rip the 2x4 to a usable thickness with your table saw.
Edit: I just measured mine. 1 1/2 should work perfect. That would allow the bearing to ride against the side of the 2x4 and as you lower it, it will begin to cut your pattern.
Edit2: Check out the picture. That is 2ea. 3/4 inch pieces of plywood, so almost 1 1/2 inches thick. The bearing will ride against your 2x4 piece. Shouldn't be a problem. Make a couple of passes either 1/16 or 1/8th inch per pass.
That's my story and I'm stickin' to it!
Last edited by MT Stringer; 01-20-2018 at 10:43 AM.