Answering the demand for deep, straight holes with a 1/8 inch diameter, these long drill bits are designed to reach farther into wood, plastic, metal, and composite materials. They’re best for professionals and DIYers who need extra reach without sacrificing accuracy. This guide highlights five long, durable options and explains who each is best for, plus practical buying tips. The included summary table helps compare key features at a glance.
Product Quick Reference
| Product | Length | Material/Coating | Best For |
|---|---|---|---|
| HLOFIZI 1/8″ x 12″ Extra Long Drill Bits (2 Pack) | 12″ | M2 HSS, Black & Gold coating | Deep pockets in wood, plastic, thin metal |
| Greycore Tools 1/8 Inch x 12 Inch Cobalt Aircraft Extension Bit | 12″ | M35 Cobalt with Titanium coating | Hard metals, steel, high-heat environments |
| VALYRIANTOOL 1/8 in. x 12 in. Cobalt Drill Bits Set (5PCS) | 12″ | M35 Cobalt with Titanium coating | Versatile metal, plastic, and wood drilling |
| DEWALT DW1602-1/8-Inch by 12-Inch Extra Long Black Oxide Drill Bit | 12″ | Black oxide finish, HSS | General-purpose long-hole drilling |
| Greycore Tools 1/8 Inch x 6 Inch Black Oxide Aircraft Extension Bit | 6″ | Black oxide, HSS | Long reach in lighter tasks and thin-material work |
HLOFIZI 1/8″ x 12″ Extra Long Drill Bits (2 Pack)
Type: Aircraft extension drill bits. Length: 12 inches. Material: M2 high-speed steel with black and gold coating for heat resistance and rust protection. Features fully ground technology for precision and burr-free holes. Best for deep drilling in wood, plastic, and thin metal sheets. This set provides extended reach for tasks where standard bits fall short.
- Best for long reach in vertical or overhead drilling.
- Choose this if you need two long bits to cover multiple projects without changing tools.
- Caution: Longer bits can flex more under load; maintain steady pressure and correct drill speed to avoid wandering.
Greycore Tools 1/8 Inch x 12 Inch Cobalt Aircraft Extension Bit
Material and coating: M35 cobalt (5% cobalt) with industrial titanium coating. Length: 12 inches. This bit is designed for fast penetration into hardened steel and other tough metals, while maintaining wear resistance in high-heat environments. It’s ideal for metalworking where deep, precise holes are required.
- Best for hard metals and extended drilling in metal fabrication.
- Choose this if you need superior heat resistance and durability.
- Caution: Cobalt bits are sharper and can be more brittle if misused in misaligned holes; ensure proper alignment before drilling.
Greycore Tools 1/8 Inch x 12 Inch Cobalt Aircraft Extension Bit
Includes: 1 bit per set. Material: M35 cobalt with titanium coating, 12 inches long. Designed for fast penetration and long life in steel, hard metals, wood, and plastics. Fully ground for precision and reduced heat generation during drilling.
- Best for single-use deep-hole projects in metal or wood.
- Better for users who want a sturdy, long-life option with cobalt protection.
- Caution: Requires appropriate drill press or stable hand guidance to avoid drift on long cuts.
VALYRIANTOOL 1/8 in. x 12 in. Cobalt Drill Bits Set (5PCS)
Contents: 5 pieces, each 1/8″ diameter and 12″ length. Material: M35 cobalt (5%), with titanium coating. Features fully ground spiral grooves for fast debris removal and 135-degree split point to prevent walking. No center punch needed.
- Best for versatile metal drilling, including stainless steel and hard plastics.
- Choose this set if you want multiple long bits with consistent performance.
- Caution: 12″ long bits are more challenging to control for beginners; use a drill with good guidance and lower speeds to start.
Buying Guide: Long 1/8 Drill Bits Buyer Considerations
What material will you drill?
For soft woods and plastics, standard high-speed steel bits are often sufficient, but extended reach helps avoid repositioning. For metals, especially hardened steel, cobalt (M35) bits provide greater wear resistance and longer life.
How long should the bit be?
12-inch bits offer the deepest reach, ideal for through-holes or long cavities. 6-inch bits strike a balance between reach and control, suitable for overhead or vertical drilling where space is limited.
Coating and heat management
Black oxide and titanium coatings reduce friction and heat buildup, aiding longevity and smoother chips evacuation. Cobalt bits substantially improve heat resistance and performance in hard metals.
Drill speed and technique
Use slower speeds with longer bits to prevent flex and wandering. Apply steady, even pressure and use pilot holes when needed. For cobalt and HSS bits, avoid overheating by backing out chips periodically.
Tool compatibility
Ensure your drill and chuck can handle 12-inch bits and the straight shank. For longer bits, consider using a drill guide or a magnetic drill stand for improved accuracy.
Durability and cost considerations
Longer bits with cobalt coatings tend to last longer in tough materials but cost more. For occasional deep drilling in metal, consider a mixed set to cover both wood and metal tasks.
FAQ
- Are cobalt bits worth it for wood? Yes, cobalt bits are durable and reduce wear when drilling through mixed materials, but for pure wood tasks you can use high-speed steel options as a budget-friendly alternative.
- Can I use 12″ bits in a standard handheld drill? Some handheld drills can accommodate 12″ bits, but you may need a guide or support to maintain straight alignment and reduce deflection.
- What is the advantage of a 135-degree split point? It helps prevent walking and enables faster, cleaner entry into the material, especially on metal.
- How do I prevent bit breakage on long bits? Use proper drill speed, steady pressure, and support at the bit tip to minimize bending and snapping.
- When should I choose black oxide vs cobalt? Black oxide is good for general long-reach tasks and corrosion resistance; cobalt is preferred for hard metals and high-heat conditions.
- Is a longer bit always better? Not necessarily. Longer bits offer reach but can be harder to control; choose length based on hole depth and access constraints.