A vertical frame supports an interchangeable mandrel or die which receives the center portion of an elongated metal rod having opposite threaded end portions, and the rod is clamped to the die by a pivotal locking bar secured by a wedge actuated by a hydraulic cylinder. The frame also includes a vertical plate having upper and lower corner blocks connected by a pair of vertical guide rods. The rods support a horizontal carriage cross bar for vertical movement, and the cross bar pivotally supports upper end portions of a pair of arms each formed by rigidly connected parallel spaced plates having aligned straight cam slots. A pair of bending rollers are supported by the lower end portions of the arms, and a hub member extends between the plates of each arm and supports slide blocks which move within the cam slots. A hydraulic cylinder moves the cross bar vertically to move the arms and bending rollers along converging paths for overbending the rod around the die. An elongated adjustment screw is rotatably supported by the lower corner blocks and a center block and extends between the plates forming the arms. The screw has oppositely threaded portions engaging the hub members to provide for conveniently and precisely adjusting the spacing between the bending rollers for accommodating dies and rods of different sizes and shapes.