A good fly cutter on a CNC is like a good hammer for a carpenter: an essential tool. Fly cutters should be run at least once a day to ensure your spoilboard surface is flat and provides consistent vacuum hold-down across the full table. A 2.5" fly cutter is a practical choice for smaller machines, while machines with a 4x8 table or larger benefit from a 4" fly cutter to cover more surface area per pass and reduce surfacing time. PCD fly cutters offer significantly extended service life and eliminate the need to turn or replace carbide inserts as frequently, making them the right investment for shops that surface their spoilboard daily.