ed.
The machine shown in Fig. 22 is a special design for boring four
cylinders which are cast _en bloc_ or in one solid casting. The work is
held in a box jig which has a top plate equipped with guide bearings for
holding the spindles rigidly while boring. The lower end of each spindle
has attached to it a cutter-head and the boring is done by feeding the
table and casting vertically. This feeding movement is effected by power
and it is disengaged automatically when the cutters have bored to the
required depth. The particular machine illustrated is used for rough
boring only, the cylinders being finished by reaming in another similar
machine. The cylinders are bored to a diameter of 3-5/8 inches, and
about 3/8 inch of metal is removed by the roughing cut. The spindles
have fixed center-to-center distances as the machine is intended for
constant use on cylinders of one size, so that adjustment is not
necessary. Of course, a special machine of this kind is only used in
shops where large numbers of cylinders of one design are required
continually. Some cylinder boring machines of the vertical type have
spindles which can be adjusted for different center-to-center distances
if this should be necessary in order to accommodate a cylinder of
another size.

CHAPTER VII

HORIZONTAL BORING MACHINES

A boring machine of the horizontal type is shown in Fig. 1. The
construction and operation of this machine is very different from that
of a vertical boring mill and it is also used for an entirely different
class of work. The horizontal machine is employed principally for
boring, drilling or milling, whereas the vertical design is especially
adapted to turning and boring. The horizontal type is also used for
turning or facing flanges or similar surfaces when such an operation can
be performed to advantage in connection with other machine work on the
same part.

The type of machine illustrated in Fig. 1 has a heavy base or bed to
which is bolted the column _C_ having vertical ways on which the
spindle-head _H_ is mounted. This head contains a sleeve or quill in
which the spindle _S_ slides longitudinally. The spindle carries cutters
for boring, whereas milling cutters or the auxiliary facing arm are
bolted to the end _A_ of the spindle sleeve. The work itself is attached
either directly or indirectly to the table or platen _P_. When the
machine is in operation, the cutter or tool revolves with the spindle
sleeve or spindl