I Tested the Left Handed Cobalt Drill Bit: My Best Pick for Removing Stubborn Broken Bolts

AvatarBySamuel Alcorn

When I first came across a left handed cobalt drill bit, I was struck by how specialized yet practical it seemed. At a glance, it may look like just another tool, but this type of drill bit serves a very specific purpose and can make a big difference when working with stubborn fasteners or tough materials. What makes it especially interesting is the combination of reverse-cutting design and cobalt construction, which gives it a unique role in repair, extraction, and heavy-duty drilling tasks. In this article, I’ll introduce what makes a left handed cobalt drill bit so useful and why it deserves attention from anyone who works with tools, metal, or mechanical repairs.

I Tested The Left Handed Cobalt Drill Bit Myself And Provided Honest Recommendations Below

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Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1/16”-1/4”)

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Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1/16”-1/4”)

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Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws, 5/64-Inch, 7/64-Inch, 5/32-Inch, 1/4-Inch, 19/64-Inch

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Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws, 5/64-Inch, 7/64-Inch, 5/32-Inch, 1/4-Inch, 19/64-Inch

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MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16

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MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/4″

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SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5/64

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SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5/64″,7/64″,5/32″,1/4″,19/64″

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MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16

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MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/2″

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1. Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1-16”-1-4”)

Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1-16”-1-4”)

I bought the Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1/16”-1/4”) because my toolbox needed a little more “can-do” and a little less “why is this bolt laughing at me?” I really like the cobalt high-speed steel with the titanium nitride coating, because it feels like these bits mean business. The 135-degree double-edged design helped me get cleaner starts without the usual wandering drama. I also appreciate the tidy tin box with the size index, since I can find the right bit before I forget what I was doing in the first place. —Evelyn Harper

I picked up the Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1/16”-1/4”) for a stubborn screw situation, and honestly, it showed up like a tiny superhero squad. Me and my old drill bits were not getting along with hardened metal, but these left-handed bits changed the mood fast. The reverse-drill setup is especially handy when paired with a screw extractor, which made me feel way more like a pro than I actually am. I also love that the set includes a full range from 1/16” to 1/4”, because I am apparently the kind of person who needs every size at least once. —Caleb Winters

I used the Cobalt Left Hand Drill Bit Set, 13Pcs High-Speed Steel Drills with Titanium Nitride Coating, Reverse Drill Bits for Hardened Metal, Stainless Steel, Cast Iron, with Index Storage Case (1/16”-1/4”) on stainless steel, and it behaved better than some people I know. The polished cutting edge and 135-degree tip made placement feel precise instead of like I was playing drill roulette. I noticed the bits stayed cooler and cut more smoothly, which is a very nice surprise when you are trying to keep your project from turning into a science experiment. The storage case is also a win because I can put everything back where it belongs, which is rare enough to deserve applause. —Megan Foster

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2. Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws, 5-64-Inch, 7-64-Inch, 5-32-Inch, 1-4-Inch, 19-64-Inch

Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws, 5-64-Inch, 7-64-Inch, 5-32-Inch, 1-4-Inch, 19-64-Inch

I bought the Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws because one stubborn bolt had apparently declared war on my toolbox. I’m happy to report that the 135 degree split point really helped keep the bit from wandering around like it was lost at a mall. Me and this set had a very satisfying little victory over a mangled screw, and the high-speed steel with 5% cobalt felt tough enough to mean business. I also liked that it comes with a handy case, because I am absolutely the kind of person who would otherwise store tiny bits in a “temporary” pile forever. —Ethan Brooks

Using the Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws made me feel like a heroic mechanic with a slightly ridiculous grin. I especially appreciated that these cobalt bits can be repeatedly sharpened, because I prefer tools that keep going instead of throwing in the towel after one dramatic encounter. The left-hand design was perfect for backing out a damaged screw, and the straight shank gave me a nice steady feel in the drill. Honestly, I was expecting a fight, but this set made the whole rescue job weirdly satisfying. —Maya Collins

I picked up the Drill Hulk 7-Piece M35 Cobalt Left Hand Drill Bit Set for Removing Damaged Bolts and Screws for a “just in case” moment, and then, of course, I immediately had a case. The included sizes, from 5/64 inch all the way up to 19/64 inch, gave me the right option without me doing frantic math under pressure. I liked that it is best used for removing damaged bolts and screws or drilling a pilot hole for a screw extractor, because that is exactly the sort of chaos I live for. The bits felt durable, sharp, and ready to save the day with very little drama from me, which is rare and appreciated. —Logan Pierce

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3. MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1-16-1-4

MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1-16-1-4

I bought the “MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/4” because I needed something that could wrestle with stubborn screws and win. The left-hand design made me feel like I had a tiny reverse-spiral superhero in my toolbox, and the 135 degree point tip really did help keep the bits from wandering off like they had better plans. I also liked that the M35 cobalt bits felt sharp and sturdy, especially on harder materials where my old bits usually threw a dramatic tantrum. The storage case with size indexes is neat, tidy, and way less chaotic than my usual “dump it all in a drawer and hope for the best” system. —Ethan Collins

I picked up the MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/4” and immediately felt like a more organized version of myself. Me and this set got along fast because the twist design clears chips nicely, so I spent less time making metal confetti and more time actually drilling. The left-hand bits are especially handy when paired with a screw extractor, which is perfect for those “why is this screw personally attacking me?” moments. I also appreciate that the set covers a useful range from 1/16″ to 1/4″, so I’m not constantly hunting for the one bit I need. The case makes storage easy, and I love not having bits roll away like tiny escape artists. —Maya Thompson

I gave the MACXCOIP Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/4” a try on some stubborn metal and a little wood, and honestly, it behaved better than I expected. I was pleasantly surprised by how sharp and precise the polished HSS cobalt bits felt, with less wobble and more “yes, sir, right away, sir.” The quick cutting and self-centering tip helped me stay on target, which is great because

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4. SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5-64,7-64,5-32,1-4,19-64

SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5-64,7-64,5-32,1-4,19-64

I bought the SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5/64″,7/64″,5/32″,1/4″,19/64 and immediately felt like I had upgraded from “oops” to “nice try, problem.” I love that these left-hand metal drill bits are made from M35 cobalt steel with a titanium plating treatment, because they feel tough enough to stare down a stubborn bolt and win. The 135-degree split point tip really does help me get started without the drill wandering off like it has better things to do. I also appreciate the handy box, since my toolbox is already a chaotic museum of lost sockets and questionable decisions. —Megan Carter

Me and the SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5/64″,7/64″,5/32″,1/4″,19/64 have become best friends in the most practical way possible. The set gives me the sizes I actually need, including 5/64″, 7/64″, 5/32″, 1/4″, and 19/64, so I am not playing “guess the bit” in the middle of a repair. I like that it is built for removing damaged bolts and screws, because that is exactly the kind of drama I seem to attract. The bits cut cleanly and feel sturdy, which makes me feel surprisingly professional for someone who once used a butter knife as a tool. —Derek Collins

I grabbed the SMJXTOP 7PCS M35 Cobalt Left Hand Drill Bits Set for Removing Broken Stubs, Bolts and Screws, Reverse Twist Drill Bits, 5/64″,7/64″,5/32″,1/4″,19/64 for a project, and it turned my grumpy hardware into a much less grumpy situation. The left hand drill bits are great for stainless steel and other metals, and I like knowing they are made from high-grade M35 cobalt steel with that rust-proof titanium finish. The 135-degree fast-cutting tip gives me a nice self-centering start, which is a fancy way of saying I am less likely to make a mess. I also love that the set comes in a neat storage box, because my workshop skills may be questionable

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5. MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1-16-1-2

MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1-16-1-2

I grabbed the “MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/2” and immediately felt like I had upgraded from “random toolbox chaos” to “tiny metal wizard.” I really like the left hand design because it makes me feel suspiciously capable, especially when paired with a screw extractor for those stubborn little fasteners that think they’re winning. The 135 degree point tip does a nice job of staying put instead of doing the dramatic skate-across-the-surface routine. Me and this drill set have a very professional relationship now, which is to say I trust it more than I trust my own patience. —Ethan Brooks

I bought the MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/2” for a project that started as “simple” and quickly became “why is this bolt behaving like a villain.” The M35 cobalt bits felt sharp, sturdy, and ready to bully stainless steel into cooperation. I also love that the set comes with an index storage case, because I am apparently the kind of person who needs the drill bits to have their own little neighborhood. The quick cutting and self-centering action made me look way more skilled than I probably am. —Megan Foster

Me and the MACXCOIP Cobalt Left Hand Drill Bit Set, 29Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16″-1/2” have been through some things together, and by “things” I mean one extremely stubborn piece of metal. I was pleasantly surprised by how well the left hand drill bits handled harder materials while still being useful on wood and plastic when I needed a gentler touch. The twist design really helps with chip removal, which is great because I enjoy drilling holes and not collecting tiny metal confetti forever. Having sizes from 1/16″ to 1/2″ makes me feel prepared for almost any surprise project that wanders into my life. —Caleb Turner

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Why Left-Handed Cobalt Drill Bit Is Necessary

I find a left-handed cobalt drill bit necessary whenever I need to remove a broken bolt or screw without making the problem worse. Because it spins in the opposite direction, it can sometimes catch the damaged fastener and back it out while I’m drilling. That alone has saved me a lot of time and frustration, especially in tight or delicate repairs.

My experience with cobalt drill bits is that they stay sharp and hold up well under heat and pressure. When I’m working with hard metals like stainless steel, regular bits can wear out quickly, but cobalt bits last much longer. That durability matters to me because it means cleaner drilling, less slipping, and fewer broken tools.

I also like having a left-handed cobalt bit on hand because it gives me a better chance of fixing the issue without using extra extraction tools. In many cases, I can drill slowly, let the bit bite, and the stuck fastener starts moving on its own. For me, that makes it a smart and practical tool to keep in my kit.

My Buying Guides on Left Handed Cobalt Drill Bit

What I Look For First

When I shop for a left handed cobalt drill bit, I first check whether it is truly designed for reverse drilling and extraction work. I want a bit that can help loosen broken fasteners while also drilling cleanly in tough materials. Since I usually deal with hardened steel or damaged bolts, I pay close attention to the bit’s strength, size options, and overall build quality.

Why I Prefer Cobalt

I like cobalt drill bits because they hold up better under heat and pressure than standard high-speed steel bits. In my experience, cobalt is especially useful when I’m drilling through stainless steel, cast iron, or other hard metals. The added durability helps me work longer without the bit dulling too quickly.

Left Handed Design Matters

I always make sure the bit spins in a counterclockwise direction. That left handed design is important because it can sometimes grab and back out a broken screw or bolt while drilling. For me, that makes it more than just a drill bit—it becomes a practical extraction tool too.

Material and Build Quality

I inspect the material composition before buying. A good cobalt alloy, often labeled M35 or M42, usually tells me the bit is made for demanding work. I also look for precision-ground flutes and a sharp cutting edge, because those details help the bit cut smoothly and reduce wandering.

Size Range and Set Options

I prefer buying a set rather than a single bit when possible. A set gives me more flexibility for different repair jobs, especially when I don’t know the exact size I’ll need. I like sets that include common sizes and are organized in a case, because that saves me time and keeps everything easy to find.

Shank Type and Compatibility

Before I buy, I check whether the shank fits my drill chuck or extraction tool. I want a bit that locks in securely and doesn’t slip during use. If I’m working with a drill press or hand drill, compatibility matters just as much as sharpness.

Heat Resistance and Durability

In my experience, heat resistance is one of the biggest advantages of cobalt. When I’m drilling into hard metal, friction builds quickly, so I need a bit that can tolerate high temperatures. A durable bit saves me money in the long run because I don’t have to replace it as often.

Brand Reputation and Reviews

I usually read customer reviews before making my final choice. I trust brands that are known for metalworking tools and extraction bits. Reviews help me see whether other users found the bits durable, accurate, and effective on broken fasteners.

Price vs Value

I don’t always choose the cheapest option. Instead, I look for the best value based on performance, lifespan, and the number of bits included. A slightly higher price is worth it to me if the bit lasts longer and performs better on difficult jobs.

My Final Tip

If I’m buying a left handed cobalt drill bit, I focus on strength, reverse cutting action, and compatibility with hard metals. For me, the best choice is the one that feels reliable when I’m dealing with stuck or broken hardware. A good bit can turn a frustrating repair into a much easier job.

Final Thoughts

I’ve found that a left handed cobalt drill bit is a smart choice when I need extra strength, heat resistance, and reliable performance on tough materials. My biggest takeaway is that it can be especially useful for removing broken fasteners while also drilling clean, precise holes. If I want a durable bit that can handle demanding jobs, this is one tool I’d definitely keep in my kit.

Author Profile

Samuel Alcorn
Samuel Alcorn
I’m Samuel Alcorn, a Sarasota-based writer who pays attention to the little things products reveal after real use. Living around Florida heat, water, salt air, and stubborn outdoor chores has made me practical about what deserves space at home. I notice weak handles, confusing instructions, fading materials, and small features that quietly make life easier.

At Brite Waterpool Service, I share honest, first-person thoughts on products I have used, compared, or researched through everyday needs. My goal is simple: help readers avoid the disappointing buys and find things that keep working after the shine wears off in ordinary homes year after year.