BOSCH BL2747 5/16 in x 12 in Aircraft Black Oxide Drill Bit - Extra

In this review the BOSCH BL2747 5/16 in x 12 in extra length black oxide drill bit is evaluated for tradespeople and DIYers who need reach through walls or deep assemblies. The bottom line: this pack of three aircraft-length bits stands out for its extended reach and sturdy black oxide finish, making it the sensible choice when standard jobber bits are too short. The review focuses on real-world cutting performance in metal, wood and plastic, longevity under repeated use, and where the bit's length and design make the biggest practical difference.

Key Features

• Extra length aircraft design: The 12 in length lets users drill through deep workpieces or boxed framing without switching to extensions, saving time on long-reach tasks.
• Black oxide finish: Reduces heat and friction for smoother drilling and helps extend tool life compared to uncoated high-speed steel bits.
• Speed helix geometry: Cuts faster than standard bits by evacuating chips efficiently, which improves drilling pace in thin metals and plastics.
• Multi-material use: Cuts cleanly in steel, aluminum, brass, oak, maple, MDF, PVC and common plastics, offering versatility for mixed projects.
• Pack of three: Having multiple identical bits on hand reduces downtime from dulling or accidental breakage during a job.

Who It's For

The BL2747 suits contractors, electricians, plumbers and hobbyists who frequently encounter deep or hard-to-reach holes in light-gauge metal, wood framing and plastic panels, and who value the convenience of a ready extra-length bit in the drill. Its design is especially useful for through-wall conduit runs, metal bracket mounting and cabinetry work where longer reach prevents the need for extensions.

Those who only drill short, superficial holes or need specialty coatings for very hard alloys should consider jobber-length HSS or carbide-tipped bits instead, since the aircraft length is unnecessary for routine shallow work and tougher materials may require different bit metallurgy.

Pros & Cons

Pros

• Extra length gives access to deep holes without extensions, speeding work in framing and retrofit jobs.
• Black oxide finish and speed helix combine for easier drilling with reduced heat and improved chip removal.
• Versatile across metals, woods and many plastics, reducing tool changes on mixed-material jobs.

Cons

• Durability is mixed in reports; some users found breakage on first use, so care is needed during aggressive side loading.

Specifications

Our Verdict

The BOSCH BL2747 5/16 in x 12 in extra length bit is a practical, cost-effective choice for anyone needing genuine reach with reliable cutting in common metals, woods and plastics. It offers good value for routine and retrofit work, though users should avoid excessive side loading to reduce breakage risk. Overall, it is recommended for tradespeople and DIYers who value extra bit length and dependable black oxide performance.

Frequently Asked Questions

Can these bits be used in steel?
Yes, the bits are suitable for light-gauge steel and common softer metals like aluminum and brass when used with correct speed and pressure.

Will the length affect accuracy?
Longer reach can flex more than shorter bits, so clamp work and use steady drill technique to maintain drill accuracy.

Are these bits good for plastics and wood?
Yes, the BL2747 cuts well in wood and many plastics and produces clean holes when run at appropriate speeds.