Lately I have been examining a lot of ladies watches. The parts in these watches are extrimely tiny compared to the parts in clocks. The pivots in these watches are typically .004 inches or .1mm. If you end up with a .002 inch or .05mm taper on one of these things you have tapered the pivot by 1/2 of its diameter. If you are off .002 inches on a clock pivot it probably won’t be noticed. I have some equipment that allows me to examine these things that would not be part of a normal watch or clock repair shop. The Jacot tool takes the “eyeball” method out of the process. In a tool and die environment this tool would be known as a jig.