# Assembly and nonprinted parts - 28.1 / R3.4

Website version **28.1** = engineering **R3.4 Print Prototype**, prepared 14 September 2026. R3.4 filenames are intentional. This is the R3.3-derived branch; keep it separate from 28.2 and earlier R3.2 A files.

## Modeled fastener references - 24 total

| Use | Qty | Nominal screw | Reference head / material |
| --- | --- | --- | --- |
| Shell closure | 4 | M2.5 x 14 | ISO 7046 countersunk, metal |
| Front switch clamp | 2 | M2 x 8 | ISO 7046 countersunk, metal |
| Speaker keepers | 4 | M2 x 5 | ISO 7046 countersunk, metal |
| Microphone keeper | 2 | M2 x 4 | ISO 7046 countersunk, metal |
| LED keeper | 2 | M2 x 5 | ISO 7046 countersunk, metal |
| Antenna service frames | 4 | M2 x 3 | ISO 1580 pan/slotted, nylon |
| PTT guides | 2 | M2 x 5 | Modeled reference; match actual head |
| Battery keepers | 4 | M2 x 6 | Modeled reference; pilot unqualified |

These are CAD reference quantities and inherited nominal selections, not a procurement-qualified screw order. The first 18 remain from R3.1; R3.2 A adds two PTT guide references and R3.3 adds four battery keeper references. R3.4 moves the guide fixings (upper 0.8 mm / lower 0.6 mm) and retains the M2 x 5 reference lengths.

Countersunk nominal length includes the head; pan-head length is measured under it. Confirm actual head diameter/angle, engagement, blind depth, pilot/tapping process and tightening on spare prints. Do not substitute metal for the four nylon antenna-frame screws. No insert conversion is released here.

## Other components

| Component | Qty / status | Current reference |
| --- | --- | --- |
| Populated PCB | 1 assembly | Flux fb5acde7; 60 x 80 mm outline. U6 SIM7670G included on PCB, not a separate purchase. |
| Battery | 1 | Adafruit 2011, 3.7 V / 2000 mAh. Nominal 60 x 36 x 7 mm; measure actual pack and intact leads. |
| Speaker | 1 | Same Sky CMS-40504N-L152. Use actual frame and received wire exit. |
| Microphone | 1 | Adafruit 3421 SPH0645 breakout. Bottom acoustic port faces the offset seal. |
| RGB LED | 1 | Kingbright WP154A4SUREQBFZGW; four separately insulated leads to J8. |
| Cellular antenna | 1 | Taoglas FXUB63.07.0150C with supplied 150 mm coax. J5 CELL_RF; no GNSS antenna/cable. |
| Tactile switches | 4 | LIDUOLE: one 6 x 6 x 6 PTT; two 6 x 6 x 5 volume; one 12 x 12 x 4.3 front. Nominal assortment dimensions only. |
| Grille + acoustic scrim | 1 set | Purchased graphite woven mesh and black scrim; retained, finished edges. A solid PLA patch blocks sound. |
| Pads, seals, films, contacts | Per installed stack | Die-cut compliant stock and adhesives. Current installed-space geometry controls; grade/compression/bond remain to qualify. |
| Harness + connectors | Unreleased schedule | Use the released board nets; exact cable-side parts, routes, lengths and branch mapping require completion. |

Stock layers retained from the current reference include compliant contacts (PTT/front 0.25 mm, volume 0.20 mm), side backing 0.15 mm and installed rear pads 0.50 mm. These include adhesive where applicable and remain trial values. The R3.3 front battery-pad reference is 0.8 mm installed space, not foam free thickness or compression approval. PTT bond-film position moves by 0.5 mm in R3.4; use the current assembly datum.

Do not add the old 0.40 mm seat shims, paired 0.10 mm stop shims, separate play/volume cap bond films, or superseded front battery pads. These old reference bodies may remain for history in the full reference file; they are not current extra fabrication jobs. Mesh geometry is a visual reservation, not a wire-manufacturing job. Current stock thickness/contour needs supplier confirmation before cutting a batch.

## First fit assembly

1. **Start with the small fit plate.** Print plate 01 first. Remove supports, trial the four real switches and their solder/insulation envelopes, and check seating without forcing the cradles.

2. **Prepare shells and retainers.** Print plates 02-04. Clean active holes, guide bores, mounting seats and the seam. Inspect pilot depth and screw-tip clearance before tapping or fastening.

3. **Build the front face down.** Keep the front shell face down while fitting the carriers, switches and broad rails; the rear shell completes capture. Install current compliant contacts/backings/pads, but no old seat or stop shims.

4. **Fit acoustic parts and optics.** Support the speaker frame, not its cone. Keep the mic bottom port and offset seal open. Fit a real clear lens/guide for light testing; opaque PLA L01/L02 are fit proxies only. Preserve LED lead insulation and forming space.

5. **Fit guides, antenna and electronics.** Fit P17/P18 and trial the long PTT at center and both ends. Use nylon screws at antenna frames. Fit PCB/battery cushions and keepers to measured hardware; preserve stock battery connector and coax route.

6. **Resolve and dry-fit the complete harness.** The R3.3 connector/adapter study has unresolved collisions. Validate actual sockets, all return branches, service slack and solder insulation before claiming a closed-case fit; do not force the cover over wiring.

7. **Close by hand and inspect.** Verify the cover seats without screws pulling an interference together. Tighten only using the established sample fastening method; recheck free return and electrical release of all controls.

8. **Finish after fit checks.** Add purchased mesh/scrim, flexible rim/grip and appropriate bonding stock. Test indicator output, sound, cellular RF and powered thermal/charging behavior before any production/casting approval.


### Electrical boundaries carried forward

J2: pin 1 battery cell positive, pin 2 ground; confirm stock pack polarity. J10: SPK_P/SPK_N differential output, neither speaker lead is ground. J8: red/green/blue/common-cathode ground on pins 1/2/3/4; lamp pins map 1/4/3/2 respectively. Confirm actual lamp orientation before termination.

J3 physical pin order and the four control-to-J9 input assignments still require an agreed wiring drawing. Four switches need four signal branches and four local common-return branches, not merely a five-wire trunk. J12 remains reserved. The nominal cable/terminal reservations and twenty geometric motion samples do not close these wiring gates.