{
  "name": "Shallow case / one-beam CoreXY — preferred design direction",
  "status": "Dimensional packing study, not released mechanical CAD or a print pack",
  "checked_at": "2026-10-24",
  "viewer": "render-thin/index.html",
  "design_basis": "docs/reference-adaptation.md",
  "references": [
    {"name": "Greg06 — Automated Chessboard", "url": "https://www.instructables.com/Automated-Chessboard/", "published_enclosure_mm": [460, 460, 100], "guide_type": "V-slot wheels", "extrusion_total_mm": 1750, "sensor_type": "64 reed switches"},
    {"name": "Joshua Stanley Robotics — ChessBot V1", "url": "https://github.com/JoshuaStanleyRobotics/ChessBot-V1", "video": "https://youtu.be/tLgXvUgsYmw", "guide_type": "8 mm rods, 250/265 mm lengths", "motor_body_mm": 22.5, "license": "MIT", "sensor_type": "64 AH49FNTR-G1 analog Hall sensors"}
  ],
  "service_access": "Lift-off sensor lid with keyed connectors and a restrained service loop. Hinge design is deferred.",
  "footprint_mm": [720, 630],
  "top_panel_mm": [700, 600, 4],
  "playing_grid_mm": [400, 400],
  "reference_height_mm": 140,
  "reference_extrusion_installed_mm": 6980,
  "proposed_extrusion_installed_mm": 580,
  "remaining_extrusion": "One 580 mm 2020 crossbeam, retained for stiffness and straightforward rail fastening; a closed light box beam is a later alternative.",
  "base": "One flat 6-9 mm birch-plywood panel. The calculation initially uses 6 mm; loaded flatness is not established.",
  "printed_parts": ["Segmented perimeter walls and corners", "Rail locating/drilling templates and small mounting pads", "Redesigned Y end brackets and belt idler mounts", "Short X carriage and coil retainer", "Electronics brackets and strain relief", "Existing top-panel concept and chess pieces"],
  "remove_from_reference": ["Four 700 mm perimeter extrusions", "Four 560 mm perimeter extrusions", "Four 90 mm upright extrusions", "Two 500 mm extrusion rail supports", "Deep lower carriage skirts", "Tall motor risers and fixed-magnet stand"],
  "packing_mm": {
    "feet": 3,
    "base": 6,
    "top_and_cover": 4.5,
    "motor_body_assumed": 34,
    "motor_shaft_assumed": 24,
    "upper_pulley_offset_above_face": 20,
    "lower_pulley_offset_above_face": 8,
    "idler_width": 8,
    "upper_retainer_allowance": 5,
    "clearance_above_other_hardware": 3.5,
    "beam": 20,
    "beam_bottom_clearance": 2,
    "x_rail_block_stack": 13,
    "y_rail_block_stack": 13,
    "carriage_plate": 4,
    "coil_body": 20,
    "pole_to_cover_gap": 1.5
  },
  "height_formula": "feet + base + max(motor_body + shaft, motor_body + upper_pulley_offset + idler_width/2 + upper_retainer, beam_bottom_clearance + beam + X_rail_block_stack + carriage_plate + coil_body) + hardware_clearance + top_and_cover",
  "default_height_target_mm": 80,
  "layout": "Y rails face upward on the flat base. The X beam hangs between end brackets rather than stacking its full height on top of the Y blocks. Motors sit in front corner pockets with shafts upward; belts run above the moving bridge on two levels. Electronics sit outside the bridge sweep, or in an external box if the owned drivers are large.",
  "limits": [
    "Owned motor and driver models/dimensions have not been supplied. Shaft reach, pulley hubs, connectors and driver height can raise the enclosure target.",
    "This arithmetic checks height envelopes only. It does not prove full-travel collision freedom, structural stiffness, rail parallelism or magnetic release.",
    "Existing side-mounted Y adapters, motor mounts, idler mounts, carriage and magnet stand are incompatible with this arrangement and require new CAD/STLs.",
    "A large printed top still needs stiffness and loaded-flatness qualification; a new laminate changes magnetic distance unless the panel stack is redesigned.",
    "The plywood base must maintain guide alignment under belt loads, temperature and moisture; use a stiffer base or validated bracing if necessary.",
    "A 50-60 mm enclosure is a later target requiring compact motors and further nesting/guide/fastener changes, not just shorter uprights.",
    "The active 140 mm CAD, print pack and assembly viewer have not been changed by this study."
  ],
  "commercial_reference": {
    "name": "Square Off Grand Kingdom Set",
    "manufacturer_height_mm": 49,
    "url": "https://api.squareoffnow.com/product/gks",
    "scope": "Manufacturer-listed self-moving board thickness supports feasibility of thin products. It does not identify the internal frame or prove our off-the-shelf CoreXY components fit that height."
  }
}