# Walter R07 — prototype engineering handoff

## Order scope

Quote a staged prototype, beginning with the separate11-piece first-fit coupon kit and a physical component survey. Do not quote this as a guaranteed-fit, finished full-head order. R07 contains20 enclosure/carrier pieces plus dimensioned reference hardware and empty planning allowances.

Preserve the smooth blue astronaut-helmet character, rounded ear pods and vertical circular displays. Do not scale electronic parts or uniformly shrink the assembly to fit a printer. Keep main touch glass exposed. The screens' artwork is preview content, not printable geometry.

## Dimensions and structure

Approximate overall envelope230.6W ×212D ×366.2H mm. Base split near60mm; crowns split at276.8/277.2mm. Crown front/rear seam nominalY−0.7 to−0.3mm; lower-shell seamY−0.2 to+0.3mm. Export tolerances can affect measured edge clearance.

Nominal shell allowance3.2mm is radial loft subtraction, not a constant normal wall. Crown cap becomes solid from349mm upward to close the loft. Maker must inspect wall thickness, slicer sections and support removal. Small cosmetic ridges and exposed base mounting features remain development details to refine after the assembly trials.

Bottom cover166×126mm; cover screws nominal160×80mm centres, tray100×80mm. Split rack uses two12×48×3mm splice plates with38mm hole spacing. M3/M4 clearance and nut-pocket values are coupon dimensions, not compensated for a particular printer. Final screw lengths, washer/nut/insert selection, engagement and tool access are not signed off.

## Part evidence

Main display uses the manufacturer's126×126×17.1mm mechanical model and75mm-square mount pattern. Speakers use published100×45×21mm housings and92×36mm mounting centres. Pi PCB footprint85×56mm, mount58×49mm. Verify the actual purchased revisions, driver mounting bores, all projecting connectors and screw penetration limits.

Small display outlines40.4×37.5mm are source based;8mm depth and connector exits are assumptions. Camera depth/lens and cooler revision are reservations. USB plug projection/strain relief and radar case total depth need confirmation. Do not treat a simple box as a surveyed detailed device.

No battery is selected. The120×60×140mm bay is a planning allowance, not a pack model. Include connector, strap, charging access, protection/regulation and removal volume in the selected power design. The thermal printer is deferred; no paper roll or printer mechanism fits by claim.

## Mounting and service work still required

1. Verify actual component dimensions and plug exits; record them in the supplied measurement log.
2. Test the coupon patterns and print compensation. Secure actual components to the open rack, using removable fasteners and appropriate insulation/standoffs.
3. Finish positive retention for the rear service blank and capacitive-touch cartridge. Final auxiliary-screen and camera retention must match the actual boards. Do not rely on loose friction or glue over service access.
4. Confirm every shell screw is reachable and each component can be unplugged before removal. Review horizontal crown joints, rack splices and base posts for load path and cosmetic integration.
5. Build complete harness routes with the real cables. Current tubes reserve local bend space only; no continuous end-to-end harness, bend compliance or strain relief has been verified. Keep cooler intake and the main forward cable lane clear.
6. Validate power topology, GPIO assignment, USB negotiation/current, ground/reference paths, audio feedback and charging/safe shutdown with the selected hardware.

## Thermal and electrical acceptance evidence

The included heat/power page is a preliminary lumped sizing model, not CFD. It compares cooling scenarios using assumed heat transfer and fan data. The case fan is not selected or mounted in this CAD. Doubling the exhaust is not already modeled in the print files.

Measure electrical input at idle, bright displays, camera/radar active, loud audio and combined workload, including boot/current peaks. Repeat with the intended supply, cable and battery mode. Record peripheral current independently from the Pi feed where possible. Do not infer5V/5A negotiation from headline battery wattage.

Run the closed unfinished enclosure at the intended maximum ambient until temperatures stabilize. Record ambient, Pi telemetry, cooler inlet/outlet air, battery surface, regulator and hottest accessible enclosure/screen region. Acceptance limits must come from the selected components/materials and intended use; none are certified by this model. Evaluate recirculation, acoustic noise and microphone feedback with fan/speakers running.

For CFD: create the internal air domain from the final geometry; specify heat-source distributions, material conductivities, actual fan P–Q curve, gravity/orientation, inlet/outlet conditions and leaks; check mesh refinement and energy balance; correlate against physical temperatures. No CFD run is supplied or claimed.

## Print and finish

The256mm bed check is only an axis-aligned size screen. The maker must choose orientations, supports, layer strategy and compensation using the actual printer/material. Review thin grilles, nut pockets, crown overhangs and support access in a slicer. No G-code or machine-specific slicer profile is supplied.

Test body-touch coupons0.8/1.2/1.6/2.0mm with the actual electrode/controller and planned finish. Metallic paint can alter sensing; test the finished stack. Structural walls should not be globally thinned to make touch work. Finish only after an unfinished closed shell passes fit, access, thermal and electrical tests.

## Files

- `engineering-R07/cad/`: native STEP parts and assembly.
- `engineering-R07/development-stl/`:20 development enclosure meshes.
- `reference-*-DO-NOT-PRINT/`: electronics and reserved spaces only.
- `assets/assembly.json`: exact mesh hashes, dimensions, positions and confidence.
- `electrical-interface-map.json`: source-derived pin contract; not live continuity proof.
- `physics-validation.json`, `service-*-validation.json`, native/mesh reports: computational evidence with stated limits.

The first-fit kit is the sensible initial print. Full-shell approval depends on the measurements and tests above, not on a clean collision result alone.