The Horizontal with Stationary Tools, represented in Figure 5 Gm 27), holds the tool in a support, which allows it to be placed obliquely and to be shifted vertically. The support itself can be shifted upon a horizontal prism extending the whole width of the machine. A slight lateral feed (generally also a shifting in the vertical sense) can thus be imparted to the tool by a special mechanism after each cut. The piece of metal is secured by suitable screws, stays, etc., to a cast-iron table, which can be horizontally shifted upon a long and strong cast-iron bed by a par tially-executed prismatic guide. Upon the under side of the table is a rack, which meshes with a gear upon a horizontal shaft and receives a back-and-forward motion from the driving-shaft. Thus it will be seen how after suitably setting the tool the surface of the piece of metal can be smoothly planed. To get sufficient space for working articles of some height the horizontal prism carrying the support is so arranged that it can be vertically shifted on the front side of two cast-iron uprights screwed or cast to the above-mentioned cast-iron bed and connected at the top by a cross-piece. The support is raised or lowered by two vertical screws of equal pitch, which can be turned simultaneously and at the same speed by a horizontal shaft above the uprights. Fastened on the side of the table, at a distance from each other corresponding to the length of the piece of metal, are two tappets, which by striking against a short lever reverse the table motion at the proper time and simultaneously effect the lateral shift ing of the tool-bit.
Whitworth effect its reverse motion the Whitworth planer has a combination of three pulleys with three bevel-wheels. There are upon one shaft three pulleys, the central one of which is idle and rides loose; the outer pulley is keyed to a shaft ending in a bevel-wheel, and the pulley at the inner end of the set fits upon a pipe, through which the shaft passes, and upon which is a bevel-wheel with its teeth pointing toward the first bevel-wheel. At the end of the shaft, which is to be reversed, is a bevel-wheel, which engages with both the other bevel-wheels. When the belt is shifted from the inner to the outer one of the three pulleys, the shaft is reversed; if kept upon the middle pulley, there is no motion. The objection to this arrangement is that the motion is at the same speed in each direction, necessitating a reversing-tool or "jack in the box." This is worked upon the same principle as the hand-drills, in NV111(211 the rotation is effected by pushing a nut up and down a rod, upon which there is formed a screw of rapid pitch, so as to cause the spindle to rotate first in one and then in the other direction as the nut rises and falls.
Me Sellers shown on Plate 28 (fig.. I), has its recip
rocating motion given by spiral gearing without the intervention of bevel wheels, the intention being to obviate the chatter-marks by other kinds of gearing. The reciprocating motion is not produced by shifting belts, but by friction clutches, and the driving and shifting arc so positive that the machine will plane to a shoulder. The table has one plane and one flat angular way, the latter having four bearing-surfaces, two to carry the weight and two to take the side-thrust. The table is guided laterally by two surfaces, both nearly vertical. The feed is distinct from the motion of the table and is driven positively from a slow-running pulley by an ingenious appliance for transmitting and arresting motion. It is caused by adjustable stops on the table, and takes place while the machine is reversing, and at the end of the back stroke if desired, no matter in which direction the feed is working. The machine is operated from either side by levers that control the table motion and can at will at the same time cut loose and arrest the feed, so that the table can be run past the stops as often as required for examination or adjustment of the work. The cross-head, which Meioses the saddles, takes up the wear. On planers of 36 by 36 inches, and larger, when fitted with two saddles on one cross head, the feed-screws and rods to each are separate, so that each can be operated in all respects independently except in the amount of feed, which will be the saute for both saddles; the amount of feed to each saddle can also be made independent. The feed is adjustable, from one whole revolution of the feed-screws clown to nothing., by an infinite gra dation, there being no teeth in the feed-ratchet to limit the changes. Planers 25 by 25 inches, and larger, are fitted with a tool-lifter, raising both tools on the back stroke, no matter in which angle the planing-tool may be advancing. The tools of both vertical slides stand in line with the main tools, are operated by separate feed, and can be lowered below the top of the table when not in use. For the cross-head large planers have lifting machinery operated by friction-wheels, which can be held to their work without much effort, but which, to avoid accidents, stop as soon as the workman releases his hold on the lever. Machines up to 54 by 54 inches, inclusive, have a return speed eight times greater than the speed of cut, or about 15o feet per minute. Machines of 6o inches, and larger, have a return speed six times greater than the speed of cut, or about feet per minute. Machines of the latter class stand parallel with the line shaft, economizing room in the shop, and, having no shifting-belts from the counter-shaft, the position of the latter is not so limited as on old styles.