Page:Practical Treatise on Milling and Milling Machines.djvu/91

85 necessary. Fig. 42 shows an indexing attachment designed for this purpose. It consists of a bracket that is fastened in the table T slot at the left-hand end. The bracket carries a locking disk, together with change gears for gearing to the feed screw. To index any required spacing, * change gears are selected that Fig. 42 will produce one or more whole turns of the locking disk. For each division the locking pin is withdrawn and the table advanced by the crank on the feed screw until the pin drops into the slot again, and locks the disk. This method of indexing is therefore much easier than relying upon a dial such as ordinarily used for the purpose.

Tilting Table. A handy attachment, known as a Tilting Table, is shown in Fig. 43. It is designed primarily for use in connection with index centres when fluting taper reamers, taps, etc. In addition to this work, many other kinds of taper pieces can be accurately reproduced. Its general characteristics, the manner in which it is fastened to the table, and the way that it is elevated, are all clearly shown in the cut.

Fig. 43

Cam Cutting Attachment. The Cam Cutting Attachment, shown in Fig. 44, is used for cutting either Face, Peripheral or Cylindrical Cams from a flat former. The former is made from a disk about $1⁄2$ inch thick, on which the required outline is laid out. The disk is machined or filed to the required shape.

The table of the machine remains clamped in one position during cutting, and the necessary rotative and longitudinal movements are contained in the mechanism itself. The rotative movement is obtained by a worm driving a wheel fixed to the spindle of the attachment. The former is secured to the face of the worm wheel, and as the wheel revolves, the former depresses a sliding rack that