Waldown tool post grinder - TPG
Mount the shaft in a chuck at each end, set the facing tip angle at 10 degrees below centre and away from the direction of rotation, wind in the tailstock to lock the morse taper on the tailstock, set the diamond tip cutting depth with the cross slide, then lock the cross slide. Now fire up the grinder and use the carriage handwheel to move the diamond tip across the stone surface slowly.