All the operations of the machine are intended to be conducted from the front side, without any change in the position of the operator. The feed can be thrown out by hand at any moment by means of a rod which connects with the latch shown in the front of the cut, and the power quick-return applied; or the table can be run back by hand, and the feed thrown in by a foot lever, which lifts the drop box shown in front of cut. Adjustable dogs automatically drop the feed motion at any point.
The machine is massive in all its parts, and is intended for heavy milling of any description, but more particularly for shafting, railroad, or engineering shops, being specially adapted for key-seating long and heavy shafting, finishing guide bars, connecting rods, &c.
Its weight is 7,500 pounds. The work table is 7 feet long by 20 inches wide; length of longitudinal feed, 84 inches; distance between uprights, 24 inches. The cast-steel spindle is 4 inches in diameter, and the mill arbor 21⁄2 inches diameter. Arm for outer centre support 5 inches diameter at its smallest part.
Fig. 1909.
Fig. 1910.
Milling Cutters or Mills.—The simplest form of milling cutter is that shown in [Fig. 1909], the teeth being equidistantly arranged upon the circumference only. Its size is usually designated by its length, which is termed the face. Thus a cutter having its teeth parallel to its axis and an inch long would be said to have 1 inch face. Cutters of more than about half an inch face usually, however, have their teeth cut spirally, as in [Fig. 1910]; the degree of spiral is one turn in a length of 3 feet for cutters between 21⁄4 and 4 inches in diameter. For cutters of less than 21⁄4 the degree in the spiral is increased; thus for an inch cutter, the degree is one turn in 15 inches, while for 6 inches one turn in about 60 inches is used.