Fixture plates have a grid of 1/4 "-20 threaded holes spaced 1/2 " apart for attaching components. Alpha-numeric markings around the edges of the plates make it easier to identify holes and repeat tasks. Use aluminum plates with CMMs and optical comparators. Use acrylic plates on vision systems. They are transparent to provide your system with a view of the workpiece.Screw thread grid plates made from steel - Vacuum Tables USAOur screw thread grid plate 3010 is made from C45/1.1730 tooling steel and thermally stress relived and face milled.Dimensions:300 x 100 x 20 mmM6 Thread.. $112.97. Add to Cart. Compare. Buy Now Ask Question. Quickview. Model:GRP2020. Dimensions:200.00mm x 200.00mm x 20.00mm.