Mention of this has been made in the body of the work. It is used for
turning rings and washers, and various sizes of these can be turned
upon the same mandrel, so that a set of three will suffice for all
the work likely to be met with even in the largest factories. Fig.
1 represents the mandrel complete. F, F is the central part, with
a conical boss, A, cast upon it, and the whole turned with great
accuracy. Four longitudinal dovetailed slots, seen plainly in Fig. 3,
are then planed in the conical part, and into these are fitted
steel wedges, Fig. 2, A and B, and B, Fig. 3. C, Fig. 1, is a hollow
conical washer, which can be advanced over the central part when
driven forward by the nut D. This washer, acting on the ends of the
sliding wedges, causes them to move towards the large end of the cone
A, and, from the form of these and of the cone, any washer or ring
will be held tightly when placed outside these wedges, and will also
be mounted concentrically.
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
[Illustration: FIG. 3.]