Abstract: A portable sheet metal bending brake of enhanced clamping and bending capacity and wherein a cam-actuated clamping structure is provided. The brake includes a plurality of upstanding structural castings which are partially bifurcated to pivotally support upper clamping arms cooperable with lower, casting-mounted workpiece support and bending elements. The bifurcated castings also provide support for a cam shaft on which individual cams are fixed for clamping contact with the clamping arms. The cam clamping force exertible on each arm cam be individually adjusted through a slide plate mounted on the arm and movable to vary the precise cam-arm contact point. Thus, the brake can be assembled completely and the cam plates individually adjusted to ensure uniform clamping of the workpiece along the entire length of the brake.