I've been hooking up my buildcraft machines to my power grid via power pipes and iron OR gates. The gates send a red pipe signal if the Has Work condition is fulfilled (I believe this condition comes from Extra Bees, which I have in.) The red pipe signal triggers a redstone signal on my engines. This Has Work condition is not available on most non forestry machines, and the thermal expansion trigger for energy storage won't work with the fabricator since the heat is constantly dropping. What would be a way to have the engine only running when it has things to craft?