Cobalt Left Hand Drill Bit Set 29Pc M35 HSS - For Hardened Metal

In this review of the Cobalt Left Hand Drill Bit Set, the bottom line is simple: it is aimed at mechanics and metalworkers who need a range of left-hand bits that can tackle hardened metal and also pair with screw extractors. The reviewer found the M35 cobalt composition and 135 degree point make these bits dependable for drilling stainless steel, cast iron and other tough materials while remaining usable on softer metals, wood and plastic. The left-hand twist design is the standout feature because it helps with drilling into damaged fasteners and speeds chip evacuation during heavy cuts.

Key Features

• Left-hand design: The set includes 29 left-hand sizes which can be used with screw extractors and reduce binding when removing broken fasteners.
• M35 cobalt steel: Cobalt alloy provides improved heat resistance and edge retention when cutting stainless steel and iron castings.
• 135 degree point tip: The split-style 135 degree tip self-centers to reduce walk-off and starts holes cleanly in metal.
• Wide size range: Sizes from 1/16in to 1/2in cover common drilling tasks so you rarely need an extra bit for a new job.
• Indexed storage case: The included case keeps bits organized by size for quick selection and compact storage on the bench or in a toolbox.

Who It's For

This set is best for hobbyists, home mechanics and professional tradespeople who regularly drill into harder metals like stainless steel, cast iron and tool steels and want left-hand geometry to assist with extractor work. It is also useful for general-purpose shops that need a broad size range without buying individual bits.

Those who primarily drill only wood or occasional soft materials and who never need left-hand bits may find a standard right-hand HSS set more economical. Buyers who expect carbide performance on extremely hard or abrasive alloys should consider specialty carbide options instead.

Pros & Cons

Pros

• Durable M35 cobalt alloy offers better heat resistance and longer life on hard metals.
• Comprehensive 29-piece range from 1/16in to 1/2in handles most shop needs without gaps.
• Left-hand twist and 135 degree point combine to reduce walking and help with stuck fastener removal.
• Compact indexed case keeps bits organized and easy to transport.

Cons

• Some users reported mixed opinions about long-term durability compared with premium branded bits.
• Left-hand geometry is a specialty feature that not every user will need.

Specifications

Our Verdict

The Cobalt Left Hand Drill Bit Set is a practical value for anyone who drills hardened metals and wants left-hand geometry for extractor use; the M35 construction and 135 degree tip make it a reliable general-purpose metalworking kit. It delivers broad size coverage and tidy storage, though users seeking premium longevity may prefer top-tier branded bits for heavy daily use.

Frequently Asked Questions

Can these bits be used on stainless steel?
Yes, the M35 cobalt composition is suitable for stainless steel and other hardened metals.

Are the bits stored in a usable case?
Yes, the set ships in an indexed storage case that keeps each size organized and easy to identify.

Do the left-hand bits help with screw extractor work?
Yes, left-hand rotation can assist extractor engagement and sometimes helps back out broken fasteners while drilling.