With the Induction Furnace(IC 1.15), and an extraction pipe from Buildcraft 2.2.1, the dusts to be smelted get extracted out of the furnace to the side faster than they can smelt, even at 100% heat. The extraction pipe sucks the items out of the input first, THEN and ONLY then does it start taking from the output side. I really hope this gets fixed soon, as this bug causes a lot of excess piping that shouldnt be necessary to set up a diamond factory shop.