# Walkie One v30-Polished-R1 Selective

**Recommended mechanical prototype candidate for RPS review and first-article fit testing. Not a production release or a tested powered build.** Units are millimetres. Use the STEP files for RPS. The failed full-skin candidate is preserved separately in RECOVERY-CHECKPOINT-NOT-FOR-FABRICATION.zip and is not included in the recommended fabrication folders.

## What changed

The original v30 envelope and exact supplied electronics remain the mechanical foundation. The accepted Play C/0.40 parts, PTT linkage/pivots, volume reaction lands, speaker and microphone gasket interfaces are retained. No electronics were relocated or scaled.

The silicone is now a **selective nominal 1.00 mm perimeter/side band**, between Z3.8 and Z18.0, instead of a full rear membrane. The rear panel is deliberately exposed rigid material. Radiused PTT, volume and USB lands also remain rigid. There is no 0.30 mm rear skin or 0.35 mm volume-bay membrane in the recommended model. The band has registration keys and a nominal 0.15 mm seat/bond allowance. A qualified serviceable silicone bond is permitted; a removable dry-fit is not a release requirement.

Useful first-pass improvements retained: two integral 10 mm-wide wire guides at X54.2, actual perforated grille, backing rebate and two vent-relieved adhesive rings, organized native assembly, and open USB liner architecture. The central lower film is additionally relieved to maximum Z4.35 to provide a real tolerance allocation rather than relying on the original 0.0319 mm floor gap.

### Alternatives considered

| Approach | Decision |
|---|---|
| Full silicone coverage with 0.30/0.35 mm local membranes | Rejected from recommended fabrication: thin membranes and reduced rigid floors were avoidable. |
| Moving electronics to recover skin thickness | Not needed. A selective band preserves the original electronics positions and avoids changing the accepted mechanism interfaces. No unverified relocation was applied. |
| Selective perimeter with exposed rear/control lands | Implemented. Retains the original critical rear material and avoids the thin membranes while staying in the same finished envelope. |
| Serviceable bonded silicone | Permitted option. Supplier must select silicone, primer/adhesive and process; the CAD seat allowance is not a validated bond-line specification. |

## Local section budget, not an average

The four specified zero-based PCB solids 22, 96, 112 and 158 remain at their supplied locations. At their centroid XY positions, the rear rigid section is restored to **Z0..1.210223486**, with **no silicone on that rear surface**. The connector-lead region retains **Z0..1.315**. The sampled general rear wall remains **2.0**, and the battery seat remains **2.4**. These are explicit section checks, not a complete global minimum-wall proof.

The sampled plain side wall is **1.60 mm rigid + 0.15 mm nominal seat allowance + 1.00 mm silicone = the original 2.75 mm allocation**. The original 1.37 mm volume-side rigid wall is retained on its exposed land rather than being cut to accommodate rubber. Sampled rear bridges of the silicone band are 1.8 mm at PTT and 1.5 mm at the volume land. Refer to `verification/selective-wall-envelope-check.json` for coordinates, intervals and complete raw numbers.

The finished rigid-plus-silicone body is constrained to **73.5 × 143.25 × 19.4**. Existing volume-cap and LED projections are not included in that body size; the full nominal assembly envelope remains approximately **74.3 × 143.25 × 21.4**. Numerical CAD tolerances are not manufactured-part tolerances.

## Assembly sequence

1. **Use only the recommended parts.** Inspect and clean the rigid prototypes. Install the source M2 inserts before electronics and let them cool. The source knurl/pilot geometry is 3.2/2.7 mm with nominal 2.9 mm printed pilots; intended insert interference is not a rigid-part clash. Do not substitute countersunk heads.
2. **Prepare the acoustic stack.** Deburr the custom 46 × 46 × 0.50 R8 perforated grille. Fit the 42 × 42 R6 permeable backing into its 0.18 mm allocation. Use one outer structural adhesive ring and one inner backing-retention ring. Their gap avoids the backing-rebate clearance, and vent reliefs must remain open. Do not bridge the acoustic opening with adhesive or substitute solid plastic for the acoustic backing.
3. **Fit speaker and microphone.** Keep the separate speaker gasket, 0.5 stock compressed to 0.3. Speaker fastening stack toward the front: head, 0.7 printed spacer, speaker tab, 0.3 metal washer, flush short insert. Microphone gasket remains 5.6 OD /2.6 ID, 0.5 stock assembled to 0.4. Keep the inlet clear.
4. **Install Play, PTT and LED using the original datums.** Retain Play C/0.40 and the existing lead preparation. Assemble the PTT moving sleeves/links to the cap, enter from the open back, then secure the fixed pivots and switch cassette. PTT screws must bear on the shoulder sleeves, not clamp the free links. Thread the source upper-wire channel before closing the cassette. Insert the LED/retainer/formed-lead assembly toward the front from the open back; do not rely on the obstructed sideways slide.
5. **Install the volume module.** Use the supplied 6 ×6 ×4.3 switch geometry, two-dot caps and original X67.5 reaction lands. The two 4 ×4 ×0.26 adhesive pads retain the released switch position; the rigid lands carry press loads. Confirm no preload and full return.
6. **Prepare the revised USB liner off the electronics.** Do not use the deleted E floor-lift patch. Follow the controlled-trim starters and the maximum-material CAD envelope. The lower central free-film field must remain at or below Z4.35; side-return lower ends remain at or above Z5.45. Keep the forward board-edge face single-layer. No exposed adhesive or loose edge may enter the mating path. The more open lower mask may reveal a small part of the PCB edge; do not conceal it by reinstating the tight floor stack.
7. **Seat the exact PCB and battery without force.** The v30 electronics configuration is complete as a working mechanical assumption. Do not add the earlier separate Taoglas antenna or coax. Physical procurement identity and final wiring/pinout have not been independently confirmed.
8. **Route and restrain wires.** Preserve supplied local exit and solder-joint allowances. The two guides provide a nominal 7.6 ×1.9 radiused opening; use flexible insulated signal wire within the source 0.8 mm OD allowance and non-metallic lacing/soft restraints. Keep solder joints within their source keepouts and leave service slack away from PTT links, volume guides, the acoustic throat, battery edges and the case seam. The guides are routing/strain-relief attachment features, not a validated electrical harness. Do not infer net assignments, conductor count or cut lengths from CAD paths.
9. **Close the case gently.** No screw force may be used to crush a wire or seat a mislocated part. The four case screws remain M2×12; their reference positions are shifted +1.0 Z to the unified Z2.8 bearing planes, with tip relief to Z15.3. Nominal tip reserve is 0.5. Screw torque and insert pull-out strength require the actual material and kit.
10. **Fit the selective band last.** Register the four keys while keeping all rigid control lands uncovered. A dry-fit band may be removed by peeling progressively from an exposed control/USB land, not by pulling a thin edge. For a serviceable bonded build, RPS must qualify the silicone-compatible bond/primer, use the seat allowance deliberately and preserve access to the rear screws. No shrink compensation is built into the installed master.

## USB tolerance plan

The original two-layer floor had 0.0319 nominal clearance and 0.0059 at the stated tape upper tolerance. Removing the floor patch improved it, but the earlier 0.291752 lower-film clearance still failed the deliberately allocated budget below. The selected Z4.35 relief gives approximately **0.772688 mm** lower free-film clearance to the exact supplied receptacle.

| Budget item | Allocated adverse variation (mm) | Status |
|---|---:|---|
| Printed collar/fixture position | 0.127 | Uses the published RPS generic SLA first-inch accuracy as an allocation, not as a guarantee for this geometry. |
| Receptacle position | 0.100 | Engineering allocation; verify actual PCB/receptacle. |
| Hand forming/trimming | 0.100 | Process allocation; measure finished liner. |
| One film layer | 0.013 | Stated 1350F-1 thickness tolerance. |
| Total allocation | 0.340 | Not supplier acceptance. |
| Nominal remaining clearance | 0.432688 | Above proposed minimum as-built acceptance of 0.25. |

Inspect the **actual** lower free-film clearance and full seating/removal with the intended USB cables and overmolds. Reject snagging, wrinkles, exposed adhesive, lost seating depth or shifting tape. The model does not qualify every aftermarket plug. The recorded budget must be revisited if measured variations exceed its allocations.

## Material and process decisions

- **Rigid prototypes:** RPS-selected SLA/cast material or an appropriately resliced print. Original accepted mechanism clearances include 0.025–0.075 mm local gaps; these are not guaranteed by general SLA accuracy. Reuse accepted Play hardware where available and inspect any new reproduction.
- **Silicone:** 30A is an unselected design target, not a purchased grade. Dragon Skin 10NV is a distinct **10A prototype alternative**, not an equivalent 30A material. Its bulk data do not qualify this band, bond, shrink compensation or fatigue life. Supplier choice remains open. ([Smooth-On bulletin](https://www.smooth-on.com/tb/files/DRAGON_SKIN_10NV_TB.pdf))
- **Grille:** custom photo-etched stainless candidate with 1153 actual Ø0.8 holes, 1.2 triangular pitch and nominal 0.4 webs. Generic process capability supports a DFM discussion, not acceptance of this particular alloy, artwork, finish, cusp, flatness or part. ([Precision Micro guidelines](https://www.precisionmicro.com/chemical-etching/technical-guidelines/))
- **Backing:** 0.18 mm is an allocated space, not a verified SKU. Select a black permeable acoustic construction and test the actual stack. SAATI Acoustex is a family lead only. ([SAATI](https://www.saati.com/products/filtration/brands/saatifil-acoustex/))
- **Adhesives/tape:** F9473PC is nominally 0.26 mm; 1350F-1 is 0.064 ±0.013 mm per layer. Neither data sheet establishes adhesion or durability in this assembly. ([3M F9473PC](https://multimedia.3m.com/mws/media/2366138O/3M-VHB-Adhesive-Transfer-Tape-F9473PC.pdf?pif=000023), [3M 1350F-1](https://multimedia.3m.com/mws/media/86180O/3m-polyester-film-electrical-tape-1350f-1-1350f-2-data-sheet-78-8125-9473-3-b.pdf))
- **Wire:** Alpha 1850 at nominal 0.74 mm OD is a signal-only candidate; Alpha 1851 at 0.81 mm exceeds the retained 0.80 mm allowance. Electrical sizing, OD tolerance and termination suitability require the approved map and actual loading. The 4 mm routing radius is an engineering layout assumption; supplier bend rating is unspecified. ([Alpha Wire catalog](https://www.alphawire.com/en/onlinetools/~/media/files/mastercatalog2011/hookupwire.pdf))

RPS advertises casting, silicone material options, finishes/overmolds and integration of client-supplied electronics; these service descriptions are **not acceptance of this design, its wall thicknesses or tolerances**. ([RPS casting services](https://www.rapid-products.com/service/urethane-castings/), [RPS concept/assembly services](https://www.rapid-products.com/service/concept-and-presentation-models/))

## Inherited acoustic condition

The source v30 reports a small speaker-root acoustic mask of approximately **3.235195 mm³** for its R19.69 probe. It is an inherited acoustic condition, not a physical-fit or acoustic-performance pass. This revision does not relocate the speaker or redesign that throat/root. Confirm actual response and sealing on the first article.

## Printing and release boundaries

Only `exports/rigid/` contains rigid printable parts. `exports/elastomer/` contains the **installed silicone master**, not a rigid part or shrink-compensated mold. Cutstock, electronics, hardware and wire envelopes must not be rigid-printed. STLs use millimetres by convention and remain in assembly coordinates; they are not a new plated/sliced printer project. The old A1 mini/PLA+ Bambu projects are not new R1 slicing evidence and are excluded from this recommended package.

No physical switch-force/return, acoustic, drop, fatigue, ingress, adhesive-aging, charging or powered-electrical qualification is claimed. Obtain the separately requested approved electrical pin map before wiring or powering the prototype. See `FIRST_ARTICLE_CHECKS.csv`, `BOM.csv` and the machine-readable verification folder.