opening in the opposite block said protrusion having a first angled lateral side and an opposite angled lateral side the first opposite block portion situated opposite said first angled lateral side of the protrusion has a mating surface to the first angled side of the protrusion the second opposite block portion is situated opposite said second angled lateral side and in said closed position said first and second opposite block portions engage the respective first and second angled sides of the protrusions thereby creating increased clamping force in the closed position as shown in fig4 b the opposite block is the cavity block and cavity wedges are secured to the first and second cavity block portions if cavity wedges are present they have mating surfaces to the angled sides of the protrusion or if desired such as shown a protrusion wedge shown on one side as item 120 or protrusion wedges on both sides of the protrusion may be utilized if protrusion wedges are utilized the sides of the protrusion itself may or may not be angled and said cavity wedges engage the angled sides of the protrusion wedges the angled sides of the protrusion or if present protrusion wedges attached to the protrusion are typically angled each angled at a range of 0 u00b0 to 30 u00b0 to said direction of mold movement but may be even greater an angle an alternate embodiment is presented in fig9 the design is similar to that of.