The 90-Degree Tenon Cutter can cut logs, branches, and even square wood if you're looking for the ease of creating the mortise. It is a total pain to chisel out a square mortice. It is so much simpler to use a forstner bit to drill the mortise, and have everything fit.
You have to pre-drill and 3/8" guide hole for the cutter to to follow. You can drill that hole at any angle. Whether you're trying to join up a stair rail at an angle to connect it to a wall, or if you're intricate with your log furniture building skills. There is a lot more gluing surface, and the EZ-90 is great for rustic table legs. Check it out.