A bending brake for sheet material includes frames; an upper jaw and a lower jaw that cooperate to hold the sheet material a bending surface pivotally connected to the lower jaw to bend the sheet material against an anvil of the upper jaw; an interlocking unit connected to the frame and having a cam surface which has having a locking position; and an elongated pipe assembly for rotation by a user. The elongated body bears against the cam surface and rests in the locking position to clamp the sheet material with reduced freedom of play.