Router machine

A router machine for making repetitive router cuts at predetermined positions on two stacked workpieces, said router machine comprising a free standing main frame having an open work horizontal platform for supporting said workpieces, said horizontal platform having a longitudinal front edge, a vertical fence located along said longitudinal fence, horizontal and vertical fluid actuated clamping mechanisms for clamping said stacked workpieces against said fence and against said horizontal platform at said predetermined positions, a workpiece feed mechanism for advancing said workpieces to each of said predetermine positions, two spaced routers with opposed, vertically oriented, coaxial bits, a movable support assembly for said routers, said routers being shiftable vertically on said support assembly toward each other to an extended cutting position and away from each other to a retracted non-cutting position, a pair of linear actuator assemblies each having a first end pivotally attached to said frame and a second end pivotally engaged with an upstanding pivot pin affixed to said router support assembly to shift said routers through said repetitive router cuts, said pivot pin being coaxial with said router bits, a programmable electronic control system having output signals controlling said workpiece clamp mechanism cylinders, said workpiece feed mechanism, said routers, said vertical position of said routers between said extended cutting position and said retracted non-cutting position, and said linear actuator assemblies.

A pair of identical stair stringers having formed therein corresponding mirror image sets of tread and riser grooves, a plurality of treads and risers equal in number respectively to the number of tread and riser grooves in each stringer, each tread groove in said risers being wider than the thickness of said treads with a first rectalinear upper edge which is horizontal and a second lower edge which slopes downwardly and rearwardly when its respective stringer is installed in place, each riser groove in said stringers being wider than the thickness of said risers with a first rectalinear forward edge which is vertical and a second rearward edge which slopes downwardly and rearwardly when its respective stringer is installed in place, said tread and riser grooves having base portions parallel to the outside surfaces of their respective stringer and said side walls of said tread and riser grooves sloping toward each other forming angles of about 4.degree. with their respective bases, a tread wedge for each tread groove and a riser wedge for each riser groove, said tread and riser wedges having a base, side walls, a forward end and a rearward end, said side walls tapering longitudinally toward each other from said rearward end to said forward end, said side walls tapering transversely toward each other forming angles of about 2.degree. with said base, each tread being located in its respective tread groove of each stringer and being forced against said first edges of said tread grooves by tread wedges located in each tread groove between said tread and said second edges of said tread grooves, each riser being located in its respective riser groove of each stringer and being forced against said first edges of said tread grooves by riser wedges located in said each riser groove between said riser and said second edges of said riser grooves, each riser abuting its respective tread, the forward ends of said tread wedges abuting said riser and said forward ends of said riser wedges abuting said tread wedges, said tread wedges and said riser wedges being tilted within their respective tread and riser grooves with said second tread and riser groove edges parallel to and abutting said adjacent side wall of their respective tread and riser wedges, said treads and risers being additionally affixed within their respective tread and riser grooves by at least one of fasteners and glue.