A friend of mine is a sign guy who contracted with the railroad to make 500 hand held signs. Big reflective circles with a wooden handle. Does anyone have an idea how to cut a 1/8" groove length wise, half way through a 1" diameter dowel 10" long to accept the sign? A table saw won't leave a clean, square edge at the end of the slot. I thought a straight cut router bit would clean it up but I can't seem to find one small enough. Any ideas?? Please keep in mind he needs to make 500!!