A drill bit that skates across hardened steel, snaps on the third hole, or arrives dull from the factory is the single most frustrating speed bump in any metalworking project. The difference between a clean hole and a ruined workpiece often comes down to the exact metallurgy, point geometry, and coating chemistry hidden inside that small spiral shaft. The market is flooded with sets that look identical in the package but behave completely differently under load — separating the real performers from the shelf ornaments requires understanding what actually happens at the cutting edge.
I’m Mo Maruf — the founder and writer behind The Tools Trunk. I’ve spent years cross-referencing customer durability reports and manufacturer spec sheets on drill bit alloys, heat-treatment processes, and tip geometries to identify which sets deliver consistent results across stainless steel, cast iron, and hardened alloys without breaking the bank.
After analyzing hundreds of real-world drilling accounts and technical specifications, I’ve narrowed the field to the five sets that genuinely hold an edge. This guide covers the best drill bits for everything from light wood boring to extracting broken studs from turbo housings.
How To Choose The Best Drill Bits
Selecting the right drill bit set requires more than grabbing whatever is on the shelf. Three factors — material composition, point geometry, and coating — define whether a bit cuts cleanly or burns out after a few holes. Understanding each one prevents wasted money and ruined projects.
Material: HSS, Cobalt, or Titanium Coated
Standard high-speed steel (HSS) bits handle wood and soft metals but lose their edge quickly on stainless steel or hardened alloys. M35 cobalt steel contains 5 percent cobalt, which increases red hardness — the ability to stay hard at high cutting temperatures. This makes cobalt bits the go-to choice for drilling into cast iron, stainless, and bolt extractor applications. Titanium nitride (TiN) coated bits reduce friction and extend edge life on general-purpose work, but the coating is a surface layer and does not change the base hardness of the steel underneath.
Point Geometry: The Split-Point Advantage
A 135-degree split-point tip creates two cutting edges that engage the material simultaneously, which virtually eliminates walking on curved or hardened surfaces. Standard 118-degree points require a center punch to stay on target. For anyone drilling into metal without a drill press, the 135-degree split-point is the difference between a hole exactly where you want it and a gouge that ruins the workpiece.
Shank Design: Preventing Chuck Slippage
Round shanks on bits larger than 3/16-inch can spin inside the drill chuck under heavy torque, especially when the bit grabs. Three-flat shanks provide three contact points that lock the bit securely in the jaws, transferring full power to the cutting edge rather than wasting it as friction heat on the shank surface. This feature matters most for bits 1/4-inch and above.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Milwaukee 48-89-4630 Shockwave TiN | Premium | High-torque impact drilling | 3-flute split-point TiN | Amazon |
| DEWALT DW1361 Pilot Point TiN | Premium | Clean holes in metal & wood | Pilot point tip, 21 pieces | Amazon |
| RCINDUS 3/16″ Cobalt 20-Pack | Mid-Range | Hardened steel & stainless | M35 cobalt, 135° split-point | Amazon |
| WildBossy M35 Cobalt 20-Piece | Mid-Range | Diverse size range, hard metals | M35 cobalt, Ti surface, 67 HRC | Amazon |
| Bosch BL21A Black Oxide 21-Piece | Entry-Level | Light-gauge metal & wood | Black oxide, 3-flat shank | Amazon |
In‑Depth Reviews
1. Milwaukee 48-89-4630 Shockwave TiN 15-Piece
Milwaukee’s Shockwave line is engineered for the high-torque bursts of impact drivers, not just standard chucks. The 135-degree split-point and titanium nitride coating work together to reduce walking and keep the cutting edge cool during aggressive drilling into steel studs, angle iron, and sheet metal. The three-flute design clears chips faster than a standard two-flute geometry, which prevents binding in deeper holes.
Users consistently report that these bits outlast standard cobalt sets in everyday fabrication work, even when drilling through tougher alloys. The 15-piece assortment covers the sizes most mechanics and electricians reach for daily, from 1/16-inch up to 1/2-inch. The plastic case is compact enough for a toolbox drawer but keeps every bit securely in place during transport.
The biggest trade-off is the piece count — 15 bits versus the 20 or 21 pieces offered by competitors at similar tiers. For someone who needs the full stair-step range from 1/16-inch to 1/2-inch without duplicates, the smaller set may require supplementing with individual bits. But for sheer cutting aggression on hard materials, this set pulls ahead of the field.
What works
- Impact-rated design handles hammering torque without shattering
- Three-flute chip evacuation reduces binding in deep holes
- TiN coating extends edge life beyond uncoated cobalt bits
What doesn’t
- Only 15 bits in the set, fewer than premium competitors
- Smaller bits feel short for drilling through 2x lumber
2. DEWALT DW1361 Titanium Nitride Coated Pilot Point 21-Piece
The DEWALT DW1361 stands apart because of its pilot point tip — a self-starting geometry that pulls the bit into the material on contact, eliminating the need for a center punch on most surfaces. The titanium nitride coating reduces friction significantly, which means less heat buildup and longer cutting life compared to black oxide or bare HSS bits. The set includes 21 pieces, covering 1/16-inch through 1/2-inch with duplicates of the most commonly lost smaller sizes.
In practice, these bits excel in wood and light-gauge metal. The pilot point keeps the bit tracking straight even when entering at a slight angle, which is a major advantage for trim carpentry and electrical box installation. On thicker steel, the larger bits maintain their edge well, though the coating will eventually wear through at the cutting edge under heavy use.
The hex shank design on sizes above 1/4-inch provides a no-slip grip in standard three-jaw chucks, though the smaller bits still use a round shank. Some users report that the coating on bits 1/4-inch and smaller wears faster when drilling into hardened steel repeatedly. For a mixed-material shop that needs a versatile daily driver, this is the most complete set in the premium tier.
What works
- Pilot point eliminates walking and center punching on most materials
- 21-piece set includes duplicates of common sizes
- TiN coating provides excellent friction reduction for wood and light metal
What doesn’t
- Coating wears faster on hardened steel than cobalt alternatives
- Smaller bits lack the hex shank for anti-slip grip
3. RCINDUS 3/16″ Cobalt 20-Piece Set
This RCINDUS set is a single-size bulk pack of 20 3/16-inch cobalt bits, which sounds niche until you realize that 3/16-inch is the most common size for pre-drilling deck screws, removing stripped bolt heads, and drilling through mild steel. The M35 cobalt content delivers the red hardness needed to drill into stainless steel and cast iron without the edge crumbling, and the 135-degree split-point prevents walking on the curved surfaces of bolts and pipes.
Real-world reports confirm that these bits handle tasks that kill standard HSS bits within seconds. Drilling through 1/8-inch steel plate, the bits maintain sharpness across multiple holes — one user drilled ten holes in steel with a single bit and saw no degradation. Another used them to extract broken bolts from old tractor parts, a job that typically chews through cheap bits in one or two attempts.
The trade-off is that you only get one size. For a shop that needs a complete range from 1/16-inch to 1/2-inch, this set cannot stand alone. But as a refill pack for the most frequently replaced size in any metalworking shop, it offers lower per-bit cost than buying individual cobalt bits and outperforms any multi-purpose set on hard metal.
What works
- Genuine M35 cobalt steel handles stainless and hardened alloys
- 20 identical bits mean spares when one dulls or snaps
- 135-degree split-point prevents walking on curved surfaces
What doesn’t
- Single-size set only covers 3/16-inch
- Uncoated finish offers less friction reduction than TiN
4. WildBossy M35 Cobalt 20-Piece Set (1/16″ — 1/2″)
The WildBossy set brings M35 cobalt metallurgy into a full-range kit spanning 1/16-inch through 1/2-inch, with duplicates of the most common smaller sizes. The manufacturer advertises a Rockwell hardness of 67 HRC, which puts the cutting edge well into the range needed for stainless steel, cast iron, and hardened alloys. The addition of a titanium surface layer on the cobalt base aims to reduce friction further than bare cobalt alone.
User reports are mixed but revealing. Several users found the bits cut through stainless steel with surprising ease, and one reported using them to drill out snapped-off taps and studs from turbocharger housings — a job that demands both edge hardness and thermal resistance. However, a minority of users received bits that were dull out of the box or snapped on the first use, suggesting some batch inconsistency in heat treatment or grinding.
For the price, this set offers the most complete cobalt selection available in a single indexed case. The 3-flat shank on bits 3/16-inch and larger prevents chuck slippage during high-torque drilling. If you need a one-box cobalt solution and are willing to accept a small chance of a dud bit, this is the most economical way to cover all your hard-metal drilling needs without buying individual sizes.
What works
- Full 20-piece range from 1/16-inch to 1/2-inch with duplicates
- M35 cobalt at 67 HRC handles hardened alloys
- Titanium surface layer adds some friction protection
What doesn’t
- Some bits arrive dull or snap on first use
- Not suitable for glass or ceramic materials
5. Bosch BL21A Black Oxide 21-Piece Assorted Set
Bosch’s BL21A set uses high-carbon steel with a black oxide coating that reduces friction and provides corrosion resistance for general-purpose drilling. The 135-degree split-point tip is present across all sizes, giving even the smallest bits a no-walk start on wood, plastic, and light-gauge metal. The 21-piece assortment covers 1/16-inch through 1/2-inch with duplicates of the most commonly lost sizes.
This is not a hard-metal drilling set — and Bosch does not market it as one. The black oxide coating sits a tier below titanium nitride in heat and friction resistance, and the base high-carbon steel lacks the red hardness of M35 cobalt. Users report that these bits cut wood like butter but require slow speeds and cutting oil for metal, with a higher risk of tip breakage if you push too hard at breakthrough.
The 3-flat shank on bits 3/16-inch and larger provides noticeably better grip in standard chucks compared to fully round shanks. For a homeowner or light contractor who primarily drills wood, plastic, and occasional thin metal, this is the most complete and reliable entry-level set available. The case is durable and keeps every bit organized without jostling them loose.
What works
- Split-point tip on all sizes prevents walking on hard surfaces
- 3-flat shank provides anti-slip grip on 3/16-inch and larger bits
- 21-piece set covers full range with duplicates of small sizes
What doesn’t
- High-carbon steel dulls quickly on hardened metal
- Black oxide coating offers less friction reduction than TiN
Hardware & Specs Guide
Cobalt Content and Red Hardness
The percentage of cobalt in M35 high-speed steel directly determines the bit’s ability to maintain hardness at elevated cutting temperatures. Standard HSS bits begin to soften around 500°F, while M35 cobalt retains its edge up to approximately 1100°F. This is the single most important specification when drilling stainless steel or hardened alloys. Bits labeled “cobalt” that do not specify M35 or a percentage of cobalt content may use a lower-grade alloy that does not deliver the same thermal performance.
Point Angle and Self-Centering
The 135-degree split-point geometry creates two independently cutting edges that meet at the exact center of the bit. This design eliminates the need for a center punch on most materials because the bit drills itself into the surface rather than skating sideways. Standard 118-degree points require a pilot divot for accurate placement. The split-point also reduces the thrust force required to penetrate the material, which lowers the risk of bit breakage during hand drilling.
FAQ
Can cobalt drill bits be used in a standard drill or only a drill press?
Is titanium nitride coating better than black oxide for drilling metal?
Final Thoughts: The Verdict
For most users, the drill bits winner is the Milwaukee 48-89-4630 Shockwave TiN because its impact-rated three-flute design and split-point geometry deliver unmatched cutting aggression on hard metals without shattering under torque. If you want a complete multi-material set with a self-starting pilot point, grab the DEWALT DW1361 Pilot Point TiN. And for budget-conscious metalworkers who need a bulk supply of the most commonly used size, nothing beats the RCINDUS 3/16-inch Cobalt 20-Pack.