later I've only used it on plastic where I needed to cut a 1 3/4" hole. It did what it needed to do and cut through the plastic with ease. The only one Problem I had was the drill bit had some trouble cutting through the original pilot hole.There weren't too many problems as a bit more force forced the hole through.I had no problem with the larger hole drill bit cutting through cut the plastic.quickly and evenly.The drill bits are oiled probably to prevent rusting.But figuring out how to put the drill bits together was pretty easy.