# Final adapter seat and fasteners

The final adapter has rear-access screws, a clear carrier pocket and supported soft-pad lands. The original carrier, PCB headers, electronics, factory battery plug and cable endpoints keep their positions. Use this document with the separate **Adapter Carrier Fabrication** drawing and net-map procedure.

## Selected assembly

| Feature | Final specification |
|---|---|
| Cover | K03 rear-access cover; reinforced rails and positive termination clearance; STEP hash starts `580eec6470b4` |
| Grommet crossbar | 6.0 mm depth; lower rail at least 2.025 mm, upper rail at least 2.14 mm |
| Termination clearance | Rounded R0.20 front opening; minimum 0.36 mm to the corrected insulation |
| Screws | Two M2 × 6 machine screws, pan heads within Ø4 × 1.6 mm |
| Axes | X15.6 and 28.1, Y−6.05; installed from the open rear toward +Z |
| Cover ears / hard seat | 2.0 mm thick; hard seat Z−6.5 |
| Thread / point clearance | 4.0 mm nominal material engagement; 3.0 mm design allowance after a 1.0 mm tip/runout reserve; 0.60 mm point-to-pilot-floor gap |
| Pilots | Ø1.7 mm, controlled M2 × 0.4 tapping; floor Z−1.9 |
| Carrier | Corrected 8 × 6 × 1 mm FR4 drawing; drills follow the actual header tail row |
| Pads | Four installed 0.25 mm pads. Front lands support 0.6 of the 0.8 mm pad width: 3.6 mm² each |
| Clearances | Carrier 0.25 mm to rigid supports through the pads; lateral/end allowance 0.30 mm; header 0.399 mm to front backing |
| Cable route | Use the new CK2 front lane, shifted 1 mm inboard. Factory battery cables and J9 routes are unchanged |

Actual head-bearing areas are 8.765044 mm² left and 8.763837 mm² right. The right seat retains 99.986% of the ideal annulus. The bounded front crescent trim is outside the nominal head footprint; see [K03 cover review](K03_REAR_ACCESS_REVIEW.md).

## What remains tight

The right receiver has a 0.95 mm minimum carrier-side ligament and a 0.96161 mm ligament to the J9 clearance channel. The left channel ligament is 1.20548 mm. Both pilot floors leave 1.8999 mm to the original exterior. The right screw head has 0.2472 mm to the installed rear carrier pad. The cover's nonbearing front crescent has 0.20 mm clearance from the carrier backing.

These are measured nominal CAD limits for this specific supported geometry. They are **not general wall-thickness recommendations**. Do not force self-tapping screws into these receivers. Qualify the actual pilot fit, tap depth, screw point, material and tightening torque with QF01B before assembling an active battery.

## Installation and qualification

**QF01B is the stationary seat coupon, not a copy of K03.** It reproduces the local P01 posts, pilot walls, wire reliefs and carrier supports. It contains neither the cover's 2.025 mm lower rail nor its 2.14 mm upper rail. Qualification therefore requires a separately printed **actual final K03** (selected source STEP hash `580eec6470b4…`), fitted to QF01B with the specified hardware, carrier, pads and grommet. A bare coupon or an older cover cannot qualify the final rails or termination opening.

1. Print QF01B and the actual final K03 with the same respective material, orientation, cure and finishing planned for the product. Measure the coupon channels, pilot walls and pad seats, and the cover rails and rounded termination opening. Remove debris without gouging the narrow receiver walls or cover passages.
2. Support the coupon and hand-tap the selected M2 × 0.4 pilots with controlled depth. Establish a usable thread and tightening window through measured coupon tests. The CAD file does not establish a safe universal torque.
3. Fabricate the corrected passive carrier. Thread the two manufactured bare pigtail ends through the loose final K03 passage before soldering or fitting the finished termination insulation. Then solder, fit the controlled insulation and electrically test the completed adapter. Follow its drill/pad and insulation drawings; do not infer polarity from geometry.
4. With the main PCB/module still removed, preassemble the soldered carrier, header, fitted insulation, four pads, grommet and K03 outside the shell. Insert that complete module from the open rear, with its manufactured flexible pigtail undressed and factory battery plug disconnected. Seat it on the locating faces and hard supports, then install the two screws through the open rear. Do not tighten against a trapped wire, bowed board or incorrectly seated pad.
5. On the unpowered QF01B assembly with the actual final K03, apply separate 5 N pull screens to the mating plug housing and outgoing cable; the carrier, cover and grommet must transfer the load to the seat without movement at solder joints. Repeat ten removal/refit cycles. Inspect both cover rails, their roots, screw ears and the insulation opening after each cycle. Reject cracks, stripping, residual set, pad crushing, cable slip, jacket damage or insulation rubbing. Before crediting the analytical 10 N cover screen, use a separate sacrificial final-cover assembly and a jacketed dummy lead/grommet load fixture to reproduce that load path; the coupon-only thread test does not establish the cover's 10 N capacity.
6. Complete the full first-article fit and function checks after the coupon passes. A cropped coupon cannot prove full-shell distortion, long-term creep, environmental aging or electrical/RF performance.

## Evidence and limits

The complete P01 was rebuilt from the original-host checkpoint with every retained cut replayed. It remains one valid solid after each operation. The final K03 has zero overlap with P01; the corrected carrier and termination references clear both parts. Nine sampled positions of the complete preassembled module pass rear insertion. Cover-only insertion past already fixed solder joints is unsuitable and is not the selected sequence. Straight rear-driver access passes with the main PCB/module removed. QF01B is a valid solid with a watertight STL.

A simplified isolated-post 5 N calculation gives 1.99/2.20 MPa; a conservative 5 N load at the end of one carrier backing gives 7.86 MPa. The cover's final calculations include a factor of two on nominal stress: lower rail 7.07 MPa, upper rail 6.33 MPa and longitudinal web 7.28 MPa. All use a hypothetical 8 MPa comparison value, not tested print properties. They do not predict thread splitting, anisotropic fracture, creep or repeated tightening. **No physical coupon, assembly load test or electrical qualification was completed by this CAD work.**