Page:Practical Treatise on Milling and Milling Machines.djvu/134

128 Milling Sides of Foot-stock for Spiral Head on a No. 3 B Heavy Plain Milling Machine

This operation is of interest largely because the height of the sides milled is such that a gang of cutters of unusually large diameter is required. Three castings are lined up, strapped to the table, and milled at one cut. The outsides of the uprights are surfaced, and the space between is cut to the required width.

The cutters employed are inserted tooth side milling cutters 12 inches in diameter. Teeth are set parallel with the axis in the outside cutters, as their width is not great. In the middle cutter, which is wider, the teeth are set at an angle to give a shearing cut, and are nicked to break up the chips.