Recalibrate S1 vehicle family to coherent 1:87 dimensions and regenerate CAD assets

[recklessnode]

Objective

Recalibrate the S1 vehicle family around a coherent 1:87 project scale while allowing ATOS vehicles to differ from conventional railway proportions. Dimensions must be internally correct for each vehicle’s intended real-world role, payload, passenger capacity, container geometry, maglev stabilization hardware, stations, guideway, tiles, buildings, and scenery.

This follows Issue #17 and merged PR #20. Preserve the current parametric CAD, validation, preview, and provenance structure where useful; revise dimensions rather than starting a parallel system.

Design principles

• Treat 1:87 as the common world scale, not a requirement to copy conventional HO rolling-stock dimensions.
• Derive each model dimension from a documented full-size design assumption.
• Preserve correct relationships between sled, module, payload, station, guideway, stabilization structures, and scenery.
• Do not scale the existing models uniformly. Re-derive dimensions by function.
• Keep the S1 sled/module identity and four-point interface architecture unless analysis documents a necessary revision.
• Keep values parametric and distinguish reference dimensions from printer-specific manufacturing choices.

Required work

1. Create a dimensional basis document

Add docs/engineering/s1-1-87-dimensional-basis.md containing:

• scale convention and conversion method;
• full-size assumptions and resulting model dimensions;
• source or rationale for each assumption;
• dimensional envelopes for sled, stabilization structures, couplers, modules, stations, platforms, and guideway clearances;
• comparison with the current PR [codex] Generate S1 printable prototype kit #20 geometry;
• explicit decisions for dimensions intentionally larger or smaller than conventional rail equipment.

Include a table with full-size and 1:87 dimensions for every vehicle/module.

2. Recalibrate vehicle dimensions

Review and revise at least:

• S1 sled overall length, structural deck, width, height, coupler spacing, support-node spacing, and stabilization envelope;
• commuter passenger pod dimensions and documented target capacity;
• overnight pod dimensions and documented berth/cabin capacity;
• battery pod dimensions based on service access, thermal volume, and equipment packaging assumptions;
• 40-foot container adapter based on an actual 40-foot ISO container envelope at 1:87 plus required retention and maglev clearances;
• twin 20-foot adapter based on two actual 20-foot container envelopes, separation, retention, and end clearances;
• open-bin module based on a stated full-size payload volume;
• ballast/CG test module and fixtures.

The current 320 mm assembled sled length may remain if the documented full-size vehicle length supports it. Ensure “length over coupler faces” and printed body length are not conflated.

3. Passenger-capacity validation

For commuter and overnight modules, document a simple interior layout showing:

• aisle width;
• seating or berth arrangement;
• door/service zones;
• wall thickness and technical-space allowance;
• resulting capacity.

The external dimensions and claimed capacity must agree at the chosen full-size scale.

4. Container and payload validation

Use real container proportions for 20-foot and 40-foot equivalents. Show how much additional model width and length are required for:

• retention hardware;
• aerodynamic fairings, if present;
• maglev guidance/stabilization structures;
• service and handling clearances.

Do not label a 240 mm model as a 40-foot-equivalent adapter unless the dimensional basis explains the discrepancy.

5. Update parametric CAD

Update shared parameters and all affected OpenSCAD sources under cad/s1/. Avoid hard-coded per-file dimensions where a shared parameter or derived formula is appropriate.

Preserve:

• interchangeability across the common S1 interface;
• ballast and CG experiment capability;
• alignment keys and sockets;
• inspectable retention geometry;
• replaceable coupler and stabilization parts.

6. Regenerate manufacturing assets

Regenerate and validate:

• full-size STL files for every required part;
• 220 x 220 mm split alternatives where necessary;
• one-piece H2C-oriented assets for a nominal 300+ mm build plate where practical;
• Bambu Studio-compatible 3MF projects for the major complete cars and modules.

3MF projects should preserve 100% scale, intended orientation, part grouping, and recommended print settings. Do not embed proprietary or machine-specific secrets.

7. Validation

Extend the CAD tooling to verify:

• expected files exist;
• STL meshes are watertight/manifold;
• declared 1:87 envelopes match generated bounding boxes;
• 20-foot and 40-foot payload reference dimensions are correct within documented tolerance;
• modules use the shared S1 attachment geometry;
• full and split variants preserve external dimensions;
• H2C-oriented layouts fit the declared usable bed with margin;
• 3MF archives open and contain expected objects at 100% scale.

Generate an updated asset report and preview/contact sheet.

8. Cross-system impact

Audit and update any affected:

• vehicle manifests and schemas;
• route-admission envelopes;
• station/platform dimensions;
• guideway clearance assumptions;
• tile and city-layout references;
• architecture diagrams and documentation.

Do not silently change simulation or dispatch semantics; document any required follow-up issues.

Acceptance criteria

• Every vehicle/module has a documented full-size basis and calculated 1:87 dimensions.
• Passenger capacities agree with documented interior layouts.
• 20-foot and 40-foot adapters use correct payload proportions plus documented ATOS clearances.
• Sled body length and length over coupler faces are distinct and consistent.
• Revised OpenSCAD remains parametric and uses the shared S1 interface.
• All required STLs regenerate and pass mesh/envelope validation.
• 220 mm split assets remain available where needed.
• H2C-oriented one-piece assets and Bambu-compatible 3MF projects are generated where practical.
• Stations, guideway, tiles, and scenery impacts are audited and documented.
• npm test, npm run lint, npm run build, and VITE_BASE_PATH=/ATOS/ npm run build pass.
• AI provenance is recorded truthfully.

Scope warning

These remain prototype models and dimensional studies, not certified passenger, structural, battery, electrical, or maglev hardware.

END ISSUE #21

[recklessnode]

Multi-scale parametric generation extension

Use 1:87 as the baseline ATOS world-scale profile, but make the CAD and asset workflow able to regenerate the same full-size design at other model scales.

Required named profiles:

• N scale, 1:160
• HO scale, 1:87
• O scale, 1:48
• a validated custom scale ratio

Requirements:

• Store full-size reference dimensions once, then derive model dimensions from the selected scale ratio.
• Do not create O scale by simply doubling finished HO STL files. The correct HO-to-O geometric multiplier is about 1.815, and manufacturing details must be regenerated from source.
• Separate scale-dependent geometry from manufacturing parameters such as wall thickness, nozzle-driven minimums, clearances, screw holes, pins, magnets, bearings, flexures, wiring channels, and split-joint tolerances.
• Preserve relative geometry across cars, couplers, track, guideway, stations, platforms, tiles, buildings, scenery, and clearance fixtures.
• Recompute curve radius, coupler articulation, body overhang, swept envelope, station clearance, and stabilization clearance for each profile.
• Generate additional engineered splits when a selected scale exceeds the target printer bed. For the H2C, O-scale long cars and many modules will require split models even when the equivalent HO parts fit one-piece.
• Validate every profile independently for manifold meshes, envelope consistency, interface fit, curve and clearance behavior, and declared printer-bed fit.

Output organization must identify the scale in the directory path or file name. Preferred structure:

cad/s1/generated/ho-1-87/stl/
cad/s1/generated/ho-1-87/3mf/
cad/s1/generated/o-1-48/stl/
cad/s1/generated/o-1-48/3mf/
cad/s1/generated/n-1-160/stl/

Previews, contact sheets, manifests, asset reports, and validation outputs must also identify the scale profile so files from different scales cannot be confused.

Acceptance additions:

• A single command or documented option selects the scale profile.
• N, HO, O, and custom profiles are generated from the same shared source dimensions.
• Coupler, track, module-interface, and stabilization geometry remain mutually compatible within each profile.
• Hardware-dependent features are not blindly scaled.
• Generated STL and 3MF assets carry unambiguous scale-specific paths or names.
• Validation reports include selected ratio, resulting major dimensions, printer-bed fit, and any required splits.

This extends Issue #21; it does not replace the requirement to establish a coherent full-size dimensional basis first.

END MULTI-SCALE EXTENSION