# Source 3D Models (STEP) for Off-the-Shelf BOM Parts (procurement)

To design printed mounts and the chassis that *fit real sourced parts*, we need accurate
3D models (*STEP*) of the off-the-shelf components in the [BOM](../../BOM.md) — the
drive-wheel assembly, the suction fan/blower (several candidate models), the caster wheel,
the side-brush motor, and more. Manufacturers rarely publish these, so the community needs
to *obtain, measure, and model* them. Every printed mount and the chassis references this
geometry — see [ARCHITECTURE.md](../../docs/ARCHITECTURE.md) §5.2 (mechanical interface
standard). Missing models block or force guesswork on the mechanical modules.

This is a great *first contribution* for anyone with CAD skills and calipers — no
robotics or programming needed, and the modules can be modeled *in parallel*.

## Priority parts (from the [BOM](../../BOM.md))

Start with the "ready now" mechanical parts:
- *Drive wheel assembly pair* (e.g. Roborock S5/S50/S55/S6/S7-family modules)
- *Caster / universal wheel* (e.g. Roomba i/j/e/500–900 caster)
- *Suction fan / blower* — model the option(s) we shortlist (e.g. Dreame L10s / Nidec /
  Roborock S8-family blowers listed in the BOM)
- *Side-brush motor*, *main-brush assembly*, *water pump*, *battery pack*, etc.

See [BOM.md](../../BOM.md) for the full list, the exact candidate models, and AliExpress
search links, plus [docs/ali_express_research.md](../../docs/ali_express_research.md) for
sourcing notes.

# Request for Contribution - Instructions

- *Pick a part* from the [BOM](../../BOM.md) and *claim it* in
  [Project Discussions](https://github.com/makerspet/oomwoo/discussions?discussions_q=) or
  [Discord](https://discord.gg/3y2JKz5T25) so two people don't model the same thing. Post progress too.
- *Get an accurate model* — two paths:
  1. *Find an existing STEP* (manufacturer site, GrabCAD, etc.) and *verify it against the
     real part* (dimensions match). Fastest — but confirm it's the same model/revision.
  2. *Model it yourself*: order the exact part (AliExpress links are in the BOM), measure
     with calipers, optionally use a 3D scanner and build an accurate STEP.
- *Capture the interface-relevant geometry* (external only — internal detail is not needed):
  - Overall *bounding envelope* (so it fits the chassis space / height budget)
  - *Mounting features*: holes, bosses, clips, bolt pattern — and their exact positions
  - *Functional interfaces*: axle/shaft position + axis, wheel contact plane, fan air
    inlet/outlet, connector / wire-exit locations
  - *Mating faces* where other modules attach
  - Note the *key overall dimensions*
- *Record provenance* — the exact vendor + link + which model/revision you measured. Parts
  vary between sellers and revisions; say which one this model represents.
- *Submit a PR* to `contributions/source-3d-models/<your-github-username>/<part-name>/`:
  - the *STEP* file (primary deliverable) + native CAD source (Fusion/SolidWorks/etc.) if you modeled it
  - a *photo* of the real part (ideally next to your model / with calipers)
  - the *source link* (AliExpress/vendor) and *key dimensions*
  - notes on tolerances and how you measured
  - announce it in [Project Discussions](https://github.com/makerspet/oomwoo/discussions?discussions_q=)
- Iterate with review.
- TBD, expect the RFC to evolve.

(*) If you have a strong reason to model a different variant than the BOM lists, post your
rationale in [discussions](https://github.com/makerspet/oomwoo/discussions?discussions_q=) first.

## Acceptance criteria

Objective, measurable. Examples:
- Accurate *STEP* of the specified part — bounding envelope, mounting features, and
  functional interfaces match the measured real part (within a stated tolerance)
- Includes the *exact source link*, *key dimensions*, and a *photo* of the real part
  - Please make sure the model is licensed as open-source
- *Verifiable/reproducible* by someone else who buys the same part
- STEP provided (+ native CAD source if self-modeled)
- Documented well enough that a mount designer can build against it with confidence
- TBD, expect criteria to evolve

The maintainer selects among compliant candidates using these criteria. Multiple attempts
are welcome and useful even if not selected — models are swappable, and a non-selected
model is still a valid reference and a fallback.