An entry diameter can meet its size limits while leaving the rest of a bore uncharacterized. BTA quality planning begins by separating the characteristics on the drawing and the coverage required to inspect them.
Catalogue grades are scoped screening information
Page 5 of botek’s V38 catalogue gives quality entries by tool family. Such entries identify the supplier’s stated scope; they are not measurements of the part being accepted. Keep the tool and conditions with a cited entry rather than assigning one grade or texture value to the process name.
Size is not a record of the bore path
As an assumed example, a 20.000 mm diameter with ±0.020 mm limits has an allowed size interval from 19.980 to 20.020 mm. A recorded 20.010 mm entry value is inside that interval at the inspected location. It does not describe the diameter deeper in the bore or establish the location of its axis relative to a datum.
The illustration below goes a step further: its invented paths share entry and exit coordinates but differ at an interior station. They are not measured profiles or straightness calculations. They show why endpoint agreement cannot fill a gap in interior coverage.
Choose the measurement for the characteristic
Retain reach, station locations, datum interpretation and uncertainty with each result. A diameter method and an axis-path method answer different questions. Texture also needs its named parameter and evaluated region; it should not be inferred from a photograph or a size check.
If finishing is included, define the incoming bore and the final acceptance stage separately. An as-drilled measurement and a finished result belong to different route endpoints.
Use the quality worksheet below to retain requirements and coverage. Continue to measurement methods when selecting inspection equipment and the tolerance guide for grades and characteristic definitions. A reported value becomes meaningful when its measurement boundary is clear.
Revision note
October 8, 2026: revised the technical explanation and connected reading after source review. Original publication date and URL retained.
