Brief mention has been made of cutters to generate irregular contours. These cutters are known as form cutters, and, except in certain shapes, such as quarter- and half-rounds, are not carried in stock, but are made only to order. There is such a large variety of forms for which such cutters may be used that it is impossible to give more than typical examples. The form shown in Fig. 213 consists in reality of several cutters, some of them of ordinary shapes and sizes, with others of special forms, the whole making a gang cutter whose object is very apparent.

Fig. 213. Gang of Form Cutters.

Among the standard shapes of form cutters are some which are now carried in stock for producing certain tools requiring cutters of definite yet peculiar form. Among these may be mentioned cutters for fluting taps, reamers, and twist drills; cutters for sprocket and gear teeth; and cutters known as hobs, for the production of worm gears, Fig. 214.

Sprocket Cutters..

TAP AND Reamer Cutter..

Worm Gear Hob..

Fig. 214. Standard Shapes of Form Cutters.