I've had these parts for a few months now. I'm a welder by trade, so I know my tools. They are suitable for wood, but not for steel. Upon delivery, some bits were sharp, others not sharp at all; you could physically feel it on the spot. When I tried drilling with them they didn't cut at all. They are also very brittle. I have broken 5 bits since purchase. The last one I broke sent a bit into my baby's chest. It scared him a little and scared him a lot. I understand drill bits break from time to