unnecessary.

[Illustration: Fig. 8. Different Types of Box-tools for Turret Lathe]

The finishing box-tool _B_ is also used to follow a hollow mill if
special accuracy or smoothness is desired. This tool is only intended
for light finishing cuts, the allowances varying from 0.005 inch to
0.015 inch in diameter. The cutters are made of square tool steel of
commercial size, and are ground and set to take a scraping end cut. This
particular tool has two tool-holders which permit finishing two
diameters at once. If a larger number of sizes must be turned, extra
tool-holders can be applied.

The single-cutter box-tool shown at _C_ is bolted directly to the face
of the turret instead of being held by a shank in the turret hole, and
it is adapted for heavy cuts such as are necessary when turning
comparatively large bar stock. The tool-holder _a_ swivels on a stud,
thus allowing the cutter to be withdrawn from the work while being
returned, which prevents marring the turned surface. The high-speed
steel cutter is ground to take a side cut on the end of the bar. The
latter is supported by hardened and ground tool-steel rolls _b_ which
revolve on hardened and ground studs. These rolls are mounted on
swinging arms which have a screw adjustment for different diameters.
They can also be adjusted parallel to the bar, thus enabling them to be
set either in advance of or back of the cutter. The opening in the base
allows the stock to pass into the turret when it is not larger than the
turret hole.

The box-tool shown at _D_ is similar to the one just described, except
that it has two or more cutters and roller back-rests, thus enabling
different diameters to be turned simultaneously. The cutters are ground
to take a side cut. Ordinarily this gives a satisfactory finish, but if
special accuracy and smoothness are desired, two tools should be used,
one for roughing and one for finishing, the latter being ground to take
a light scraping end cut.

The taper-turning box-tool shown at _E_ is designed for accurately
turning tapers on brass or cast-iron parts, when there is a small amount
of stock to be removed. The taper is obtained by cross motion imparted
to the cutter slide as the turret advances. The taper-turning box-tool
shown at _F_, instead of having a single-point cutter, is provided with
a wide cutter _a_. This tool is designed to turn tapering parts of
small or medium diameter, requiring the use of a support which cannot be