Patent ID: 8499935

Claim:
A tool assembly comprising: a sleeve having a groove opening at one end thereof and extending thereinto, said groove having a generally square cross-section in a plane transverse to a longitudinal axis of said sleeve, said sleeve having four walls defining sides of said groove, said sleeve having edges defined between adjacent walls of said four walls, said sleeve having a concave camber formed into at least one of said four walls; a pillar having a polygonal cross-section in a plane transverse to a longitudinal axis of said pillar, said pillar having a top side and an underside and a plurality of circumferential sides, each of said plurality of circumferential sides having an abutment surface, said pillar having convex corners formed between adjacent abutment surfaces, said abutment surface for abutting the wall of said sleeve, said convex corners allowing rotation of said pillar with respect to said four walls of said sleeve; at least one positioning part formed on at least one of said abutment surfaces and extending convexly outwardly therefrom, the positioning part interlockable with said concave camber, said sleeve rotatable with respect to said pillar such that the positioning part moves toward said concave camber; and at least one lateral through hole extending from one of said plurality of circumferential sides without the position part thereon to another of said plurality of circumferential sides without the positioning part thereon, the lateral through hole opening at the abutment surface, the lateral through hole defining a wall rim between the abutment surface and the convex corner such that the positioning part can be flexibly squeezed.