Mars-Tool 2-Pack Solid Carbide Drill Bit for Hardened Steel Hard Ness HRa 91

Jobber Drill Bits by Mars-Tool. 2 It is a very hard material being a 9 on the Mohs scale where diamond is a 10, quartz a 7 and hard steel around 4.5. Due to its hardness, it will chew down into most anything But that hardness makes them brittle on side load with virtually no plastic deformation before failure. 3 Any movement while drilling can result in a broken bit. These drills like a rigid drilling setup like a drill press or a machining center, they do not like hand drills. 4 You can use them in a hand held drill but you have to make sure not to misalign the drill, the drill must be perfectly square for the whole…