Page:Practical Treatise on Milling and Milling Machines.djvu/208

202 Milling Flutes of Twist Drill

This operation is very similar to that of cutting a spiral gear. The drill blank is mounted on the spiral head centres and fastened to the spindle with a dog. The spiral head is geared for the required lead and the necessary angle is obtained by swinging the swivel table.

As the character of the cut is heavy, the arm braces are employed to give additional rigidity to the arbor. A stock cutter of special form, known as a twist drill cutter, is employed and oil is used in cutting.

More complete information on this subject can be found in Chapter IV.