Sounds like I wasn't clear in my last post. The rafters I am referring to might be called something else. I'm building a pergola, sometimes referred to as an arbor. THe 2 x 6's will lay across the joists parallel with the ground and at right angles to the joists. I just want to fit the rafter or whatever you call it, down a couple of inches over the joist. No angles involved. I know my terminology is not correct but hope I get the idea across.