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 CHAPTER V MACHINE SHOPS—FRAMES AND CYLINDERS Frames.—The frames come into the frame shop from the steel plate manufacturers, in whose works they are rolled in a similar manner to boiler plates. They are thicker than the latter, the usual thickness in British practice being from 1 in. to 1⅛ in. They arrive cut to a general all round size as shown by the outer rectangle in Fig. 17, this size being the smallest possible to allow of the finished frame being cut out from it. The frame plates are first tried over for straightness, and then levelled and straightened by means of hydraulic jacks.

They are then marked off, and roughly punched out to shape by making a series of interlacing consecutive holes outside the marked lines as in Fig. 18, leaving about ¼ in to enable them to be machined to size. After being punched, the plates are heated in a furnace and annealed or cooled slowly to remove injury to the material caused by the punch. When cold they are slotted