# PTT fixed rear pad: final edge trim

**Cut the fixed rear PTT pad to 5.2 × 9.0 × 0.50 mm installed.** Replace the earlier 5.7 × 9.0 × 0.50 mm reference. This is purchased compliant stock, not a printed part. Keep the existing material qualification and installed thickness, including adhesive where applicable; no material grade or compression is newly approved here.

## Placement

- Assembly bounds: **X−36.7…−31.5, Y12.5…21.5, Z−12.7…−12.2 mm**.
- Preserve the inboard edge at X−31.5 and both Y edges. Remove only the 0.50 mm strip at the old outboard edge, X−37.2…−36.7.
- Keep the 0.50 mm installed thickness. Do not stack another layer, leave an adhesive overhang, or rely on the pad compressing to clear the moving carrier.
- Use `R36_STOCK_PTT_REAR_PAD_TRIMMED_5p2x9x0p50_FINAL.step` as the placement reference. The original `C28_R3_PTT_Rear_Keeper_Pad_0p50` is superseded.

## Reason for the trim

The original pad's overhang contacts P05 after approximately 0.25 mm of PTT travel. At 0.30 mm travel the nominal overlap is 0.225 mm³. That contact could add drag or prevent reliable release. The edge trim clears this overhang while retaining **91.23% of the pad's total face area** and **all of its measured bearing areas**.

| Interface | Original area | Trimmed area |
|---|---:|---:|
| Rear pad face on P01 support | 45.45 mm² | 45.45 mm² |
| Front pad face on P08 cradle | 15.95703 mm² | 15.95703 mm² |
| Front pad face on nominal switch housing | 21.60 mm² | 21.60 mm² |

## Verification

The local audit uses frozen assembly manifest `6fdae6ead77e1f605f65ddccadd628b276b5eb5e7ae24ed651b96775a93649b2`.

- All four PTT moving items—P05, F02 grip, contact pad and bond film—clear the trimmed pad at seven positions through 0…0.45 mm travel. Minimum sampled clearance is **0.30 mm**. Continuous translation distance bounds remain positive, with a minimum conservative bound of **0.2625 mm**.
- All 32 mover/pose checks at midstroke, using ±0.25° and ±0.50° about the Y and Z axes, clear the trimmed pad. Minimum gap is **0.28765 mm**. These are limited packaging probes, not a guide-flex or slop certification.
- The new stock is a strict subset of the old stock: **zero added volume**, 2.25 mm³ removed. All **206 local static pairs** with the other references, printed parts and hardware have zero volumetric overlap.
- The original source STEP and frozen assembly files are unchanged. The separate stock-only manifest supplies the replacement.

See `PTT_PAD_MOTION_CORRECTION_CHECKS.json` for input hashes, individual measurements, exact support-area comparisons and the removal-only proof. `PTT_PAD_FINAL_CORRECTION_MANIFEST.json` has no shell operations. Root's complete final operating-clearance audit must run after this stock replacement is integrated.

## First-article checks

Check the cut edge and installed thickness on the actual assembly. Confirm free PTT movement and electrical release from centre and end presses, including with the case tightened. Watch for adhesive creep, a lifted edge, rubbing or permanent pad displacement. The existing requirements for **10 service cycles and 1,000 PTT actuations** remain. A passing nominal geometry check does not certify the selected pad material or a printed manufacturing process.