I am a new user and and having a hard time with cutting .050 prepainted aluminum for channel letter backs. I am using a Onsrud 63-606 up bit and have tried many many settings.I have a standard shopbot with a Porter router.I can get an OK cut, with a slight buhr on the top edge and my cuts have slight choppyness on the edges. I am screwing the 4' x8' sheet down to the table with cardboard between the sheet & the mdf top. Can anyone give me advice on feeds & speedsfor this typeof setup?