6 Best Left Hand Drill Bits for Removing Broken Screws
Left-hand drill bits remove broken screws from old gear by biting counter-clockwise. This action often extracts the fastener as you drill. We review the best.
There’s no feeling quite like the sharp snap of a bolt head shearing off on a piece of equipment you’ve had for decades. Suddenly, a five-minute adjustment turns into a weekend-long project that threatens to damage an irreplaceable part. This is where a good set of left-hand drill bits becomes one of the most valuable tools in your farm shop.
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Why Left-Hand Bits Save Old Tractor Parts
A standard drill bit spins clockwise, drilling deeper into whatever you’re working on. If you use one on a broken bolt, you’re just drilling a hole while potentially tightening the seized threads even further. It’s counterproductive.
A left-hand drill bit does the opposite. It’s designed to cut while spinning counter-clockwise—the same direction you’d turn a wrench to loosen a bolt. This simple reversal of mechanics is the key. As the bit drills into the broken fastener, its sharp flutes can bite into the metal.
When that bite happens, the bit’s counter-clockwise torque is transferred directly to the broken bolt shank. Often, this is enough to overcome the friction holding the threads, and the bolt backs itself right out of the hole. You’ve just removed a broken fastener without needing a screw extractor, which saves time and, more importantly, reduces the risk of damaging the delicate threads in an old cast-iron housing.
This is critical when working on vintage machinery where a replacement water pump housing or transmission case is either impossible to find or costs a fortune. A $30 set of bits can easily save you from a $500 headache. It’s one of the best investments you can make for your workshop.
Irwin Hanson Cobalt Bits for Pro-Grade Durability
When you’re drilling into a broken bolt, you’re not cutting into fresh, soft metal. You’re often dealing with steel that has been work-hardened from the stress of breaking, or a high-grade fastener like a Grade 8 bolt. This is where cobalt bits earn their keep.
The Irwin Hanson cobalt set is built for exactly this kind of abuse. Unlike titanium-coated bits, where the hardness is just a thin layer, these bits are made from a solid cobalt steel alloy. This means they hold their edge and resist heat far better than standard high-speed steel (HSS) bits. The hardness runs through the entire bit, so you can sharpen it without losing performance.
Think of these as your first line of defense for serious problems, like a sheared exhaust manifold stud or a snapped-off bolt on a plow frame. They cost more than a standard set, but the first time one bites into a hardened bolt that a cheaper bit couldn’t even scratch, you’ll understand the value. This is the set you buy if you plan on keeping old iron running for another 20 years.
Neiko 10037A Titanium Set for Rusted Bolts
Not every broken fastener is a hardened, high-torque nightmare. Sometimes, it’s just an old, rusted-out bolt on a fender, a mower deck, or a battery tray. For these more common, lower-stress jobs, the Neiko 10037A titanium-coated set is an excellent and affordable choice.
The titanium nitride coating reduces friction and helps dissipate heat, which keeps the cutting edge sharp longer than an uncoated HSS bit. It’s a noticeable improvement for general-purpose work. This set gives you a wide range of sizes, so you’ll likely have the right one on hand when you need it.
The tradeoff is that the coating is just that—a coating. If you’re drilling into extremely hard material or you need to resharpen the bit, you’ll lose that benefit. But for the price, it’s hard to beat for a homeowner or hobby farmer who needs a reliable set for occasional use on mild steel and moderately seized bolts. It’s the perfect "just-in-case" kit to keep in the toolbox.
Drill Hog M7 Left-Hand Bits with Lifetime Warranty
Drill bits used for bolt extraction are considered consumable items. They are put under incredible stress and are expected to break eventually. Drill Hog turns that expectation on its head by offering a lifetime warranty on their bits, which is a massive vote of confidence in their product.
These bits are made from M7 high-speed steel, a tough and heat-resistant material that sits comfortably between standard HSS and premium cobalt. This makes them well-suited for a wide range of farm repairs, from equipment frames to small engine casings. The warranty means that if you do manage to snap one while trying to extract a particularly stubborn bolt, you can get a replacement.
This is the ideal choice for someone who is tough on tools and values peace of mind. Knowing you have a lifetime backup removes the hesitation to apply the necessary pressure to get a job done. For a working farm shop where tools are used hard, that kind of guarantee is worth its weight in gold.
Viking Drill 240-UB Set Tackles Hardened Steel
Sometimes you run into a problem that standard tools just can’t solve. A shear pin on a post-hole digger snaps off flush, or a high-tensile bolt on a loader arm breaks under load. These fasteners are made of hardened steel, and trying to drill them with a regular bit is like trying to cut rock with a butter knife.
The Viking Drill 240-UB set is specifically designed for these worst-case scenarios. Made from Hi-Molybdenum M7 steel and featuring a 135-degree split point, these bits are engineered to start cutting on hard surfaces without "walking" or wandering. They can bite into hardened bolts and even other broken drill bits or easy-outs that have snapped off in a hole.
This isn’t your everyday set; it’s the specialist you call in when everything else has failed. If you frequently work on heavy-duty implements or modern equipment built with high-strength alloys, having a set of Vikings on hand can be the difference between a quick repair and a trip to a machine shop. They are an investment in overcoming the absolute toughest extraction jobs.
COMOWARE Left Hand Drill Bit Set for Versatility
For many hobby farmers, the need for a left-hand drill bit might only pop up a few times a year. You don’t need a top-of-the-line cobalt set for every task, but you definitely need something reliable when a bolt does snap. The COMOWARE set fills this niche perfectly, offering solid performance at a budget-friendly price.
This is a great all-around set to have on the pegboard. It’s made from classic high-speed steel with a black oxide finish for some corrosion resistance. While it won’t power through a Grade 8 bolt like a cobalt or Viking bit, it’s more than capable of handling the majority of broken screws and bolts you’ll find on older, simpler equipment.
Think of this as the perfect entry-level or backup set. It gives you the capability to handle unexpected repairs without a major investment. For the farmer who needs a functional solution for common problems, this set provides excellent value and ensures you’re prepared for that next inevitable snap.
IRWIN Industrial 11119 Set for Stubborn Shears
While specialty bits have their place, sometimes you just need a comprehensive, reliable set that covers all the common sizes you’re likely to encounter. The IRWIN Industrial 11119 set is a workshop staple, offering a range of sizes that are perfect for everything from small engine work to heavy implement repair.
These bits are made from M-2 high-speed steel, a proven material known for its good balance of toughness and heat resistance. They feature a 135-degree split point tip, which helps prevent the bit from wandering when you start drilling—a critical feature when you’re trying to center a hole on the uneven surface of a broken bolt.
This is the kind of set you reach for to remove a busted shear bolt on a brush hog or a snapped fastener on a three-point hitch arm. It’s not an exotic, specialized tool; it’s a dependable workhorse. Its value lies in its reliability and the completeness of the size run, ensuring you have the right tool ready to go when a repair can’t wait.
Proper Technique for Using Left-Hand Drill Bits
Owning the best drill bits in the world won’t help if you don’t use them correctly. The right technique is just as important as the tool itself. Rushing the job is the fastest way to break a bit and make the problem ten times worse.
First, preparation is everything. Use a sharp center punch to create a divot exactly in the center of the broken bolt. This is the single most important step. It gives the tip of your drill bit a place to start and prevents it from wandering off-center and destroying the threads you’re trying to save.
Second, set your drill correctly. Make sure your drill is in reverse (counter-clockwise). Start with a slow speed and apply firm, steady pressure. Don’t use a high-speed drill setting; you’ll generate too much heat and dull the bit instantly. Use plenty of cutting oil to lubricate the cut and keep things cool. The goal is to create a clean shaving, not blue-hot dust.
Finally, have patience. Let the bit do the work. As it drills, the flutes will try to grab the metal. You might feel the drill suddenly jerk or stop—that’s often the moment the bit has dug in and the bolt is starting to turn. If you’ve done it right, the broken piece will thread itself out onto the drill bit, saving you hours of frustration.
A set of left-hand drill bits isn’t a luxury; it’s a fundamental tool for anyone maintaining older farm equipment. It’s a small investment that pays for itself over and over, turning potential disasters into minor inconveniences. Having the right set on hand is the key to keeping that reliable old machinery earning its keep for years to come.
