{
 "id": "63-hinge-knuckle",
 "name": "Hinge leaf with knuckles",
 "description": "40x30x3 leaf; knuckle cylinder r4 along X at (y=33, z=4); d4 pin hole; gap x 12..28 (y 29..40) cut through all from z=0, which removes the knuckle between x=12 and 28.",
 "exercises": [
  "sketch_yz",
  "extrude_join",
  "extrude_cut",
  "symmetric",
  "realistic"
 ],
 "units": {
  "length": "mm",
  "angle": "deg",
  "area": "mm2",
  "volume": "mm3"
 },
 "conventions": {
  "world": "right-handed; Z up. XY/XZ/YZ are the origin planes.",
  "sketch_frame": "sketch-local 2D coords; world = plane.origin + x*plane.x_dir + y*plane.y_dir (origin in mm). Profile 'loops' list sketch entity ids.",
  "point_refs": "'<id>.start' / '<id>.end' / '<id>.center' reuse (share) that existing sketch point; 'at' is its position when referenced.",
  "extrude_direction": "positive = along sketch plane normal unless stated",
  "selections": "selected faces/edges carry 'point': a world-space point on the face / the edge's parametric midpoint; pick the nearest face/edge to it."
 },
 "parameters": [],
 "features": [
  {
   "op": "sketch",
   "name": "Leaf_sketch",
   "plane": {
    "ref": "XY",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     1.0,
     0.0,
     0.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     0.0,
     0.0,
     1.0
    ]
   },
   "entities": [
    {
     "type": "line",
     "start": {
      "at": [
       0,
       0
      ]
     },
     "end": {
      "at": [
       40,
       0
      ]
     },
     "id": "l1"
    },
    {
     "type": "line",
     "start": {
      "ref": "l1.end",
      "at": [
       40.0,
       0.0
      ]
     },
     "end": {
      "at": [
       40,
       30
      ]
     },
     "id": "l2"
    },
    {
     "type": "line",
     "start": {
      "ref": "l2.end",
      "at": [
       40.0,
       30.0
      ]
     },
     "end": {
      "at": [
       0,
       30
      ]
     },
     "id": "l3"
    },
    {
     "type": "line",
     "start": {
      "ref": "l3.end",
      "at": [
       0.0,
       30.0
      ]
     },
     "end": {
      "ref": "l1.start",
      "at": [
       0.0,
       0.0
      ]
     },
     "id": "l4"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "extrude",
   "name": "Leaf",
   "operation": "new",
   "profiles": [
    {
     "sketch": "Leaf_sketch",
     "loops": [
      {
       "outer": true,
       "curves": [
        "l1",
        "l2",
        "l3",
        "l4"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "distance",
    "distance": 3,
    "direction": "positive"
   },
   "result_bodies": [
    "Hinge"
   ]
  },
  {
   "op": "sketch",
   "name": "Knuckle",
   "plane": {
    "ref": "YZ",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     0.0,
     0.0,
     -1.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     1.0,
     0.0,
     0.0
    ]
   },
   "entities": [
    {
     "type": "circle",
     "center": {
      "at": [
       -4.0,
       33.0
      ]
     },
     "radius": 4,
     "id": "c1"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "extrude",
   "name": "Knuckle",
   "operation": "join",
   "profiles": [
    {
     "sketch": "Knuckle",
     "loops": [
      {
       "outer": true,
       "curves": [
        "c1"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "distance",
    "distance": 40,
    "direction": "positive"
   },
   "result_bodies": [
    "Hinge"
   ]
  },
  {
   "op": "sketch",
   "name": "Pin",
   "plane": {
    "ref": "YZ",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     0.0,
     0.0,
     -1.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     1.0,
     0.0,
     0.0
    ]
   },
   "entities": [
    {
     "type": "circle",
     "center": {
      "at": [
       -4.0,
       33.0
      ]
     },
     "radius": 2,
     "id": "c1"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "extrude",
   "name": "PinHole",
   "operation": "cut",
   "profiles": [
    {
     "sketch": "Pin",
     "loops": [
      {
       "outer": true,
       "curves": [
        "c1"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "symmetric",
    "distance": 100,
    "is_full_length": false,
    "meaning": "distance on each side"
   },
   "result_bodies": [
    "Hinge"
   ]
  },
  {
   "op": "sketch",
   "name": "Gap",
   "plane": {
    "ref": "XY",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     1.0,
     0.0,
     0.0
    ],
    "y_dir": [
     0.0,
     1.0,
     0.0
    ],
    "normal": [
     0.0,
     0.0,
     1.0
    ]
   },
   "entities": [
    {
     "type": "line",
     "start": {
      "at": [
       12,
       29
      ]
     },
     "end": {
      "at": [
       28,
       29
      ]
     },
     "id": "l1"
    },
    {
     "type": "line",
     "start": {
      "ref": "l1.end",
      "at": [
       28.0,
       29.0
      ]
     },
     "end": {
      "at": [
       28,
       40
      ]
     },
     "id": "l2"
    },
    {
     "type": "line",
     "start": {
      "ref": "l2.end",
      "at": [
       28.0,
       40.0
      ]
     },
     "end": {
      "at": [
       12,
       40
      ]
     },
     "id": "l3"
    },
    {
     "type": "line",
     "start": {
      "ref": "l3.end",
      "at": [
       12.0,
       40.0
      ]
     },
     "end": {
      "ref": "l1.start",
      "at": [
       12.0,
       29.0
      ]
     },
     "id": "l4"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "extrude",
   "name": "Gap",
   "operation": "cut",
   "profiles": [
    {
     "sketch": "Gap",
     "loops": [
      {
       "outer": true,
       "curves": [
        "l1",
        "l2",
        "l3",
        "l4"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "through_all",
    "direction": "positive"
   },
   "result_bodies": [
    "Hinge"
   ]
  }
 ]
}