That’s an accurate way to cut the 22* angles. 

What kind of miter saw is that and can a poor bloke like me on a budget get one on the cheep?

Can you get cuts on it without the jig like  45* angles for perfect miters for making boxes?
I have trouble cutting perfect 45’s on my Ryobi I have to make them on my table saw using an Incra miter sled. 

Maybe if I make a jig like yours but for 45’s I’ll get better results. Thanks for the tip.