A hinge assembly and frame structure, comprising: a first generally flat plate having an inner face, an outer face and a bolt-receiving bore therethrough, the bolt-receiving bore extending between the inner face and the outer face along a bore axis at an acute angle to the outer face; and a second generally flat plate pivotably connected to the first plate, the second plate having an inner face, an outer face and a bolt-receiving bore therethrough, the bolt-receiving bore extending between the inner face and the outer face along a bore axis at an acute angle to the outer face; and further comprising: a first bolt extending through the bolt-receiving bore in the first plate; a second bolt extending through the bolt-receiving bore in the second plate; a first elongated frame member having a surface with a slot extending therein; a second elongated frame member having a surface with a slot extending therein; a first nut receivable in the slot in the first elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the first bolt in a mating relationship; and a second nut receivable in the slot in the second elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the second bolt in a mating relationship; wherein each slot is defined by first and second converging sidewalls (34, 36), the sidewalls (34, 36) lying in corresponding planes which are at acute angles to the surface in which the slot extends; and wherein the first and second converging sidewalls (34, 36) have first terminal edges (34a, 36a) and wherein each slot is further defined by first and second diverging outer abutment walls (42, 44) which extend from the first terminal edges (34a, 36a) of the first and second converging sidewalls (34, 36) and have second terminal edges (42a, 44a); and wherein each slot is further defined by first and second diverging inner abutment walls (46, 48) extending from the second terminal edges (42a, 44a) of the first and second diverging outer abutment walls (42, 44) toward the surface in which the slot extends, the first and second diverging inner abutment walls (44, 48) having third terminal edges (46a, 48a); and wherein the third terminal edges (46a, 48a) of the first and second diverging inner abutment walls (46, 48) defining each slot are interconnected by a generally concave terminal wall. a first generally flat plate having an inner face, an outer face and a bolt-receiving bore therethrough, the bolt-receiving bore extending between the inner face and the outer face along a bore axis at an acute angle to the outer face; and a second generally flat plate pivotably connected to the first plate, the second plate having an inner face, an outer face and a bolt-receiving bore therethrough, the bolt-receiving bore extending between the inner face and the outer face along a bore axis at an acute angle to the outer face; and further comprising: a first bolt extending through the bolt-receiving bore in the first plate; a second bolt extending through the bolt-receiving bore in the second plate; a first elongated frame member having a surface with a slot extending therein; a second elongated frame member having a surface with a slot extending therein; a first nut receivable in the slot in the first elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the first bolt in a mating relationship; and a second nut receivable in the slot in the second elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the second bolt in a mating relationship; a first bolt extending through the bolt-receiving bore in the first plate; a second bolt extending through the bolt-receiving bore in the second plate; a first elongated frame member having a surface with a slot extending therein; a second elongated frame member having a surface with a slot extending therein; a first nut receivable in the slot in the first elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the first bolt in a mating relationship; and a second nut receivable in the slot in the second elongated frame member and including a bolt-receiving bore therein, the bolt-receiving bore adapted for receiving the second bolt in a mating relationship; wherein each slot is defined by first and second converging sidewalls (34, 36), the sidewalls (34, 36) lying in corresponding planes which are at acute angles to the surface in which the slot extends; and wherein the first and second converging sidewalls (34, 36) have first terminal edges (34a, 36a) and wherein each slot is further defined by first and second diverging outer abutment walls (42, 44) which extend from the first terminal edges (34a, 36a) of the first and second converging sidewalls (34, 36) and have second terminal edges (42a, 44a); and wherein each slot is further defined by first and second diverging inner abutment walls (46, 48) extending from the second terminal edges (42a, 44a) of the first and second diverging outer abutment walls (42, 44) toward the surface in which the slot extends, the first and second diverging inner abutment walls (44, 48) having third terminal edges (46a, 48a); and wherein the third terminal edges (46a, 48a) of the first and second diverging inner abutment walls (46, 48) defining each slot are interconnected by a generally concave terminal wall.