I made one for doing rail and stile doors. and after I used it once couldn't see the use for it. I'm not sure if they all are the same but I had to set my bit much higher than usual to make up for the thickness of the plexiglass that I used. I went back to the old method which is to use a miter gauge at a true 90 degree angle to the fence. I also use a backer board to prevent splitting.