Acute Angle Jig for a Miter Saw
If you need to make an acute miter cut (greater than the 45° capacity of the saw), you’ll want to use a jig like the one shown in the photo below. Never try to make a cut like this “freehand.”
The jig is made with the two faces meeting at a 30° angle. This extra 30° allows you make miter cuts of up to 75°.
When using the jig, you should always clamp it securely to the saw fence (or auxiliary fence) and also use a clamp to hold the workpiece in place.