FORE:Shaping machines are generally provided with adjustable vices, devices for planing circular forms, and other details which cannot be so conveniently employed with planing machines. Another feature of shaping machines is a positive range of the cutting stroke produced by crank motion, which permits tools to be stopped with precision at any point; this admits of planing [136] slots, keyways, and such work as cannot well be performed upon common planing machines.
FORE:The most perfect castings for gear wheels and pulleys and other pieces which can be so moulded, are made by drawing the patterns through templates without rapping. These templates are simply plates of metal perforated so that the pattern can be forced through them by screws or levers, leaving the sand intact. Such templates are expensive to begin with, because of the accurate fitting that is required, especially around the teeth of wheels, and the mechanism that is required in drawing the patterns, but when a large number of pieces are to be made from one pattern, such as gear wheels and pulleys, the saving of labour will soon pay for the templates and machinery required, to say nothing of the saving of metal, which often amounts to ten per cent., and the increased value of the castings because of their accuracy.
FORE:(1.) What peculiarity belongs to the operation of forging to distinguish it from most others?(2.) Describe in a general way what forging operations consist in.(3.) Name some machines having percussive action.(4.) What may this principle of operating have to do with the framing of a machine?(5.) If a steam-hammer were employed as a punching-machine, what changes would be required in its framing?(6.) Explain the functions performed by a hand-hammer.
THREE:It is a matter of courtesy in the usages of a shop, and one of expediency to a learner, to ask questions from those who are presumed to be best informed on the subject to which the questions relate; and it is equally a matter of courtesy to ask questions of different workmen, being careful, however, never to ask two different persons the same question, nor questions that [169] may call out conflicting answers.
THREE:"Numbers?" Prout snapped. "Which part of them?""And what can I do for you?" he asked.
