M35 Four Spiral Flute Cobalt Step Drill Bit Set 1/8in-7/8in - Durable

In this review the M35 Four Spiral Flute Cobalt Step Drill Bit Set is evaluated for metalworkers and DIYers who need a compact set of step bits that tackle a wide range of hole sizes. The bottom line: this three-piece set stands out for its M35 cobalt HSS construction and industrial-grade TiAlN coating, which together provide real heat and wear resistance when drilling thin metal, stainless steel, aluminum and typical workshop materials. It is best for users who value cutting stability and step range rather than a large assortment of individual bits.

Key Features

• Four-flute design: The extra flutes increase stability and deliver smoother, faster cutting with less wobble when stepping up hole sizes.
• TiAlN coating: An industrial-grade coating improves oxidation resistance and thermal hardness to reduce wear during continuous drilling.
• M35 cobalt HSS: High red hardness and wear resistance make the bits suitable for stainless steel and other tougher sheet metals.
• Wide step range: Three bits cover 34 step sizes from 1/8in to 7/8in, letting you drill many common hole diameters without changing tools.
• 1/4in hex shank: The hex shank offers secure chuck engagement in handheld drills and quick bit changes in impact drivers and drivers with hex chucks.
• 135 cutting angle: The flatter face reduces self-wear and provides a larger contact area for cleaner, more efficient drilling.

Who It's For

These bits are aimed at hobbyists, electricians, and metalworkers who frequently drill holes in thin metal, aluminum, copper, plastic and wood and want a compact, multi-step solution. The set is especially handy for tasks such as enlarging knockouts in panels or making clean openings for grommets and conduit fittings.

Users who need single-diameter carbide or high-volume production tooling may want a different solution; the set is optimized for versatility across many diameters rather than high-speed production on thick plate or composite laminates.

Pros & Cons

Pros

• Excellent heat and wear resistance thanks to M35 cobalt and TiAlN coating, extending useful life under tougher conditions.
• Four-flute geometry improves stability and cutting speed compared with two-flute step bits.
• Broad step coverage with three bits replaces many single-size bits and reduces tool changes.

Cons

• Some users report variable durability; a minority experienced dulling after limited use, so cooling and cutting oil are recommended for continuous tasks.

Specifications

Material	M35 cobalt high speed steel
Coating	Industrial-grade TiAlN
Shank	1/4in hex shank
Step range	Three bits covering 1/8in-1/2in, 1/4in-3/4in, 3/16in-7/8in (34 total sizes)
Cutting angle	135 degrees
Flute design	Four spiral flutes for stability

Our Verdict

The M35 Four Spiral Flute Cobalt Step Drill Bit Set is a solid choice for DIYers and trade users who need a flexible, durable set for sheet metal, stainless steel and common workshop materials. Its combination of M35 cobalt and TiAlN coating delivers real thermal and wear benefits, and the four-flute design improves cut quality. Buy it if you want fewer bit changes and cleaner stepped holes; use cutting oil for long runs to get the best life from the bits.

Frequently Asked Questions

Can these bits drill stainless steel?
Yes, M35 cobalt HSS and the TiAlN coating make them suitable for stainless steel and other harder sheet metals when used with proper feed and cooling.

What drills accept the shank?
The 1/4in hex shank fits most handheld drills, impact drivers and quick-change chucks that accept hex bits.

Do they need coolant?
For continuous or heavy work it is recommended to use cutting oil or spray water to cool the bits and minimize wear.