Best HSS Drill Bits for Stainless Steel: Five Cobalt Sets Compared
For drilling stainless steel, choose a cobalt-alloy high-speed steel set rather than relying on ordinary HSS bits. The five sets below are listed as M35 cobalt and include stainless steel in their stated applications. The 29-piece set suits general shop use, the 101- and 115-piece sets offer broader size coverage, the stepped-point set is a specialized option, and the 13-piece set is a compact choice for smaller holes.
| Set | Best For | Notable Detail |
|---|---|---|
| 29-piece M35 set | Everyday size coverage | 1/16 to 1/2 inch |
| 101-piece M35 set | Broad bit selection | 1/16 to 1/2 inch |
| Crosstar 21-piece set | Stepped-point drilling | TiAlN coating and three-flat shank |
| 115-piece M35 set | Fractional, letter, and number sizes | Metal index case |
| 13-piece M35 set | Smaller holes and compact storage | 1/16 to 1/4 inch |
29-Piece M35 Cobalt Drill Bit Set
Best for: DIY users and general-purpose shops that want fractional sizes from 1/16 to 1/2 inch. Its M35 cobalt HSS construction and listed applications include stainless steel, hardened metal, cast iron, wood, and plastic. The index storage case keeps the set organized. It is a practical middle ground between a small starter set and a much larger assortment, which is why it is selected as a versatile option.
Limitation: The listing does not specify individual bit sizes beyond the overall range or provide additional details such as coating or point angle.
101-Piece M35 Cobalt Drill Bit Set
Best for: Users who want a large selection of jobber-style twist bits for repeated metalworking tasks. The listing identifies M35 high-speed steel, hardened metal and stainless steel applications, a 1/16-to-1/2-inch range, and a plastic index storage case. Choose this set over a smaller kit if having more pieces and a broad fractional range is the priority.
Limitation: The provided product details do not break down how the 101 pieces are distributed among sizes, so check the listing if particular diameters are essential.
Crosstar 21-Piece Stepped-Point Cobalt Set
Best for: Buyers looking for the set’s stepped-point design rather than a conventional assortment of standard twist bits. Its listed details include M35 HSS, TiAlN coating, a 1/16-to-1/2-inch range, a three-flat shank, and an indexed case. It is listed for hardened steel, making it a specialized candidate for users who value these design features.
Limitation: The stepped-point format differs from ordinary drill-bit sets, so compare the intended hole sizes and bit design before choosing it for general drilling.
115-Piece M35 Cobalt Drill Bit Set
Best for: Users who need more than fractional sizes. This 115-piece set is listed with fractional sizes from 1/16 to 1/2 inch, letter sizes A–Z, and number sizes 1–60. Its M35 HSS bits are listed for stainless steel, hardened metal, cast iron, plastic, and wood. The metal index box and expanded size system make it the broadest selection here.
Limitation: A large assortment takes more storage space, and the supplied details do not identify the count for each individual size.
13-Piece M35 Cobalt Drill Bit Set
Best for: Buyers who mainly drill smaller holes and prefer a compact set. It covers 1/16 to 1/4 inch and includes 13 sizes. The listed features include M35 cobalt material, a 135-degree point, twist design, self-centering, and chip removal. Stainless steel is among its stated applications, along with cast iron, softer metals, plastic, and wood.
Limitation: The range stops at 1/4 inch, so choose a larger set if your projects require wider holes.
Buying Guide: Choosing HSS Bits For Stainless Steel
Does cobalt M35 matter?
Each selected product is described as M35 cobalt HSS. That material designation makes these sets more directly suited to stainless steel than a basic HSS set without a stated cobalt grade. Compare the listed material and intended use rather than assuming every bit labeled HSS is the same.
Which size range do you need?
For common fractional holes through 1/2 inch, compare the 29-piece and 101-piece options. The 13-piece kit is limited to 1/4 inch. The 115-piece set adds letter and number sizes, which can be useful when a project calls for a specific non-fractional drill size. Confirm the exact included sizes in the product listing.
What design details should you compare?
The Crosstar listing highlights stepped points, TiAlN coating, and a three-flat shank. The 13-piece set lists a 135-degree point and self-centering twist design. The other supplied descriptions emphasize M35 material, size range, and storage case. These are listed features, not a guarantee of performance in every setup.
How should you drill stainless steel?
Use a sharp bit and steady, controlled pressure. Avoid letting the bit spin without cutting, since friction can heat the workpiece and bit. Secure the metal, use an appropriate cutting lubricant, and follow the tool and bit manufacturer’s guidance for speed and operation. The supplied product details do not specify recommended drilling speeds.
Frequently Asked Questions
Are cobalt drill bits considered HSS?
Yes. These listings describe their cobalt bits as M35 high-speed steel, a cobalt-alloy HSS type.
Which set covers the most sizes?
The 115-piece set lists fractional, letter, and number sizes, making it the broadest size selection in this comparison.
Which set is best for holes up to 1/4 inch?
The 13-piece set is a compact option for smaller holes and includes sizes from 1/16 to 1/4 inch.
Is the stepped-point set the same as a standard twist-bit set?
No. Its listing specifically describes stepped-point bits. Choose it when that design suits your work; select a conventional assortment if standard twist bits are required.
Can these bits also drill materials besides stainless steel?
The product listings name other applications, including hardened metal, cast iron, wood, and plastic, though the stated materials differ by set.