{
 "id": "61-shaft-keyway",
 "name": "Stepped shaft with keyway and chamfers",
 "description": "Revolved stepped shaft (d20 x30, d25 x60, d20 x30 along Z); end edges chamfered 1; 8 mm wide R4-ended keyway 4 deep on the d25 section (z 45..75), cut from a tangent plane at x=12.5.",
 "exercises": [
  "revolve",
  "chamfer",
  "offset_plane",
  "extrude_cut",
  "keyway",
  "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": "Profile",
   "plane": {
    "ref": "XZ",
    "origin": [
     0.0,
     0.0,
     0.0
    ],
    "x_dir": [
     1.0,
     0.0,
     0.0
    ],
    "y_dir": [
     0.0,
     0.0,
     -1.0
    ],
    "normal": [
     0.0,
     1.0,
     0.0
    ]
   },
   "entities": [
    {
     "type": "line",
     "start": {
      "at": [
       0.0,
       0.0
      ]
     },
     "end": {
      "at": [
       10.0,
       0.0
      ]
     },
     "id": "l1"
    },
    {
     "type": "line",
     "start": {
      "ref": "l1.end",
      "at": [
       10.0,
       0.0
      ]
     },
     "end": {
      "at": [
       10.0,
       -30.0
      ]
     },
     "id": "l2"
    },
    {
     "type": "line",
     "start": {
      "ref": "l2.end",
      "at": [
       10.0,
       -30.0
      ]
     },
     "end": {
      "at": [
       12.5,
       -30.0
      ]
     },
     "id": "l3"
    },
    {
     "type": "line",
     "start": {
      "ref": "l3.end",
      "at": [
       12.5,
       -30.0
      ]
     },
     "end": {
      "at": [
       12.5,
       -90.0
      ]
     },
     "id": "l4"
    },
    {
     "type": "line",
     "start": {
      "ref": "l4.end",
      "at": [
       12.5,
       -90.0
      ]
     },
     "end": {
      "at": [
       10.0,
       -90.0
      ]
     },
     "id": "l5"
    },
    {
     "type": "line",
     "start": {
      "ref": "l5.end",
      "at": [
       10.0,
       -90.0
      ]
     },
     "end": {
      "at": [
       10.0,
       -120.0
      ]
     },
     "id": "l6"
    },
    {
     "type": "line",
     "start": {
      "ref": "l6.end",
      "at": [
       10.0,
       -120.0
      ]
     },
     "end": {
      "at": [
       0.0,
       -120.0
      ]
     },
     "id": "l7"
    },
    {
     "type": "line",
     "start": {
      "ref": "l7.end",
      "at": [
       0.0,
       -120.0
      ]
     },
     "end": {
      "ref": "l1.start",
      "at": [
       0.0,
       0.0
      ]
     },
     "id": "l8"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "revolve",
   "name": "Revolve1",
   "operation": "new",
   "profile": {
    "sketch": "Profile",
    "loops": [
     {
      "outer": true,
      "curves": [
       "l1",
       "l2",
       "l3",
       "l4",
       "l5",
       "l6",
       "l7",
       "l8"
      ]
     }
    ]
   },
   "axis": {
    "ref": "world Z axis",
    "origin": [
     0,
     0,
     0
    ],
    "dir": [
     0,
     0,
     1
    ]
   },
   "angle": 360,
   "result_bodies": [
    "Shaft"
   ]
  },
  {
   "op": "chamfer",
   "name": "EndChamfers",
   "type": "equal_distance",
   "distance": 1,
   "tangent_chain": false,
   "edge_selection": "end circles r=10 at z=0 and z=120",
   "edges": [
    {
     "type": "circle",
     "start": [
      10.0,
      0.0,
      0.0
     ],
     "end": [
      10.0,
      0.0,
      0.0
     ],
     "center": [
      0.0,
      0.0,
      0.0
     ],
     "axis": [
      0.0,
      0.0,
      1.0
     ],
     "point": [
      -10.0,
      0.0,
      0.0
     ]
    },
    {
     "type": "circle",
     "start": [
      10.0,
      0.0,
      120.0
     ],
     "end": [
      10.0,
      0.0,
      120.0
     ],
     "center": [
      0.0,
      0.0,
      120.0
     ],
     "axis": [
      0.0,
      0.0,
      1.0
     ],
     "point": [
      -10.0,
      0.0,
      120.0
     ]
    }
   ]
  },
  {
   "op": "construction_plane",
   "name": "Tangent",
   "method": "offset",
   "base": "YZ",
   "offset": 12.5
  },
  {
   "op": "sketch",
   "name": "KeywaySketch",
   "plane": {
    "ref": "construction plane Tangent (YZ offset 12.5)",
    "origin": [
     12.5,
     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": "arc_center_start_sweep",
     "center": {
      "at": [
       -45.0,
       0.0
      ]
     },
     "start": {
      "at": [
       -45.0,
       4.0
      ]
     },
     "sweep_deg": 180,
     "id": "a1"
    },
    {
     "type": "arc_center_start_sweep",
     "center": {
      "at": [
       -75.0,
       0.0
      ]
     },
     "start": {
      "at": [
       -75.0,
       -4.0
      ]
     },
     "sweep_deg": 180,
     "id": "a2"
    },
    {
     "type": "line",
     "start": {
      "ref": "a1.end",
      "at": [
       -45.0,
       -4.0
      ]
     },
     "end": {
      "ref": "a2.start",
      "at": [
       -75.0,
       -4.0
      ]
     },
     "id": "l1"
    },
    {
     "type": "line",
     "start": {
      "ref": "a2.end",
      "at": [
       -75.0,
       4.0
      ]
     },
     "end": {
      "ref": "a1.start",
      "at": [
       -45.0,
       4.0
      ]
     },
     "id": "l2"
    }
   ],
   "constraints": [],
   "dimensions": []
  },
  {
   "op": "extrude",
   "name": "Keyway",
   "operation": "cut",
   "profiles": [
    {
     "sketch": "KeywaySketch",
     "loops": [
      {
       "outer": true,
       "curves": [
        "a1",
        "a2",
        "l1",
        "l2"
       ]
      }
     ]
    }
   ],
   "extent": {
    "type": "distance",
    "distance": 4,
    "direction": "negative"
   },
   "result_bodies": [
    "Shaft"
   ]
  }
 ]
}