Someone was asking what the flatness tolerance for the different grades of surface plates.

Here's the flatness tolerance formula:

• Laboratory Grade AA: (40 + diagonal [in inches] of surface plate squared / 25) x 0.000001 inches.

• Inspection Grade A: Laboratory Grade AA x 2

• Inspection Grade B: Laboratory Grade AA x 4

Source: http://www.mahr.com/index.php?NodeID...Language=EN-US

Here's the flatness tolerance formula:

• Laboratory Grade AA: (40 + diagonal [in inches] of surface plate squared / 25) x 0.000001 inches.

• Inspection Grade A: Laboratory Grade AA x 2

• Inspection Grade B: Laboratory Grade AA x 4

Source: http://www.mahr.com/index.php?NodeID...Language=EN-US

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