Drilling stainless steel, cast iron, and mixed shop materials asks more from a bit than wood or plastic ever will. That’s why this roundup focuses on 8mm choices, plus a few close-size kits that fit the same heavy-duty job profile. You get a clear mix of single-bit focus, small packs, and broader sets, so your pick matches the work on your bench instead of forcing a compromise.
Quick Look At The Shortlist
Narwhal 1/8 Inch M35 Cobalt Drill Bits 13 Pack
STROTON Metric M42 8% Cobalt Drill Bits 8mm x 3pcs
Neiko 10052A Spot Weld Drill Bits 8mm
RMTCEG 200MM x 8MM Extra Long Twist Drill Bits Set
uxcell Straight Shank Twist Drill Bits 8mm
M MIMHOOY 8mm M35 Cobalt Drill Bits 2 Pcs
HYMNORQ 8-Piece Metric HSS Drill Bit Set 3mm-10mm
Sinyeenglon Cobalt Drill Bits Set M35 99Pcs
More Details On Our Top Picks
A 13-pack of 1/8-inch bits makes sense for repeated metal drilling, especially in a garage where small sizes vanish fast. The 135-degree split point should help the bit start with less wandering on hard surfaces, and the 2.55-inch length keeps it in a familiar jobber-bit range.
M35 cobalt is the real draw here, since that alloy is usually chosen for tougher work like stainless steel and cast iron. The trade-off is simple, this is a focused set, so you get one size in quantity rather than a wide spread of diameters.
Strong Points
- Thirteen pieces give you a useful backup supply for a size that disappears often.
- The 135-degree split point helps the bit bite sooner on slick metal.
- M35 cobalt suits harder materials better than plain HSS in everyday shop use.
- The compact 2.55-inch length keeps handling familiar in a handheld drill.
Points To Note
- You only get one diameter, so this works best alongside a broader set.
- Small cobalt bits still benefit from steady pressure and sensible speed selection.
- Storage matters here, since loose packs can get separated in busy tool drawers.
Feature Snapshot
Who It Suits Best
Metalworkers and DIY repair folks who keep using the same small diameter will get the most from this pack.
Where A Sibling Pick Shines
STROTON Metric M42 8% Cobalt Drill Bits 8mm x 3pcs suits you better when your work centers on a single 8mm hole size in stainless steel.
M42 cobalt is the stronger alloy call in this group, and that matters most for shoppers drilling hard stainless or other stubborn metals in a home shop. Three 8mm bits also make sense for repeat work, especially on fixtures, brackets, and repair jobs where the same hole size keeps coming up.
Compared with the Narwhal pack, this feels more like a purpose-built steel bit set than a bulk backup bundle. The honest read is that you pay for heavier-duty material, so it makes the most sense when 8mm is the size you reach for often.
Highlights
- M42 material suits demanding metal drilling.
- The 8mm size lines up well with common hardware and fabrication tasks.
- Three-piece count gives you backup without turning into a large kit.
- It feels like a focused choice for stainless work rather than a general drawer filler.
Softer Spots
- The pack is narrow, so you need other sizes for broader projects.
- Harder alloy bits usually reward careful feed pressure and a steady hand.
- Tool storage stays important, since a small pack is easy to misplace between jobs.
Core Details
Made For
Shop users who keep drilling 8mm holes in stainless steel or similar hard stock will get the most from this set.
A Better Fit Elsewhere
Sinyeenglon Cobalt Drill Bits Set M35 99Pcs is the stronger choice for you when a full range of diameters matters more than a single-size focus.
This Neiko set speaks to a narrower job than the first two picks, and that focus helps in body-shop style work where spot welds need attention. The titanium coating should add surface hardness and smoother wear behavior in normal use, while the cobalt steel base supports metal drilling more confidently than plain economy steel.
Because it’s sold as a spot weld bit, it makes more sense for repair work than general drilling around the house. You may find it a little specialized for casual users, but that same specialization is useful when the job is specific and the material is stubborn.
What We Like
- It’s tailored to spot weld removal, not vague all-purpose use.
- The cobalt steel base suits metal-focused work.
- Titanium coating adds another layer of wear resistance on the surface.
- The 8mm size gives you a clear, familiar cutting width.
Room For Improvement
- The specialized design may feel narrow for general workshop duty.
- Coated bits still need clean storage so the cutting edge stays protected.
- It’s less of a broad kit and more of a task-specific tool.
Details At A Glance
Whose Shelf It Belongs On
Body-shop hobbyists and repair-minded DIYers who deal with spot welds more than general drilling will get the most value from it.
Look Elsewhere When
Narwhal 1/8 Inch M35 Cobalt Drill Bits 13 Pack fits you better when your work is broader and you want several small metal bits in one bundle.
Length is the whole story here, and 200mm gives you reach that standard jobber bits simply can’t match. That makes this pair useful for deeper holes, awkward fixture layouts, and situations where the drill body sits too close to the work surface.
The straight shank keeps compatibility broad, which matters for shop setups that rotate between handheld drills and drill presses. Compared with the Neiko pick, this one is less specialized and more about reach, though the extra length can feel less rigid during hand drilling.
Best Bits
- The 200mm length helps you work into deeper or harder-to-reach spots.
- Two bits are enough for a backup pair without bulk.
- Straight shank design keeps tool compatibility simple.
- It suits mixed materials listed by the maker, so the set covers more than just metal.
Small Caveats
- Long bits can feel less rigid than shorter ones during use.
- Storage takes a little care, since long pieces can get bent or cluttered in drawers.
- The pair format is useful, but it does not cover multiple diameters.
Feature Card
The Right Fit
DIYers who need extra reach for cabinetry, fixture work, or deeper access holes will appreciate this pair most.
Skip It When
STROTON Metric M42 8% Cobalt Drill Bits 8mm x 3pcs suits you better when compact, hard-metal drilling matters more than reach.
The coating story matters here, because gold titanium plus black nitride usually points to a more wear-conscious bit surface. In normal shop use, that can be a nice middle ground for mixed materials like stainless, alloy metal, plastic, and wood, especially when your tool bin needs one bit to cover many chores.
Compared with the pure cobalt options earlier in the list, this one leans more toward versatility than hard-metal specialization. The trade-off shows up in serious stainless work, where a cobalt-heavy bit can be the better fit, but this uxcell option stays attractive for general-purpose drilling.
Upsides
- The dual coating adds a more finished, durable feel to the surface.
- It covers a wide material mix, which suits grab-and-go use.
- The 8mm size keeps it relevant for medium-sized holes.
- Straight shank design keeps the setup straightforward in standard chucks.
Worth Noting
- It’s a general-purpose choice, so heavy stainless work may favor a tougher cobalt bit.
- Coated finishes benefit from careful cleaning after dusty jobs.
- One-size coverage keeps the kit simple, but not especially broad.
Technical Sheet
Perfect Match For
Home repair users who move between metal, plastic, and wood work will get the most from this one-bit option.
Another Choice May Suit
Sinyeenglon Cobalt Drill Bits Set M35 99Pcs is the better route for you when broad size coverage matters more than a single 8mm drill bit.
Two 8mm M35 bits keep this set simple, which is useful for quick repair work or for a toolbox that doesn’t need extra clutter. The jobber-bit shape gives you a familiar all-purpose profile, and the cobalt alloy suggests a better fit for steel than basic high-speed steel alone.
That simplicity is the point, though it also means this is not the set for someone building a full drill cabinet. For a weekend project bench or a small metalworking kit, it feels practical and easy to understand.
Positives
- M35 cobalt is well suited to steel-focused tasks.
- The two-piece count keeps storage and sorting simple.
- 8mm is a handy size for many metal repair jobs.
- Jobber-bit proportions make the set easy to recognize and use.
Areas To Watch
- You only get one diameter, so the set is narrow by design.
- Like most cobalt bits, it rewards a steady hand and controlled feed pressure.
- A small pair is easy to misplace, so a labeled case helps.
Quick Facts
Right Fit For
DIYers who need a small, straightforward 8mm metal bit pair for repair work will appreciate this set.
Swap It Out When
Narwhal 1/8 Inch M35 Cobalt Drill Bits 13 Pack suits you better when you want more pieces in a smaller diameter rather than just two 8mm bits.
This set spreads from 3mm to 10mm, so it covers a nice working range for lighter shop tasks and general home drilling. The roll-forged construction is worth noting because roll forging shapes metal under pressure, which can help bits feel more consistent than basic cut blanks in everyday use.
Compared with the heavier cobalt-focused picks, this one belongs in a lighter-duty corner of the toolbox. That makes it a sound choice for wood, plastic, iron, PVC, and aluminum work, though it’s not the first pick for hardened stainless.
Bright Spots
- The 3mm to 10mm spread gives you several common sizes in one case.
- Roll-forged construction points to a sturdier build style.
- The indexed case helps keep sizes sorted instead of loose in a drawer.
- It covers lighter materials well, which is useful for household and craft work.
Minor Gripes
- This is not the best match for very hard steel or stainless jobs.
- The set focuses on lighter materials, so metal-shop duty has limits.
- Keeping the case closed matters, since mixed sizes can be annoying to sort by hand.
Spec Overview
Built With In Mind
Home improvers and hobby makers who work with wood, plastic, aluminum, or PVC will get the most from this set.
Consider Something Else When
STROTON Metric M42 8% Cobalt Drill Bits 8mm x 3pcs fits better for you when stainless steel is the main task and 8mm is the size you need most.
For someone building a real drill drawer, the big selling point here is range. Ninety-nine pieces from 1/16 inch to 3/8 inch cover a wide spread, so you’re less likely to stop mid-project because the size you need is missing.
This set also leans into the storage side of ownership with a plastic index case, which makes the large count easier to live with. The trade-off is plain, a broad kit can be overkill for casual users, but it pays off fast in a busy shop where different hole sizes come up all the time.
Reasons To Buy
- The size spread is broad enough for many common metalwork tasks.
- Ninety-nine pieces reduce the chance of running short on a needed diameter.
- The index case helps keep a large set organized.
- It’s a practical match for workshops that handle mixed drilling jobs.
Honest Caveats
- Large sets take more storage space than a small pack.
- A set this broad can feel excessive for occasional home use.
- Keeping the index case tidy matters, or the advantage fades quickly.
Core Details
Who Should Grab It
Workshop users who want one large set to cover many drill sizes will get the most from this kit.
Where A Sibling Pick Shines
HYMNORQ 8-Piece Metric HSS Drill Bit Set 3mm-10mm is a cleaner fit for light-duty users who prefer a smaller case and fewer pieces.
How To Choose The Right Cobalt Drill Bits 8mm
Material Strength Comes First
Cobalt drill bits earn their place in the toolbox because the alloy holds up better in hard metal than plain high-speed steel in many real shop jobs. M35 and M42 are the two names you’ll see most here, and M42 usually signals a tougher alloy mix for harder stainless or repeated work. The trade-off is cost and, in some cases, less need for them on soft materials like wood or plastic.
You get the most value from cobalt when you drill stainless steel, cast iron, or alloy metal often enough to notice wear on cheaper bits. For occasional household holes, a standard HSS bit may still be enough, but that’s not the point of this category. These are work tools for harder stock.
Point Geometry Changes The Start
Split-point tips help the bit start without skating across metal, which matters on curved brackets and polished faces. A 135-degree tip often gives a steadier bite than a more blunt style, especially in handheld work. The downside is that a sharper start does not replace good clamping or even pressure.
That detail matters more than it sounds, because many drill frustrations start before the cut really begins. You feel the benefit most when you’re lining up a hole in a finished part and do not want the bit wandering off mark.
Length And Shank Shape Affect Fit
Jobber-length bits suit most everyday drilling because they balance reach and stiffness well. Extra-long bits solve reach problems, but they can flex more, especially in a hand drill. Straight shanks stay broadly compatible, which is useful in mixed tool shops.
You should match length to the job, not to the wish list. Deep access work needs more reach, while typical bracket, plate, and fixture drilling usually goes smoother with a standard-length option.
Kit Size Should Match Your Workflow
Single-size packs make sense when you keep returning to the same hole diameter, such as 8mm for fixtures or a 1/8-inch pilot size. Larger sets save time only when your work truly spans many sizes. A 99-piece kit can be a blessing in a busy garage, but it feels heavy if you only drill once in a while.
Storage matters too, because cobalt bits last longer when they’re returned to a case instead of tossed loose. That’s a small habit, yet it keeps the cutting edges cleaner and the sizes easier to find.
Things Worth Knowing First
Where Shoppers Go Wrong
A common mistake is choosing the alloy and ignoring the actual size you need. An 8mm bit helps only when 8mm is the hole you plan to drill, so a full set or a second size may suit the job better. Another slip is buying extra-long bits for normal work, where a standard length feels steadier.
Many people also overlook storage. A large set without an index case turns into a mess fast, and even a small two-pack benefits from a labeled box or tray.
What The Higher Tier Buys
More expensive cobalt bits usually spend the money on alloy quality, surface finish, and better tip shaping. Those details matter most when the work is frequent, the metal is hard, or the hole count is high. For lighter weekend use, the upgrade can feel unnecessary.
You notice the difference in smoother starts and less mid-cut frustration, not magic. That’s why the premium route makes sense for stainless steel, fabrication, and repeat repair work, while casual users may be fine with a simpler set.
Frequently Asked Questions
What makes cobalt bits useful for metal?
Cobalt content helps the bit cope with harder metal better than basic steel in many workshop situations. That makes it a practical choice for stainless steel, cast iron, and similar material.
Is 8mm a common drill size?
Yes, 8mm sits in a useful middle range for many repair and fabrication tasks. It often works well for brackets, fixtures, and medium-sized mounting holes.
Should you choose M35 or M42?
M42 usually points to a tougher alloy mix, so it often fits harder or more frequent metal drilling. M35 still covers serious metal work well and can be enough for many home shops.
Do longer bits help with every job?
Longer bits help when the work area is recessed or the drill body sits close to the surface. For normal drilling, standard-length bits usually feel steadier and easier to control.
How should you store cobalt drill bits?
A case or indexed tray keeps the cutting edges from knocking against each other. It also saves time when you need one size fast and don’t want to hunt through a drawer.
Closing Thoughts
Your best match depends on the kind of metal work you actually do, not on the biggest set or the toughest alloy name alone. For repeated 8mm drilling, STROTON and M MIMHOOY make a strong case, while Narwhal is handy for smaller repeated sizes and Sinyeenglon is the broad shop kit. If your work leans lighter, uxcell or HYMNORQ may be the calmer fit. Pick the bit that fits your material, your storage, and the way your bench really works.
