Page:Practical Treatise on Milling and Milling Machines.djvu/176

170 Cutting a Short Lead Spiral Gear, Using a Vertical Spindle Milling Attachment

When the table cannot be swung to the required angle, a vertical spindle attachment may be used. The attachment is swung 90° up from zero, and the required angle of the spiral is then obtained by the swivel table.

Where the lead is as short as that above, it is better to employ the special attachment shown in Chapter V, for the ratio of gearing of the spiral head is such that severe stresses are brought to bear upon it in feeding the work. If, however, the job is set up as above, it is necessary to feed the work by hand.