{
 "id": "65-sketch-gear-tooth",
 "name": "Sketch solver: gear-tooth sector",
 "description": "30 deg sector with one tooth: root arcs R40 and tip arc R50 centred on the origin, R15 flank arcs, symmetric about a vertical construction line; fully constrained; extruded 8.",
 "exercises": [
  "sketch_only",
  "sketch_constraints",
  "symmetric",
  "angle_dim",
  "arcs"
 ],
 "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": "Tooth",
   "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": {
      "ref": "origin",
      "at": [
       0.0,
       0.0
      ]
     },
     "end": {
      "at": [
       0,
       58
      ]
     },
     "id": "l0",
     "construction": true
    },
    {
     "type": "line",
     "start": {
      "ref": "origin",
      "at": [
       0.0,
       0.0
      ]
     },
     "end": {
      "at": [
       9.193,
       36.8712
      ]
     },
     "id": "s1"
    },
    {
     "type": "arc_three_point",
     "start": {
      "ref": "s1.end",
      "at": [
       9.193,
       36.8712
      ]
     },
     "mid": [
      6.7619,
      37.3935
     ],
     "end": {
      "at": [
       4.3017,
       37.7557
      ]
     },
     "id": "r1"
    },
    {
     "type": "arc_three_point",
     "start": {
      "ref": "r1.end",
      "at": [
       4.3017,
       37.7557
      ]
     },
     "mid": [
      4.4596,
      42.995
     ],
     "end": {
      "at": [
       2.6794,
       47.9252
      ]
     },
     "id": "f1"
    },
    {
     "type": "arc_three_point",
     "start": {
      "ref": "f1.end",
      "at": [
       2.6794,
       47.9252
      ]
     },
     "mid": [
      0.0,
      48.0
     ],
     "end": {
      "at": [
       -2.6794,
       47.9252
      ]
     },
     "id": "t1"
    },
    {
     "type": "arc_three_point",
     "start": {
      "ref": "t1.end",
      "at": [
       -2.6794,
       47.9252
      ]
     },
     "mid": [
      -4.4596,
      42.995
     ],
     "end": {
      "at": [
       -4.3017,
       37.7557
      ]
     },
     "id": "f2"
    },
    {
     "type": "arc_three_point",
     "start": {
      "ref": "f2.end",
      "at": [
       -4.3017,
       37.7557
      ]
     },
     "mid": [
      -6.7619,
      37.3935
     ],
     "end": {
      "at": [
       -9.193,
       36.8712
      ]
     },
     "id": "r2"
    },
    {
     "type": "line",
     "start": {
      "ref": "r2.end",
      "at": [
       -9.193,
       36.8712
      ]
     },
     "end": {
      "ref": "origin",
      "at": [
       0.0,
       0.0
      ]
     },
     "id": "s2"
    }
   ],
   "constraints": [
    {
     "type": "coincident",
     "refs": [
      "r1.center",
      "origin"
     ]
    },
    {
     "type": "coincident",
     "refs": [
      "t1.center",
      "origin"
     ]
    },
    {
     "type": "coincident",
     "refs": [
      "r2.center",
      "origin"
     ]
    },
    {
     "type": "vertical",
     "refs": [
      "l0"
     ]
    },
    {
     "type": "equal",
     "refs": [
      "f1",
      "f2"
     ]
    },
    {
     "type": "symmetric",
     "refs": [
      "r1.end",
      "f2.end",
      "l0"
     ]
    },
    {
     "type": "horizontal_points",
     "refs": [
      "f1.end",
      "t1.end"
     ]
    },
    {
     "type": "horizontal_points",
     "refs": [
      "s1.end",
      "r2.end"
     ]
    }
   ],
   "dimensions": [
    {
     "type": "distance",
     "refs": [
      "l0.start",
      "l0.end"
     ],
     "value": 60,
     "unit": "mm",
     "orientation": "vertical"
    },
    {
     "type": "radius",
     "refs": [
      "r1"
     ],
     "value": 40,
     "unit": "mm"
    },
    {
     "type": "radius",
     "refs": [
      "t1"
     ],
     "value": 50,
     "unit": "mm"
    },
    {
     "type": "radius",
     "refs": [
      "f1"
     ],
     "value": 15,
     "unit": "mm"
    },
    {
     "type": "angle",
     "refs": [
      "l0",
      "s1"
     ],
     "value": 15,
     "unit": "deg",
     "text_at": [
      2,
      20
     ]
    },
    {
     "type": "distance",
     "refs": [
      "r1.end",
      "f2.end"
     ],
     "value": 8.4,
     "unit": "mm",
     "orientation": "horizontal"
    },
    {
     "type": "distance",
     "refs": [
      "f1.end",
      "t1.end"
     ],
     "value": 5,
     "unit": "mm",
     "orientation": "horizontal"
    }
   ]
  },
  {
   "op": "extrude",
   "name": "Extrude1",
   "operation": "new",
   "profiles": [
    {
     "sketch": "Tooth",
     "loops": [
      {
       "outer": true,
       "curves": [
        "f1",
        "f2",
        "r1",
        "r2",
        "s1",
        "s2",
        "t1"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "distance",
    "distance": 8,
    "direction": "positive"
   },
   "result_bodies": [
    "Tooth"
   ]
  }
 ]
}