Shave shallow layers of material off your workpiece to create a smooth even finish. These fly cutters hold a lathe tool (sold separately) and run on your milling machine. Compared to end mills, these make a wider cut per pass. They also generate less heat, so you can run them at higher speeds. In the long run, these cutters will save you the cost of replacing entire end mills once they dull—you can either sharpen your worn lathe tool or just replace that one part.

Instead of widening a hole using a lathe, which turns the workpiece while the cutting tool stays still, use these holders to turn your boring bar in a milling machine and keep the workpiece stationary. They’re good for creating holes that are too large to drill or a diameter you don’t have a drill bit for. To help you bore holes to precise diameters, these holders have an adjustment dial with fine increments. Mount them in your milling machine using their shank. They’re also known as boring heads.