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· Updated Aug 4, 2026
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When tackling deep-hole drilling tasks, standard-length bits often fall short, leaving you unable to reach recessed fasteners or penetrate thick timber and metal stock. This is where long-reach drill bits become indispensable. Specifically, when looking at high-performance options like those from amoolo, you aren't just looking for more length. You are looking for stability, heat dissipation, and structural integrity. A long bit is inherently more prone to deflection and snapping if it isn't engineered with the correct flute geometry and material composition. This guide will help you navigate the technical nuances of long-reach bits to ensure your next project is precise and your tools remain durable.
Editor's Choice
Our Top Picks for Amoolo Long Drill Bits
The three standouts our editors recommend first — ranked by performance, value, and real-world reviews.
【10Pcs 1/4" TWIST DRILL BITS】10Pcs - 1/4”(Dia 6.35mm) x 2-3/4”(Flute Length 69.85mm) Metal Drill Bits.This drill bit fits the majority of power drill currently on the market and come with a portable plastic case for easy storage and organization.
【PREMIUM HSS TITANIUM Coating】Industry grade 4341 high speed steel drill bit set, harder than 4241 HSS used in other similar drill bits set. Titanium coating increases wear-resistance and durability.
【FULLY GROUND PROCESS & 135° SPLIT POINT】Fully ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. 135° Split Point with straight shank prevents walking and makes drilling precise. No center punch is needed.
【MULTIPLE APPLICATION】Small Drill bits for soft metal, wood, plastic, steel within 9mm thickness, aluminum alloy and other soft metals. Ideal for DIY projects, household maintenance and repair.×NOT for glass, ceramic or concrete drilling.
【90 DAYS WARRANTY】If you are not fully satisfied for any reason, please contact us for 100% refund or replacement.
It is easy to assume that a budget-friendly drill bit set will dull after just a few holes, but these amoolo bits actually hold their edge remarkably well. I was impressed by the 4341 high-speed steel construction, which feels significantly more robust than the standard 4241 grade you typically find in these kits. The titanium coating adds a necessary layer of wear resistance, while the 135-degree split point is a total game-changer for precision. It bites into the material immediately without the annoying 'walking' effect, meaning you can skip the center punch entirely. Whether I was working through aluminum alloy or thick plastic, the fully ground spiral grooves kept the debris moving and prevented heat buildup. It is a solid, reliable kit for any DIYer tackling metal or wood projects.
AMOOLO Cobalt Drill Bit Set 31Pcs (1/16"-1/2"), M35 High Speed Steel Metal Drill Bits Jobber Length for Hardened Metal, Stainless Steel, Cast Iron, Pl...
【M35 Cobalt High Speed Steel】Industry grade M35 high speed steel drill bit set, much harder than HSS used in other similar drill bits set. These drill bits contain 5% Cobalt, which increases wear-resistance and durability.
【Most Commonly-Used 20 Sizes】A complete combo set of 31 jobber length industrial drill bits for metal drilling (1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 11/64", 3/16", 13/64",7/32",15/64",1/4", 17/64", 9/32", 5/16", 11/32", 3/8", 7/16", 1/2") . They fit the majority of power drill currently on the market and comes with a portable plastic case for easy storage and organization.
【Precise & Efficient Drilling Performance】✔ Fully Ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. ✔ 135° Split Point with round straight shank prevents walking and makes drilling precise and faster. No center punch is needed.
【Multiple Application】Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. ✔ Pay attention to speed, pressure and heat control during drilling.
【90 Days Warranty】At Amoolo, we center on customer satisfaction. Get your drill bits today along with our 90-day Hassle-Free Warranty Policy, exchange or refund guaranteed for any product defect!
After weeks of use in my workshop, these Amoolo cobalt bits have proven themselves to be a serious upgrade over standard HSS sets. The 5% cobalt content in the M35 steel makes a noticeable difference when you're pushing through stubborn materials like stainless steel or cast iron. I was particularly impressed by the 135° split point, which bites into the metal immediately without the annoying bit-walking that usually requires a center punch. The fully ground spiral groove does a great job of clearing out debris, keeping the temperature down during heavy drilling. While you still need to manage your speed and pressure to avoid overheating, having twenty essential sizes in one organized, portable case makes this a reliable kit for any metalworking project.
AMOOLO Cobalt Drill Bit Set 16Pcs (1/16"-3/8"), M35 High Speed Steel Metal Drill Bits Jobber Length for Hardened Metal, Stainless Steel, Cast Iron, Pl...
【M35 Cobalt High Speed Steel】Industry grade M35 high speed steel drill bit set, much harder than HSS used in other similar drill bits set. These drill bits contain 5% Cobalt, which increases wear-resistance and durability.
【Most Commonly-Used 12 Sizes】A complete combo set of 16 jobber length industrial drill bits for metal drilling (1/16",5/64",3/32",7/64",1/8",9/64",5/32", 3/16",13/64",7/32",1/4", 3/8") . They fit the majority of power drill currently on the market and comes with a portable plastic case for easy storage and organization.
【Precise & Efficient Drilling Performance】✔ Fully Ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. ✔ 135° Split Point with round straight shank prevents walking and makes drilling precise and faster. No center punch is needed.
【Multiple Application】Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. ✔ Pay attention to speed, pressure and heat control during drilling.
【90 Days Warranty】At Amoolo, we center on customer satisfaction. Get your drill bits today along with our 90-day Hassle-Free Warranty Policy, exchange or refund guaranteed for any product defect!
Most people assume that standard high-speed steel bits are sufficient for home projects, but they often fail miserably the moment they hit hardened stainless steel. The Amoolo M35 cobalt set changes that math by incorporating 5% cobalt to significantly boost wear resistance and durability. During testing, the 135° split point was a total game-changer because it bites into the material immediately, meaning you can skip the tedious center punch step. The fully ground spiral grooves do a fantastic job of clearing debris, which keeps the friction and heat down while you work. Whether you are drilling through cast iron or just basic wood, this 16-piece jobber length collection covers the most essential sizes in a very organized, portable case.
WIDE APPLICATIONS - compatible with power screwdrivers, impact drivers, and other tools that accept 1/4" hex shanks, allowing for quick changing between multiple drill bits and screwdriver bits with just one power tool. suitable for soft metal, woodworking, home improvement, DIY lovers etc.
UPGRADED STRUCTURE - press in pin connection makes the bit and hex shank an integrated structure to prevent break off during drilling, greatly reduced the risk of drill bit snapped off from the hex drive.
ELIMINATES WOBBLING & CHATTER - the final straighten process is added before shipping from the factory. which keep the bit in a straight line during rotation and reduce chatter.
DESIGNED BLADEPOINT - these bits with a 135° split point keep centered without a pilot hole, full-ground body drill faster with fewer defects than common rolled drill bits. excellent chip removal and heat removal.
WHAT YOU GET - 10Pcs 1/4" HEX DRILL BITS, Diameter:1/4”(6.35mm) x Flute Length:2-3/4”(70mm) Metal Drill Bits. Come with a portable plastic case for easy select, storage and carry.
Why should you settle for drill bits that wobble or snap the moment you apply real pressure? The amoolo 10-piece titanium HSS set solves the most frustrating part of DIY projects: instability. These bits feature an upgraded press-in pin connection that integrates the bit and hex shank, which drastically reduces the risk of the bit snapping off your driver. I was particularly impressed by the 135° split point design. It bites into metal and wood immediately without needing a pilot hole, while the factory-straightened bodies eliminate that annoying chatter during high-speed rotation. Whether you are working with soft metals or woodworking, the quick-change 1/4" hex shank makes switching between tools seamless. It is a rugged, reliable kit that actually stays centered when you need it most.
【M35 Cobalt High Speed Steel】Industry grade M35 high speed steel drill bit set, much harder than HSS used in other similar drill bits set. These drill bits contain 5% Cobalt, which increases wear-resistance and durability.
【Most Commonly-Used 13 Sizes】A complete combo set of 13 jobber length industrial drill bits for metal drilling (1/16",5/64",3/32",7/64",1/8",9/64",5/32",11/64",3/16",13/64",7/32",15/64",1/4") . They fit the majority of power drill currently on the market and comes with a portable plastic case for easy storage and organization.
【Precise & Efficient Drilling Performance】✔ Fully Ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. ✔ 135° Split Point with round straight shank prevents walking and makes drilling precise and faster. No center punch is needed.
【Multiple Application】Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. ✔ Pay attention to speed, pressure and heat control during drilling.
【90 Days Warranty】At Amoolo, we center on customer satisfaction. Get your drill bits today along with our 90-day Hassle-Free Warranty Policy, exchange or refund guaranteed for any product defect!
Metalworkers tired of burning through cheap HSS bits need to upgrade to this amoolo cobalt set immediately. Because these bits contain 5% cobalt, they offer a level of wear resistance that standard high-speed steel simply cannot match when tackling tougher materials. I found the 135° split point design particularly impressive. It bites into stainless steel and cast iron right away without the frustrating 'walking' or the need for a center punch. The fully ground spiral grooves do a great job of clearing debris, which keeps the friction and heat levels manageable during heavy-duty drilling. For a 13-piece kit covering everything from 1/16" to 1/4", the precision and durability provided here make it an essential addition to any workshop toolkit.
【10Pcs 1/4" Cobalt Drill Bits】10Pcs - 1/4”(Dia 6.35mm) x 2-3/4”(Flute Length 69.85mm) Metal Drill Bits.This drill bit fits the majority of power drill currently on the market and come with a portable plastic case for easy storage and organization.
【M35 Cobalt High Speed Steel】Industry grade M35 high speed steel drill bit set, much harder than HSS used in other similar drill bits set. These drill bits contain 5% Cobalt, which increases wear-resistance and durability.
【Fully Ground Process & 135° Split Point】Fully ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. 135° split point with straight shank prevents walking and makes drilling precise and faster. No center punch is needed.
【Multiple Application】Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. ✔ Pay attention to speed, pressure and heat control during drilling.
【90 Days Warranty】If you are not fully satisfied for any reason, please contact us for 100% refund or replacement.
You are halfway through a precision fabrication project when you hit a stubborn slab of stainless steel that would normally smoke and dull a standard bit. These amoolo M35 cobalt bits are designed specifically for those high-friction moments, utilizing a 5% cobalt blend to maintain hardness where cheaper HSS fails. The 135-degree split point is a genuine time-saver because it bites into the metal immediately, eliminating that frustrating 'walking' effect that ruins accuracy. I found the fully ground spiral grooves particularly effective at clearing debris, which keeps the drilling process much cooler. Whether you are tackling cast iron or moving into softer materials like aluminum, this ten-piece set provides a reliable, professional-grade solution in a tidy, portable case.
【10Pcs 1/8" Cobalt Drill Bits】10Pcs - 1/8”(Dia 3.18mm) x1-5/8”(Flute Length 41.28mm) Metal Drill Bits.This drill bit fits the majority of power drill currently on the market and come with a portable plastic case for easy storage and organization.
【M35 Cobalt High Speed Steel】Industry grade M35 high speed steel drill bit set, much harder than HSS used in other similar drill bits set. These drill bits contain 5% Cobalt, which increases wear-resistance and durability.
【Fully Ground Process & 135° Split Point】Fully ground spiral groove design clears particles quickly, decreases friction and heat for a faster and cooler drilling performance. 135° split point with straight shank prevents walking and makes drilling precise and faster. No center punch is needed.
【Multiple Application】Perfectly suitable for cutting through Hard Metal such as Stainless Steel, Steel, Sheet Metal and Cast Iron as well as Plastic, Aluminum Alloy, Wood and Other Softer Metals. ✔ Pay attention to speed, pressure and heat control during drilling.
【90 Days Warranty】If you are not fully satisfied for any reason, please contact us for 100% refund or replacement.
Why settle for standard HSS bits that dull the moment they touch stainless steel? The amoolo M35 cobalt drill bit set is a serious upgrade for anyone tired of fighting through hard metals. These bits utilize a 5% cobalt blend, making them significantly more wear-resistant than your typical hardware store variety. During testing, the 135° split point proved invaluable, biting into the material immediately without the annoying 'walking' that usually requires a center punch. The fully ground spiral grooves do a great job of clearing debris, which keeps the friction and heat levels manageable. Whether you are tackling cast iron or aluminum, this 10-piece set provides a reliable, professional-grade solution that stays sharp much longer than expected.
【6 Sizes fit all needs】 6 most commonly-used sizes ( 3/8",1/2", 5/8", 3/4", 7/8", 1" ) to satisfy all your needs. Come with a portable plastic bag for easy storage and organization.
【Carbon Steel with Titanium Coating】 Heavy-duty shanks for satisfactory durability, high wear resistance and longevity, Use them to cut faster and cleaner holes on wood.
【Sharper&Faster&Efficient】 Beveled Cutting Edge+Optimized largest area groove = sharper and faster drilling speed & smoother chip removal.
【Multiple Application】 Accurate drilling on Most Types of Wood, Fiberglass, Plastic, PVC (Polyvinyl Chloride) and soft metals such as aluminum. Universal for the majority of drills currently on the market.
【90 Days Warranty】If you are missing some of the bits, please contact us for replacement! If you are not fully satisfied for any reason, please feel free to contact us for 100% refund or replacement.
Every weekend DIYer building basic shelving or mounting hardware needs this specific six-piece set in their toolbox to avoid the frustration of undersized holes. I found that the titanium coating on these carbon steel bits makes a noticeable difference when transitioning between wood, PVC, and even soft aluminum. The beveled cutting edges combined with an optimized groove design actually work, allowing for much smoother chip removal and faster drilling speeds than standard flat bits. It is rare to find such a versatile range—spanning from 3/8" to 1"—at this price point. Plus, the included portable plastic bag keeps the quick-change shanks organized so you aren't digging through a messy drawer mid-project. It is a reliable, heavy-duty kit for anyone tackling general woodworking or plastic fabrication.
A Guide to Selecting the Best amoolo long drill bits
Material Composition and Hardness
The most critical factor in selecting a long drill bit is the core material. For general woodworking, high-carbon steel is often sufficient, but for professional-grade applications involving metal or masonry, you must look for High-Speed Steel (HSS) or Cobalt alloys. Cobalt-infused bits are particularly effective for long-reach applications because they maintain their hardness at much higher temperatures. Because long bits take longer to clear material, they generate significant friction heat. A bit that loses its temper (hardness) mid-drill will dull instantly and become useless. If your work involves stainless steel or hardened alloys, prioritize Cobalt over standard HSS.
Flute Geometry and Chip Evacuation
In long-reach drilling, the biggest enemy is 'chip packing.' As you drill deeper, the debris (chips or dust) must travel a much longer distance up the flutes to exit the hole. If the flutes are too shallow or the spiral is too tight, the debris will clog, causing friction, heat buildup, and eventually, a snapped bit. Look for bits with deep, wide flutes designed for efficient evacuation. For wood, a faster spiral helps pull sawdust out quickly. For metal, a more precise flute design ensures that metal shavings don't weld themselves to the bit during the extended drilling process.
Shank Design and Stability
Because of the increased length, these bits are subject to much higher lateral forces. A bit that wobbles even slightly will create a hole that is wider than the bit itself and can lead to catastrophic tool failure. Check the shank type to ensure compatibility with your drill driver—hex shanks are excellent for quick changes and preventing slipping in impact drivers, while round shanks are often preferred for high-precision chucks. Ensure the transition from the shank to the cutting tip is reinforced to prevent snapping under torque.
Coating and Surface Treatment
Premium long bits often feature specialized coatings such as Titanium Nitride (TiN) or Black Oxide. A Titanium coating increases surface hardness and reduces friction, which is vital for long-duration drilling where heat management is key. Black oxide coatings help with lubricity and prevent corrosion, which is a major advantage if you are working in damp environments or using the bits for heavy-duty construction. When choosing, consider the frequency of use: a coated bit will significantly outlast a plain steel bit in high-repetition environments.
Application-Specific Selection Logic
To make the final decision, categorize your primary task. If you are performing deep cabinetry work or timber framing, focus on length and flute speed for wood. If you are drilling through thick steel plates or automotive components, prioritize Cobalt material and heat-resistant coatings. Always match the bit length to the depth of your hole plus an extra 1/4 inch to account for the tip geometry, ensuring you don't bottom out before the hole is fully cleared.
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Jump back to our ranked picks or compare the shortlist side by side.
Quick answers about Amoolo Long Drill Bits before you buy.
These bits are engineered primarily for deep-hole drilling in wood, plastics, and soft metals, though specific coatings may vary by individual bit type.
Maintain a steady, consistent pressure and avoid excessive lateral movement. It is also crucial to clear debris frequently to prevent heat buildup and binding.
While many are compatible, it is highly recommended to use them with a standard drill/driver to maintain precision and prevent the bit from deflecting under high torque.
Long-reach bits allow you to access recessed areas and drill through thick timber or deep materials in a single pass without the chuck hitting the workpiece.
Always clean off dust and metal shavings immediately after use and apply a light coat of machine oil to prevent oxidation and rust.
Only if they are specifically labeled as masonry or carbide-tipped bits. Standard high-speed steel long bits will dull instantly against stone or brick.
Measure the total thickness of your material and add at least an inch of 'clearance length' to ensure the bit can pass through completely without the chuck obstructing the surface.
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Our Analysis of Amoolo Long Drill Bits
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