What angle do you cut 38° crown molding at?

Cut flat on the table, 38° crown in a square corner is 31.6° miter and 33.9° bevel. Nested against the fence it is a single 45° miter. Settings for every corner.

Miter 31.6°, bevel 33.9° — cutting 38° crown flat on the saw table in a square corner.

Cutting it nested instead — held upside down against the fence at its spring angle, blade straight up — it is a single miter of 45.0° and no bevel at all.

How that is worked out

  1. Crown leans out from the wall, so its face is in neither the horizontal nor the vertical plane. Cut flat on the table, the saw has to tilt *and* swing to put the blade in the plane of the joint — hence two settings.
  2. Both settings follow from two angles: the spring angle the molding sits at, and the angle the walls actually meet at. Nothing about the profile matters.
  3. Nested is the other way to do it: hold the molding at its spring angle against the fence, so the saw only has to swing. One setting, half the arithmetic, and a harder piece of wood to hold steady.

Flat-on-the-table settings, inside corners

Flat-on-the-table settings, inside corners
Spring angle90° corner — miter / bevel120° corner — miter / bevel135° corner — miter / bevelNested miter (90°)
38°31.6° / 33.9°19.6° / 23.2°14.3° / 17.6°45.0°
45°35.3° / 30.0°22.2° / 20.7°16.3° / 15.7°45.0°
52°38.2° / 25.8°24.5° / 17.9°18.1° / 13.6°45.0°

Worth knowing

  • Check the spring angle before you trust any of this. Stand an offcut in the corner the way it will sit, measure the drop down the wall and the reach across the ceiling, and work back from those — 38° and 52° are the two common ones and the profile does not tell you which you have.
  • Almost no corner in a real house is 90°. Measure the actual corner angle and use that row, or cut a test pair from offcuts and adjust. A degree out shows as a gap you can see from the doorway.
  • An outside corner uses the same settings with the miter swung the other way. The piece that runs long is the one on the wall you see first.
  • Coping beats mitering on an inside corner in a house that moves. A coped joint closes up as the wall shifts; a mitered one opens.