With all due respect to anyone's methods, I can't see grinding scarfs when you can cut them in a second.
Everyone these days has a chop saw. I just made a triangle out of 1 x 1 stock with a scarf angle. One edge is against the fence (clamped - spring clamp) and you put a strip(s) against the slight angle and cut. The strip is coming straight out from the blade and suspended on a stand or whatever. I can put 5 strips against the angle fence. I clamp them with a spring clamp and cut all 5 at once in one second. Perfect scarfs. I will shoot a picture of this simple set up and post it. This whole grinding and planing scarf joints is just old stuff before chop saws where a staple.

I suppose you could set the saw a a slight angle, but this simple jig allows you to use a spring clamp to hold the strip and not get your hands close to the blade.