1. Hexagon Measurement Systems
  2. Metrology Software
  3. PC-DMIS
  4. Ideas
0

FIX XACT MEASURE (DATUM SHIFT ERROR)

A SNAPP 4 years ago in Metrology Software / PC-DMIS • updated by Jacob Cheverie 4 years ago • 1

XACT MEASURE SHOULD UTILIZE THE PCDMIS SIZE FUNCTION WHEN EVALUATING FOR DATUM SHIFT INSTEAD OF WHAT APPEARS TO BE L^2.

WHEN MEASURING A CASTING THAT HAD AN AS CAST DATUM ID DIAMETER THAT WAS 4.4300 +/- .020, THE ACUTAL MEASURED FEATURE WAS OUT OF ROUND AND MEASURED +.0218 AND  -.0235 ON SIZE, BUT WHEN USING THE XACT MEASURE IT CALCULATED AN L^2 (LEAST SQUARES) AT 4.4286 ALLOWING FOR .0186 DATUM SHIFT. WHEN THE DATUM MATING EVELOPE IS LESS THAN THE LOWEST POSSIBLE SIZE YOU DO NOT GET DATUM SHIFT. THIS ERROR NEEDS TO BE FIXED IN ORDER TO FOLLOW ASME Y14.5.

Jacob Cheverie 4 years ago

XactMeasure will evaluate the feature using the algorithm specified upon feature definition. If the feature is defined (and measured) using a traditional least squares fitting algorithm, XactMeasure will use that. To make XactMeasure use a functional fitting algorithm (max inscribed, min circumscribed, etc...) then you can either choose the desired algorithm in the feature definition or you can construct a feature using the measured points and the desired fitting algorithm.

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