What are the grades of granite surface plates?
Manufacturers use three standard grades of flatness defined by the federal specification: Laboratory grade AA: (40 + diagonal [in inches] of surface plate squared/25) x 0.000001 in. Inspection grade A: Laboratory Grade AA x 2. Tool room grade B: Laboratory Grade AA x 4.
What are granite surface plates used for?
JASH Granite Surface Plates are used for precision gauging, inspection, layout and marking purposes. They are preferred by Precision Tool Rooms, Engineering Industries and Research Laboratories because of their following outstanding advantages.
What is a precision granite surface plate?
Precision Surface Plates. Starrett Precision Granite Surface Plates provide a 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.
What is a grade A surface plate?
The highest accuracy plates are called Grade AA, and they are often found in calibration laboratories. Grade B plates are the lowest accuracy plates, and they might be found on shop floors. The middle grade plates, Grade A, are often used in inspection areas.
What is the best granite for surface plate?
You can find both black and pink granite used to make surface plates, with black granite being more popular. Pink granite has more quartz, and is therefore more wear-resistant than black granite. However, it isn’t as strong and so it is normally desirable for a pink granite surface plate to be thicker.
Why granite is the most popular material for surface plates?
Granite is considered to be the best material for a surface plate due to its surface hardness, low thermal expansion, no rust or corrosion, little warping, and long wear life attributes. These attributes result in very accurate, stable and precise measurements.
How do you calibrate a granite surface plate?
Pour a small amount of surface plate cleaner on a clean, soft cloth and wipe the surface of the granite. Immediately dry the cleaner off the surface plate with a dry cloth. Do not allow the cleaning liquid to air-dry. Place a repeat measuring gauge on the center of the granite surface plate.
Why is granite precision?
Granite – A modern material for high-precision parts Natural hard stone is the ideal basis for the manufacture of precision products due to its fine crystalline structure, low coefficient of expansion, high abrasion resistance, optimum vibration damping and freedom from unwanted internal stresses.
How do you support a granite surface plate?
A) A surface plate should be supported at 3 points, ideally located 20% of the length in from the ends of the plate. Two supports should be located 20% of the width in from the long sides, and the remaining support should be centered. Only 3 points can rest solidly on anything but a precision surface.
What is the best surface plate?
Granite is considered the best material for surface plates because its properties (e.g., surface hardness, low thermal expansion, no rust or corrosion, little warping, longer wear life) result in very accurate, stable, and precise surfaces.