Drilling through stainless steel is a different beast. The work-hardening nature of the alloy means a standard high-speed steel bit will skid, glaze, and dull within seconds, leaving you with a ruined workpiece and a smoking shank. The only way through is with a bit engineered to handle the heat and abrasion — specifically, cobalt alloys and carbide-tipped geometries designed to bite into hard metal without annealing on contact.
I’m Mo Maruf — the founder and writer behind The Tools Trunk. I spend my time dissecting metallurgy specs, cutting-angle data, and real-user durability reports to separate marketing fluff from actual drilling performance.
This breakdown is focused on the hardware that actually works, organized into a definitive guide to the drill bits for stainless steel that can handle the torque without self-destructing.
How To Choose The Best Drill Bits For Stainless Steel
Stainless steel work-hardens at the point of cut. A dull or poorly ground bit generates friction that instantly hardens the surface, making subsequent passes nearly impossible. The selection criteria here revolve around three pillars: material hardness, point geometry, and heat management through coatings.
The Cobalt Content Threshold
M35 cobalt steel contains 5% cobalt, raising the alloy’s red hardness so the edge retains its temper at temperatures that would soften ordinary HSS. For stainless steel, M35 or higher (M42 with 8% cobalt) is the baseline. Bits labeled “cobalt steel” without an M-grade designation are often just HSS with a cobalt dusting — they will fail on the second hole. Look for explicit M35 or M42 marking on the shank.
Point Geometry and Self-Centering
A 135° split point is the standard for hard metals because it reduces the contact area at the tip, lowering the thrust force needed to initiate the cut. It also includes a secondary grind that creates a self-centering chisel edge, preventing the bit from walking across the smooth stainless surface. Standard 118° bits will skate and ruin your layout mark.
Coating Systems for Thermal Protection
Titanium Nitride (TiN) is common but degrades above 800°F. Titanium Aluminum Nitride (TiAlN) forms an aluminum oxide layer during cutting that actually gets harder as temperature rises, surviving up to 1500°F. For stainless steel, TiAlN is the superior coating. Uncoated M35 bits still work but require stricter feed-rate and lubricant discipline.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| toolant Cobalt Pro 21pc | Twist Drill Set | Heavy production drilling in hardened steel | TiAlN coating, 89 HRC surface hardness | Amazon |
| MACXCOIP Metric 25pc M35 | Metric Twist Drill Set | Metric precision work and 3D print post-processing | M35 cobalt, straight shank, full 1-13mm range | Amazon |
| ss shovan Step Drill 3pc | Step / Unibit Set | Thin-gauge sheet metal and deburring | M35 cobalt, TiAlN coating, 1/4″ hex shank | Amazon |
| DKIBBITH TCT Hole Saw 4pc | Hole Saw Set | Cutting large diameter holes in conduit and pipe | Tungsten carbide-tipped teeth, 1″ depth | Amazon |
| WildBossy M35 20pc | Twist Drill Set | Entry-level stainless drilling at low cost | M35 cobalt, 135° split point, 3-flat shank | Amazon |
In‑Depth Reviews
1. toolant Cobalt Drill Bit Set Pro (21-Piece)
Toolant’s Pro set uses an actual TiAlN physical vapor deposition coating that raises surface hardness to 89 HRC — well into the range where the coating itself becomes the primary wear barrier against abrasive stainless swarf. The substrate is M35 cobalt steel with a 135° split point that walks zero on polished 304 sheet. The three-flat shank design prevents any slipping in the chuck when drilling at the recommended low RPM with cutting oil.
Users reported cutting dozens of holes through hardened steel without the edge rolling over, and the self-centering bullet-point tip eliminates the need for a center punch on most jobs. The 21-piece coverage from 1/16″ to 1/2″ covers nearly all common sizes, with double-stocked bits in the smaller diameters where breakage is most likely.
Warranty support stands out here — one broken bit on a grille grid was replaced with eight new bits, which signals confidence in the product and good customer service. The set ships in a molded case, though some users found the 3-flat shank slightly oversized for certain keyless chucks.
What works
- True TiAlN coating that survives high-heat production runs
- Bullet-point tip drills without walking on polished stainless
- Exceptional warranty response from manufacturer
What doesn’t
- 3-flat shank may not seat deep in all keyless chucks
- Higher sticker price than entry-level cobalt sets
2. MACXCOIP Metric 25-Piece M35 Cobalt Drill Bit Set
This MACXCOIP set covers every millimeter from 1.0mm up to 13.0mm in 0.5mm increments — a lifesaver for anyone working with metric fastener clearances or European-manufactured machinery. The M35 cobalt material provides the necessary red hardness for stainless, and the 135° split point is ground with a self-centering chisel that keeps the bit steady during the initial bite. A former CNC machinist reviewer confirmed these bits match professional-grade quality.
The jobber-length geometry is optimized for drill press use where clearance isn’t an issue, though the straight shank design fits standard three-jaw chucks without the slipping problems sometimes seen with reduced-shank bits. The storage case is slim enough for shallow tool chest drawers, a detail metric users appreciate.
One reviewer noted the shank material slipped in a drill press chuck under heavy feed pressure, suggesting the shank hardness may be lower than the cutting edge. This is common with inexpensive cobalt sets and can be mitigated by using premium drill chucks or tightening directly on the flutes for critical holes.
What works
- Complete 1-13mm metric range with 0.5mm steps
- Genuine M35 cobalt with 135° split point grind
- Flat storage case fits shallow drawers
What doesn’t
- Shank material may deform under high-torque clamping
- No coating layer — requires strict oil discipline
3. ss shovan 3-Piece M35 Cobalt Step Drill Bit Set
Step drills solve the sheet metal problem: how to drill a large diameter hole without buying ten individual bits. Shovan’s set uses M35 cobalt with a TiAlN coating, and the 1/4″ hex shank eliminates chuck slip entirely. The 118° X-type grind is not the ideal 135° for stainless, but the coating and cobalt substrate compensate when used on sub-1mm gauge material as the product explicitly specifies.
The three-bit set covers from 1/4″ up to 7/8″ across 18 stepped diameters, which is enough for most electrical and HVAC work. Users reported cutting through steel guitar chassis and sheet metal with ease, and the spiral flute design clears chips effectively without binding. The 1/4″ hex shank fits impact drivers directly, a convenience for field work.
One long-term reviewer noted that the top step on the largest bit lost its edge after about 20 uses on heavy material. The TiAlN coating delays wear but does not eliminate it — these are best reserved for thin stainless and aluminum rather than repeated production cuts on 1/4″ plate.
What works
- Hex shank prevents chuck slip, works with impact drivers
- Three bits cover 1/4″ to 7/8″ stepped diameter range
- TiAlN coating extends life on thin stainless sheet
What doesn’t
- 118° point angle not optimal for thick stainless plate
- Top step edge wears faster than main cutting edges
4. DKIBBITH 4-Piece TCT Hole Saw Set
When you need a 1-1/2″ hole in a stainless panel, a twist drill won’t cut it. DKIBBITH’s TCT hole saws use tungsten carbide-tipped teeth brazed onto a reinforced steel body, giving each tooth the ability to shear through work-hardened stainless without annealing. The 3/8″ three-flat shank grips securely in standard drill chucks, and the 1″ depth of cut handles most conduit and pipe applications.
Users described the 3/4″ saw cutting through steel “like butter” with minimal burr formation, and the carbide faces remained sharp after 16 holes in 1/2″ mild steel. The detachable pilot drill bits allow the main saw body to be reused after a pilot snaps, though one user did report a pilot failure on the second hole. The replacement policy from the manufacturer was excellent.
The set includes sizes 3/4″, 1″, 1-1/4″, and 1-1/2″ — a narrow but practical range for electrical rough-ins and plumbing penetrations. The open slot on the saw body aids chip ejection, but users must run low speed with cutting oil to prevent the carbide tips from fracturing on high-impact entry.
What works
- Carbide-tipped teeth bite through hard metals without dulling
- Detachable pilot extends saw body life
- Reinforced body resists deformation under torque
What doesn’t
- Pilot drill bits can snap on hard entry
- Limited to four specific hole diameters
5. WildBossy M35 Cobalt 20-Piece Drill Bit Set
WildBossy’s 20-piece set hits the entry-level price point for M35 cobalt with a 135° split point and a titanium surface finish that provides some lubrication. The 3-flat shank design prevents spin-out in the chuck, a common problem with budget round-shank bits. A verified user drilled through thin stainless steel successfully, noting the straight sides held well in the chuck and the bit required only slow, steady feed pressure.
The size range covers 1/16″ to 1/2″ with duplicates on the most-used small diameters, which is thoughtful for a kit that will likely see duty on broken bolt extraction and thin-gauge fabrication. The plastic index case keeps everything organized, though the case itself is basic and may not survive heavy shop abuse.
Quality control is inconsistent at this price — one user reported half the set contained dull or unusable bits, and another snapped a bit on the first attempt. These are best viewed as a consumable starter kit for occasional stainless work rather than a lifetime set for daily production drilling.
What works
- Genuine M35 cobalt at a low entry cost
- 135° split point reduces walking on smooth surfaces
- 3-flat shank prevents chuck slip
What doesn’t
- Inconsistent sharpness across bits in same set
- Basic storage case with no foam insert
Hardware & Specs Guide
M35 vs M42 Cobalt Steel
M35 contains 5% cobalt and achieves a hardness around 65-67 HRC. M42 contains 8% cobalt and reaches 68-70 HRC, offering greater heat resistance for production drilling. For most workshop stainless work, M35 is sufficient. M42 becomes necessary when drilling through hardened stainless or at higher feed rates where tip temperature exceeds 1100°F. The tradeoff is M42 bits are more brittle and prone to chipping under aggressive hand-drilling pressure.
TiAlN Coating Performance Curve
Titanium Aluminum Nitride coating creates a surface layer that oxidizes at cutting temperature, forming a hard aluminum oxide film that reduces friction and heat transfer to the substrate. The coating effective hardness reaches 89 HRC, which is harder than the base steel. TiAlN outperforms standard TiN coatings above 800°F and is preferred for stainless drilling where tip temperatures regularly exceed 1000°F. Uncoated M35 bits require more frequent sharpening but are less expensive to replace.
Cutting Speeds for Stainless Steel
Stainless steel requires low spindle speeds to prevent work-hardening. For M35 cobalt bits under 1/4″, 800-1200 RPM is the sweet spot with steady feed pressure. For 1/2″ bits, drop to 400-600 RPM. Peck drilling (withdrawing the bit every 2-3 seconds) clears chips and allows coolant to reach the cutting edge. Never let the bit spin without cutting — the friction alone will harden the surface. Cutting oil is mandatory; WD40 or dry cutting will significantly reduce tool life.
Point Angle Selection Logic
The 135° split point is the standard for stainless because the larger angle spreads the cutting force over a shorter chisel edge, reducing the axial thrust required to penetrate. The split creates a secondary cutting edge at the center that acts as a self-centering mechanism. Standard 118° bits require higher thrust, which causes the bit to deflect on entry, leading to walking and elongated holes. For sheet metal under 1/16″, a 90-100° point may be used to prevent tear-out on the exit side.
FAQ
Can I use regular HSS drill bits on stainless steel?
Why does my drill bit keep walking on the stainless steel surface?
How fast should I run my drill when using cobalt bits on stainless?
What is the best lubricant for drilling stainless steel?
Why did my cobalt bit snap while drilling stainless?
Final Thoughts: The Verdict
For most users, the drill bits for stainless steel winner is the toolant Cobalt Drill Bit Set Pro because its TiAlN coating and 135° split point deliver consistent performance across thin sheet and 1/4″ plate without annealing. If you need metric sizing for precision work, grab the MACXCOIP Metric 25pc M35. And for large-diameter holes in panels and conduit, nothing beats the DKIBBITH TCT Hole Saw.