About this calculator
Compound mitre saw settings for cutting cornice flat on the saw, for any corner angle. Also gives the simpler "nested" setting for cutting upside down against the fence.
How it’s calculated
Mitre = atan(sin(spring) ÷ tan(corner ÷ 2)). Bevel = asin(cos(spring) × cos(corner ÷ 2)). For a 90° corner with 38° spring cornice, that gives 31.6° mitre and 33.9° bevel.
Worked example
With these inputs:
- Wall corner angle
- 90
- Spring angle
- 38° (52/38 cornice)
the result is:
- Saw settings (lying flat)
- Mitre 31.6° · Bevel 33.9°
- Mitre (table) angle
- 31.62°
- Bevel (blade tilt)
- 33.86°
- Nested (upside down against the fence) mitre
- 45°, bevel 0°
Tips from the trade
- Measure the real corner with an angle finder. Walls are rarely exactly 90°.
- Most saws mark 31.6/33.9 and 35.3/30 detents for standard cornice.
- Test cut two scraps and hold them in the corner before cutting long pieces.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and SANS 10400 (the National Building Regulations) and your local municipality before ordering.