The 12-inch benchtop planers with the self feed option won't open wide enough. They usually top out around 6 inches deep. My DeWalt does, anyway. Even my 20" grizzly only opens up to 8". I agree with thomas that you can take 2 passes with the 6" Makita, then sand off the little steps. Keep a framing square close at hand and keep an eye on how square it's staying. If one side is getting higher, take an extra pass there before going back to alternating sides. This may even vary from one end of the stick to the other. Also, you'd be surprised at how much difference it can make to put a little twisting pressure on it with your wrist to make one side cut deeper than the other. CB.