A useful contrivance for measuring the deformation in the cross section of a shaft. It consists of a length of 1-1/2-in (3.8-cm) pipe fitted at one end with a micrometer and at the other end with a hard steel cone. The micrometer should have a range of 3 to 4 in (7.6 to 10 cm) and should fit into a bushing in the pipe in some manner. It may thus be removed from the bar for safe keeping or during transport.