Abstract: A sheet bending brake comprising a frame having a fixed jaw and a movable jaw and an anvil member adjustable secured to the fixed jaw. The movable jaw having a clamping surface movable between workpiece clamping and non-clamping positions relative to the anvil member. A bending member is hingedly connected to the fixed jaw. The movable jaw is releasably locked in workpiece clamping position by a structure that includes an oval shaped spring member having opposed ends and opposed walls, said member is pivoted at one end to said movable jaw and at the other end to a handle for manipulating the jaw.