Engineerinworkshop MacHines and Processes; a Handbook for the Use of Students Taking the Workshop Training

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1910 edition. Excerpt: ...at all. The wear and tear is therefore unequal, being greatest at the circumference. Still, as the end cutter is not related in size to the size of the surface, while the cylindrical cutter must have a width equal to that of the surface it machines, the end cutter is cheaper in this respect. Formed or Profile Milling Cutters.--The end or facing cutter can obviously be used only for flat surfaces, and can therefore not be applied to the class of work which is so advantageous to cylindrical cutters. This work, namely, the machining of shaped surfaces, is very common in engineering practice. If, instead of a straight cutting edge, the cutter be given a formed or profiled edge, then when it is rotated in contact with metal, the surface generated will be the negative of the profile of the cutter, which we here regard as the positive. It will be readily seen that, being provided with a correctly shaped cutter, the saving of time is enormous compared with any other method of working. Further, the high degree of accuracy attainable is in no way a disadvantage to economical work. But the greater the effect the greater the expense, and in this case the great expense is in the manufacture of the cutter. The making of such a cutter requires special machinery and expert labour, and the expense involved is only justified when repetition work is to be done--such work as gantrys for lathes and the like, and particularly for the machining of the teeth of spur and worm wheels. A set of wheels, such as the change wheels for a lathe, having to gear all together, may be cut with one and the same cutter. In addition to the accurate shape of the teeth, the pitch must be correct, and this is ensured by the use of the " dividing plate," to which the...