explained how calypso establishes / calculate a plain

[[K...]]

I developed a plain 80mm x 80mm which is measured by 20 hits within Ø 124 mm zone and in the same vector direction. The plain is upward facing from Datum A by 20 mm. Please see the data below:

-20.43, -20.13, -20.17, -20.23, +20.11, +20.15, +20.21, +20.12, …….., +20.23, +20.31, +20.45, +20.57, -20.13, -20.27, -20.33

The analysis reveals that the flatness is 0.23. It needs to be explained how calypso establishes a plain and the procedure of calculating the height from Datum A.

Thank you

[[SH...]]

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I wonder with your reading 1mm flatness!!!

It depends upon the evaluation you have used for your datum A.

[[Da...]]

A form error is always calculated from the minimum zone element (also called minmax element or Chebycheff element). To do that, Calypso calculates the points in a way that the maximum error within the points is minimized. When you want to check the values yourself, you have to make sure that you get the values of the minimum zone element (from within the minimum zone element because there the points are aligned in the element coordinate system). The distance between the high point and low point is the flatness. Calypso doesn’t make any error there, it’s airtight.

It is generally not recommended to evaluate a distance to a datum measured as a tangential element. Use Datums to align the part, not for evaluations. Flatness is okay, because it is automatically recalculated, but for distance measurements you should recalculate to a Gaussian element.

[[An...]]

See attached.

Distance_of_a_plane_1.pdf