Granite Surface Plate

Best Selling

See All- Best Selling

Finding the Right Granite Surface Plate

If you are a mechanical engineer or work in a shop that relies on CNC machines and tools, having a quality granite surface plate is critical. Your surface plate allows you to reliably collect and calibrate measurements that require a flat and level 2D plane. Finding an affordable surface plate or granite inspection table for sale on eBay can be an easy way to upgrade your shop.

Grades of granite to consider when looking at a granite surface plate for sale

The granite used in a granite surface plate is graded by quality, with these four levels of quality:

  • AA - This is a laboratory-grade granite surface.
  • A - This is an inspection-grade granite surface.
  • B - This is a toolroom-grade granite surface.
  • Workshop - This granite surface grade is the lowest and may not be suitable for precise CNC machine tooling tasks.
Why are certain types of granite used in surface plates?

Surface plates can be made from a variety of materials, including cast iron, glass, steel, and granite. During World War II, when metal was necessary for military production, using granite for surface plates came into common use. There are two types of granite commonly favored in surface plate construction:

  • Pink granite - This type of granite is more durable due to the amount of quartz in the stone. It is usually cut in thick slabs.
  • Black granite - This type of granite is the preferred standard for granite surface plates due to its greater strength.
What features should you consider when purchasing a used surface plate?

Purchasing a used surface plate or used granite inspection table for sale on eBay can be an affordable way to equip your CNC shop with the necessary surface plate for measurement tasks that require a level plane. When considering a preowned surface plate for sale, carefully check for these conditions and features:

  • Signs of wear - Chipping or warping can happen to a surface plate over time; if the granite surface is regularly calibrated and tools are routinely rotated, this wear can be lessened. You can generally expect a used surface plate to show some cosmetic damage, but it should still function properly.
  • Stand or cover - The granite surface plate may be a solo item or may come with a stand that makes it a functional inspection table; additionally, it may have a cover for the granite surface to protect it when not in use.