Hardened steel can turn a routine hole into a frustrating stall, especially in a busy garage, fabrication shop, or home workshop. You need bits that stay steady, bite cleanly, and fit the drill press or hand drill you already use. This roundup focuses on cobalt and carbide options that match different hole sizes, shank styles, and job types, so you can choose with fewer surprises.
Quick Look At The Strongest Options
IRWIN Drill Bit Set, M35 Cobalt Alloy Steel, 29-Piece
IRWIN Cobalt Reduced Shank 1/2-Inch x 6-Inch
Norseman 44170 Ultra Dex 240-UB 29-Piece Set
Narwhal 1/2-Inch Cobalt Drill Bits, 3-Pack
CaRoller Cobalt Drill Bit Set 29-Piece
GSTK Heavy Duty Carbide Hole Saw 14-Piece
RCINDUS 1/8-Inch Cobalt Drill Bits, 20-Piece
WildBossy M35 Cobalt Drill Bit Set 20-Piece
That 29-piece spread gives you room to move from pilot holes to larger fasteners without hunting for a second set. The 135-degree split point helps the bit start with less wandering, which matters on slick steel surfaces and curved stock.
For a home shop that sees brackets, angle iron, and repair jobs, this set feels like the steady middle ground. The trade-off is simple, though, you get breadth more than a specialty layout for one very narrow task.
Strong Points
- Wide 1/16-inch to 1/2-inch spread for many common hole sizes.
- 1/64-inch steps help you match fasteners more closely.
- Split-point tip starts more cleanly on hard surfaces.
- Set format keeps a single case organized for garage storage.
Small Caveats
- Jobber-length bits can feel long in tight corners.
- The range is broad, but it is still a general-purpose set.
Feature Snapshot
Who It Suits Best
Home mechanics and general repair work benefit most from this broad, orderly set.
Where A Sibling Pick Shines
WildBossy M35 Cobalt Drill Bit Set 20-Piece suits you better when you want a smaller, more compact range with an index case for quick grab-and-go storage.
The reduced shank design is the key here, since it lets a 1/2-inch bit work with tools that cannot take a full 1/2-inch round shank. That makes it handy in a field drill or older hand drill where chuck capacity matters more than size charts.
Compared with the full set above, this one is for a single larger hole and a more specific machine setup. You may find the 6-inch length useful for reach, though it also asks for steadier handling and a bit more space around the workpiece.
What We Like
- Reduced shank broadens tool compatibility.
- 1/2-inch cutting size covers larger hardware holes.
- 6-inch length helps with deeper access.
- Cobalt alloy suits demanding metal drilling.
Worth Noting
- Single-bit format means no backup size in the box.
- Longer reach can feel less nimble on handheld work.
- The large diameter asks for a steadier setup and good clamping.
Core Details
Who Should Grab It
You get the most value from this bit in older drills, portable setups, and jobs that need a large opening in hard steel.
Look Elsewhere When
Norseman 44170 Ultra Dex 240-UB 29-Piece Set fits better for frequent size changes, since you can keep multiple diameters close at hand.
This set leans into a shop-grade feel, especially for work that asks for repeat hole quality across many sizes. The 135-degree split point is a practical touch on hardened steel, because it helps the tip settle in before the cut starts to run away.
Compared with the IRWIN 29-piece set, the Norseman name and Ultra Dex format make this feel a touch more specialized for frequent metal drilling. The honest read is that it suits committed workshop use better than a once-in-a-while toolbox slot.
Highlights
- 29-piece layout gives broad sizing coverage.
- Split-point tip helps the bit stay planted at the start.
- Jobber length fits many common drill setups.
- Well suited to repeated steel drilling tasks.
- Good match for organized bench storage.
Areas To Watch
- More of a serious-shop choice than a casual spare set.
- Smaller spaces still ask for careful alignment.
Details At A Glance
Made For
Metalworking setups and frequent steel drilling tasks are the best match for this set.
Swap It Out When
IRWIN Drill Bit Set, M35 Cobalt Alloy Steel, 29-Piece is a better fit for you when you want a more familiar all-around set layout at the same size count.
Three identical 1/2-inch bits make this an easy choice for repeated oversized holes, especially in thicker brackets or stainless work. The 6-inch length and 135-degree split point bring useful reach and steadier starts, which helps when the workpiece already feels unforgiving.
Compared with the single IRWIN 1/2-inch bit, this pack gives you a small buffer for wear, breakage, or duplicate jobs. That said, the fixed size means it only makes sense for projects where 1/2 inch is the size you reach for again and again.
Best Bits
- Three-pack layout supports repeat jobs.
- 1/2-inch size handles larger opening needs.
- 6-inch length adds reach for deeper work.
- Split point helps reduce tip wandering.
Room For Improvement
- Only one diameter, so flexibility stays narrow.
- Long bits need careful storage to avoid knocks.
Technical Sheet
Built With In Mind
You should look at this pack for repeated 1/2-inch holes in metal-heavy projects.
Reach For A Different Pick When
CaRoller Cobalt Drill Bit Set 29-Piece makes more sense when your work changes size often and you want a broader set in one case.
This set tries to cover a lot of ground, from steel to wood and plastic sheet material, so it suits a mixed home workshop better than a single-purpose bench. The round shank is the simple kind, which keeps compatibility straightforward for common drill chucks.
Compared with the more steel-focused Norseman set, CaRoller leans a bit more toward flexibility and storage convenience. You may find the included cup-style holder helpful in a drawer or on a pegboard, though it still pays to keep the sizes in order after use.
Reasons To Buy
- 29-piece spread supports many common hole sizes.
- Round shank fits standard drill chucks easily.
- Useful across steel, wood, plastic sheet, and similar materials.
- Cup-style holder helps keep the set together.
Softer Spots
- Mixed-material focus may matter less for pure hardened steel work.
- Holder style is useful, though it still needs a tidy storage spot.
Feature Rundown
Whose Shelf It Belongs On
Mixed-use home shops and weekend repair stations get the most out of this set.
Another Choice May Suit
IRWIN Drill Bit Set, M35 Cobalt Alloy Steel, 29-Piece suits you better when your work stays closer to hardened steel and you want a more direct metal-drilling focus.
This is the outlier in the group, because it cuts larger circles rather than drilling standard twist-bit holes. TCT, or tungsten carbide tipped, means a carbide edge at the cutting face, and that matters for panel work where you want a clean opening through steel sheet.
Compared with the cobalt twist sets, this GSTK kit suits electrical cutouts, fixtures, and larger pass-through holes more than small precision fasteners. The trade-off is obvious, it solves a different problem, so it belongs with you only when hole saw work is part of the job.
Upsides
- Hole saw format handles larger round openings.
- TCT cutting edge supports tougher material work.
- Includes extra pilot center drills for setup support.
- Two L-wrenches help with routine adjustment and tightening.
Points To Note
- Not a twist-bit set, so it serves a narrower job.
- More parts means more pieces to keep track of.
- Panel work usually asks for careful marking before cutting.
Core Details
The Right Fit
Panel installers and fixture work benefit most from this kit.
Not Your Match When
RCINDUS 1/8-Inch Cobalt Drill Bits is the better route for small fastener holes and repeated detail drilling.
Small-diameter work lives or dies on consistency, and this 1/8-inch set is built around that narrow lane. The M35 cobalt and HSS pairing, where HSS means high-speed steel, gives you a familiar drill-bit structure with a harder-edge focus for metal, plastic, and wood tasks.
Compared with the bigger 29-piece sets, this one is less about variety and more about a single size you may reach for often in fastening prep. It suits hinge work, small hardware, and repeated pilot holes, though the narrow size means it should not be your only set for heavier fabrication.
Positives
- Twenty identical bits suit repeated small-hole jobs.
- 1/8-inch size works well for pilots and light hardware.
- M35 cobalt blend helps in tougher material work.
- Useful across metal, plastic, wood, and cast iron.
Things To Consider
- Only one diameter, so flexibility stays very narrow.
- Bulk storage is simple, but tracking identical bits still matters.
- Smaller bits can feel more fragile under heavy pressure.
Spec Overview
Best Suited To
Fine fastening prep, small brackets, and light fabrication suit this set well.
A Better Fit Elsewhere
WildBossy M35 Cobalt Drill Bit Set 20-Piece is the smarter choice when you want a broader diameter spread in a similar shop-friendly package.
This set lands in a very useful middle zone, because it spans 1/16 inch through 1/2 inch without feeling bloated. The index storage case helps the set stay orderly, and that matters in a garage where bits tend to disappear just when a project starts.
Compared with the CaRoller set, WildBossy feels more like a hardened-metal kit first and a mixed-material kit second. That makes it a strong fit for home mechanics and small shops that want one clean, compact case for common steel sizes.
Bright Spots
- 20-piece layout still covers a wide useful range.
- 1/16-inch to 1/2-inch sizing supports many jobs.
- Index case makes storage and retrieval simpler.
- Jobber length works with common drill setups.
Minor Gripes
- Smaller set count means fewer extras than a 29-piece kit.
- Case organization matters, because the range is broad.
At A Glance
Who Will Love This
You get the most from this kit in a home garage or compact workshop that needs a tidy range of steel-ready sizes.
Where Shoppers Go Wrong
GSTK Heavy Duty Carbide Hole Saw 14-Piece is the better route when the job is large round cutouts rather than twist-bit drilling.
How To Choose The Right Cobalt Drill Bits For Hardened Steel
Match The Bit Style To The Job
Twist bits handle most pilot holes, fastener prep, and general metal drilling, while hole saws belong in larger round cutouts. A split point, which is the sharpened tip geometry that helps the bit start without skating, matters a lot on slick steel surfaces.
Jobber length is the common all-purpose style, so it works for many home shops and maintenance carts. Reduced shank bits matter when your drill chuck cannot accept a full large diameter, and that detail can save you from a frustrating mismatch.
Choose The Right Size Range
Broad sets help when your projects jump from small pilots to larger bolts, especially in fabrication, repair, and bracket work. A narrow pack makes more sense only when you keep drilling the same diameter again and again.
Home mechanics often benefit from a 20- or 29-piece layout because it cuts down on extra trips to the drawer. Larger single bits are better for one job, but a set usually gives you more room to adapt during the week.
Pay Attention To Material And Storage
M35 cobalt is a useful marker for harder metal work, and HSS, short for high-speed steel, still matters when the rest of the geometry is right. A cup holder or index case sounds minor, yet it keeps bits sorted and reduces the chance of grabbing the wrong size mid-project.
In a busy garage, storage matters as much as cutting ability. Loose bits wear out their welcome fast, and a neat case makes the whole set easier to keep complete.
Think About Tool Compatibility And Reach
Shank style tells you how the bit fits your drill, and that can matter more than the size on the label. Reduced shank, round shank, and long-reach layouts all solve different tool setups, so the right choice depends on the drill you already own.
Longer bits help with clearance on thicker stock, but they ask for a steadier hand and better clamping. Shorter bits feel easier to control, which is why many quick tasks stay with the simpler lengths.
A Quick Reality Check Before You Choose
Mistakes Worth Dodging
Many shoppers focus only on the word cobalt and ignore the bit format, which is where the real fit shows up. A twist bit, hole saw, and reduced shank bit each solve a different problem.
Another common slip is buying too narrow a size range for a workshop that changes tasks often. That leaves you reaching for a second set sooner than you planned.
Why Top Tier Costs More
Higher-tier options usually pay for better sizing, cleaner geometry, and more specialized layouts. Sets with organized cases or added pilot pieces also ask more from the maker because the package supports real shop routine, not just a single hole.
That upgrade makes sense when you drill hard metal often, depend on consistent starts, or keep a kit in daily rotation. For occasional use, a simpler set can still cover the job without extra clutter.
Frequently Asked Questions
What makes cobalt bits useful on hardened steel?
Cobalt alloy is suited to harder drilling work, so it pairs well with steel that can dull softer bits quickly. The cutting geometry still matters, though, so a good tip style remains important.
Do I need a split point on these bits?
A split point helps the bit start with less wandering on hard or slick surfaces. That makes layout marks easier to respect when the workpiece is already stubborn.
Is a set better than a single bit?
A set helps when your projects vary in diameter, which is common in general metalwork and repair jobs. A single bit makes more sense only when you keep repeating the same hole size.
What does reduced shank actually change?
It lets a larger bit fit drills that cannot hold a full-size shank. That matters in older tools or lighter-duty setups with smaller chucks.
Should you pick a hole saw instead of twist bits?
Hole saws fit larger round cutouts, such as panel openings and fixture work. Twist bits are the better fit for standard drilled holes and smaller fastener sizes.
Final Thoughts
You get the best result by matching the bit style to the hole you need, not by chasing the biggest size count on the page. The IRWIN and Norseman sets make strong all-around choices for steady metal drilling, while the Narwhal and WildBossy options suit repeated larger or mixed-size jobs. GSTK stands apart for hole saw work, and RCINDUS fills a narrow but useful small-diameter role. Choose the set that fits your drill, your storage space, and the kind of hardened steel work you actually face.
