This form of cutter is used in milling surfaces too large to be cut with the ordinary form of milling cutter held on an arbor passing over the work. As the full diameter of the face of the cutter can be used, it can have less than one-half the size that would be necessary for a side milling cutter. A side milling cutter must be double the diameter of the surface to be cut, plus the diameter of the collar on the arbor. For instance, if a surface as A, Fig. 247, were to be milled, it would be necessary to use a cutter somewhat larger in diameter than twice the height of the surface plus the diameter of collar B; whereas, if a face milling cutter of the form shown in Fig. 248 were used, the diameter need not be much greater than the height of the face of the piece of work being milled.

Generally speaking, cutters of this description are necessarily of a diameter that makes it advisable to use inserted teeth. The body may be made of cast iron, having a taper hole and key-way, and held in place on the arbor by a screw.

Fig. 245. Section of T-Slot Cutler.

Fig. 248. Grinding Attachment for Shank Cutters Courtsey of Norton GrindingCompany.

Fig. 247. Side Milling Cutter on End Work.

Table VIII. Dimensions Of Face Milling: Cutters

The teeth should be made of tool steel and hardened, or of high-speed steel, if the cutter is to be subjected to rough usage. In either case, they can be fitted to the slots by grinding on a surface grinder, and held in place by taper bushings and screws, as explained under "Milling Cutters with Inserted Teeth". The construction of the body can be readily understood from the sectional view given in Fig. 249. The letters A, B, and C represent diameter of cutter, width of face, and number of taper of the hole, respectively, while D represents the keyway.

Table VIII gives the dimensions of face milling cutters of different diameters.

After the taper hole has been bored and reamed, the body of the cutter should be placed on a taper mandrel fitting the hole, and the ends and circumference finished to size. It is then put in the vise on the shaper or planer at the proper angle, and the spline slot cut to an equal depth at each end of the taper hole. The burrs having been removed, the cutter should be placed between the centers on the milling machine, and the slots cut for the teeth.

Fig. 248. Face Milling Cutler.

Fig. 249. Body of Face Mill.

• When the teeth are firmly secured in their proper places, they should be ground for clearance, in accordance with the general instructions already given for grinding other forms of milling cutters.