Granite Surface Pla tes and Accessories OEM Capabilities Our Starrett Tru-Stone Granite Division continues to provide solutions to customers in precision granite, carbon fiber, ceramic, high precision vacuum chucks and other materials. We offer granite machine bases and surface plates to meet your requirements up to 55 feet long and weighing 72 tons. Whether your application requires a simple standard surface plate or a large OEM assembly, the Starrett Tru-Stone Division will work with you to fulfill those requirements. Every linear measurement depends on an accurate reference surface from which final dimensions are taken. Starrett Precision Granite Surface Plates provide this reference plane for work inspection and for work layout. Their high degree of flatness, overall quality and workmanship also make them ideal bases for mounting sophisticated mechanical, electronic and optical gaging systems. Ma terial The granite for Starrett surface plates has been selected for the best balance of physical properties, maximum resistance to wear and for deflection under load. Each plate has been lapped to a fine microinch finish to minimize tool wear and drag. The most important element in the performance and life of granite surface plates is the percentage of quartz that is present in the stone. Quartz is more than twice as resistant to wear as the other minerals in granite. It provides bearing points that are of a hard, highly polished, smooth character which protect the accuracy and finish of both the surface plate and the tools and instruments used on it. Starrett Crystal Pink® Granite has the highest percentage of quartz of any granite. Higher quartz content means greater wear resistance.The longer a surface plate holds its accuracy, the less often it will require resurfacing, ultimately providing better value. Selection Accuracy Under Load Starrett Crystal Pink® and Superior Black Granite plates have a thickness capable of supporting a total normal load equal to 50lb for each square foot (24kg for each 1,000 sq. cm) of surface area loaded in the center of the plate – without deflecting the plate along a diagonal of more than one- half the flatness tolerance.This is the accepted rating in the U.S. Federal Specification GGG-P-463c and ASME B89.3.7 2013. In the situations where abnormal loading conditions are anticipated, Starrett can engineer and modify surface plate thickness to meet virtually any requirement. Ledges and Clamping Surface plates without work clamping ledges are recommended for sustained accuracy and reliability. Ledges are for work clamping purposes only. If excessive torque is used when applying clamps to ledges, it can adversely affect measurements taken near the plate edges. If clamping is important, T-slots and threaded metal inserts may be installed in the surface. Accuracy Specifica tions Starrett Granite Surface Plates meet or exceed U.S. Federal Specification GGG-P-463c and ASME B89.3.7 2013. St arrett Granite Surface Pla te Calibra tion Services • Calibration of granite surface plates, granite parallels (2 and 4-sided), granite straight edges, granite tri-squares, granite angle plates and granite squares • Surface plate and granite metrology and accessory resurfacing • Calibration Lab is accredited by A2LA to ISO/IEC 17025* * The L.S. Starrett Company's accreditations are site-specific and tool-specific. The scope of accreditation is available upon request to each location. In 2006, The L.S. Starrett Company acquired Tru-Stone Technologies in Waite Park, MN. With this acquisition, a broad variety of new capabilities are now available to Starrett customers. 410 G ranite S urface P roducts