[walter]

Real granite test results



It was no contest really. This Brazillian countertop granite is pretty weak, grainy and probably full of internal cracks. I repeated the test 13 times- in all cases granite went down at 5-7.5 ft*lbs. My best E/G samples did 20 ft*lbs for the beam and 20-30 ft*lbs for the bricks. I understand now why Starret charges so much for their granite bases. It's a different type of granite..

Here's what machine builders are using:

Blue Granite (France)—Excellent wear resistance due to presence of high grade quartz. Blue granite is used for very large structures.

Black Granite (South Africa)—Low thermal expansion and low water absorption. Black granite is used for most standard applications such as metrology surface plates.

Fine Black Granite—Excellent elastic modulus due to absence of quartz and good adhesion of grains. Fine black granite is used for small structures requiring high mechanical resistance.

Sample thickness: Granite 1.125", E/G 1.375"
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