Have you ever wondered how FeatureCAM selects the drill size for a tapped hole?

The tap drill is picked from the tool crib based on the settings for "tool diameter tolerance" and "Thread %" in the "Default Attributes".  FeatureCAM defaults the "tool diameter tolerance" to +/- .002 which is accurate enough for an 0-80 thread.  You may want to set a larger "tool diameter tolerance" since +/- .005 would be the correct setting for a 1/4-20 thread.  Most tap drill charts are based on a 75% thread.

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