Cobalt Aircraft Extension Drill Bit 1/8in x 6in Pack of 12 - Long

In this review the Drill America GLBCOX61/8P12 1/8in x 6in Cobalt Aircraft Extension Drill Bit pack is examined for hobbyists and technicians who need extra reach and tougher-metal performance. The bottom line is that this 12-pack is best for users drilling stainless steel, nickel alloys or aircraft aluminum where standard jobber bits stall or walk; the combination of cobalt-enriched steel and a 135 split point gives consistent centering and penetration for through-holes in hard materials.

Key Features

• Cobalt-enriched steel: provides improved cutting performance in high tensile materials like stainless steel, inconel and titanium compared with ordinary high-speed steel.
• 135 split point tip: the self-centering tip reduces walking and lowers required thrust so holes start precisely without a pilot.
• Gold oxide finish: a thin oxide treatment that identifies the bit and behaves similarly to an uncoated tool while resisting mild surface corrosion.
• 6in overall length: extra length gives reach into deep or awkward workpieces for through drilling where standard lengths fall short.
• Round shank: allows use with a wide variety of chucks, collets and drill holders for both handheld and drill-press work.

Who It's For

The pack is aimed at mechanics, aircraft sheet metal workers, fabricators and serious DIYers who regularly drill tough alloys or need extra reach when working on frames, tubing or assemblies. It is also useful for guitar builders and small shops that value consistent tip geometry when starting holes.

Those who should look elsewhere include users who only drill soft woods or plastics and need shorter, cheaper bits, or those who require specialized coatings like TiN for high-speed production where reduced friction is a priority.

Pros & Cons

Pros

• High cutting performance in hard metals thanks to extra cobalt content.
• 135 split point starts cleanly and reduces walking for accurate hole placement.
• Long 6in length solves reach problems without resorting to extensions or awkward setups.
• Pack of 12 offers good value and spares for shop use or projects.

Cons

• Durability feedback is mixed; some users report faster wear than expected under heavy use.
• Gold oxide is a thin surface treatment and does not offer the same wear resistance as thicker modern coatings.

Specifications

Product type	Cobalt aircraft extension drill bit
Size	1/8in diameter
Overall length	6in
Point style	135 split point (self-centering)
Shank	Round shank for standard holders
Finish	Gold oxide surface treatment
Quantity	Pack of 12

Our Verdict

For shop owners and experienced hobbyists who need a dependable long-reach bit that will cut hard alloys, this 1/8in x 6in cobalt extension pack represents good value. The combination of cobalt-enriched steel and a 135 split point makes hole starting and drilling through tough materials noticeably easier, though buyers should expect average wear under heavy continuous use and plan replacements accordingly.

Frequently Asked Questions

Are these bits suitable for stainless steel?
Yes, the cobalt-enriched steel is intended to improve performance when drilling stainless steel and other high tensile materials.

Can they be used in a drill press and handheld drills?
Yes, the round shank works with a wide variety of chucks and holders for both drill presses and handheld drills.

Is the gold oxide a wear-resistant coating?
The gold oxide is a thin oxide finish used to identify cobalt tools; it behaves similarly to uncoated bits and is not a heavy wear-reducing coating.