Patent GB-447935-A (GB)
Title: Improvements in or relating to circular saw woodworking machines
IPC: B27B5/20
Filed: 1935-02-14
Abstract: 447,935. Circular - saw machines. SAGAR & CO., Ltd., J., and SAGAR, H. G., Canal Works, Halifax, Yorkshire. Feb. 14, 1935, No. 4719. [Class 145 (ii)] In an electrically-driven circular-saw machine of the type in which a driving motor having a circular saw mounted on its spindle is carried by a slide which is reciprocable horizontally in a guide or guides in a housing on a pillar or standard, one or more driven pulleys mounted on the standard or housing impart, by means of a friction band, belt, &c. carried by the slide, a traversing movement to said slide ; the return stroke is preferably faster than the working stroke. The motor c, Fig. 1, driving the saw d, is mounted on a slide b guided in a housing a<1> on the standard a ; for canting the saw, the housing a<1> is rotatably mounted in a sleeve member carried by the standard, and a toothed sector carried by the housing a<1> is engaged by a worm on a spindle journalled in said sleeve member and rotated by a hand wheel e<2>. A motor f, mounted on the housing a<1> drives through reduction gearing a pulley having steps g<1>, ,g<2> ; the housing carries guide pulleys h<1>, h<2>. A friction band i is secured at its ends i<1>, i<2> to the ram band passes around one of the steps g<1>, g<2> according to the rate of traverse required. The speed of the motor f is controlled by a selector switch j. When the pedal k<1> is up, the ram is traversed rearwardly ; when the pedal is depressed, the motion of the ram is reversed. The backward traverse of the ram is cushioned by a dashpot, and the forward traverse is cushioned by a spring b<1>. Switches may be actuated by the ram at the ends of its forward and backward strokes to interrupt the circuit of the motor f so that the ram comes to rest. The motor f runs faster in one direction than in the other, whereby a quick return is obtained. In a modification, Fig. 3, a non- reversible motor is used. One band p passes around guide pulleys p<1>, p<1> and one step g<2> of the driven pulley ; the other band r passes around guide pulleys r<1>, r<1> and the other step g<1> of the driven pulley. The guide pulleys are carried by a vertically movable plate s actuated by toggle levers s<1> controlled by an arm s<2> adapted to be engaged at the ends of the stroke of the ram by adjustable stops s<3> and s<4> mounted on a rod s<5> carried by the ram, whereby reversal and change of speed are automatically effected. In a modification, the guide pulleys are fixed, the vertically movable plate carrying the driving motor. In a further modification, the motor drives the pulley through a clutch operated by a lever controlled by stops on the ram whereby the clutch is disengaged at the end of the forward stroke of the ram, rapid return of the ram being effected by weight or spring arrangements. In a further modification, the friction band is transferred from one pulley to another rotating in the opposite direction. Modifications referred to in the Provisional Specification comprise automatic reversal at the end of the forward and backward strokes, and the use of chains and sprockets.