A joint clamp for a surgical retractor system includes clamps, a cam bolt, and a cam lever. The cam bolt passes through the clamps. A cam lever comprising a cam head pivotally attached an upper portion the cam bolt to permit rotation about a pivot axis that is perpendicular to a longitudinal axis of the cam bolt. The cam head includes an outer surface that results in a distance between the pivot axis and an upper surface of the clamps being greater when the cam lever is rotated about the pivot axis to a clamping position than when the cam lever is rotated about the pivot axis to a non-clamping position. The clamping force may be calibrated or set via a cam bolt having an adjustable length and/or via a setting screw.