Large Step Drill Bit for Steel 1-5/8 in 13-Hole M35 Cobalt - Extra

In this review the Large Step Drill Bit for Steel 1-5/8 in (Co158Z) is evaluated for tradespeople and serious DIYers who need one bit capable of cutting multiple hole sizes in tough materials. The bottom line: this is an industrial-grade, M35 cobalt 13-step bit built to bite into stainless steel and other hard metals where standard bits fail. It stands out for its longevity and ability to clear chips with the two straight flutes, making it a practical single-tool solution when drilling progressively larger holes through sheet metal, aluminum, wood or copper.

Key Features

• Extra-heavy duty M35 cobalt: The M35 alloy is supplied for longer life and improved heat resistance when cutting stainless steel and hard metals.
• 13 stepped sizes: A single bit covers sizes from 3/16 in up to 1-5/8 in so users can enlarge holes without changing tools.
• Two straight flutes: Straight flute design clears chips quickly to reduce clogging and maintain cutting speed in sheet materials.
• 3/8 in tri-flat shank: The tri-shank seats securely in chucks and reduces slippage when applying higher torque.
• Wide material compatibility: Rated for stainless steel, hard metal, aluminum, wood, PVC and copper for versatile shop or field use.
• Industrial grade construction: Built as an extra-heavy duty step bit intended for repeated work on tough panels and components.

Who It's For

The Large Step Drill Bit is best for mechanics, fabricators, HVAC installers and serious DIYers who regularly drill through sheet metal, stainless plates and structural iron where a durable single-bit solution saves time. Its design suits use with a drill or impact driver that accepts a 3/8 in tri-flat shank.

Less suitable are users who need precision countersinks or very fine finish holes in delicate electronics; for thin, fragile plastics or where hole edge finish is critical, a dedicated step drill with a specialized coating or a conventional twist bit may be preferable.

Pros & Cons

Pros

• Long life and heat resistance from M35 cobalt make it reliable on stainless steel and other hard metals.
• Wide size range of 13 steps reduces tool changes and speeds up progressive enlarging of holes.
• Straight flutes and heavy-duty construction clear chips fast and handle demanding jobs.

Cons

• Drilling accuracy is mixed for thin or soft materials; some users may find the finish less refined on aluminum.
• The large step increases required torque and may be challenging on low-power drills for biggest sizes.

Specifications

Material	M35 cobalt steel
Size range	3/16 in to 1-5/8 in (13 steps)
Shank	3/8 in tri-flat shank
Flute type	Two straight flutes
Duty	Extra heavy-duty / industrial grade
Applies to	Stainless steel, hard metal, aluminum, wood, PVC, copper

Our Verdict

The Large Step Drill Bit Co158Z is a solid value for anyone who needs a durable, all-in-one step bit capable of tackling stainless steel and other tough materials. It excels when a single robust bit that covers many hole sizes is preferred over swapping multiple bits, though users should match it with a suitably powerful drill for the largest steps.

Frequently Asked Questions

Can this bit cut stainless steel?
The M35 cobalt construction is designed for stainless steel and heavy metal cutting and performs much better than standard HSS bits.

What size shank does it require?
The bit uses a 3/8 in tri-flat shank that fits chucks accepting hex or tri-flat shanks for reduced slippage.

Will it work on aluminum and wood?
Yes, it is specified for aluminum and wood, but finish and accuracy can vary compared with dedicated bits for those softer materials.