In Fig. 250 is shown an arbor to be used in connection with face milling cutters. The shank A fits the hole in the spindle of the milling machine. B is the body which fits the taper hole in the cutter; this portion of the arbor has a spline which fits a spline slot in the cutter. The screw C enters the body of the arbor, and holds the cutter on the arbor. D is a nut used to force the cutter off the arbor when it is necessary.

Stock used in making such an arbor should be strong and stiff, and on this account tool steel is generally used. With the ends squared and the circumference roughed out, one end should be run in the steady rest, and the screw hole in the end drilled and tapped; after which the arbor should be countersunk at the end to furnish a center for use in turning and finishing. If necessary to harden the end of the tenon, that should be done before finish-turning the arbor, to prevent springing when heating. When the taper has been turned to fit the hole in the milling machine spindle, and, on the opposite end, to fit the cutter, the thread can be cut for the nut D, after which the arbor is cut for the spline as already explained.

Arbor for Face Milling Cutter.

Fig. 250. Arbor for Face Milling Cutter.

The result will be more satisfactory if the two tapers are left a trifle large until after making the spline cut, and are then ground to fit. Although the spline is intended to fit snugly in the slot in the arbor, the fit should not require pressure enough to endanger the trueness of the arbor when it is pressed to position.