Interesting method to cut the compound mitre. When I made an octagon beveled out to 30°, I found a website that calculated compound mitres and used that information to build a sled for my table saw.

The sled fence was angled at 11.7° and the blade beveled to 19.4° if I recall. This achieved mitering for an octagon (22.5°) with an outward bevel of 30°.

Honestly, I didn’t even think about using my CMS. I suppose I could have saved a bunch of math and jig building headaches if I’d used it. I mean, duh… It says what it does right in its label. LOL

Losing fingers since 1969