Wall Plate (Waldo)

A clean face with a mechanical job

Waldo was the wall plate for NOON’s lighting system: a molded cover over a stamped metal chassis, with no visible screws on the finished face. Behind that simple surface, the cover had to enter its openings, engage its snaps, seat against the chassis and help retain the Bazooka module. Each interface could work nominally while another failed at a tolerance extreme.

My role was mechanical product architecture and reliability oversight within the NOON program. The detailed tolerance sheets credit Colin Davis as engineer, and the supplier correspondence records decisions by the wider Locoroll, Function Engineering, FIH and Tongda teams. The account below follows that shared engineering work from stamping feedback through fit analysis and physical testing.

The two-gang cover render shows the visible product. Its stamped chassis exposes the mechanism: openings, folded edges and hooks that locate the parts behind it. These are design renders; the later test photographs show physical samples.

Making the chassis manufacturable

The chassis was more than a backing plate. Its thin stamped features had to provide strength, permit assembly and give the mating parts controlled contact points. A February DFM exchange shows how a small manufacturing accommodation could affect that job.

Tongda proposed cutting 4 mm from a hook. Locoroll asked whether 2 mm could be the minimum, and Tongda confirmed that 2 mm was workable. The marked-up hook detail preserves the proposal and response together. Other comments addressed corner radii and cracking risks. The exchange establishes a negotiated stamping limit; it does not identify a single person as author of the complete chassis.

The design-issues review broadened the work beyond that relief. It called out slide-lock and hook fit, plating chipped by repeated Bazooka installation, high folded edges, bowed cutouts that might affect the cover, and mounting-slot adjustment. A round pip was proposed in place of a pillowed square dimple. Those were distinct mechanical and finish issues with named team owners, rather than one universal fix for assembly.

The prototype records show different ways of obtaining parts for that work. A February 27 order lists nylon-12 laser-sintered finish plates; March quotes consider machined chassis in several metals and four-gang covers made by machining or stereolithography. These are prototype procurement states, not evidence of the final molded cover material, released snap geometry or successful fit.

The cover could enter and still come loose

The April fit studies separated perimeter clearance from snap entry and retention. That distinction became decisive when the analysis allowed the cover to move relative to the chassis.

The April 13 perimeter sheet uses a four-gang width with tolerances borrowed from the two-gang drawing. Its 0.48 mm nominal clearance spans 0.23 to 0.73 mm under worst case. The accompanying note makes the conclusion conditional on similar four-gang tolerance capability. This supports a clearance calculation, not a claim that every gang count had been validated.

On April 14, the attachment report showed 0.3 mm minimum Y overlap with the cover centered and concluded that the snaps would engage. The April 17 revision added a consequential condition: the cover could translate by ±0.43 mm. That movement was enough for the snaps to disengage despite the positive centered overlap.

The revised Y-engagement diagram proposed three coordinated changes: move the chassis slots inward by 0.1 mm per side, lengthen each snap tip by 0.1 mm, and reduce the top and bottom perimeter gaps from 0.3 to 0.2 mm per side. The perimeter gap was therefore part of retention, as well as appearance. Restricting cover movement protected the overlap available to the snaps.

This is the central engineering lesson of Waldo’s fit work: evaluating the parts only in their centered position can hide the failure created by the clearance that lets them assemble. The April 17 proposal addressed the moving system. The reviewed record does not establish which combination became the final production geometry.

A May 22 drawing review gives a later, bounded view of that follow-through. Colin Davis observed that the snap-fit adjustments appeared mostly implemented on the drawing: shorter snaps, a changed lead-out angle and a reduced perimeter gap. His chassis comments also noted coined holes while retaining slot and datum concerns. These observations advance the drawing history without proving a physically qualified or released assembly.

Seating required its own controlled surfaces

Z seating presented a different problem. The April 13 snap sheet calculated a nominal 0.16 mm stack with a worst-case range of -0.04 to 0.36 mm and warned that the snaps might not fully engage or seat. One rib dimension was assumed because it was absent from the drawing.

The April 17 Z-seating study used a revised nominal stack of 0.14 mm and a range of -0.06 to 0.34 mm. At one end, a lead-in could leave the cover snug without complete seating. At the other, it could be loose. Only one of the three dimensions in that chain was controlled on the drawing.

The proposed response was local: add mating pads that could be controlled and tuned, and tighten the existing ±0.1 mm tolerance on the controlled dimension. That connected the calculation to an inspectable physical feature. The two dated stacks describe different analysis states; averaging them or treating the later proposal as an implemented fix would erase the actual decision.

Retaining the module behind the plate

Waldo also contributed to Bazooka retention. Ribs on the cover limited how far the module could slide back out of its chassis hooks. The April 17 retention study examined both directions of cover movement: biased down, the rib could just clear the module at a zero-gap extreme; biased up, the module could move 1.29 mm against approximately 2.5 mm nominal slide engagement. The report expected it to remain engaged, assuming that the module’s Y stop was already defined.

Reducing the cover’s top and bottom gaps from about 0.3 to 0.2 mm was proposed here too. The same perimeter change could improve the snap-overlap condition and the module-retention chain. This made the interface between Waldo and Bazooka a system decision.

Physical checks supplied a separate kind of evidence. The April 27 status sheet records difficult removal after dust testing for seven Sativa and seven Elvis units. It then says that a repeat check combining the device with Bazooka and Waldo passed. That is a recorded system retest, without evidence assigning the improvement to a particular dimple, slot or cover revision. The same sheet lists rapid pull as deferred; it does not substantiate the former 40 kg pull claim for Waldo.

A white surface still had to survive handling

Material, texture and coating choices continued alongside the mechanical work. The CMF sheet calls for an injection-molded white polycarbonate cover with a satin VDI 15 texture, matched to the Elvis main switch. Its internal revision is February 8, 2017, Version 15, despite the later version and date in its filename. It is a dated appearance specification, not proof of the final resin used in production.

The action review explicitly includes the Waldo faceplate in the agreement to remove UV coating for EVT2. It also warns that injection marks and weld lines remain visible. The Waldo schedule records a subsequent PC+ABS material lead-time problem and later chassis and faceplate green lights on April 28 and 29. The listed DVT tooling and delivery dates are schedules, not shipping receipts.

A separate April 13 EVT2 solvent-test table names Waldo samples 1, 2 and 3. Each records Level 0 for artificial sweat labelled 8.0 and 4.5, nail-polish remover, isopropanol and petroleum ether. The procedure describes 200 hand wipes over about two minutes and accepts Levels 0-1. Jaz Yang is the named tester and Sunny Yen the verifier. These are bounded surface-test results; the report does not identify the Waldo samples by resin, coating revision or production serial number.

The physical surface results were mixed. The April 13 EVT2 pencil-hardness report lists three Waldo samples passing the H-pencil check under a 1 kgf load. The June 28 DVT report lists three Waldo samples failing the same stated hardness/load condition. The EVT2 result and DVT result retain their sample tables and photographs. They are separate sample sets; the records do not isolate a coating or resin change as the cause.

Packaging review also shows bubbles under the protective film on Waldo covers. This is evidence of a handling and presentation problem on recognizable wall plates. The reviewed pages do not establish a final film formulation, an adhesive-residue fix or a closed production-quality result.

What this work established

Waldo’s engineering account is the progression from a clean exterior to controlled interfaces: negotiate stamped features, account for cover movement, define the surfaces that determine seating, and test the cosmetic part as a physical product. The April revision made an initially reassuring snap calculation more useful by exposing the condition under which engagement could be lost.

The surviving record establishes those decisions and proposals, a combined-system dust retest, and distinct finish-test outcomes. It leaves the final as-built snap arrangement and complete production qualification unresolved. My contribution belongs within the mechanical architecture and reliability program; the calculations, supplier decisions and test reports retain their individual authorship and scope.

Source trail

• Product and manufacture: Waldo chassis/cover renders; February chassis DFM correspondence; design-issues review; the internally dated February CMF sheet.
• Fit and retention: April 13 stack sheets and the April 14/17 Function Engineering attachment reports; April 17 Bazooka/Waldo retention report.
• Build and test: Locoroll action review, April 27 reliability status, EVT2 and DVT hardness reports, and packaging-test review. Dates in the account follow the relevant report or action entry, rather than later PDF-export timestamps.