A clamping assembly includes first and second jaws supported above a base in opposed, spaced-apart alignment on opposite sides of a central clamp axis, each jaw having a proximal end portion adjacent the base and an opposite distal end portion, where the jaws are pivotable between an open position and a closed position. A wedge movable along the central clamp axis between the proximal end portions of the pair of jaws in response to moving a handle between a first handle position and a second handle position. A cam assembly between the wedge and the base includes a cam, a follower on the proximal handle end portion, and a spring between the cam and the base. Compressing the spring increases an axial distance between the cam and the wedge.