Digging around for alternatives, I found this much simpler design. Don, Marlin and Hal, glad someone else around here is making frames or stuff with miter joints. Nothing like the miter trimmer though. The quality of the cut is terrific, the angle is exact and it doesn't take much glue to hold it together for the spline. Only problem I still have occasionally is with a warp or twist in the stock. So I always buy extra stock. Getting into using multiple pieces, cuts, fancy trim, to make stock that fits the picture. For example, rope trim for nautical paintings. I use some hardwood sometimes, but often make frames from 1x4 pine I carefully pick at HD.
Anyway, here's the alternative. I'd still put a little sandpaper on it to make shure it doesn't slip. It's a pain when the corner slips and the glue has set.
The more I do, the less I accomplish.