21/64" HSS Drill Bit Long Series Carded 2500-21/64S by Bordo Metal Diamond Cutting|Abrasive Wheels and Cups 4mm x 75mm

4mm x 75mm

Specifications: Drive Shank: 11

The stocks are made of Rosewood / Walnut (depending on availaibilty at time of manufacture)

Increased Molybdenum Manganese and Nickel content provide greater strength and corrosion resistance

With cutting edges (hardness approx

21/64" HSS Drill Bit Long Series Carded 2500-21/64S by Bordo Metal Diamond Cutting|Abrasive Wheels and Cups 4mm x 75mmBLACK FINISH (also called blue finish) A black finish is achieved by steam tempering, a thermal process resulting in a porous tool coating. This surface helps to keep lubricant on the tool, particularly important on the cutting edges, thus reducing friction and cold welding. The result is increased tool life. Black finish tools are generally recommended for ferrous applications where the oxide layer aids chip flow and heat dissipation. Specifications: