Granite Surface Plates Accessories
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Granite Surface Plates Accessories Granite Surface Plates and Accessories 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. OEM Capabilities Selection Our Starrett Granite Division continues to Accuracy Under Load provide solutions to customers in precision Starrett Crystal Pink® and Superior Black granite, carbon fiber, ceramic, high precision Granite plates have a thickness capable of vacuum chucks and other materials. We offer supporting a total normal load equal to 50lb granite machine bases and surface plates to for each square foot (24kg for each 1,000 sq. meet your requirements up to 55 feet long cm) of surface area loaded in the center of and weighing 72 tons. the plate – without deflecting the plate along a diagonal of more than one-half the flatness Whether your application requires a simple tolerance. This is the accepted rating in the standard surface plate or a large OEM U.S. Federal Specification GGG-P-463c and assembly, the Starrett Granite Division will ASME B89.3.7 2013. work with you to fulfill those requirements. Granite Surface Plates Granite Surface In the situations where abnormal loading Every linear measurement depends on an conditions are anticipated, Starrett can accurate reference surface from which final engineer and modify surface plate thickness dimensions are taken. Starrett Precision to meet virtually any requirement. Granite Surface Plates provide this reference plane for work inspection and for work layout. Ledges and Clamping Their high degree of flatness, overall quality Surface plates without work clamping ledges and workmanship also make them ideal are recommended for sustained accuracy bases for mounting sophisticated mechanical, and reliability. Ledges are for work clamping electronic and optical gaging systems. purposes only. If excessive torque is used Material when applying clamps to ledges, it can adversely affect measurements taken near The granite for Starrett surface plates has the plate edges. If clamping is important, been selected for the best balance of physical T-slots and threaded metal inserts may be properties, maximum resistance to wear and installed in the surface. for deflection under load. Each plate has been lapped to a fine microinch finish to minimize Accuracy tool wear and drag. Specifications The most important element in the Starrett Granite Surface Plates meet or performance and life of granite surface plates exceed U.S. Federal Specification GGG-P- is the percentage of quartz that is present 463c and ASME B89.3.7 2013. in the stone. Quartz is more than twice as Starrett Granite resistant to wear as the other minerals in Surface Plate granite. It provides bearing points that are Calibration of a hard, highly polished, smooth character • Calibration of granite surface plates, which protect the accuracy and finish of granite parallels (2 and 4-sided), granite both the surface plate and the tools and straight edges, granite tri-squares, instruments used on it. granite angle plates and granite squares Starrett Crystal Pink® Granite has the • Surface plate and granite metrology and highest percentage of quartz of any granite. accessory resurfacing Higher quartz content means greater wear • Calibration Lab is accredited by A2LA to resistance. The longer a surface plate holds ISO/IEC 17025* its accuracy, the less often it will require resurfacing, ultimately providing better value. * The L.S. Starrett Company’s accreditations are site-specific and tool-specific. The scope of accreditation is available upon request to each location. 408 Technical Information Accuracy Certified Accuracy Starrett Granite Surface Plates are manufactured in three grades of Before shipment, each surface plate must pass a critical final accuracy: inspection to prove that its entire surface is within the specified tolerance. The final inspection is done with an autocollimator in a • Grade AA – Laboratory Grade controlled environment. This instrument is checked and certified This is typically specified for precision operations in constant against standards traceable to the U.S. National Institute of Standards temperature gaging rooms and metrology departments. and Technology (NIST). The instrument’s certification is on file at the • Grade A – Inspection Grade Starrett Tru-Stone Technologies Division in Waite Park, MN. This is typically specified for general work in quality control. All shipments of Starrett precision granite products include a • Grade B – Toolroom Grade calibration certificate which verifies traceability to NIST as well as This is typically specified for production checking work certifying that the inspection requirements of U.S. MIL-I-45208A and throughout the shop. Federal Spec. GGG-P-463c and ASME B89.3.7 2013 have been met. Unilateral Flatness Tolerance Periodic Inspection Overall flatness tolerance is based on unilateral measurement. All Every surface plate in use should be frequently inspected, especially points on the work surface shall be contained between two parallel when used in shop conditions where abrasion is common. An planes separated at a distance no greater than the amount specified effective inspection program should include regular checks with an Plates Granite Surface for each particular grade and size as shown in our listings. autocollimator. If tolerance variations are excessive, the plate can be Repeat Reading Tolerance transferred to work involving less accuracy or it can be resurfaced to Repeat reading tolerance is easily checked with a Repeat Reading restore its original level of accuracy. Gage. This gage detects local areas, not overall flatness. Resurfacing Services In addition to the overall flatness tolerance referred to above, Starrett Resurfacing for Starrett and other brands of granite surface plates are provides repeat reading tolerances as follows: available in our plant or yours. Full Indicator Movement Design Assistance (F.I.M.) in Microinches and (Microns) Starrett engineers will provide prompt assistance with any problem Diagonal Inches (mm) Grade AA Grade A Grade B Obtained related to surface plate design, installation or use. Our staff is Through 30" (750) 35 (.9) 60 (1.5) 110 (2.8) available to assist in your design of larger OEM projects. Over 30-60" (750-1500) 45 (1.1) 70 (1.8) 120 (3) Over 60-90" (1500-2250) 60 (1.5) 80 (2) 160 (4) When Not To get the best service and value from any granite plate, contact Over 90-120" (2250-3000) 75 (1.9) 100 (2.5) 200 (5) Specified Over 120-150" (3000-3800) 90 (2.3) 120 (3) 240 (6) Starrett Tru-Stone. Over 150" (3800) 100 (2.5) 140 (3.6) 280 (7) All Sizes 25 (.6) 50 (1.3) 100 (2.5) When Specified A repeat reading gage detects minute variations of the surface within the unilateral flatness tolerance of the whole surface. Inspecting a granite plate with an autocollimator starrett.com 409 Tru-Vac Vacuum and Granite Solutions Air-lift Technology Starrett provides both standard and custom Custom Engineered Modifying standard solutions for vacuum chucking, positioning Granite Solutions plates: or air-lift part transfer. Our innovative Tru- For Oversize Parts and The second general category relates to Vac technology integrates the stability and Assembling modifying standard plates or building special precision flatness of granite with a porous Starrett has unparalleled experience and surface plates for work-holding attachments medium, usually ceramic. expertise in building special, extra-large of many different types. Tru-Vac can eliminate the need for granite surface plates and custom products Threaded and solid inserts, adaptor holes, mechanical clamping with its inherent from granite to meet specific requirements. T-slots, dovetails – almost anything added part distortion or damage risk by utilizing All Starrett special surface plates are made to conventional gaging fixtures can also be vacuum draw at specific locations or from single, solid slabs of granite quarried added to Starrett surface plates, extending distributed over the entire surface of your in one piece, machined in one piece and their accuracy and versatility for numerous part. finished to your specified dimensions and applications. Precision edges, made square Conversely, Tru-Vac technology can be tolerances. with the top surface and adjacent edges, as well as precision graduated rules can also be utilized to provide positive pressure to Special plates are added. allow delicate parts to glide on a cushion usually requested of air from which they can be safely lifted Granite Surface Plates Granite Surface in two categories: We can build and assemble this work-holding or transferred to the next operation. Inspecting oversize or special gaging equipment to very close parts: tolerance in either fractional, decimal inch Starrett engineers will work with you to or metric dimensions. All special plates are select the best porous medium for your The first category is for inspecting oversize quoted on an individual basis, based on application based on surface area, flatness, parts and assemblies such as diesel engine complexity and tolerance requirements. We wear, and desired airflow characteristics. blocks and crankshafts, vehicle frames, will work with you to give you the best, most missile components and ground support Tru-Vac technology can be utilized in economical solution for your application. equipment. air chucks smaller than a hockey puck The uses of Starrett special granite surface or larger than a conference room table. Inquiries for granite surface plates to plates are limited only by the imagination of Vacuum zones can be of nearly any shape accommodate oversize parts and assemblies the creative tool designer. Inquiries for special by virtue of our CNC milling capabilities. should indicate: surface plates like the type shown will be Multiple zones can be utilized to studied and recommendations given without 1. Type of part to be staged accommodate a variety of part sizes or obligation. 2. Distribution of weight even to provide a combination of negative and positive 3. Inspection accuracy required pressure for 4.