Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . to be placed ona mandrel be-tween the cen-ters of a lathe,notched to pre-sent cntting-edges, and to in cutting screw-tools, chasing-tools, etc. The chasing-tool, forinstance, is laid on the rest and pressed forciblyagainst the hub. (Fig. 2600.) 2. {Die-sinkuig.) A cjlindrical piece of steel onwhich tlie design for a coin is engraved in engravi
Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . to be placed ona mandrel be-tween the cen-ters of a lathe,notched to pre-sent cntting-edges, and to in cutting screw-tools, chasing-tools, etc. The chasing-tool, forinstance, is laid on the rest and pressed forciblyagainst the hub. (Fig. 2600.) 2. {Die-sinkuig.) A cjlindrical piece of steel onwhich tlie design for a coin is engraved in engraving is done while the steel is soft, and,after hardening, the hub is used to make malrixcs,from which are made punches which impress the(/(?<?« used in coi/«)M/. (See Matrix ; Punch; Dik.)Tlie hub or the punch is pressed upon the softenedsteel blank in a powerful screw-press ; and the matrixor die is removed, annealed, and replaced severaltimes, as the pressure the efiect of hardening. 3. (Vehicles.) The central portion of a wheel Fig. Carriage and Wagon Huhs. which is slipped npon the arm of the axle, and in I chariot, found in Eg>pt, and now in a Europeanwhich the spokes are set radially. The nnve. \ museum, probably that of Berlin. It is supposed to A bronze hub, -with peripheral sockets for the i have been carried to Egvpt as a trophy by a con-reception of the spokes, is in an ancient Scythian queror of that nation. See Ch.^riot. HUB. 1140 HUB-BORING MACHINE. a is a lull) liaving a circumferential gi-oove, inwhich the shoulders form a continuous hanJ, whilethe tenons of the spokes set in mortises in the bot-tom of the groove. b is a metallic hub, one portion of which formsthe arounil whicli are the nuts on the innerends of tlic duulile set of iron spokes. c has two circumferential metallic bands, betweenwhich tile sjiokes, forming a solid circular series, areclamped and bolted ; tlie clamps also holding theWooden sleeves around the axle-box. (I
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