Fig. 786.
Fig. 787.
[Figs. 786], [787], [788], and [789] represent an expanding mandrel designed by Mr. Hugh Thomas, of New York City. The body b of the mandrel is provided with a taper section g, and either three or four gripping pieces a, a, a, a, let through mortises or slots in a sleeve c, which fits the body of the mandrel at each end.
Fig. 788.
This sleeve when forced up the mandrel by the nut d, carries the gripping pieces along the cone at g, and causes them to expand outwards and grip the bore of the work, which is shown in the end view in [Fig. 788] to be a ring or washer w.