# Walkie One — Simple S1 · Open speaker

Clean-sheet enclosure built in Autodesk Fusion, September 16, 2026. The chalk face, warm grey perimeter, orange talk paddle and silver controls follow Chalk Ember / concept 28.5. At the owner’s request, the speaker now has one open 35 mm circular cutout: no perforated backing, grille bars, stock mesh or decorative grille recess.

**8 printed parts. 6 screws. Finished CAD envelope: 78 × 150 × 24 mm, including the side buttons.** The main shell is 76 mm wide. The PCB lies flat with its components toward the front. There is no separate PCB carrier, bumper, speaker keeper, microphone bracket, button retainer or USB sleeve.

Open `CAD/Walkie_One_S1_PRINT_ONLY_8_PARTS.f3d` for the uncluttered native Fusion model. `CAD/Walkie_One_Simple_S1_Assembly.f3d` also includes the purchased component references and the native construction features. Use the **eight individual files in PRINT_STL** for printing; each is already oriented on Z=0. Matching STEP files use assembly coordinates in millimetres.

| Part | Qty | Process / finish |
|---|---:|---|
| 01 Front shell | 1 | PETG; chalk face, warm grey perimeter; open speaker aperture |
| 02 Rear cover | 1 | PETG; warm grey |
| 03 Talk paddle | 1 | PETG; ember orange |
| 04 Volume up | 1 | PETG; satin silver finish |
| 05 Volume down | 1 | PETG; satin silver finish |
| 06 Play button | 1 | PETG; satin silver finish |
| 07 Control bridge | 1 | PETG; interior, no cosmetic finish needed |
| 08 Light guide | 1 | Clear SLA resin; polish entry, exit and 45° turning face |

The side/rear walls and bridge floor are 2.4 mm; the bridge's long arm is reinforced to 4.0 mm. The front is 3.0 mm around the open speaker aperture. Button retaining flanges are 2.4 mm. The buttons slide against positive stops; there are no thin printed snap hooks or flexures.

**Rubber bumper: deferred, still required.** S1's warm grey perimeter is rigid printed plastic. No separate rubber/TPU band or finished band interface is included. The owner accepts this for the simplified first build and wants a band in a later revision. That revision must allocate space by recessing or reducing the rigid case so the band, controls and finish together stay within the same 78 × 150 × 24 mm limit. Do not add a band over this shell and increase the overall size.

`review/05_finish_preview_from_CAD.png` is rendered from these actual CAD meshes. This view isolates the front shell to show the open aperture; paint and lighting illustrate its finish. The speaker and other components are omitted in this view. `review/06_eight_print_parts.png` shows the actual eight prints. Native Fusion views and the actual sliced toolpaths are also included.

The final exported files pass independent solid/mesh checks: one valid, watertight connected solid per print; no print-to-print or print-to-purchased-reference intersections; clear PH connector reservations; 0.50 mm plastic button travel with positive stops; sampled straight-in installation paths; nominal screw and USB access checks. The print-only F3D was reopened and verified to contain exactly eight solid components.

All seven rigid parts were sliced together without warnings on a **sample Bambu P1S / 0.4 mm / PETG / 0.20 mm** setup: about **3 h 58 min and 112 g**, including supports and brim. This is an offline feasibility check, not a universal printer profile. The clear part is a separate process. See `PRINT_AND_ASSEMBLY.md` for the short shop brief.

This is a digitally checked first article. Actual switch travel and terminals, received board population, battery thickness, wire dressing, microphone seal, sound, light output, RF performance and drop strength still require a physical build. The CAD does not establish those results. In particular, the compact rear antenna position is not RF-qualified, and the optical part has not been light-tested.

Source references: [approved 28.5](https://walkieone.com/cad-handoff/concept-28-5), [Adafruit SPH0645 / 3421](https://www.adafruit.com/product/3421), [JST PH dimensions](https://www.jst-mfg.com/product/pdf/eng/ePH.pdf), [CNC Kitchen short M3 inserts](https://cnckitchen.store/products/heat-set-insert-m3-x-3-short-version-100-pieces). The original PCB mechanical reference and its hash are recorded in `references/purchased_manifest.json`. The microphone remains the owner's Adafruit part, as confirmed in this task.