are these ones from Zapp Automation : SY85STH156-4208. I ordered the 2-4 Axis Nema 34 kit 2 and went for the bigger motors. With these motors I should have plenty of torque to drive the machine around as it will be quite heavy when finished and I prefer to have the drive system over-rated a bit :whistling:
The frame extrusion is heavy walled 80mm x 80mm with 80mm x 40mm cross bars. I cant remember the exact size for the Y axis, around 340mm x 40mm I think and again the heavy walled section.