# From model proposal to compiled CAD

This crosswalk was authored after the model review and CAD compilation. The model proposal IDs and the CAD instance IDs are separate namespaces. Mapping a part does not mean that the model approved its later construction details.

Sources: [actual orchestrator review](review-notes.md), [mechanical contract](mechanical-design.json), [compiled inventory](parts.json), [CAD implementation and checks](cad-manifest.json), [machine-readable crosswalk and bound checks](design-to-cad-map.json).

The inventory contains 20 component instances and 0 fastener envelopes, with 10 distinct non-fastener designs and 4 functional subassemblies. These physical groups sit inside the three LIGHT planning modules.

## Part crosswalk

| Model proposal | Meaning | CAD design ID | Actual CAD instances |
| --- | --- | --- | --- |
| BOM | Base | `fixture-base` | `F01` |
| BOM | Foot | `fixture-foot` | `F02_1`, `F02_2`, `F02_3`, `F02_4` |
| BOM | Guide rod | `guide-rod-10x200` | `F03_1`, `F03_2` |
| BOM | End support | `fixture-end-support` | `F04_1`, `F04_2` |
| BOM | Jaw | `fixture-jaw` | `F05_1`, `F05_2` |
| BOM | Bushing | `fixture-bushing` | `F06_1_1`, `F06_1_2`, `F06_2_1`, `F06_2_2` |
| BOM | Pad | `fixture-jaw-pad` | `F07_1`, `F07_2` |
| BOM | Lead screw | `fixture-screw` | `F08` |
| BOM | Nut | `fixture-travel-nut` | `F09` |
| BOM | Hand knob | `fixture-handwheel` | `F10` |

## Implementation decisions and limits

- Added explicit through-bores for the rods and screw, replaceable bushing seats, a nominal travel nut and a bored handwheel; these are CAD implementation details, not tested retention interfaces.
- The shown jaw opening is 78 mm. The proposed 60 mm stroke is a closing-direction hypothesis only; opening by 60 mm would collide with the right support. No motion simulation was performed.
- The CAD author implemented the proposal of four bushings, two per jaw, and placed both pads inward. The model had explicitly treated the bushing count/allocation as provisional.
- The [CAD source](source.py) adds rod/screw passages and bushing seats. The source and static gaps do not establish tested attachment, thrust retention, screw engagement or holding force.

Unresolved in the CAD author’s own manifest:

- Guide/screw axial retention, jaw locking, practical travel stops and manufacturing fits remain undefined.

Feet extend below the base-origin plane as an explicit authored placement. The model-reviewed outer dimensions remain traceable; added features and extra designs are identified separately.

Independent inventory comparison: **34 selected bounds, positions and counts agree** within 0.0001 mm numeric tolerance. This checks the compiled inventory against the supplied values; it does not repeat the CAD kernel or prove that every interface, bore, wall, stroke or attachment is correct.

The 78 mm pad gap is the compiled static pose. A 60 mm opening stroke would conflict with the right support. Closing-direction travel remains a hypothesis, and no motion simulation or retention test is claimed.