# Part_023 horn-arm fit correction

The user reported that the printed cylindrical horn seat fits, but the arm
cannot enter its cavity. The exact previously successful printed revision
could not be identified from the available history.

## Source finding

The horn's exterior was not shrunk: the original and current reference
outlines agree within 0.00004 mm after rigid alignment. Earlier work changed
pilot holes, and replaced Part_023's cavity with the Part_009 cavity during
the recessed-horn redesign. The angled-link redesign then rebuilt the pocket
from the modeled horn silhouette with 0.12 mm perimeter clearance. The
original Part_023 cavity profile was therefore not preserved.

## Correction

- Only the horn-arm cavity is enlarged, by 5% in its plane, including length.
- The enlargement blends in near the hub; the cylindrical mating region
  within a 4.05 mm radius is excluded from all material removal.
- Cavity floor, external carrier shape, pivot axes and mounting-hole positions
  are retained. The real horn reference is unchanged.
- Four live Part_023 objects and the Part_023 print-layout object are updated.
- The other leg designs and motions are retained, including the shorter
  Part_027 legs and the single-leg Part_026 curve test.

Use `Part_023-Horn-Arm-Clearance-Plus5pct.stl` for the corrected print. Units
are millimetres; the STL is placed on its flat printing face. Historical
STLs in older revision folders remain unchanged.

`design-report.json` contains measured cavity widths and removed volume;
`application.json` identifies the live file, pre-edit backup and object hashes.
`capture.py`, `build.py`, and `apply.py` document the edit.

Closed-mesh and cylindrical-region preservation checks passed. Physical fit
with the user's purchased horn still requires a new print; the earlier
printed failure is not treated as a passed fit check.