SpeTool Carbide Spiral Router Bits UpDown Compression Bit 1/4 X 1 inch Cutting Size with 1/4 inch Shank for Woodwork CNC Router Bit Engraving Carving Mortise Groove Tools.

The compression cutters are designed with both up and downcut flutes. The top portion of the length of cut, closest to the shank, has a left hand spiral, forcing chips down. The bottom portion of the length of cut, closest to the end, has a right hand spiral, forcing chips up. When cutting, the opposing flute directions generate counteracting upcut and downcut forces. The opposing cutting forces stabilize the material removal, which compresses the composite layers, combatting delamination on the top and bottom of a workpiece. Since compression cutters do not pull up or press down on a workpiece, they leave an excellent finish on layered composites and lightweight materials like plywood. It is important to note, however, that compression cutters are suited specifically to profiling, as the benefits of the up and downcut geometry are not utilized in slotting or plunging operations.