The half-tone process; a practical manual of photo-engraving in half-tone on zinc, copper, and brass, with a chapter on three-colour work

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. 1907 Excerpt: ...will cause the cutting to be not so smooth, and the cutters will be blunted sooner, besides the machines wearing more rapidly. A good ceiling for fixing countershafting is an advantage,; but it is, as a rule, possible to fix it to the floor, if space permits, or to the wall. Where the luxury of a separate electric motor for each machine can be afforded, all countershafting is dispensed with, and the machines can be placed anywhere that suits best. There is no doubt that this is the ideal way of driving the machinery. The power for driving machinery is invariably the electric motor, unless power shafting is already running Fig. 138. in the place. Even then it is generally an advantage to have a motor, as this renders the photo-engraving department independent, and able to run when the rest of the establishment is shut down. About 2 h.p. to 3 h.p. will run all the machines likely to be required in a photo-engraving establishment, and each separate machine can be run by a motor of from h.p. to i h.p. It is becoming quite a common practice now to have an independent motor for each machine. Continuous current motors are the most satisfactory wherever this current can be obtained, as they will stand a temporary overload better than alternating current motors. All the machines being run at a comparatively high speed, the shafting should be light and free running, with good lubrication, well-balanced pulleys, and very flexible belting with neatly-made joints. Routers. The most important machine is the router, the purpose of which is to rout or hollow out portions of the plate which are to be left white in the finished proof. This is requisite in vignetted and shaped blocks, and especially in blocks for catalogue illustration. The router (fig. 138) is made in a vari...