m. The order of the operations is as
follows:

The rear end of the hub is faced by the back facing bar; the cored hole
is started by a four-lipped drill in the turret and the front end of the
hub is rough-faced. (These tools are on the rear side of the turret
when the latter is in the position shown in the illustration.) After the
turret indexes, the hole is rough-bored by tool _A_ and while this is
being done, the outside of the rim is rough-turned by tool _B_ held in a
special bracket attached to the turret. Both sides of the rim are also
rough-faced by tools _C_ and _D_ held at the front of the cross-slide,
this operation taking place at the same time that the rim is turned and
the hole is being bored.

[Illustration: Fig. 40. Machining Flywheels in Potter & Johnston
Automatic Chucking and Turning Machine]

The turret again automatically recedes and indexes, thus locating bar
_E_ and turning tool _G_ in the working position. The hole is then
finish-bored by tool _E_ and the hub is finish-faced by blade _F_; at
the same time the rim is finish-turned by tool _G_ and the sides are
finish-faced to the proper width by two tools held at the rear of the
cross-slide. The turret automatically recedes and indexes a third time,
thus locating the flat-cutter reamer-bar _H_ in the working position and
then the hole is reamed to the required diameter. This completes the
cycle of operations. The total time for machining this flywheel is forty
minutes.

=Automatic Multiple-spindle Chucking Machine.=--An example of the
specialized machines now used for producing duplicate parts, is shown in
Fig. 41. This is a "New Britain" automatic multiple-spindle chucking
machine of the single-head type and it is especially adapted for boring,
reaming and facing operations on castings or forgings which can readily
be held in chuck jaws. This particular machine has five spindles, which
carry and revolve the tools. The work being machined is held stationary
in the multiple chuck turret _A_ which holds each part in line with one
of the spindles and automatically indexes, so that the work passes from
one spindle to another until it is finished. The turret then indexes the
finished piece to a sixth or "loading position" which is not opposite a
spindle, where the part is removed and replaced with a rough casting.
Each pair of chuck jaws is operated independently of the others by the
use of a chuck wrench. These jaws are made to suit the shape of the