milling-cutters, and typical of those used for gear teeth. A concave cutter is
used for producing beads, and combinations of these and similar outlines
are often made for special work.
Gang Cutters.—These, of which figs. 24, 25, 26, 27 are typical, are
Fig. 27.—Four Cutters in Gang, with Distance-pieces
used extensively on all the horizontal milling machines, but mostly on the
piano-millers. Single cutters are built up to suit requirements. Fig. 24
shows three for cutting faces and edges simultaneously. These are fre-
quently interlocked, with provisions for taking up lateral wear. Fig. 25
illustrates two, fig.
27 four on an
arbor, with sepa-
pieces. The group
(fig. 26) shows vari-
ous operations. At
A an edge mill is
tooling the bottom
of a bed. At B
gang mills are tool-
ing faces and edges,
c, D, E show three
sets of operations
on a bed. At F
and G cutters are
H shows the milling of a
CUTTER CARRIER DISC
SECTIONAL TOP ELLEV.
Fig. 28.—Inserted Cutters, set spirally, held with Pins flattened to bear
at work on the bottoms and faces of bearings,
long strip on five faces.
Inserted-tooth Cutters.—When a cutter exceeds a few inches in
diameter it cannot be hardened and tempered like the smaller tools. Inserted
teeth of high-speed steel are fastened in bodies of cast iron or of mild steel.
Cutting points are often identical in shape with the single-edged tools,
are set straight-faced or spirally, and are fastened in many ways,
shows spiral blades held with flattened pins. Side cutters are located