Fig. 32.
Fig. 33.
Still-another kind of metal spinning can be done in the lathe. This relates to making circular shapes, or cylindrical, more properly—such as napkin rings, the tops of steam pipes, or similar things. To do this, a mandrel is requisite. The mandrel must be of steel, and turned to the desired pattern—like [Fig. 34], for instance.
Fig. 34.
A ferrule is then made and soldered together with lapped edges, so that there will be no seam. The mandrel must be as much smaller than the size of the finished work as will allow it to come off freely, for it will be apparent that if the work was spun up on the mandrel, it could never be taken off. The ferrule, when put on them, will stand eccentric to the mandrel, as in this figure—that is, when the tool bears on it. In other respects the process is just the same as spinning on the face plate. Tripoli, chalk, whiting, rotten-stone, and similar substances are used to give the fine polish on such work.
Fig. 35.
