Spiral Router Bits

Select diameter based on the width of the cut you need; larger diameters remove more material and are stiffer for straight cuts. Choose flute length so it matches or slightly exceeds the thickness of the material to avoid chipping or overload; for deep plunge cuts, use bits specifically rated for that depth

Up-cut bits evacuate chips up and are good for fast material removal but can lift veneers. Down-cut bits push chips down for a cleaner top surface but slower removal. Compression bits combine both: the top flutes push down and the bottom push up, producing clean edges on both faces for laminated or veneered workpieces

High-speed steel (HSS) bits are economical for softwoods; carbide-tipped or solid carbide bits hold an edge longer and suit hardwoods, composites, and high-volume work. Coatings like TiN or TiAlN can reduce wear and heat buildup, but for most woodworking carbide construction is the primary performance factor

Match the bit shank to your router’s collet—common sizes are 1/4" and 1/2"; 1/2" shanks offer greater rigidity and less vibration. Use only well-seated shanks without burrs and avoid excessive stick-out beyond the collet to maintain concentricity and reduce chatter

Keep bits clean of resin and pitch buildup, use a bit cleaner or a mild solvent, and sharpen or replace bits when they produce burn marks or tearout. Run routers at recommended speeds for the bit diameter, use proper feed rates, and avoid overheating by taking multiple shallow passes on hard materials

Use appropriate guards, a secure work-holding method (clamps or jigs), and eye and hearing protection. Ensure the router is unplugged when changing bits, verify the bit is tightened properly, and feed the workpiece against the rotation of the bit to maintain control

Higher-priced spiral bits often use better carbide, tighter tolerances, and longer-lasting coatings, which pays off for frequent use, harder materials, or production environments. For occasional hobby work, budget-friendly carbide-tipped options typically offer acceptable life and performance