Drill America 1/4" - 1/2" Cobalt Heavy Duty Jobber Length Drill Bit

1/4"–1/2" Cobalt Jobber Drill Set

This 16-piece Drill America set covers diameters from 1/4" to 1/2" in cobalt steel. Each bit meets National Aerospace Standard 907 and features a 135° split point for self-centering starts. The heavy-duty jobber length suits machine or handheld drilling in tough alloys. Cobalt construction maintains hardness at elevated temperatures.

Metalworkers drilling stainless, Inconel, titanium

Shops that need faster penetration in high-tensile alloys will benefit from the 30% speed gain over M2 high-speed steel. The 135° split point reduces thrust and walking on hard surfaces. Buyers who only drill wood, plastic or soft aluminium will not use the heat resistance this set provides. Sets requiring sizes below 1/16" or above 1/2" must look elsewhere.

135° split point geometry

The 135° split point centres without a centre punch and cuts thrust force, letting the cobalt substrate run up to 30% faster in stainless steel, Inconel and titanium. Smaller bits below 1/16" or #52 and larger bits above 1/2" revert to a 118° standard point. This single angle change determines whether the bit walks or bites in hard metal.