Page:Practical Treatise on Milling and Milling Machines.djvu/195

Rh Milling Slot in Bushing, Using High Speed Milling Attachment

This operation furnishes a good illustration of the use of the high speed milling attachment. The end mill is only $3⁄8$ '' in diameter, and where such small mills are used, it is necessary to run them at much higher speeds than are ordinarily obtainable on the machine, otherwise the finest feeds, either by power or hand, present material to the cutter faster than the teeth can remove it, and as a result, there is constant danger of breaking the mill. With the high speed attachment, the machine spindle speeds are multiplied so that suitable speeds to combine with the available feeds are obtainable.

The bushing being slotted is fastened in the vise at a proper height to bring the slot central.