Abstract: A special router for cutting an L-shaped groove in elongated frame members has an elongated cutter stem and an axis about which the stem is rotatable; the stem has substantially parallelogram cross sections in planes normal to that axis; and a cutter head is provided at the end of the stem and integral therewith, the head also having substantially prallelogram cross sections in planes normal to that axis. Further, the router head has generally outwardly convex outer surfaces and opposite flat sides intersecting said curved outer surfaces. The router is movable laterally to cut L-shaped grooves in the frame members, which are adapted to have their grooved ends joined by an L-shaped bracket receivable into the grooves to hold the members in L-shaped assembly.

Abstract: A lock-up corner bracket for frame parts is characterized by:(a) the bracket having legs that extend in planes which define a corner angle,(b) the legs having terminal enlargements that are elongated in parallel directions of forward insertion of the legs relatively into recesses formed in said parts, for retaining said parts in assembled relation.