Hi Hood: yes, quite repeatable in the manner you describe. Always moving the slide the same way to the measurement point to eliminate backlash.
Rich, I'm not sure who the original pulley supplier was, they were ordered through RS Components. I mounted then in a 4-jaw by the hub, centred on the existing small centre hole (DTI), and drilled and reamed out to 0.25 inch for the motor or 8mm for the L/S shaft. However the holes were too small to easily bore so some inaccuracy may have crept in. Surely backlash shouldn't affect CNC turning to a diameter any more than it does manual as the feed direction is always one way? And my measurement was ~.02 on a radius which is .04mm on a diameter = .0016".
OK, I realise I may be trying too hard here, but if for example I want to turn down a shaft to be a running fit in a bored hole of a given diameter using CNC, should I expect to be able to do this in one program or to stop a few thou short and use semi-manual techniques for the final fit?
Thanks, John.