Many thanks...John you reinforce a good point there - I'll try & get a bit of aluminium round bar almost as long as the stepper shaft itself - I recall a technique where say the faceplate could be heated & the stepper motor placed in the fridge...if the hole is bored at just the right diameter it should only just coax onto the stepper shaft under this 'thermal difference' condition...as everything returns to room temperature, the faceplate should be held onto the shaft solid. (a bit like wagon wheesl - no not the tuckshop biscuits, but in the wild west - except no fridges or Apaches involved)

What's this method called?