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It is absolutely necessary that saws should have their teeth set with regularity and certainty, and it is almost an impossibility to do this perfectly by hand. The invention which is the subject of our engravings is a machine for effecting this with the precision that machinery can only attain. Fig. 1 is a view of the arrangement used for filing, Fig. 2 is the essential part separated, and Fig. 3 is a representation of the gaging apparatus. A is the saw, and B the bench in which a slotted piece, C, is set, and to this the invention can be secured. D is a piece which carries the apparatus, and is fastened to it by means of the screw pin, P ; this piece, D, can I moye along the slot to accommodate itself to the saw, and it is fixed by the screw, a. In Fig 1, G is a horse-shoe shaped piece of metal, between the two arms of which the saw passes, and it has on one end the cam and lever, T, by which the saw is held tight in its position when fixed. G also has on it the standard, I, carrying by means of a hinge screw the bent frame, J, and on this is mounted a frame with two rollers, K, capable of being turned by the pointer, L, which moves along a graduated or other scale ; this will incline the rollers to any angle in relation to the edge of the saw teeth, and it is by pressing the file on these rollers that the proper " rake" is given to the teeth of the saw. When once in the proper position they are retained so by the screw, c, being screwed tight. M is a plate against which the teeth are placed, and it prevents them from projecting too much beyond K ; it is connected by the screw, d, All this, however, will be better seen by reference to Fig. 2. The setting gage is represented in Fig. 3, which consists of two jaws, N 0, movable upon the arm, E. 0 slides in a groove in N to regulate the width of the set of the saw, A, the two being firmly secured together by the set screw, 11. An adjusting screw7, Q, is provided in a projection on the end of the arm, E, which is fixed in the side of the jaw, N, by a pin, and by means of it the jaws are drawn back and forth on the arm to adjust the opening to the saw; two set screws, S, tighten them on the arm. A recess is made on the inner side of each jaw, in which a piece of file rubbing stone or hone, g g, is secured. These surfaces being adjusted to the exact width of set required (that is, the space of the key) that the saw is to cut, the teeth are set by any ordinary means until the points will touch the file or rubbing surfaces, g g. As it is impossible to get the set of every tooth exactly correct, and as the point is liable to be left with a burr in filing, the tendency of which would be to scratch and injure the lumber sawed, the rubbing surfaces, g g, will, by slowly revolving the saw between them, reduce them to a perfect uniformity and a smooth finish adapted to the best kind of sawing. One of these was on exhibition at the Crystal Palace during the Fail.-. It was patented on the 14th July, 1857, by the inventor, Emanuel Andrews, of Elmira, N. Y., from whom all further particulars and information may be obtained.
