The Virtual Machine Shop

Center

1) A point around which things revolve or rotate.

2) In the machine shop this often refers to a centering device usually affixed to the tailstock of a lathe, which is used to support a work piece with a pre-drilled center hole. The center and the pre-drilled hole have 60 degree included angles. The center usually has a Morse taper on the opposite end for snug fitting into the tailstock. Live-centers have ball bearings for rotation. Dead centers do not rotate and require lubrication. The top image is a dead center. The bottom image is a live-center.