Drilling into stainless steel is a test of patience and tool quality. The material’s hardness and work-hardening nature will destroy a standard high-speed steel bit in seconds, turning a five-minute job into a frustrating hour of burned fingertips and walking drill points. The right bit, however, cuts cleanly, stays sharp, and makes the process almost boring.
I’m Mohammad Maruf — the founder and writer behind WellFizz. I’ve spent hundreds of hours analyzing metallurgy specs, customer performance data, and real-world failure patterns to find the bits that actually survive contact with stainless steel.
This guide breaks down the top options for the best bit for drilling stainless steel, focusing on cobalt content, point geometry, and the specific coating technologies that separate a one-hole wonder from a dependable tool.
How To Choose The Best Bit For Drilling Stainless Steel
Choosing a drill bit for stainless steel is not about brand loyalty or price. It is about matching three specific variables to your material thickness and hardness. Ignore any one of them and you will be buying replacements within a week.
Cobalt Content and Steel Grade
M35 cobalt high-speed steel contains 5% cobalt, which improves hot hardness and wear resistance. This is the entry-level requirement for stainless steel. M42 cobalt steel (8% cobalt) offers even higher red hardness but costs more and is more brittle. For home workshops and most fabricators, M35 provides the best balance of durability and cost-per-hole.
Point Geometry and Split Points
A 135° split point is non-negotiable for stainless steel. The self-centering tip eliminates walking and reduces the need for a center punch on most surfaces. Standard 118° points are designed for softer materials and will skate across hardened steel, creating dangerous wandering and uneven holes.
Coatings and Surface Treatments
Titanium Aluminum Nitride (TiAlN) coatings handle higher temperatures than black oxide and are ideal for stainless steel at lower cutting speeds. Black oxide retains oil and reduces friction on softer metals but degrades quickly on harder alloys. Uncoated cobalt bits are acceptable but require constant lubrication to avoid work-hardening the steel.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| STROTON 17-Piece | Premium Cobalt | Demanding stainless steel jobs | 68 HRC, 1/16″ to 1/2″ | Amazon |
| WildBossy M35 20-Piece | Mid-Range Set | Thin stainless steel and general metal | Ti surface, 3-flat shank | Amazon |
| ss shovan Unibit Set | Step Drill | Sheet metal and thin plate | TiAlN coated, hex shank | Amazon |
| ZNXIMER 16-Piece | Value Set | Mixed materials, budget-conscious | 5% cobalt, 1/16″ to 3/8″ | Amazon |
| DelitonGude 13-Piece | Entry Level | Light duty and DIY | Black oxide, 135° tip | Amazon |
In‑Depth Reviews
1. STROTON Cobalt Drill Bit Set (17-Piece)
The STROTON 17-piece set is built around M35 cobalt steel with a reported 68 HRC hardness rating, placing it near the top of the consumer-grade market. Each cutting edge is ground three times, which produces a sharpness that cuts clean long stringy chips rather than grinding dust. This is exactly the behavior you want when drilling stainless — it means the bit is actually shearing the metal rather than work-hardening it.
The set spans from 1/16-inch up to 1/2-inch, with duplicate 1/16, 3/32, 1/8, and 1/4-inch bits for the sizes most likely to wear or break. Users report drilling eight half-inch holes through quarter-inch steel plate with no noticeable dulling. The heavy-duty plastic storage case has tight clamps that hold each bit securely, a small detail that matters when you are reaching for a bit mid-project.
The only notable weakness is brittleness in bits smaller than 3/16-inch — several users reported breakage on thin metal studs over six months of use. This is a common trade-off with high-hardness cobalt steel: extreme wear resistance comes with reduced toughness at small diameters. For most stainless steel work above 1/8-inch, this set is the strongest option in this lineup.
Why it’s great
- Triple-ground cutting edges deliver clean shearing action on stainless.
- Covers a wide range from 1/16″ to 1/2″ with duplicates on common sizes.
- Hard plastic case keeps bits organized and protected.
Good to know
- Smaller bits (under 3/16″) are brittle and prone to snapping under side load.
- Premium pricing relative to other M35 sets of similar size.
2. WildBossy M35 Cobalt Drill Bit Set (20-Piece)
The WildBossy 20-piece set uses M35 cobalt steel with a titanium surface treatment and a 135° split point. The 3-flat shank design is a smart inclusion — it prevents the bit from spinning in the chuck under high torque, a common annoyance when drilling through tough stainless workpieces. The set covers 1/16-inch up to 1/2-inch, giving you the most size options of any set in this review.
Users report that these bits cut through thin stainless steel with surprising ease when paired with cutting oil at slow drill speeds. The two flat sides on the shank are a practical upgrade over the typical fully round shanks found on cheaper sets. The bits are jobber length, which means they are long enough for most metalworking tasks but not so long that they deflect under load.
Quality control is inconsistent — one user reported that half the set arrived with bits that wouldn’t cut, and others snapped on the first use. Users who got a good set, however, report drilling out hardened taps and studs from turbo housings, suggesting the metallurgy is correct when the grinding is done right. This makes it a high-variance option worth considering if you are willing to inspect and test each bit before relying on it.
Why it’s great
- 20-piece set offers the widest size range in this group.
- 3-flat shank prevents slipping in drill chucks under load.
- Users report excellent performance on thin stainless with cutting oil.
Good to know
- Inconsistent quality — some bits arrive dull or snap immediately.
- Long-term durability data is limited due to mixed user experiences.
3. ss shovan Unibit Step Drill Bit Set (3-Piece)
This three-piece step drill bit set from ss shovan uses M35 cobalt steel with a Titanium Aluminum Nitride coating, a heat-resistant layer that performs well at the lower RPMs needed for stainless steel. Each bit covers multiple hole sizes — the largest goes from 5/16-inch up to 7/8-inch — which means one bit can replace an entire set of twist drills for sheet metal work. The hex shank eliminates chuck slipping entirely, a genuine advantage when drilling thin stainless that tends to grab and bind.
HVAC professionals report using these bits on stainless steel sheet metal with cutting oil and getting clean, burr-free holes without the chatter typical of twist drills on thin material. The step geometry also deburrs the hole as you drill, saving an extra pass. The included storage box keeps the three bits organized and protected.
The primary limitation is material thickness — the manufacturer recommends these bits for stainless steel under 1mm thick. Users who tried them on thicker material report that the top step loses its edge after about 20 uses. For thin gauge stainless (enclosures, panels, kitchen equipment), this set is a fast, precise solution. For structural thickness, stick to twist drills.
Why it’s great
- TiAlN coating handles the heat generated when drilling stainless.
- One bit replaces multiple twist drills for sheet metal work.
- Hex shank eliminates chuck slippage under torque.
Good to know
- Limited to stainless steel thinner than 1mm for best results.
- Top step may dull faster than lower steps with repeated use.
4. ZNXIMER Cobalt Drill Bit Set (16-Piece)
The ZNXIMER 16-piece set is the most affordable fully cobalt-based option in this lineup, offering sizes from 1/16-inch up to 3/8-inch in a molded index storage case. It uses M35 high-speed steel with 5% cobalt content and a 135° split point, hitting the three critical specs for stainless steel drilling at a price point that undercuts most competitors. The set includes duplicates of the most common small sizes, which helps when you inevitably snap a 1/16-inch bit on a tough spot.
One user reported using two bits from this set to drill 24 holes through a steel trailer frame after a local brand’s bit failed after just eight. The bits feature a flat spot on the shank that provides better grip in the chuck, reducing the frustration of bits spinning mid-hole. For mixed-material work (wood, aluminum, steel, stainless), this set handles the range without requiring a separate purchase.
The caveat is that spark testing suggests the actual cobalt content may be lower than advertised — the grinding sparks fell between standard HSS and true high-cobalt patterns, and the blue coloring may be a surface treatment rather than an indicator of internal cobalt percentage. For light-to-moderate stainless work with proper lubrication, the performance is solid for the price. For heavy production runs, the composition inconsistency becomes a risk.
Why it’s great
- Most affordable fully cobalt-based set in this comparison.
- Duplicate small-size bits extend working life on common diameters.
- Flat-spot shank improves chuck grip under torque.
Good to know
- Spark testing suggests cobalt content may be lower than claimed.
- Best suited for light-to-moderate stainless duty, not production work.
5. DelitonGude Cobalt Twist Drill Bit Set (13-Piece)
The DelitonGude 13-piece set is the most budget-friendly entry in this list, offering 13 imperial sizes from 1/16-inch to 1/4-inch in M35 cobalt steel with a black oxide finish. The 135° tip and split-point design help with self-centering, and the spiral groove geometry is optimized for chip removal. This is a set designed for the DIYer who needs to drill stainless occasionally, not a pro working through sheet after sheet.
Users report drilling multiple holes in bronze and metal studs with cutting oil at slow speed, noting that these bits outperformed a premium Milwaukee titanium set in direct comparison. Another user successfully drilled multiple holes in stainless steel with cutting oil and found the bits held up well. The black oxide finish helps retain lubricant and reduces friction during the cut, but it does not provide the same high-temperature protection as TiAlN coatings.
The major limitation is that the 13/64-inch bit struggled with hard T-posts, managing only 5 holes before dulling, while smaller bits in the same set failed after 1–4 holes on the same material. The seller offered full refunds for those who had issues, and the customer service response was excellent. For occasional stainless work on thinner stock, this set is a solid value. For heavy or repeated hard-steel drilling, the ZNXIMER or STROTON sets are better investments.
Why it’s great
- Lowest entry price for a full M35 cobalt set with 135° split point.
- Black oxide finish helps retain cutting oil during drilling.
- Seller responsive to quality issues with full refund offers.
Good to know
- Limited to 1/4″ max — insufficient for larger diameter holes.
- Performance drops significantly on harder materials above 80 Rb.
FAQ
Can I use standard HSS bits on stainless steel?
What RPM should I use when drilling stainless steel?
Are step drill bits effective on stainless steel?
Why does my drill bit keep breaking on stainless steel?
Final Thoughts: The Verdict
For most users, the best bit for drilling stainless steel winner is the STROTON 17-Piece Cobalt Set because its triple-ground edges and 68 HRC hardness deliver clean cuts through stainless without premature dulling. If you want a wide size range with a 3-flat shank for better chuck grip, grab the WildBossy M35 20-Piece Set. And for thin sheet metal work where speed and burr-free holes matter most, nothing beats the ss shovan Unibit Step Drill Bit Set.
Mo Maruf
I created WellFizz to bridge the gap between vague wellness advice and actionable solutions. My mission is simple: to decode the research and give you practical tools you can actually use.
Beyond the data, I am a passionate traveler. I believe that stepping away from the screen to explore new environments is essential for mental clarity and physical vitality.