Ski insert for anchoring a ski binding screw in a ski

Claim 1

In combination with a ski, a ski insert for anchoring a ski binding screw, the insert comprising (a) a tubular metallic body having an axis and external and internal threads extending about said axis and along the body, the ski defining an opening into which said body is closely received, the external thread penetrating the ski about said opening, (b) the external thread being locally interrupted along an arcuate locus intersecting at least three successive turns to form three chisel cutting edges proximate one end of the body and adapted to cut into the ski material upon twisting of the insert into said opening in the ski, the external thread having opposite flanks defining an angle less than about 31° in axial radial planes, one of said cutting edges having zero spacing from an axial radial plane and two adjacent cutting edges at opposite sides of said one edge having positive spacings from said plane, there being a recess sunk in the body and having an arcuate side wall adjacent the roots of said three turns, said recess being shallow and having a bottom wall extending from said arcuate wall to the body surface near continuations of said turns, said bottom wall defining a plane generally tangent to terminals defined by said continuations, said recess sized to collect cuttings, the outermost radial dimension of said chisel edges and said continuations closest to said edges being the same as the outer radius of said external thread, said continuations being spaced from said chisel edges by the dimension of said interruptions, said continuations having edges which extend at sharp angles relative to intersecting radii from said axis, and relatively away from said chisel edges, the interruptions of said turns subtending angles substantially less than 90° about said axis, (c) the internal thread receiving a ski binding screw.