The work head on my antique grinder is in need of some remedial work. When I measure the run-out (wobble) it is 0.006”. Might not seem like much but when you need to grind a shaft down to some size it would be great if the result were actually round!

The shaft is steel with a 1MT taper inside. The outside is brass, or maybe bronze. That taper is B&S which is 0.502” per foot. With the shaft between centres on the lathe I can measure the outside run-out, the inside being on the centres. So it is the outside which is wrong. The taper is also not a straight line.

A few very light cuts remove the wobble. The shaft now fits tightly but turns as well as it should.