Hi everyone,
I just want to give you a small tip for if you are using a quarry from the buildcraft mod. When you place your quarry, let it dig down 1 layer and turn it off. Now you need to place a water bucket in one of the corners. Start your quarry again. The effect of doing this is that your quarry can mine trough lava, since it turns to cobble or obsidian when the water touches it.
Hope this tip helps you guys!