A saw when it is to be gummed should be held perfectly firm that it may be cut quite true, and the cutting tool should be of such construction that it will fairly cut away the metal and not tear it. The machine for filing, gumming and jointing saws (of which our illustration is a perspective view) is the inventioA of H. 0. Elmer, of Mexico, N. Y., and was patented by him Feb. 2, 1858, and assigned to J. P. Slack and P. J. Bab-cock, of the same place. A represents the bed or frame of the machine. This frame is composed of two parallel metal bars connected at one end by a bolt passing through a block that determines the distance apart between the parallel bars. B B represent two bars, each of which is provided with friction rollers, d d, running in grooves, a, of the frame, A. The front end of the bars are connected by a curved traverse bar, /, in which the end of a screw rod, C, is fitted and allowed to turn freely. A spiral spring is placed on the end of this rod and confined between the bar,/, and a plate, A, attached to the bar, the curve of the bar forming a place to receive the spring. The rod, C, passes through a nut, D, placed on the end of the frame, and the outer end of the screw rod is provided with a hand wheel, E. F is a shaft which is placed transversely on the bars, B B, and it carries the cutter, G. This cutter is cylindrical, and the cutting edges are of a zig-zag form, or are placed spirally around it. A crank, H, is used to rotate the cutters. It will be seen that by rotating the wheel, E, the bars,B B, and cutter, G, may be moved back and forth on the frame, A. To the inner side of one of the frame bars is attached a plate, I, and at the outside is a lever, J, provided with a cam so arranged that by pulling out the lever, J, the cam will force the saw against the plate, I, and hold it firm in the frame between the bars. a' a' are grooves in bars of the frame to lighten it, and at the same time not to interfere with the grip. K is the saw. The implement is used as follows:—The frame is passed on the saw, and the bed is firmly clamped to the saw by turning the lever, J, so that it will be pressed against the plate, I. The gummer is then rotated with one hand by the crank, H, while the other hand is employed in operating the wheel, E, which keeps the cutters against the saw which operate on the upper and under surfaces of the teeth, thus making them of uniform size, and the spaces between are also made uniform. By this mode of constructing the frame the gummer is applicable to reciprocating as well as circular saws, for the back being open, it can be fixed on a saw of any width. Any further information concerning this gummer can be obtained by addressing the assignees as above.
This article was originally published with the title "Elmer's Machine for Gumming Saws" in Scientific American 13, 41, 321 (June 1858)