Downcut Rougher, Spiral Router Bits - (2 Flute) Solid Carbide - Vortex 1180. Cutting Edge Diameter 3/4 Cutting Edge Length 2 1/2 Shank Diameter 3/4 Overall Length 5. Roughing tools are designed for high feed rates on CNC routers. These tools are used when surface finish is not important in dense materials such as hardwoods and plywood. Roughing tools are very successful in CNC applications where this bit makes the first cut, followed by a second cut using a profile type tool. This tool will produce a rippled edge cut and is extrememly quiet and smooth cutting, even in heavy cuts and high feed rates. Avoid using this tool at lower feed rates which generate chip loads under.005.