A bracket b supports the outer end of the head; at its upper end b is split so that by means of a bolt it may firmly clamp the cylindrical end of a, which carries the dead centre piece d. The two lower ends of b are bolted to the frame f.
The work table t is gibbed to slideways in f, and is provided with suitable automatic feed and stop motion, and of course with a hand feed also.
To adjust the height of the cutter, the lower ends of b are released from f and the head a is swung on its centre c.
It is obvious that a machine of this class is suitable for cases where a large quantity of work of one kind is to be done and frequent changes of the adjustments are not required, and that for such work the solidity of the construction and the convenience of having all the handles employed in operating the machine accessible from one position are desirable elements obtained by a very simple construction.
Fig. 1879.
[Fig. 1879] represents Pratt & Whitney’s power milling machine. The cone and live spindle are here carried in boxes carried in vertical slideways in the headstock, so as to be adjustable in height from the work table, and is provided with a footstock for supporting the outer end of the live spindle, which is necessary in all heavy milling. The carriage is adjustable along the bed, being operated by a screw whose operating hand wheel is shown at the left-hand end of the bed.
The automatic feed is obtained as follows: The large gear on the right of the main driving cone operates a pinion driving a small four-step cone connected by belt to the cone below, which, through the medium of a pair of spur-gears, drives the feed rod, on which is seen a long worm engaging a worm-wheel which drives the feed screw. A suitable stop motion is provided.
What is termed a universal milling machine is one possessing the capacity to cut spiral grooves on either taper or parallel work, and is capable of cutting the teeth of spur and bevel-gears or similar work other than that which can be held in an ordinary vice. These features may be given to a machine by devices forming virtually an integral part of the machine, or by providing the machine with separate devices which are attachable to the work table.