I work in the oilfield for a company that repairs diamond drill bits. Each drill bit is basically a cylinder with 2 to 3 inch thick "blades" extending radially from the center axis of the cylinder. Each blade holds man made diamonds that chip away the rock while drilling. These bits are spinning at high RPM's while drilling. These blades erode away radially while drilling in the hole. My question is: How can one calculate the radial erosion of each blade using a ring and shims, and if they don't have some sort of Coordinate Measuring Machine? I'm hoping there is a formula of some sort I can plug in using the amount of blades, diameter of the ring, and thickness of the shims. This method would probably only be used for 3 and 5 bladed bits, and the blades are evenly spaced.
Just to clarify a little more: The ring and shims are a measuring device to check erosion. The ring is placed around the eroded bits and then shimmed tight by contacting at least two blades on ones side of the ID of the ring and shimming against one blade opposite those two on the ID of the ring. If it makes the problem easier you can assume that all blades erode equally, but in reality the erosion is different on each blade.