HIDOTOL Cobalt Drill Bit Set 15 PCS - M35 High Speed Steel T

The Verdict

Opening: Why this set earns its keep

Most drill bit sets under $30 are junk. You know the ones — they smoke on the first hole through a steel bracket, dull before you finish the job, and leave you questioning every life choice that led to that moment. The HIDOTOL M35 cobalt set is not that. It’s not a miracle worker either, but for the price, it punches well above its weight class.

What you actually get

Fifteen twist bits sized 1mm through 10mm in metric increments, each made from M35 high-speed steel with 5% cobalt content. That cobalt matters — it keeps the cutting edges hard even when friction heats things up past what standard HSS can survive. The set ships in a black metal index case with drilled holes sized to match each bit. The case closes securely with a friction latch and won’t fall open in your toolbox drawer. Bits are marked with their size on the shank, though the etching on the smaller ones is tough to read without magnification.

Performance and real-world use

The 135-degree split point is the standout feature here. Unlike conventional chisel-point bits that skitter across the surface before biting, these grab immediately. On a recent job drilling through 1/4-inch steel angle iron, I didn’t need a center punch — the bit locked in place on the first rotation. That split point also reduces thrust pressure, which means less arm fatigue during longer drilling sessions.

I tested these on mild steel, 304 stainless, and cast iron. The stainless was where the M35 composition earned its keep — the bits held their edge through a dozen holes without visible wear or discoloration at the tip. At higher RPMs, they ran hot but didn’t soften, which aligns with M35’s heat resistance rating. For wood and plastic, they’re almost overkill. They’ll chew through a 2x4 like it’s butter, though you’ll want to back off the speed to avoid burning.

The 1mm and 1.5mm bits are the weak link. They’re thin, brittle, and unforgiving if you apply lateral pressure. One reviewer noted, “The small bits snapped on the second use — but honestly, that’s every small bit I’ve ever owned.” Fair point. These are meant for light work, not heavy muscle.

What buyers consistently praise

Across 220 ratings (4.4 average), the recurring themes are value and durability. One verified purchaser wrote, “I’ve used these on stainless steel exhaust components and they cut clean without needing constant resharpening.” Another said, “The case alone is worth the price — my old bits were rolling around loose in a drawer.” Multiple reviewers compared them favorably to sets costing twice as much from big-box brands.

Where it falls short

The metric-only sizing will frustrate imperial-standard users. There are no 1/8-inch, 3/16-inch, or 5/16-inch bits in this set. If your projects involve standard US hardware, you’ll need to supplement with a fractional set. The case is also not foam-lined — the bits sit in individual holes but can rattle slightly during transport. Minor, but worth knowing.

Who should buy this

This set is ideal for hobbyist metalworkers, DIYers who work with stainless appliances, and anyone who needs reliable bits for occasional steel drilling without paying premium prices. It’s also a solid backup set for professionals who want a spare in the truck. Skip it if you need fractional sizes, do heavy production drilling daily, or work primarily with wood — cheaper HSS bits will do that job fine.

FAQ

Will these fit a standard 3/8-inch drill chuck? Yes. The largest bit is 10mm (0.39 inches), which fits comfortably in any standard chuck.

Can they drill through hardened steel like drill bits or lathe tools? They’ll handle annealed tool steel and mild steel well. For fully hardened steel, you’ll want carbide or a stepped approach with lubrication, even with M35 cobalt.

Do I need cutting fluid? Not strictly, but it extends bit life dramatically on stainless and deep holes. Use a light oil or dedicated cutting fluid and run at moderate speed.

The Verdict

Buy it if you need a dependable metal-drilling set at a budget price and you’re comfortable with metric sizing. Skip it if you require fractional bits or plan to do heavy industrial drilling daily.

Rating: 4.2/5 — A strong value with genuine M35 performance, held back only by limited size options and fragile small bits.

Where to Buy

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Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.