Apparatus for casting material using a collapsible structure

Claim 1

Collapsible apparatus for rigidly locking together a collapsible form structure comprising: a. an outer clamping structure having diverging first and second interconnected sides, facing and diverging surfaces, one on each of the sides, for engaging and supporting one of a pair of form sides to be clamped, a stop affixed on each of said surfaces and spaced away from the edge of the respective side opposite from the interconnection, each stop defining a plane against which the edge of one of such form sides may be positioned, the outer clamping structure having at least one opening therethrough intermediate said sides; b. a ''''T'''' shaped wedge comprising an elongated, substantially flat rectangular-shaped wedge member in between the planes formed by the diverging surfaces and a leg member intersecting the wedge member comprising first and second spaced apart sharp corners on the wedge member each associated with a different one of the diverging surfaces to engage and wedge in between such pair of form sides and thereby lock the form sides in place against the diverging surfaces, said sharp corners each being defined by two further surfaces on the wedge member, the planes of each such two further surfaces each having a diverging angle with respect to the associated surface of said first and second sides; c. a coupling member movably extending through said opening and having an end coupled to said leg member; and d. a retracting and locking member for retracting said wedge toward both said diverging surfaces to thereby wedge and hold such pair of positioned form sides against the facing surfaces.