On my mark 1 Student the pulley is 5 inches – same as the top one with the brake assembly. it will shortly be 125mm in diameter when I've got around to replacing the old temporary (since 1990!) single phase 2.2kW (3 HP) with a new 3 phase inverter powered motor. The error is around 79thou. I'm working out how to switch the inverters 24 volts control line so I can keep the on/off lever, brake, and reversing switch. I've been told that the three phase switches at the rear of the headstock are not suitable for 24 volts. If so it's probably going to be microswitches round the back. The coolant pump may well remain as the cheapo 240 volt one from Graham Engineering of Roebuck Lane. Naturally there will be a big red stop button somewhere on the outside of the black box that used to house the Crabtree contactors. I'm hoping this will stop the ripple marks on cuts, due I'm told to a single phase motor!!!

Geoff