I didn't even know these parts existed but damn I'm glad they existed! Although I've used one to help me repair a steel garage door, I find they drill wood just as well. In fact, they can easily replace (almost) all the drills I currently own. IMO, the only time you will NOT want to use one of these is when you need to drill a hole of a certain diameter - no more, no less. Then you will definitely want to use a conventional drill. However, if you're starting with a small hole and need to get big, these bits are definitely worth using. HIGHLY RECOMMENDED for the specific purposes above; NOT for general purpose drilling where a specific diameter is required.