Flatness tester

A test apparatus for measuring the distance between a portion of the test apparatus and a portion of an object, comprising, in combination:

• a) a surface plate with a solid datum plane testing surface having a plurality of points, with the points contained between two parallel planes and with the testing surface having deviations between the two parallel planes, with the planes being separated by a distance measured to a first sensitivity, with the deviations being measured to a second sensitivity greater than the first sensitivity, with the testing surface defined by one of the planes, with the testing surface having a periphery, with the surface plate having a bore extending at least partially therein from an opening in the testing surface, with the opening being spaced from the periphery;
• and
• b) a probe for measuring the distance between one of the planes at the opening and the portion of the object, the probe being in the bore in the surface plate and interacting with the portion of the object when the object is placed over the opening and flat on the testing surface such that the distance between said plane at the opening and the portion of the object may be measured by the probe, with the probe measuring the distance between said plane and the portion of the object to a third sensitivity, with the third sensitivity being greater than the first sensitivity.

A test apparatus for measuring the distance between a portion of the test apparatus and a side of an object, comprising, in combination:

• a) a surface plate having a solid datum plane testing surface for making contact with the side of the object, with the testing surface having a periphery, with the surface plate having a bore extending at least partially therein from an opening in the testing surface, with the opening being spaced from the periphery;
• and
• b) a probe for measuring the distance between the plane at the opening and a portion of the side of the object, the probe being set in the bore in the surface plate, with the probe interacting with the portion of the side of the object when the side of the object is place flat on the testing surface and over the opening such that the distance between the portion of the side of the object and the solid datum plane testing surface may be determined, and with the probe having a sensitivity at or greater than 10 microinches in measurement of the distance between the portion of the side of the object and the solid datum plane.