Patent GB-191009188-A (GB)
Title: Improvements in Power Hack Saws.
Inventor: BRADFORD EDWARD STANDISH
IPC: B23D49/00
Filed: 1910-04-15
Granted: 1910-09-22
Abstract: 9188. Bradford, E. S., and Olson, M. Sept. 24, 1909, [Convention date]. Reciprocating-saw machines.-A power hacksaw is provided with means (1) automatically to adjust the stroke of the saw to correspond to the width of the work to be operated upon, (2) to lift the saw slightly on its return stroke, (3) to stop the saw automatically when it has cut through the work or after a predetermined interval, and (4) to support the saw out of the operative position. The saw frame 37, Figs. 1 and 2, reciprocates on a bar 38 rigidly fixed to a disk 63 on a shaft 64 journaled in bearings 65 on the machine framework. The frame 37 is operated from a driving-pulley 20 through the medium of a. pinion 22 meshing with a gearwheel 23 formed with guides, in which is mounted a sliding plate 29, Fig. 10, carrying a pin 31 engaging with a lever 39 connected to the saw frame by a link 41. The gear-wheel 23 is fixed to a sleeve 24 mounted on a shaft 25, which carries a pinion 33 gearing with an internal rack 32 on the sliding plate 29. The work is held in jaws 44, 45 operated by a handle 48 on a right and left handed screw 46. The position of the pin is adjusted to alter the stroke to correspond to the displacement of the jaws by connecting the jaw 48 by a link 49 to one end of a bell-crank lever 51, the other end of which carries a roller 52 travelling in a circumferential groove 53 in a collar 54 provided with spiral slots 55, 57, the slot 55 being engaged by a pin 56 on the sleeve 24 and the slot 57 by a pin 58 on the shaft 25. The movement of the jaws 44, 45 causes the shaft 25 to receive a rotary displacement relative to the sleeve 24 and thus rotates the pinion 33 engaging the rack on the plate 29 carrying the pin 31. The pressure on the saw is regulated by a weight 76 adjustably secured on a rod 77 connecting the forward end of the bar 38 to the rear end of the shaft 64. The saw is lifted on its return stroke by a cam 28 on the sleeve 24 engaging an arm 70 pivoted at 71, 72 to the ends of a spring ring 68 mounted in a recess in the disk 63. The cam 28 and arm 70 are kept in engagement by a spring 74, and, when the return stroke is commenced, the cam swings the arm 70 outwardly and expands the spring ring 68, causing it to grip the disk 63 and partially rotate it, thus elevating the bar 38 on which the sawframe slides. The amount of elevation may be adjusted by a screw 75 on the framework bearing against the arm 70. The downward movement of the saw is stopped when the work is cut through by a projecting lug 78 on the disk 63 engaging a portion of the framework. The machine may be arranged to stop automatically when the work is cut through, or after a predetermined interval, by the engagement of a pawl, pivoted to the link 41 and resting on a projection 99, with a pin 94 adjustably secured to a shaft 86 carrying a cam 89 engaging a lever 91 operating the clutch between the driving-pulley 20 and the shaft 21 of the pinion 22. A hand piece 88 is also provided on the shaft 86 for operating the clutch by hand. When stopped, the saw frame may be swung upwards and supported in the raised position by means of a pivoted notched bar 81 engaging pins 79 on the bar 38. A sliding gauge 100, adjustably secured by a clamping-screw 102, is arranged on the framework. below the jaws 45 for use when a number of pieces are to be cut to the same length.