Q: What is a drill press fly cutter?

Carol Reed: It's a dangerous tool that starts with a rod chucked in your drill press. The other end of the rod has a perpendicular bar with a cutter hanging off the end of it. The bar or cutter adjusts for varying hole diameters. In my opinion, there are much better and safer tools. For large holes, use hole saws rather than a fly cutter.

Michael Dresdner: Fly cutters are commonly used by guitarmakers to cut both sound holes and rosette rings in spruce tops. Their advantage is that you can set them at any diameter within their range, and not just nominal ones, but, as Carol said, they can be very dangerous. They work best making shallow cuts in soft woods.