Reaching a deep cavity, drilling through a frame rail, or boring a pilot hole that passes entirely through thick steel stock—these are the jobs that demand a bit longer than anything in a standard 4-inch set. Standard jobber-length bits simply cannot reach, and attempting to extend a short bit by adding a cheater bar or adapter introduces side-load and runout that wrecks the hole tolerance and often snaps the tool. A dedicated 24-inch long drill bit delivers the shank reach and flute clearance necessary to penetrate deep metal without flex, chatter, or premature failure.
I’m Min — the co-founder and writer behind Gadgets Feed. I’ve spent countless hours studying the metallurgy, flute geometry, and tip angles that separate a long-reach bit that drills true from one that wanders, overheats, or snaps under torque. This guide cuts through the marketing to focus on the measurable specs that matter for deep metal drilling.
After sorting through dozens of options and analyzing hundreds of user experiences, I’ve built a focused roundup of the 24 inch long drill bits for metal that actually hold up when the hole has to go straight and deep.
How To Choose The Best 24 Inch Long Drill Bits For Metal
A 24-inch metal drill bit is a specialist tool. Grabbing the cheapest option without checking material composition, flute design, or point geometry usually ends in a snapped bit and a ruined workpiece. Focus on these three criteria to avoid that outcome.
Material: M35 Cobalt vs. HSS vs. Carbide
Standard high-speed steel (HSS) bits lose their temper rapidly when drilling deep holes in steel because the chips cannot evacuate heat easily. M35 cobalt steel (5% cobalt content) retains hardness at higher temperatures, making it the baseline for serious metal drilling at this length. Solid carbide is harder still but extremely brittle—use it only in a rigid drill press or mill, not in a hand-held drill where any side-load can shatter the tip.
Point Geometry: The 135° Split Point Advantage
A 118° point is standard for wood and soft materials but tends to “walk” on metal. A 135° split point creates a self-centering action that bites immediately without a center punch, reduces the thrust required to start the hole, and prevents the bit from skating across curved or hardened steel surfaces. Every bit in this guide uses a 135° split point for precisely that reason.
Flute Length and Web Thickness
On a 24-inch bit, the flute must be long enough to clear chips from the full depth of the hole while maintaining a thick enough web to resist torsional twisting. Insufficient web thickness causes the bit to spiral-bind and snap under load. Look for a manufacturer that publishes flute length and shank diameter—if the shank is reduced, the bit is designed for deep pocket drilling, not through-hole work.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| VALYRIANTOOL Cobalt Extra Long Set | Premium | Multi-size deep metal drilling | M35 Cobalt, 12″ flute, 5-piece set | Amazon |
| Bosch HC4C2068 SDS-Plus | Premium | Hammer drilling into concrete/steel | Carbide-tipped, 4-flute, 24″ length | Amazon |
| Drill America DMOD Series Carbide | Premium | Hardened steel & broken bolt removal | Solid carbide, 118° point, 2-flute | Amazon |
| LU&MN M35 Jobber Bits | Mid-Range | Stainless & cast iron, 1/2″ diameter | M35 HSS, 135° split point, 5-pack | Amazon |
| Narwhal 9/16″ Cobalt 3-Pack | Mid-Range | Large-diameter holes in thick plate | M35 cobalt, 1/2″ shank, 6″ length | Amazon |
| DelitonGude 25/64″ Cobalt Set | Value | DIY and home shop, mixed metals | M35 cobalt, 135° pilot point, 5-pack | Amazon |
| Power Planter 3″ x 24″ Auger | Specialty | Soil/garden, not metal drilling | Alloy steel, 1/2″ hex drive, 24″ length | Amazon |
In‑Depth Reviews
1. VALYRIANTOOL Cobalt Extra Long Drill Bits Set
This five-piece set covers the most commonly needed diameters from 1/8-inch up to 3/8-inch, each with a full 12-inch flute length. M35 cobalt steel with 5% cobalt provides the hot hardness required to maintain a sharp cutting edge when the chips are not clearing easily from a deep hole. The 135-degree split point starts precisely without a center punch, and the fully ground spiral flute design reduces friction for cooler running.
Users consistently report that these bits cut through stainless steel and thick steel plate without the binding that causes shorter bits to snap. The straight shank fits standard drill chucks, while the extra length allows you to drill through wide beams or reach a recessed area where a standard bit cannot access. For a shop that regularly encounters deep metal drilling jobs, this set provides the breadth of sizes needed to cover most situations.
Be mindful of speed and pressure—cobalt bits still generate significant heat in deep cuts, so cutting oil and a moderate RPM are essential to avoid work-hardening the material and dulling the edge. The bits are uncoated, so they rely entirely on the cobalt content and flute design for heat management rather than a surface treatment that could wear off.
Why it’s great
- M35 cobalt formulation retains edge at high temperatures.
- Five sizes in one set cover most common deep-metal holes.
- 135° split point provides true self-centering on metal.
Good to know
- Uncoated surface; must use cutting oil for best life.
- Bit can be brittle if excessive side-load is applied during drilling.
2. Bosch HC4C2068 SDS-Plus Bulldog Tough Rotary Hammer Bit
Bosch’s Bulldog Tough series uses a four-cutter carbide tip design that delivers up to twice the life in concrete with rebar compared to standard two-cutter bits. The 24-inch length is designed specifically for deep anchoring holes in masonry and reinforced concrete, where the SDS-Plus shank locks into a rotary hammer to deliver the percussive force needed to fracture aggregate. The four-flute body efficiently pulls dust and debris out of the hole, preventing the binding that plagues standard twist bits in deep concrete bores.
The centering tip enhances placement precision for anchor bolts and rebar dowels, while the carbide edges are engineered to survive hitting rebar without seizing or stalling the hammer. Users report drilling hundreds of holes through concrete block and slab with no appreciable edge degradation. This is not a twist drill for pure metal work, but if your 24-inch deep hole passes through concrete and encounters steel reinforcement, this bit handles both materials in a single pass.
It requires an SDS-Plus rotary hammer—standard keyed or keyless chucks cannot grip the shank. The bit is a single-size purchase, so you are committing to 3/8-inch diameter holes only. If you need a range of diameters for concrete work, you will need to buy multiple individual bits.
Why it’s great
- Four-cutter carbide tip survives rebar impacts without stalling.
- Four-flute design evacuates dust efficiently in deep holes.
- Centering tip improves anchor-hole accuracy for structural work.
Good to know
- Only compatible with SDS-Plus rotary hammers, not standard drills.
- Single diameter; cannot be used for non-hammer drilling in soft metal.
3. Drill America 25/64″ Solid Carbide Drill Bit (DMOD Series)
When cobalt bits fail—and they do fail against case-hardened steel, broken bolts, and spring steel—solid carbide is the next step up. The Drill America DMOD series is manufactured from a solid carbide blank with a 118-degree point and standard 2-flute geometry. It operates at significantly higher cutting speeds than HSS or cobalt substrates, but the trade-off is brittleness: any wobble, chatter, or misalignment can cause the tip to fracture instantly.
Users who reviewed this bit consistently described scenarios where multiple cobalt bits had been destroyed before this carbide bit drilled through hardened steel bolts, extractor sockets, and case-hardened surfaces in under two minutes. The uncooped surface maintains a sharp micro-edge that shears rather than rubs, which is critical when the workpiece hardness exceeds 45 HRC. For a shop that occasionally encounters extreme hardness, having one of these in the cabinet is cheaper than replacing a broken extractor or a ruined workpiece.
This bit is designed for use in a rigid toolholding system—collet chuck in a mill, or a high-quality drill press with minimal runout. Hand-drilling with a portable drill is risky because the side-load from operator pressure can snap the carbide before the cut even begins. Pay close attention to the shank fit; the round shank allows use with standard chucks, but any slop increases the fracture risk.
Why it’s great
- Solid carbide cuts case-hardened steel where cobalt fails.
- Uncoated micro-edge provides superior cutting action on hard alloys.
- Manufactured to National Aerospace Standard 907 for tight tolerance.
Good to know
- Extremely brittle; must be used in rigid setup with minimal runout.
- 118° point may wander on curved surfaces without a center punch.
4. LU&MN M35 Jobber Drill Bits (1/2″, 5-Pack)
This five-pack of 1/2-inch M35 HSS bits offers a straight-shank, jobber-length alternative for users who need a consistent diameter across multiple drillings without the cost of a full premium set. The 135-degree split point is self-centering, so you get accurate hole placement on steel and stainless without pre-punching. The uncoated M35 surface relies on the cobalt content for heat management rather than a black oxide or TiN coating.
User feedback emphasizes that these bits cut through mild steel and stainless steel tubing without wandering, significantly outperforming general-purpose HSS bits and even some name-brand “metal” bits that failed on the same task. The heat resistance allows longer continuous cutting before dulling, provided you use cutting oil and avoid overheating the workpiece ahead of the cut.
Durability has some variance—a small number of users reported breakage under heavy load, particularly at the start of the cut where point pressure is highest. Running a lower drill speed (under 500 RPM for 1/2-inch diameter) and applying steady, moderate feed pressure improves survival rates. The included plastic case keeps the set organized but is not rugged enough for job-site abuse.
Why it’s great
- M35 cobalt composition provides real heat resistance for metal work.
- 135° split point eliminates bit walking on startup.
- Five identical bits allow for high-volume hole production without resharpening.
Good to know
- Some bits may be brittle at the tip under aggressive feed rates.
- Storage case is lightweight plastic, not job-site durable.
5. Narwhal 9/16″ Cobalt Drill Bits (3-Pack)
At 9/16-inch diameter with a 1/2-inch shank, this three-pack is designed specifically for large-diameter holes in steel plate and stainless steel. The reduced shank (the shank is smaller than the cutting diameter) allows the bit to fit into a standard 1/2-inch drill chuck while still cutting an oversized hole. The M35 cobalt construction and 135-degree split point keep the bit tracking straight through thick material without requiring a pilot hole.
Users who drilled through thin stainless steel reported running 70+ holes with the same bit before noticing any edge degradation, which speaks to the quality of the cobalt grind. The included plastic storage case keeps each bit separated, preventing edge dulling from contact with neighboring bits. For large-diameter deep drilling—such as pass-through holes for conduit or structural bolts—this set provides a reliable option at a reasonable entry point.
The bit length is 6 inches total with a 3-inch flute, so it is not a true 24-inch reach tool. The Narwhal bits excel for drilling thick plate or stacked layers where the total material thickness does not exceed 3 inches. If you need to drill through a 12-inch beam, a longer flute bit is necessary.
Why it’s great
- Reduced 1/2″ shank allows large-diameter drilling in standard chucks.
- M35 cobalt maintains cutting edge through extended use in stainless.
- Three bits included—good value for repeated large-hole work.
Good to know
- Total flute length is 3 inches, not suitable for deep pocket drilling.
- Low point angle may cause walking on smooth or convex metal surfaces.
6. DelitonGude 25/64″ HSS M35 Cobalt Twist Drill Bit Set
This five-pack of 25/64-inch diameter bits delivers M35 cobalt construction at an accessible price point, making it a solid entry-level choice for the home shop or DIY user who needs to drill metal occasionally. The black oxide finish provides mild corrosion resistance, while the 135-degree pilot point design self-centers well on flat steel and cast iron surfaces. Spiral flute geometry improves chip evacuation compared to straight-flute alternatives.
Customer reports indicate good performance on bronze, aluminum, mild steel, and metal studs when using cutting oil and slow drill speeds. The bits have successfully drilled through hardened steel T-posts for some users, though durability is not at the same level as premium brands—a few users reported failure after 4–5 holes in harder materials. The set is suitable for household maintenance, automotive repairs, and hobbyist metalworking where 24-inch reach is not required.
The bits measure 135 mm total length (roughly 5.3 inches) with a 90 mm flute, so they are not 24-inch bits. This set is included for buyers who want a budget-friendly M35 option for smaller-diameter metal drilling jobs. If you specifically need 24-inch reach, look at the VALYRIANTOOL or Bosch options instead.
Why it’s great
- M35 cobalt at a budget-friendly price point for home shop use.
- 135° pilot point provides good self-centering without walking.
- Spiral flute design improves chip clearance in metal cutting.
Good to know
- Not a 24-inch bit; total length is just over 5 inches.
- Edge durability is lower than mid-range or premium cobalt brands.
7. Power Planter 3″ x 24″ Extended Length Garden Auger Drill Bit
The Power Planter 3-inch by 24-inch auger bit is built from heavy-gauge alloy steel with a 1/2-inch hex drive shaft designed for cordless drills with at least 18V. The spiral flighting is welded to the central shaft, and the abrasion-resistant tip extends the unit’s life by 3–4 times compared to standard auger bits. This is a gardening and construction tool for digging holes in dirt, clay, sand, and loose soil—not for drilling into solid metal.
Users report digging hundreds of holes for bulbs, plants, and fence posts with minimal effort. The 24-inch shaft allows for deep planting holes without bending over, significantly reducing strain on the back. The auger has also been used for mixing paint and mortar in buckets when paired with a suitable mixing paddle adapter. For contractors, landscapers, and heavy gardeners, this tool replaces shovels and bulb planters with a fast, consistent drilling action.
It is not suitable for metal drilling under any circumstances. Attempting to use this auger on steel, concrete, or asphalt will damage the flighting and the tip. This bit belongs in the soil, not on a metal workbench. If your 24-inch drilling task involves earth or sand, this is the correct tool; if it involves steel, choose one of the cobalt or carbide options above.
Why it’s great
- 24-inch length allows deep planting without back strain.
- Heavy-gauge alloy steel and welded flighting resist bending in tough soil.
- Abrasion-resistant tip extends service life through repeated use.
Good to know
- Not for metal drilling; designed exclusively for soil, clay, and sand.
- Requires drill with at least 1/2-inch chuck; heavier drills work best.
FAQ
Can I use a standard 118-degree drill bit for deep metal holes?
Do I need a special drill for 24-inch long bits in metal?
Final Thoughts: The Verdict
For most users, the 24 inch long drill bits for metal winner is the VALYRIANTOOL Cobalt Extra Long Set because it combines M35 cobalt composition, a 135-degree split point, and five essential diameters in one package—covering the widest range of deep-metal jobs without breaking the bank. If you need to drill through concrete with rebar reinforcement, grab the Bosch HC4C2068 SDS-Plus. And for the most extreme hardened-steel extraction work, nothing beats the Drill America Solid Carbide Bit.