Solid Carbide Thread Mill offers higher cutting speeds, high rigidity, excellent hardness, wear resistance and heat resistance and long tool life. Reduced Tool Inventory. One thread mill can produce internal & external threads, left hand & right hand threads, different thread diameters of the same pitch and through hole & blind hole threads. Produce coarse pitches and large diameters on lower H.P. machines. Thread harder, difficult-to-machine & gummy materials that cause problems for taps.