away from the jaw 182 and when released is moved by the leaf spring 190 to engage the adjacent chordal edge 20 of the blade 6 to push the blade 6 into contact at the opposite chordal edge with the fixed jaw 182 the bar 192 is released and is biased by the spring 200 acting through the lever 198 to contact the upper edge of the blade 6 so as to provide a preliminary holding force on the workpiece 2 the workpiece clamping element 38 is then lowered to bring the pads 58 into contact with the upper surface of the blade these pads straddling the bar 192 a stud 62 is secured to the support body 24 and extends through an opening 64 in the clamping member 26 a nut 66 engages the top end of the stud 62 and can be tightened to exert the required clamping force between the workpiece supporting element 34 and the workpiece clamping element 38 as shown in fig5 and 6 the forged workpiece of fig1 is held by the clamp with the root 8 exposed for machining thus the pads 58 on the workpiece clamping element 38 and the pads 60 on the workpiece supporting element 34 engage opposite faces of the blade 6 and grip the blade 6 firmly under the action of the nut 66 on the stud 62 during clamping the ball and socket.