with a slot just wide enough and deep enough to accommodate the vertical part 52 of the clamp foot 24 and to allow it to slide easily up and down there are two slots 53 aligned with the slots 49 the rods 28 would normally pass through these slots 53 if the guide plate 51 were in contact with the plate 48 but the exploded location of the plate 51 in fig3 is beyond the ends of the rods a cover plate 54 is held in surface to surface contact with the guide plate 51 to transform the open slot 52 into a closed tunnel to hold the vertical part 52 of the clamp foot in place when the plates 48 51 and 54 are joined together by machine screws the vertical part 52 of the clamp foot 24 has two notches 56 that are spaced apart horizontally the same distance as the slots 49 53 and 55 and are wide enough vertically to allow the rods 28 to fit therein thus vertical movement of the rods is transmitted to the clamp foot 24 the clamp frame 25 in this embodiment is shown as a rectangular plate with a rectangular open area surrounded by four sides 57 60 the side 57 has two pairs of threaded holes 62 and 63 in it the inner holes are aligned with a pair of holes 64 in the horizontal plate 66 at the bottom of the clamp foot 24 and the machine screws 26 through the holes 64 and threaded into the holes 62 hold the clamp frame rigidly attached to the clamp foot in order to facilitate aligning.