Patent GB-190614938-A (GB)
Title: Improvements in Dovetailing Machines.
Inventor: ROBINSON MARSHALL
Filed: 1906-06-30
Granted: 1907-06-29
Abstract: 14,938. Robinson, M. June 30. Dovetailing; tools.-Blind dovetails are formed by a machine of the type in which rotary cutters and chisel cutters are used, so that the work may remain in one position for the two operations. Two horizontal rotary taper cutters d, Figs. 4 and 5, are carried in bearings mounted on horizontal and vertical slides d<5>, d', and d<3>, d<2>, and driven by a belt passing over the pulley d<9> and guide-pulleys adjusted by a screw d<13>. To adjust the pitch of the cutters, a shaft h<2>, rotated by a handle h<6> having a coarse-threaded screw h<3> with holes h<7> at the bottom of the grooves to engage with a pin carried by the frame, is rotatably fixed to the slide d<4>, while a threaded hollow shaft operated by a handwheel i<2> which engages with a screwed lug on the slide d<5>, is provided for fine adjustments. Two L-shaped chisel cutters l for squaring the corners are carried upon slides l<2> working in inclined guideways above the rotary cutters and are operated by cams k through pivoted levers m. The work, clamped on a sliding carriage e, is intermittently operated by pawls of various lengths operated from a shaft c<3>. Means are provided to accommodate work of various thicknesses and also to enable dovetails to be cut at an angle, as in curved drawer fronts. The cam operating the pawls is attached to the shaft c<3> by a spring catch e<7>, Fig. 3, pivoted to the cam and engaging a tooth e<8> on the shaft. The catch e' has a lug e<9> which may be engaged by a tripping-hook f operated by a sliding bar f held in position by a tooth f<4> against the action of a spring f<5>. The bar f<1> is operated by hand or by the contact of an adjustable stop f on the carriage against one arm of a bell-crank lever f<9>, the other end of which engages a pin f<10> on the bar f<1>. The pawls are simultaneously disengaged by a transverse pin beneath their tails operated by levers from the bar f<1>. In order that the feed of the carriage may be varied to correspond with the distance between the bits, the spindle h<2> carries a pinion engaging one end of an inclined sliding rack bar j<3>, which at its other end operates a pinion gearing with teeth on a cam-bar j furnished with stepped cams, one of which makes contact from the feed-lever e<3>, allowing the lever to approach the cam e' as the bits are separated. The bits are raised into contact with the work by cams k, Fig. 4, which bear against levers k<7>, pivoted at one end k<8> to slides d<4>, d<5> and at the other end to blocks k<9> adjustable in slots by screws k<10>. The cams k are mounted similarly to the cam e<8>, and spring catches k<1> are disengaged from teeth, when it is desired to omit a dovetail, by an adjustable stop k<3> on the carriage which acts through two bell-crank levers k<4>, normally pressed against the bar f<1> and pivoted at k<5> to brackets k<6> carried by the slides d<4>, d<5>, In order that the motion of the bits may be stopped simultaneously with that of the feed-carriage, the bar f<1> has inclined slots k<x> which engage with pins to give it a transverse as well as a longitudinal movement, to operate the catches k<1> as well as catch e<7>.