This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1887 Excerpt: ...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. 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. The advantage of this form is that the cone at gcan be easily turned or ground to keep it true, and the gripping pieces a may be fastened in their mortises by means of the screws shown at /1 in the end view, and thus kept true. It is obvious that for long work there may begripping pieces at each end of the mandrel, as in Fig. 789, and the work will be held true whether its bore be parallel, stepped, or taper, a valuable feature not usually found in expanding mandrels. Vhen a mandrel is used upon work having its bore threaded the mandrel also must be threaded, and must abut against a radial face, as at a, in Fig. 790, because otherwise the pressure of the cut would hold the work still while the mandrel revolved, thus causing the work to traverse along the mandrel. If the thread of the mandrel be made so tight a fit that it will drive the work by friction it will require considerable force to remove the work from the mandrel, so much so, in fact, that finished pieces would be much damaged in the operation. It is better therefore to have the work such a fit that it can be just screwed home against the radial face of the mandrel under heavy hand pressure (if the work be not too heavy for this, in which case a clamp may be employed). Small work, as nuts, &c., are turned on a mandrel of this kind, which has a stem, and fits into the cone o...
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