The invention relates generally to molding forms and, more particularly, to an apparatus for constructing a molding form having an accurately located reference surface that establishes a border for the molded structure.
Molded structures formed along the surface of the ground, such as concrete decks, typically are constructed by preparing a firm bed upon which the deck is to rest. Border defining forms are provided for confining the uncured concrete mixture to a desired border contour. A concrete mixture is poured over the prepared bed to fill the form and the surface of the poured concrete troweled. After the concrete cures to a firm state, the forms are dismantled.
Two types of molding form structures have been used in constructing concrete decks; structures of wood form boards and stakes fastened together by nails, and structures of specially formed metal form boards and stakes held together by rigid metal wedges. The wood form structures are constructed by driving stakes into the ground at intervals along a stake line that follows the desired edge contour of the deck. Then, flexible form boards of wood, commonly referred to as bender boards, are placed against the stakes and fastened thereto by nailing. In most cases, the stakes are displaced by the force of nailing, making it virtually impossible to locate the reference surface of the bender board at the reference line for the border of the deck. In addition to not being able to locate the reference surface precisely, the manner of construction of such wood form structures causes rapid deterioration of the materials used. Repeated nailing weakens the wood bender boards and they frequently break during the assembling and dismantling of the forms. The low number of repeated uses of the wood bender boards and stakes and the consumption of nails is an expense of construction that is becoming increasingly significant with the rising costs of construction materials.
The metal type molding form structure includes a metal form board having a pair of apertured appendages extending perpendicularly from one side of a planar member, the opposite side of the planar member forming the reference surface. A support stake is inserted through apertures of the appendages and a separate rigid metal wedge is driven between the stake and the facing side of the metal form board. Driving the wedge forces the metal form board away from the support stake to cause the stake to bear forcefully against the wall of the apertures whereby the metal form board is held firmly in place relative to the support stake. A substantial force is required to drive the rigid wedge between the stake and the facing side of the form board and, frequently, the wedge galls the side and/or support stake. After many uses of the metal form boards and support stakes, galling often becomes so extensive that the metal form boards and/or support stakes are deteriorated beyond use. Even before the metal form boards and/or support stakes are deteriorated beyond use, galling may deform them to such an extent that accurate location of the reference surface that defines the border of the concrete deck is prevented. Consequently, the metal type molding form structures do not entirely alleviate the shortcomings of the previously described wood type. In addition, it is more costly to manufacture and use the metal form structures than their wood counterparts.
Accordingly, considerable advantage is to be gained by the use of inexpensive molding form components that are not easily damaged by repeated usage. Additional advantages are to be gained by the use of molding form components that permit commonly available bender boards to be used repeatedly.