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Walking, drifting, and dulling are the three things that ruin a drilling job on hard steel. A true cobalt bit solves all three at once — it starts exactly where you place it, stays sharp through dozens of holes, and shrugs off the heat that kills standard high-speed steel. This guide sorts through 9 of the best cobalt drill bits on Amazon right now, breaking down which sets win on value, which ones chew through stainless, and which are worth the premium.
I’m Rikta — the founder and writer behind FitlyFast. This guide is built by comparing the manufacturers’ published specifications and the patterns across verified customer reviews, so you get each pick’s real strengths and trade-offs instead of marketing spin.
Find the right set for your workshop without overpaying, as we compare M35 steel, split points, and piece counts across the best cobalt drill bits.
Our Picks at a Glance
How To Choose The Best Cobalt Drill Bits
You need a bit that won’t dull the moment you touch stainless steel or hardened steel. A cheap high-speed steel bit handles wood and soft metal, but it gives up fast on tougher jobs. Cobalt bits add 5% cobalt to the steel alloy, so they keep a cutting edge at high temperatures where ordinary bits fail.
Check the Steel Grade: M35 vs M42
For everyday metalwork, most sets here use M35 high-speed steel with 5% cobalt — a balance of hardness and toughness that handles the jobs you’ll actually face. M42 steel packs more cobalt (around 8%) and runs even hotter, but it’s rarer and costs more. When you drill stainless steel, cast iron, or hardened bolts, M35 with genuine 5% cobalt is the balance most shops rely on.
Look for a 135° Split Point
A split point is a notch ground into the tip that makes the bit self-centering. It stops the bit from “walking” or skating across a hard surface when you start the hole, so you get a clean, precise start without a center punch. If you see “135° split point” on the label, that is the feature doing the heavy lifting for accuracy.
Match the Set Size to Your Work
Sets range from 10 to 19 pieces, and the right number depends on your projects. A 10-piece set covering 1/16″ to 1/4″ is plenty for small fasteners and thin steel. A 17-piece set that stretches up to 1/2″ covers bigger holes in thicker plate. If you work in metric sizes, a dedicated metric set from 1mm to 10mm saves you from guessing conversions.
Quick Comparison
| Model | Best For | Pieces | Size Range | Point Style | Amazon |
|---|---|---|---|---|---|
| RCINDUS 15PCS★ Best Overall | Overall value & variety | 15 | 1/4″ (single size) | 135° Split Point | Amazon |
| STROTON 13PCSBudget Champion | Budget 1/16″-1/4″ coverage | 13 | 1/16″ – 1/4″ | Split Point | Amazon |
| BECOLLO 10 PCSSpeed Demon | Aggressive speed on steel | 10 | 1/4″ (single size) | 135° Split Point | Amazon |
| LU&MN 10 PCS | Stainless steel endurance | 10 | 1/4″ (single size) | 135° Split Point | Amazon |
| SALI 10 PCS | Storage & organization | 10 | 1/4″ (single size) | 135° Split Point | Amazon |
| Narwhal 3-Pack | Big 1/2″ holes | 3 | 1/2″ | 135° Split Point | Amazon |
| WildBossy 19PCS Metric | Metric sizes 1-10mm | 19 | 1mm – 10mm | 135° Split Point | Amazon |
| Drill America 12-Pack | Professional-grade consistency | 12 | 1/4″ (single size) | Spiral Point | Amazon |
In-Depth Reviews
1. RCINDUS 15PCS 1/4″ Cobalt Drill Bit
Our pick — over 4.5★ from 850+ verified ratings; the strongest balance of quality and price.
The value king that cuts stainless like butter and keeps 50 buyers talking about the price.
The M35 high-speed steel carries a genuine 5% cobalt content, which is what lets it chew through hardened metal, stainless steel, and cast iron without overheating.
The 135° split point is the feature owners rave about for precision — it self-centers and prevents walking on hard surfaces, so your first hole lands exactly where you marked it. Reviews mention it cuts through stainless steel sheeting easily and stays sharp during use, with diameter accuracy held within -0.03mm for consistent hole sizes.
What wins people over is the value: it is the most-mentioned aspect in the reviews by a wide margin, and buyers repeatedly call it a great set for the money. The bits work on wood, plastic, PVC board, and cast iron too, making this a true all-arounder for home projects and workshop repairs alike.
Why Shoppers Choose It
- 15 pieces for the price of smaller sets — 50% more bits than the 10-piece packs
- 135° split point stops walking for accurate first holes
- Sharp from the start and stays sharp through multiple uses
What to Expect
- All bits are the same 1/4″ size, so no size variety for smaller jobs
- Uncoated finish means you should use cutting oil on hard steel
Reach for this set if: you want maximum bits per dollar and a genuine M35 cobalt that handles the daily metal mix.
Look elsewhere if: you need a range of sizes rather than a single 1/4″ diameter.
2. STROTON 13PCS Cobalt Drill Bit Set
A 13-size ladder from 1/16″ to 1/4″ that puts a full kit in your drill bag for less.
The defining spec here is the size range: 13 jobber-length bits stepping in 1/64″ increments from 1/16″ all the way up to 1/4″. That means you grab one case and have the right bit for small pilot holes and larger fasteners alike, which is rare at this price point. The M35 steel is rated at 68 HRC (Rockwell Hardness Scale — a measure of how hard the steel is), so it is built for heavy-duty work on stainless steel, steel plate, iron sheet, and cast iron.
The split point design is particularly suited for drilling out bolts, studs, and screws — the jobs where cheaper bits slip or snap. The manufacturer claims the 5% cobalt content delivers 3X heat, wear, and chip resistance and 3X tool life compared with ordinary bits, and the fully ground process keeps the cutting edge sharp.
Buyers report mixed results on the hardest steel: one owner drilled 1 of 4 hardened 10.9 steel bolts, which shows the limit of any M35 bit on ultra-hard fasteners. The advice from experienced users is consistent — go slow, use oil, keep firm pressure, and clear chips frequently, because cobalt bits are hard but brittle.
Live with it: this is a real cobalt set that outperforms basic HSS on most metals, but it is not a miracle worker on rock-hard bolts — technique matters.
The smart budget move: a full 13-size cobalt kit for entry-level money.
Know before you buy: hardened steel bolts will test its limits — slow speed and oil are non-negotiable.
3. BECOLLO 10PCS 1/4″ Cobalt Drill Bit
The sharpest bit of the bunch — drilling 1/2″ holes in A36 steel in about one second.
Nothing in this list matches the raw bite of the BECOLLO. Review data shows it drilled 1/2″ holes in 1/4″ A36 steel in about 1 second, versus 15-20 seconds for a Bosch M35 bit — a speed gap that saves serious time on repeated holes. The fully grinding process smooths the surface to cut friction, and the 135° split point (a tip that self-centers) stops the bit from walking on the workpiece.
Quality is the #1 aspect owners mention by a huge margin, and sharpness runs a close second. The bits stayed sharp through 8 holes with no dulling, and one owner reamed through stacked 2×1/4″ steel plus 2.75″ of plywood without losing the edge. They are manufactured to ANSI B94-11M, a US standard for twist drill dimensions.
The honest trade-off: while some owners mention the bits break easily on hard metals, others note the flute scuffing after aggressive use — with no performance loss. The consensus technique is a light touch with cutting oil (Tap Magic gets named specifically) to let the sharp edge do the work. The bronze oxide finish wore off during use, but the cutting ability did not.
Where It Excels
- Aggressive cutting speed — roughly 15x faster than a Bosch M35 in one test
- Stays sharp through 8+ holes with no dulling
- 135° split point for clean, self-centering starts
Handle With Care
- Breakage reported by some owners on hard metals
- Bronze oxide finish wears off during use
Grab these if: speed on steel plate matters more than anything else.
Think twice if: you tend to push hard — this bit rewards a light touch with oil.
4. LU&MN M35 Jobber Drill Bits, 1/4″, 10 Pcs
The stainless slayer that punched 8 holes through a John Deere bucket on one bit.
The defining story here is endurance on stainless steel. The reviews tell of one bit drilling all 8 holes in a John Deere bucket to mount D-ring brackets — and staying just as sharp on the 8th hole as the first. Another owner reports cutting right through 316 stainless steel, which is notoriously tough, as long as you do not overheat the material.
The M35 high-speed steel carries 5% cobalt for superior heat and abrasion resistance over standard HSS. The 135° split point self-centers and requires less pressure for precise, clean starts. The fully ground flute design clears chips efficiently and reduces friction for smoother drilling.
Drill performance is the top-mentioned positive aspect, and the sharpness follows close behind. One owner noted these cut through metal tube that had only dented their B&D and Milwaukee 5x bits — a direct contrast that shows real cobalt advantage. The honest caveat: some owners found the smaller bits brittle, with one smallest bit breaking after a minute of use, so treat the thin sizes gently.
Real-world verdict: genuinely sharp, genuinely tough on stainless — the John Deere bucket story is the proof most buyers need.
Choose this for: stainless steel and hard metal plate where you need one bit to last.
Be careful with: the smallest sizes — they are sharp but can snap under sideways pressure.
5. SALI Cobalt Drill Bit Set, 10 Pcs
The only set here with a molded size chart on the lid so you grab the right bit instantly.
The standout feature is the index storage case with molded sizes printed on the lid — a small thing that saves real time when you are mid-job and need the right 1/4″ bit fast. The set also has a connectable accessory storage system to tune space in your toolbox. The M35 high-speed steel carries 5% cobalt for wear-resistance and durability, and the fully ground spiral groove clears particles quickly while reducing friction and heat.
The 135° split point with straight shank prevents walking and makes drilling precise and faster — the manufacturer notes no center punch is needed. Quality is the top-mentioned positive aspect, and one retired industrial tool salesman called them “as good as any drill bit I have ever used.” Customers note cutting through galvanized fence posts and security yard posts with ease.
The honest mixed note: durability and sharpness get split feedback. Some find them very tough and very sharp, while one unverified review found they dulled fast on hard metals — using 3 bits over 40 minutes on a stainless bolt. This is a bit that shines on softer metals and sheet steel, but heavy stainless work will test it.
What Stands Out
- Molded size chart on the case lid for instant identification
- Connectable storage system that saves toolbox space
- 3-flute design clears chips faster than standard 2-flute bits
Keep in Mind
- Mixed reports on longevity when drilling hard metals
- Best suited to soft metals, sheet steel, and general work
Pick this if: an organized, easy-to-read case matters as much as the bits themselves.
skip it if: your primary job is thick stainless — that is where the mixed durability reports appear.
6. Narwhal 1/2 Inch Cobalt Drill Bits (3 Pack)
Three burly 1/2″ bits with a 4″ flute that chew through 3/8″ steel at an angle.
This is the set for big holes. Each bit is 1/2″ in diameter with a 4″ flute length and 6″ total length — enough reach to get through thick plate and awkward spots. Quality is the overwhelming theme in reviews, with the most mentions of any aspect in this list’s data, and functionality runs a strong second. One owner drilled a 3/8″ thick steel plate at a 25-degree angle, which is a serious stress test for any bit.
The M35 steel contains 5% cobalt and is fully ground for a precision drilling diameter. The 135° split point makes repeated holes in harder materials easier, and a tough plastic storage case keeps the trio organized. Reviewers point out the bits stay sharp through 30 holes and can be sharpened multiple times, which stretches the value of a 3-pack considerably.
The honest trade-offs: the bits are loose in the tube, and there are no flats on the shank, so there is a slipping risk in some chucks. They are effective but not the fastest — shoppers say drilling out Jeep lug nut studs successfully but recommend cutting oil and optimal speed. One owner drilled 10 holes through 3/16″ galvanized steel with the edge staying intact.
Sharp & sturdy: this is the 1/2″ workhorse for anyone who regularly drills big holes in steel plate.
Reach for these when: you need 1/2″ holes in thick steel and want a bit that stays sharp for 30+ holes.
Mind the details: no shank flats means a firm chuck grip is essential to avoid slipping.
7. WildBossy M35 5% Cobalt Metric Drill Bits Set (19Pcs)
Nineteen metric sizes from 1mm to 10mm — the complete kit for metric workshops.
If you work in metric, this is the set that ends the guessing game. It includes 19 commonly used sizes from 1mm to 10mm, covering everything from tiny pilot holes to 10mm fasteners. The straight shank jobber design fits most standard drill chucks and offers a useful balance of reach and control. The M35 high-speed steel with 5% cobalt gives improved heat resistance over standard HSS bits.
The durability story here is remarkable: one owner burned through 3 other bits drilling 5 holes in a steel utility trailer, then drilled over 30 holes in the same frame using just one of these — and it stayed sharp. That real-world endurance justifies a cobalt purchase. Buyers mention quality most often, with sharpness close behind.
The honest negatives: some buyers report bits breaking on first use and the plastic case being flimsy — one arrived with the black holder in pieces. Multiple buyers also note poor performance on stainless steel specifically, so treat this as a general metalworking set rather than a stainless specialist. The manufacturer explicitly notes it is not intended for concrete, masonry, tile, or glass.
The Metric Advantage
- 19 metric sizes from 1mm to 10mm
- One bit drilled 30+ holes in a steel trailer frame
- Jobber length balances reach and control
Watch For
- Flimsy storage case reported by some owners
- Mixed results on stainless steel specifically
Grab this for: metric workshops, garage projects, and general metalwork where size range is king.
Look past it if: stainless steel is your main material — this set gets mixed reviews there.
8. Drill America DWDCO1/4 Cobalt Drill Bit (Pack of 12)
The aerospace-grade 1/4″ bit trusted for titanium and zirconium work.
This is the specialist’s choice. Each bit is manufactured to National Aerospace standard 907, a rigorous spec that tells you the geometry and material are held to professional tolerances. The cobalt steel is similar to high-speed steel but with more cobalt for improved performance on harder metals like stainless steel and nickel alloys. The gold oxide finish is a thin surface treatment used to identify cobalt steel tools.
The reviews show a serious user base: one owner drills titanium and zirconium with these and calls them “my go to drill bits,” while another uses them for #54-sized holes in steel and outperformed a Max Tool bit that failed. The round shanks fit a wide variety of toolholding systems, and the spiral point (a twisted tip) pushes chips up and out of the cut to reduce clogging.
Quality is the #1 mentioned aspect, with performance and value close behind. One owner drilled through 16 and 18 gauge galvanized steel and noted the bits stayed sharp. The honest caveat: 2 out of 12 bits in one pack had a quality grind issue that slipped through inspection — so check each bit before you rely on it, though 10 out of 12 being excellent is a strong hit rate.
Pro-Grade Strengths
- Aerospace standard NAS 907 manufacturing
- Handles titanium and zirconium — beyond typical stainless work
- Gold oxide identifies true cobalt steel
Pro-Grade Caveats
- Occasional grinding defect slips through inspection
- Premium price for a single-size pack
Pick this for: professional work on exotics like titanium where consistency matters most.
pass on it if: you need a range of sizes — this is a focused 1/4″ specialist, not a general kit.
Understanding the Specs
M35 Cobalt Steel (5% Cobalt)
This is the alloy that makes a bit a “cobalt” bit. Adding 5% cobalt to high-speed steel lets the cutting edge stay hard at high temperatures — the exact condition you create when drilling stainless or hardened steel. Standard HSS bits soften and dull fast under that heat; M35 keeps cutting. You will see “68 HRC” on some sets, which is the Rockwell Hardness Scale reading, telling you how hard the steel is.
135° Split Point
A split point is a notch ground into the tip of the bit. It makes the bit self-centering, which means it starts drilling exactly where you place it instead of “walking” or skating across a hard surface. This saves you from needing a center punch to create a starting dimple, and it gives you clean, precise holes from the very first rotation.
Jobber Length vs. Flute Length
Jobber length is the standard drill bit length that balances reach and control for most work. The flute is the spiral groove that pulls chips up and out of the hole — a 4″ flute on a 1/2″ bit (like the Narwhal) gives you deeper reach and better chip evacuation for thick plate. Longer flutes clear debris, which keeps the cutting edge cooler.
Cutting Oil and Speed
Cobalt bits are hard, but hardness brings brittleness. The universal advice across every review is to use cutting oil, run a slow speed, keep firm steady pressure, and let the bit cool between holes. This prevents the two failure modes: overheating (which work-hardens stainless steel) and snapping the bit from sideways pressure.
FAQ
What is the difference between cobalt and titanium drill bits?
Can cobalt drill bits drill through hardened steel bolts?
Do I need cutting oil with cobalt drill bits?
What does the 135° split point actually do?
Why do my cobalt bits keep breaking?
Is M35 or M42 cobalt steel better?
How long do cobalt drill bits last?
What is a jobber length drill bit?
Can I use cobalt bits on wood and plastic?
How do I choose the right set size?
Final Thoughts: The Verdict
For the majority of shoppers, the cobalt drill bits winner is the RCINDUS 15-piece set because it delivers the most bits per dollar with genuine M35 cobalt and a sharp 135° split point. If you want aggressive speed on steel plate, grab the BECOLLO 10-piece set. And for reaching up to 1/2″ holes, the STROTON 17-piece set is the one to reach for.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of August 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
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