When it comes to locking the tool block to the post we don t fool around with weak set screws or cam type wedges The dovetail plate is drawn back to the post with two cap head bolts from the rear. Creating a solid, vibration free, won t loosen up, work horse of a holder. To adjust center simply loosen the rear bolts, insert a hex key in the jack screw, center the tool, and lock it back in.