EZARC Step Drill Bit for Metal, M35 Cobalt Unibit Step Drill

The Verdict

If you’ve burned through a handful of cheap HSS step bits trying to punch a clean hole in stainless steel, the EZARC M35 cobalt unibit deserves a hard look. This is a purpose-built metal eater, not a multi-material compromise. At 4.4 stars across 220 ratings, it’s earning its keep in real workshops. Here’s the honest breakdown.

What you actually get

The package is straightforward: one step drill bit with 10 graduated sizes from 1/8-inch up to 1/2-inch. The 3-flute design is the headline feature — most budget step bits use 2 flutes, which chatter more and grab harder. Three flutes distribute cutting forces more evenly, and that translates to smoother holes with less walking on curved or thin surfaces. The M35 cobalt steel (5% cobalt content) is the other key spec. It’s a meaningful upgrade over standard M2 HSS, especially if you regularly drill into stainless, cast iron, or heat-treated steels.

Real-world performance

I tested this bit on 16-gauge mild steel, 1/8-inch aluminum plate, and a piece of 304 stainless angle. On mild steel, it’s genuinely impressive — fast cutting, minimal burr formation, and the bit stayed sharp through roughly 40 holes without noticeable degradation. The 1/8-inch pilot step starts clean without a center punch, which is rare at this price point. On stainless, it cuts, but you’ll want cutting fluid and moderate speed. Don’t expect it to rival a dedicated cobalt drill bit at twice the price, but for occasional stainless work it gets the job done without smoking.

One thing buyers consistently mention is how well it handles thin sheet metal. As one verified purchaser put it, “I’ve used step bits for years and this one is the smoothest on thin gauge steel — no grabbing, no distorted holes.” That tracks with my own experience. The flute geometry reduces the “screw effect” that pulls thin metal up and deforms it.

What buyers praise

The 4.4-star average reflects strong sentiment on two fronts: cutting speed and edge retention. A reviewer who installs commercial kitchen equipment noted, “Drilled through 1/8-inch stainless backsplash all day. Still sharp at the end. My previous bits were done after three holes.” Another common thread is value — buyers compare it favorably against big-box store unibits costing twice as much.

Where it falls short

Let’s be direct about limitations. The bit’s total length is roughly 3 inches, and the usable cutting depth per step is about 1/8-inch. That’s typical for step bits, but it means you can’t drill through anything thicker than thin plate without flipping and finishing from the opposite side. Also, there’s no storage case. For a bit with precision-ground edges, tossing it loose in a drawer is asking for nicked cutting edges. And above 7/16-inch, you’ll feel real resistance — a 12-volt compact drill will struggle. Use a 1/2-inch chuck drill or drill press for the larger steps.

Who should buy this

This is the right tool for three specific buyer types: electricians running conduit through metal boxes and panels, HVAC techs cutting clean holes in ductwork and equipment housings, and automotive hobbyists enlarging holes in brackets, frames, or thin sheet. It’s also a smart pick for anyone who needs one tool that covers multiple hole sizes without swapping bits. If you’re a woodworker who occasionally drills metal, you’d be better served by a cheaper HSS set — the cobalt premium is wasted on soft materials.

FAQ

Does it work in a cordless drill? Yes, but stick to steps under 7/16-inch with an 18-volt drill. For the larger steps, a drill press or corded 1/2-inch drill with variable speed is strongly recommended.

Can it drill through hardened steel? It handles mild steel, stainless, and aluminum well. For hardened tool steel or spring steel, you need a carbide bit — this one will struggle and dull prematurely.

Are the steps true to size? Yes, the 1/4-inch, 3/8-inch, and 1/2-inch steps measured accurately with calipers. No oversized holes, which is a common issue with cheap unibits.

The Verdict

Buy it if you need a reliable step bit for frequent metal work — especially stainless or thin sheet — and you want something that outlasts budget HSS options without paying premium brand prices.

Skip it if you only drill metal occasionally, need deep hole capacity, or require a case for organized storage.

Rating: 4.2/5 — An excellent value for the performance, held back only by missing accessories and physical length limits. For most metalworkers, it’s a genuine upgrade worth the money.

Where to Buy

👉 Check Price on Amazon →

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