Page:Practical Treatise on Milling and Milling Machines.djvu/197

Rh Milling Bolt Heads

The illustration above shows a method of milling the heads of square and hexagonal bolts, using a chuck on the spiral head spindle for clamping the work. It also furnishes a good example of the use of a pair of side milling cutters as "straddle mills." Two sides are finished at a cut, therefore completing a square bolt head with two cuts and a hexagonal one with three cuts.

In indexing the work, the worm of the spiral head is thrown out of mesh and the divisions are obtained from the rapid index plate on the spindle nose.

As the material is of wrought iron, oil is used in cutting.