Expanding mandrel

Expanding mandrel

This mandrel consists of a tapered spindle having sliding upon it three correspondingly tapered wedges, which can be pulled along by a nut screwed on the larger end of the spindle and embracing a projection formed on each wedge.

The work to be turned is carried on the cylindrical external surface of these wedges, which are prevented from slipping on the spindle by three fixed keys. An annular spiral spring keeps the wedges in position when the mandrel is slacked back.