Catalog item format

Every file in catalog/ is a JSON list of items in this shape. Unknown values are null, never guessed.

{
  "id": "cubemars-ak70-10",                 // vendor-model, lowercase, dashes
  "category": "leg_actuator",               // see the categories below
  "vendor": "CubeMars",
  "model": "AK70-10",
  "price_usd": 459.0,                        // one unit, before shipping and tax; null if no public price
  "price_note": "official store, single unit",
  "price_checked": "2026-10-25",
  "buy": [{"seller": "CubeMars store", "url": "https://...", "in_stock": true, "ships_from": "CN"}],
  "specs": {                                  // units are in the key names
    "mass_g": 521, "diameter_mm": 104, "length_mm": 53,
    "peak_torque_nm": 24.8, "rated_torque_nm": 8.3,
    "no_load_speed_rpm": 310, "rated_speed_rpm": null,
    "gear_ratio": 10, "voltage_nominal_v": 24, "voltage_range_v": [18, 52],
    "peak_current_a": null, "kt_nm_per_a": null,
    "interface": "CAN", "encoder": "14-bit single, dual for output?",
    "hollow_shaft_mm": null, "ip_rating": null
  },
  "cad": {"step_url": "https://...", "available": true},
  "sources": ["https://datasheet...", "https://product page..."],
  "confidence": "datasheet",                 // datasheet | product page | seller listing | estimate
  "notes": "Anything that matters for a wheel-legged robot."
}

Categories: leg_actuator, wheel_motor, motor_driver, wheel, tire, battery, bms, charger, dcdc, power_distribution, estop, can_adapter, imu, compute, sensor, display, light, wiring, fastener, bearing, cf_tube, cf_plate, sheet_material, filament, fab_service, turret.

"preferred": true marks the default choice the designer starts from. The BOM groups items into Sensors & compute (compute, sensor) and Chassis & actuators (everything else), each with its own subtotal.

Pictures and alternates

Three more files sit beside the catalogue (they are objects, not item lists, and are not in index.json):

• images.json: a picture of every part on a parts list, by catalogue key (or printed part name): {source_url, image_url, fetched, path, kind}. kind is mcmaster or vendor (a product photo, kept in references/vendor/thumbs/, gitignored: not ours to redistribute) or render (our CAD, exports/thumbs/). McMaster entries also keep the product page's delivery line on the day it was read (availability). Written by tools/part_images.py.
• alternates.json: other places to buy each bought part, by catalogue key: a list of {supplier, part_number, url, price, price_usd_each, pack_qty, stock, drop_in, changes, checked}. drop_in is true only when the alternate fits the same seat and does the same job with no CAD change; otherwise changes says what would change. price and stock are as the page showed them on checked.
• sourcing.json: what a parts list's plain-text line means (names: text or part name -> key, or a list of keys when one line buys several products), lines that are part of another (skip), where a vendor part's picture is taken from when its buy link is not the right page (image_pages, image_urls), parts that are hard to buy (risk: {level: high | medium | cost | fit | missing | check, note, checked}: hard to buy, single source, a much cheaper option, a part that does not fit the design as drawn, parts the list leaves out, a rating to check; shown on the progress page), and the bought parts no catalogue file has yet (parts, in the item shape above plus key).

cad/bom_media.py enrich(lines) adds thumb and alternates to parts-list lines from these files.