Page:Practical Treatise on Milling and Milling Machines.djvu/193

Rh Milling a Cam, Using Spiral Head and Vertical Spindle Attachment

The cam blank is mounted on an expansion arbor inserted in the taper hole of the spiral head spindle.

Suitable change gears are selected to give the approximate lead and the spiral head is elevated to obtain the exact lead; the vertical attachment is then set to bring the end mill parallel with the axis of the cam. Where such short leads as this are being milled, there is great stress brought upon the spiral head gearing in attempting to use the automatic feed. For this reason the extended crank is fastened over the regular index crank and the job is fed by hand.