- Surface Plates & Granite Shapes
- Reference Masters
- Height Masters
- Bench Centers
Surface plates are a fundamental measuring tool. They provide a nearly perfect plane on which other measurements can be made. Surface plates are available in a variety of tolerance classes:
- Grade AA is the most precise, used in laboratories
- Grade A is for general inspection work
- Grade B is for shop floor work
See: ASME B89.3.7-2013 (the older standard was Federal Specification GGG-P-463c)
Granite Master Squares
Used for checking squareness of machine tools.
Useful for creating inspection datums. Often used when a part has protrusions on an otherwise flat surface.
Granite Straight Edges
Used to compare flatness and straightness of long parts such as machine bedways.
Granite Six-Face Cubes
Granite Angle Plates
Granite angle plates can provide a perpendicular surface to the plane of a surface plate.
Gage blocks are made with extraordinary precision to very tight tolerances. They can be combined to produce a wide range of sizes.
Gage blocks are made to standard grades:
- 00 – Most exact tolerance
- 0 – Suitable for inspection
- AS -1 – Between shop floor use and inspection
- AS-2 – General shop use
See ANSI/ASME B89.1.9M (and the older U.S. Federal Specification GGG-G-15C). Former grades were AAA, AA, A, and B and .5, 1, 2, 3.
Gage blocks must be wrung together to produce accurate results.
Height masters are used to calibrate height gages.