Precision Granite Plates and Stands
Granite is one of the best materials available to meet the ever changing and sophisticated applications demanding co-planarity, perpendicularity, parallelism, flatness and straightness. It is often chosen for its stability and high accuracy.
Precision Granite steel stands are manufactured to support the weight of the surface plate plus 50 pounds per square foot load.
Granite Surface Plates
Precision Granite surface plates are manufactured to meet or exceed the tolerances specified by Federal Specification GGG-P-463c. A Precision Granite calibration certificate is included with every surface plate, guaranteeing overall surface flatness and repetitive gage measurements and is traceable to N.I.S.T. or equivalent National or International Organizations. Long-form certification is also available.
These plates are made of black granite which is stronger, denser and more stable than light colored granite. The granite properties determine the stiffness of the granite so accuracy can be guaranteed with less thickness than other types of granite. This translates to less freight and handling whenever the plate is shipped or moved.
There are three grades of surface plates:
- AA – Laboratory Grade – High precision operations in temperature controlled gaging rooms and metrology departments
- A – Inspection Grade – General quality control use
- B – Toolroom Grade – Shop work and production checking
Steel Stands
The Fed. Spec. GGG-P-463c recommends three fixed points to support the surface plate and minimize sag and warp. Precision Granite plates are marked on the bottom of the plate to coincide with the supports on the top of the stand. When aligned with each other, they uphold the accuracy of the plate.
These standard stands are manufactured to support the weight of the surface plate plus 50 pounds per square foot load.
Stands are made for each plate to meet a 36” working height unless otherwise specified.