TopLine Drill Bits Size Cobalt Cutting Tools for Industrial Drill Bits Review

This product from the industrial and scientific line was a complete letdown... As my tests showed, the size cobalt cutting tools were not nearly as effective as advertised. The drill bits were prone to breaking and did not have the longevity that should be expected from an industrial product..

Letter Size Drills. Very hard alloy. Heat resistant but can be brittle, so it's used on machine tools rather than hand drills. A torque limiting clutch is also useful to prevent breakage. Wear safety goggles, of course. Good quality.