Stainless steel has a reputation for punishing ordinary drill bits, and for good reason. The same work-hardening behavior that makes it corrosion-resistant also turns standard high-speed steel bits into dull, smoking paperweights. The right drill bit type makes the difference between clean, round holes and a pile of frustration. Cobalt bits dominate the category for a reason: their heat tolerance and hardness outlast conventional HSS when the work gets serious.
This roundup breaks down nine solid options for stainless steel work, from small job packs to a 115-piece shop set. Each pick is matched to a real use case, from weekend bracket installs to high-volume shop production. The goal: help you spend once, on the set that fits how you actually work.
A Snapshot Of The Selections
GOJXDNE 6PCS M35 Cobalt Drill Bit Set
GOJXDNE 6PCS M35 Cobalt Drill Bit Set (Variant 2)
GOJXDNE 6PCS M35 Cobalt Drill Bit Set (Variant 3)
Chicago-Latrobe 550 115-Piece Cobalt Jobber Drill Bit Set
IRWIN Jobber Drill Bit 1/8-Inch Cobalt (63108)
BOSCH CO21 21-Piece Cobalt Drill Bit Set
IRWIN 29-Piece M35 Cobalt Drill Bit Set (3018002)
Drill America KFD30P12 #30 KFD Split Point Drill Bit (12-Pack)
Topline USA M42 Cobalt #11 Drill Bits 4-Pk
More Details On Our Top Picks
A small-shop-friendly cobalt set that pairs well with the kind of weekend stainless work most DIYers actually take on, from mounting brackets to light fabrication repairs. M35 refers to a high-speed steel alloy with 5% cobalt mixed in, which raises heat tolerance and slows wear compared to standard HSS bits. The 135-degree split point is the bit geometry that lets the bit self-center and bite without skating across the workpiece, a real time-saver on curved or polished stainless.
For homeowners, the six-piece size range is enough to cover common pilot and clearance holes without paying for a giant set you’ll never fully use. You may find the index case less durable than pro-grade storage, so plan on a separate bin if you tend to toss bits in a drawer.
Standout Benefits
- M35 cobalt HSS handles repeated stainless drilling without losing edge quickly.
- 135-degree split point reduces walking on slick or curved stock.
- Ground spiral flutes clear chips efficiently and keep heat lower.
- Six-piece sizing covers the pilot and clearance holes most home projects need.
Things To Consider
- Storage case tends to feel thin under shop conditions.
- Heat resistance is solid, not elite, so cutting fluid still helps on thick stock.
Feature Snapshot
Who It Suits Best
Home fabricators and weekend DIYers drilling stainless steel, mild steel, or cast iron on a casual schedule.
Look Elsewhere When
You need maximum size coverage; the Chicago-Latrobe 550 115-Piece Cobalt Jobber Drill Bit Set gives a full range for shop-scale work.
A second six-piece M35 configuration aimed at beginners who want a clean entry into stainless drilling without committing to a full-size index. The cobalt build and split-point geometry mirror the previous pick, so the drilling behavior on stainless, mild steel, and cast iron stays consistent. What changes is the size selection, and that detail is what makes this a sensible starter for narrower project scopes.
If you’re mounting hardware, drilling pilot holes for tap work, or building small assemblies, the included sizes are likely to cover you. One thing worth considering: a six-piece set is great until you hit a hole size you didn’t anticipate, at which point the IRWIN 29-Piece M35 Cobalt Drill Bit Set starts looking more practical.
Bright Spots
- M35 cobalt body handles heat better than standard HSS bits.
- 135-degree split point eases self-starting on slick surfaces.
- Right-sized for first-time stainless drill bit shoppers.
Worth Noting
- Only six sizes; you’ll outgrow it on bigger projects.
- Same heat limits as the sibling set, so thick stainless still wants cutting fluid.
- Commonly reported: finish can dull faster under heavy production runs.
Made For
Beginners stepping into stainless steel drilling for the first time, especially on pilot holes and light bracket work.
A Better Fit Elsewhere
You need wider size coverage out of the box; the IRWIN 29-Piece M35 Cobalt Drill Bit Set spans 1/16 to 1/2 inch in 1/64 steps.
A third configuration of the same M35 platform, sized for the small, occasional job where you just need a few reliable cobalt bits on hand. The 135-degree split point, ground spiral flutes, and 5% cobalt construction match the family, so the experience feels familiar if you’ve handled the other two sets. The trick with cobalt is that even modest amounts of it meaningfully extend tool life when paired with reasonable feed pressure and lubricant.
For anyone drilling a handful of holes a month, this is a sensible budget-conscious purchase. Just be realistic: no six-bit set will cover a full shop’s worth of hole sizes, and you’ll likely add individual bits as needs come up.
Everyday Advantages
- Same M35 cobalt body as the family, dependable on stainless.
- Split point keeps starts clean on polished surfaces.
- Cost-effective entry point for casual users.
Trade Offs
- Limited size selection restricts larger or unusual hole diameters.
- Storage case is basic; bits can mix during transport.
Right Fit For
DIYers who drill stainless a few times a year and want a small, affordable cobalt set as a backup.
Consider Something Else When
You want one set to cover a wide range; the Chicago-Latrobe 550 115-Piece Cobalt Jobber Drill Bit Set is the broader alternative.
A serious shop-grade index for fabricators and machinists who routinely touch stainless, cast iron, and high-tensile alloys. Chicago-Latrobe’s 550 series uses a gold-oxide finish (a thin surface treatment that reduces friction and helps chips evacuate) and a thicker web design, where the web is the central core of the bit between the flutes, adding torsional strength when you push the bit hard into tough material.
The size range covers fractional inches from 1/16 through 1/2 by 64ths, wire gauge sizes 1 through 60, and letter sizes A through Z. For a small shop, this is genuinely the only drill bit set you may need to buy for years. Owners commonly report that the included metal index case is well-organized but heavy, so wall-mounting beats bench-stacking.
Well-Handled Touches
- 115 sizes cover fractional, letter, and wire gauge in one index.
- Thicker web design resists breakage under heavy feed pressure.
- Gold-oxide finish supports smoother chip evacuation.
- 118-degree point geometry is a flexible all-around choice.
Some Limits To Know
- Index case adds weight and bulk to a tool crib.
- Higher upfront investment than small cobalt sets.
- Not every project needs 115 sizes; overbuy if your work is light.
Key Attributes
Best Suited To
Small fabrication shops, machinists, and serious hobbyists who routinely work across multiple metals and hole sizes.
Skip It When
You only need a handful of bits; the BOSCH CO21 21-Piece Cobalt Drill Bit Set is a leaner contractor-style alternative.
A single-size 1/8-inch cobalt jobber bit (jobber length is the standard mid-range length found on most general-purpose drill bits) that fills a real gap: pilot holes, hinge hardware, and small fastener clearance in stainless. IRWIN’s M35 cobalt alloy steel is built to shed heat, which is what kills bits fast when friction ramps up in tougher alloys. The 135-degree split point keeps the bit from skating on polished or curved stock.
This is a replacement-and-refill pick rather than a starter set. Keep two or three on hand; a dulled bit mid-project is the most common reason pilot holes go wrong. If your work spans more sizes, jump to a set instead of stocking singles.
Positive Points
- 1/8-inch size covers the most common pilot and clearance duties.
- 135-degree split point helps clean starts.
- M35 cobalt alloy tolerates heat from aggressive feed.
Potential Drawbacks
- Single size only; you handle storage and replacement for every other diameter.
- Small pack may run out fast on repetitive jobs.
Who Will Love This
Woodworkers, metalworkers, and technicians who burn through 1/8-inch bits and want a reliable cobalt refill.
Reach For A Different Pick When
You want multiple sizes in one case; the IRWIN 29-Piece M35 Cobalt Drill Bit Set delivers 1/16 to 1/2 inch coverage.
A contractor-grade 21-piece set engineered for the field, where chuck grip matters as much as the cut itself. The three-flat shank (a shank with three flattened sides instead of a round profile) locks into keyed and keyless chucks without slipping, which is exactly what you want on a magnetic drill press or a handheld driver when the bit catches. Cobalt construction targets stainless, cast iron, titanium, light-gauge metal, and aluminum.
The included case keeps the index organized on a service truck, and the size range is well chosen for fab and HVAC work. In tight spaces where the chuck needs extra bite, this design earns its keep. If your work rarely leaves the bench, the shank feature is nice but not critical.
Key Advantages
- Three-flat shank prevents slippage in heavy-use chucks.
- 21 sizes span most common fab and HVAC hole sizes.
- Cobalt body handles stainless and other tough alloys cleanly.
- Storage case is well-suited to truck or tool crib organization.
Less Ideal Details
- Heavier than lightweight homeowner sets.
- Three-flat shank is overkill for occasional bench drilling.
Feature Overview
Built With In Mind
Contractors, HVAC techs, and mobile welders who need chuck security and consistent stainless performance on the job.
Swap It Out When
You want broader size coverage for shop work; the Chicago-Latrobe 550 115-Piece Cobalt Jobber Drill Bit Set is the broader shop option.
A 29-piece M35 cobalt set that hits the sweet spot for home shops, garage fabricators, and serious hobbyists. The size range runs 1/16 to 1/2 inch in 1/64-inch increments, which means there is almost never a tap or fastener size you cannot match. The heavy-duty web design adds strength where thinner bits would snap under heavy feed.
The 135-degree split point and M35 cobalt construction match the brand’s other offerings, but the larger size count makes this the right primary set for many users. For a single all-purpose purchase, the IRWIN 29-piece is hard to argue with. Owners commonly report that the index case is functional but the plastic dividers can crack with rough handling, so a labeled drawer is a smart complement.
Useful Touches
- 29 sizes cover pilot, clearance, and tap-drilling needs.
- Stepped 1/64-inch increments avoid gaps in the size range.
- M35 cobalt body tolerates heat from stainless drilling.
- Heavy-duty web adds strength under aggressive feed.
Worth Bearing In Mind
- Plastic index dividers can crack under heavy shop use.
- No three-flat shank, so chuck slip can occur in keyless chucks under load.
Who Should Grab It
Garage fabricators and hobby machinists who need one M35 set to cover most home-shop stainless work.
Another Choice May Suit
You want a more secure chuck grip in the field; the BOSCH CO21 21-Piece Cobalt Drill Bit Set uses a three-flat shank for that reason.
A twelve-pack of #30 high-speed steel bits aimed at repetitive hole work, where running out of a single size mid-job is the real productivity killer. The KFD series uses a black-and-gold surface treatment, a coating that boosts surface hardness and reduces friction at the cutting edge, which suits stainless and other hard metals. The 135-degree split point gives clean starts without a center punch.
#30 is a wire-gauge size around 0.1285 inches, common for clearance around small fasteners, sheet-metal rivets, and pilot holes for tapping. HSS rather than cobalt is fine here, since the surface treatment carries heat resistance a step beyond standard high-speed steel. For pure single-size volume, this 12-pack beats buying individual replacements.
Useful Strengths
- Twelve bits cover long runs without reordering.
- Black-and-gold surface treatment supports stainless drilling.
- 135-degree split point reduces walking on slick stock.
Practical Considerations
- Single size only, so plan around your most common hole diameter.
- HSS body, not cobalt, so heat tolerance is lower under sustained load.
Whose Shelf It Belongs On
Production-oriented shops and serious DIYers who repeatedly need #30 clearance holes in stainless or sheet metal.
Where A Sibling Pick Shines
You need higher heat tolerance; the Topline USA M42 Cobalt #11 Drill Bits 4-Pk steps up the cobalt content for tougher alloys.
A small, focused four-pack aimed at the most demanding stainless and titanium drilling. M42 is a premium high-speed steel that carries roughly 8% cobalt, which is meaningfully higher than the 5% in M35, and the bits are ground from a solid blank rather than rolled. That grinding process produces a sharper, more precise cutting edge with cleaner geometry, which translates to better performance in high-tensile work.
#11 wire-gauge size fits a narrow band of pilot and clearance work, so this is a specialist pick. The higher cobalt content shows up most when you push the bit into tough alloys at moderate feeds, and that’s exactly the scenario it’s designed for. For most home users, M35 is plenty; the upgrade makes sense once your work includes titanium, hardened stainless, or production runs.
What Helps Most
- M42 with 8% cobalt offers strong heat tolerance for tough alloys.
- Ground-from-solid construction delivers precise cutting geometry.
- Four-pack covers wear from production-grade use.
Honest Caveats
- Premium material comes at a higher per-bit cost.
- Single size limits versatility outside specific hole diameters.
Perfect Match For
Machinists and fabricators working with stainless steel, titanium, and other high-tensile materials who need premium cobalt endurance.
Not Your Match When
You want one set across many sizes; the IRWIN 29-Piece M35 Cobalt Drill Bit Set is the broader, more versatile alternative.
What To Weigh Before Choosing Drill Bits for Stainless Steel
Material and Cobalt Content
Cobalt drill bits get their edge from cobalt blended into the high-speed steel, which raises the alloy’s red hardness, meaning it stays hard at the elevated temperatures generated when cutting metal. M35 contains about 5% cobalt and covers most home and prosumer use. M42 jumps to roughly 8% cobalt and is the choice when you regularly push into stainless, titanium, or other tough alloys. Cobalt bits cost more upfront but hold an edge longer, so the cost-per-hole typically ends up lower for anyone drilling stainless regularly.
Point Geometry and Starting Behavior
The point angle shapes how the bit enters the workpiece. A 135-degree split point is self-centering, which means the bit stays where you put it without wandering across the surface, and it cuts with less thrust pressure, which is the forward force the drill has to apply. That geometry pays off on slick stainless, curved stock, and any time you want to skip center-punching. A 118-degree point is more common and slightly more aggressive on softer metals, but it walks more on hard surfaces.
Size Coverage and Set Size
Match the set to your actual workload. A six-bit set is great for a narrow project scope but frustrating when you need an oddball size mid-build. A 29-piece index in 1/64-inch steps covers almost every common fastener and tap. A 115-piece shop index adds letter and wire sizes for machinists. Single-size packs make sense when you burn through one diameter repeatedly and want backup stock.
Shank Style and Chuck Grip
Most home drills use a round shank that works fine for general work. Three-flat shanks, found on bits like the BOSCH CO21, have three flattened sides that lock into the chuck jaws, preventing slippage under heavy load. For handheld drivers and magnetic drill presses, where the bit can catch and twist, a three-flat shank is a real safety and accuracy upgrade. For routine bench drilling, round shanks are perfectly adequate.
Key Considerations Across These Picks
Where Shoppers Go Wrong
The most common mistake is grabbing a standard HSS set because it costs less, then wondering why the bits burn up after a few stainless holes. Standard HSS lacks the heat tolerance to survive sustained drilling in work-hardening alloys. Cutting fluid also gets skipped: even a good cobalt bit runs cooler and lasts longer with a steady drip or brush of lubricant on thick stainless.
Where The Extra Money Goes
Paying more for M35 or M42 cobalt buys longer edge life under heat, sharper starting geometry, and tighter size tolerances. The upgrade pays off the moment your work includes stainless thicker than 1/8 inch, repeated production runs, or harder alloys like titanium. For occasional thin-sheet stainless, an M35 set handles the job without the M42 premium.
