A bent gear shaft

 before turning a half of a rotation .

before turning a half of a rotation .

 A half of a rotation . Notice how close to the tool rest the shaft is now. 

A half of a rotation . Notice how close to the tool rest the shaft is now. 

Unbelievably this gear came out of the movement like this . My customer said it was running for years . All I do to straighten it is tap on it with a small brass hammer.  Rotate , tap , rotate , tap ..... I use my cell phone camera for these pictures so some are better than others .