Hey Bruce, You are talking about calibrations to a metrologist so I already took your measurements only as a guide. The reason I live in Barbados is because I work for an organisation where I am responsible for improving the calibration capabilities of the labs within the Caribbean. My previous job my background was calibration of pressure gauges, force equipment, torque wrenches and gauges along with some flow and volume work. Since I am now a paper pusher this is the only way I get to dirty my hands and have some fun. Gratefully there are guys like you that already did all the research so I get to do and not think so much. Everything I do would be relative to the o-rings and the shaft diameters as indicate by my instruments. The key is that I want a sealed fit between the o-ring and the bushing. Problem is in Jamaica I would have access to a machine shop. Here I will have to use a drill press and hack saw blade to make the grooves.