Fig. 31.-Medium Size Back Geared Upright Drilling Machine.

foot and a cross feed of 7 inches is provided by the fixture itself, which can, of course, be increased somewhat by swinging the drill table. The table of the attachment is provided with slots for three half-inch T-bolts for clamping work, and the vise jaws pro

vided have an opening of ten inches. The table is provided with an index support so the work may be set at any desired angle.

If possible it is well to provide a smaller drilling machine hav ing hand feed only, which is known as the sensitive drill press. This should have three or four speeds and be capable of taking drills up

to at least three-eighths of an inch in diameter. The table shoul be adjustable up or down and sideways, the arm should swing t the right or left and should be of the type that permits one to pu either a V-block or cup to support bar stock in its place. A ligh form of sensitive drill that is suitable for use on the work benc and which is electrically operated by a small motor is shown a

Fig. 32, B. A variety of speeds is obtained owing to the friction. drive. The starting rheostat and switch are mounted conveniently on a base permitting secure attachment to the bench.

Among the smaller appliances that are comparatively inexpensive and yet very useful may be mentioned the power hacksaw, which is not only simple but consumes very little power and is automatic in action after once being started. It occupies but little floor space and is very useful in cutting pieces from bar stock, such as steel, iron, or brass more than an inch in diameter. A typical power hacksaw is shown at Fig. 32, C. This consists of a frame, reciprocated by a crank, which imparts its motion to the saw frame through the medium of a connecting rod. The crank is turned by a pulley which is usually belted direct to a very small pulley on the line shaft and which turns at a speed considerably lower than that member. The feed is automatic and may be varied by altering the position of the weight regulating the amount of pressure with which the saw bears against the work. The piece to be cut is securely held in a vise attached to the bed of the machine which is supported on cast iron legs in order to raise it to a convenient height from the floor. A simple trip is provided, so that when the piece is sawed through, the drive will be interrupted and the saw frame will remain stationary.

An arbor press of large capacity is almost a necessity, and in even the smallest shops some kind of a press is essential for making force or press fits, removing parts forced on, straightening bent axles or tubular housings, and for removing arbors from parts machined on the lathes or millers. A press capable of exerting 10 to 15 tons pressure will be sufficient to cope with any work brought into the ordinary shop. One or two smaller arbor presses can be used to advantage and should be mounted directly at the ends of the large lathe beds, these serving to straighten small parts, such as valve stems, etc., and to do light work in making force fits, and in inserting and removing arbors from all work in which these are necessary.

A number of different designs of arbor presses are shown at Fig. 33. That at A, has a distance between screws of 20 inches and a distance between the head and table of 36 inches. Its capacity

is one hundred thousand pounds and it weighs 870 pounds. It is a very convenient press for use in the automobile repair shop and its construction makes it specially well adapted for pressing shafts into and from pulleys, flywheels, gearhubs, etc., and also for straightening automobile shafts. The engraving shows the con

struction and principle of operation of the machine very distinctly. Two large guide screws rise from the table upon which the cross head is adjustably supported, as it has two semi-screw nuts and toggle mechanism by which the cross head is held fast or released for vertical adjustment. The cross head is balanced by weights, as shown, and a steadying bar connects the press cup with the press screw. A spur-toothed ratchet wheel is fixed on one end of the

press screw, this being embraced by a forked lever head fulcrumed to oscillate on the press screw. A double acting spring pawl engages the teeth of the ratchet, and a hand crank is attached to the press screw in order that it may be raised or lowered quickly, if desired. After the object has been placed in the press, the cross head in which the central screw is mounted can be instantly dropped to the work, and with a few turns of the screw the required pres

sure may be applied. An important saving in time is thus effected, compared with the method where a number of blocks must be placed on the bed plate to raise the object sufficiently to be acted on by the press screw. Tapering squared sockets are provided in each end of the pawl carrier to permit the introduction of the long bars, shown leaning against the press base, which will provide a very great leverage on the screw. The small arbor press shown at C, is of the Greenerd type and is intended to be placed on the lathe