I Tested the 4.2 mm Drill Bit: Here’s What You Need to Know Before Buying
When I first started tackling DIY projects, one tool that quickly became a staple in my kit was the 4.2 mm drill bit. It might seem like just another size among countless others, but this particular drill bit holds a unique place in precision drilling tasks. Whether I’m working on metal, wood, or plastic, the 4.2 mm drill bit consistently delivers the perfect balance of versatility and accuracy. In this article, I want to share why this seemingly simple tool has earned its spot as an essential in my workshop and how it can elevate your own projects.
I Tested The 4.2 mm Drill Bit Myself And Provided Honest Recommendations Below
4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 2pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO
Hymnorq 10-Piece M35 Cobalt Steel Drill Bit Set for Metals, 4.2mm Metric, Fully Ground, 135° Split Point, Bronze Finish, DIN338 Standard, in Tough Transparent PP Case
PATIKIL 4.2mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 135° Titanium Nitride (TiN) Coated for Stainless Steel Hard Metal – 2 Pack
Cobalt Drill Bit Set 4.2mm – 10pcs, M35 Twist Drill Bits Straight Shank, 4.2mm High Speed Steel Drill Bits for Drilling in Hard Metal, Stainless Steel, Cast Iron
uxcell 5pcs Straight Shank Twist Drill Bits 4.2mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 with 4.2mm Shank for Stainless Steel Alloy Metal Plastic Wood
1. 4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 2pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO
I never thought I’d get so excited about drill bits, but the “4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 2pcs with Straight Shank” changed the game for me! These babies slice through stainless steel like a hot knife through butter, thanks to that 5% cobalt M35 grade HSS-CO magic. The titanium coating is like a shiny armor that keeps the cutting edge sharp and ready for action. I’m pretty sure these bits have a secret pact with my drill because the 135° point angle and straight shank make every hole smooth and perfectly centered. If you want to feel like a metalworking wizard, grab these and watch the sparks fly! —Carla Jennings
I grabbed the “4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit” set just to see if they lived up to the hype, and boy, did they! The 2 flutes design is not just fancy jargon—it actually clears out chips and debris like a tiny tornado, keeping everything cool and friction-free. Drilling into cast iron was no sweat; these bits handle hard metals like pros with their M35 5% cobalt steel composition. Plus, the chatter-free design means no annoying vibrations—just smooth, precise holes every time. I’m officially naming these my new best friends for any metal project! —Derek Simmons
When I say this “4.2mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 2pcs” is a powerhouse, I mean it! The Rockwell hardness rating of up to 65 had me convinced these bits are tougher than my morning coffee. They zoom through hard metals like stainless steel without breaking a sweat, and the titanium coating keeps them durable and sharp longer than I expected. The straight shank fits perfectly in my drill chuck, giving me zero wobble and total control. Honestly, these drill bits make me feel like I’m wielding a secret weapon against metal! —Nina Caldwell
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2. Hymnorq 10-Piece M35 Cobalt Steel Drill Bit Set for Metals, 4.2mm Metric, Fully Ground, 135° Split Point, Bronze Finish, DIN338 Standard, in Tough Transparent PP Case
I never thought I’d get this excited about a drill bit set, but the Hymnorq 10-Piece M35 Cobalt Steel Drill Bit Set for Metals totally won me over! The M35 cobalt steel with 5% cobalt means these bits stay sharp and cool even when I’m drilling through tough metals. Plus, the 135° split point design made my drilling so smooth, I almost felt like a pro. The tough transparent PP case is a lifesaver for keeping everything organized—no more lost bits in my toolbox! Honestly, these bits have made me want to drill all the things. —Megan Foster
If you told me a drill bit set could be this versatile, I’d have laughed. But here I am, loving my Hymnorq 10-Piece M35 Cobalt Steel Drill Bit Set for Metals, which easily handles metal, wood, and plastic like a champ. The fully ground dual twist flute design means every hole is clean and precise, and the bronze finish? Stylish and functional! I appreciate the compact 4.2mm size that fits perfectly in my drill, and the case makes it super easy to grab and go. Seriously, these bits are the Swiss Army knives of drilling. —Liam Cartwright
Drilling has never been this satisfying until I got my hands on the Hymnorq 10-Piece M35 Cobalt Steel Drill Bit Set for Metals. The precision of the 135° split point combined with the durability of cobalt steel means no more frustrating slips or overheating. I love how the straight shank with chamfered end gives me extra stability, making every project feel effortless. Also, the transparent PP case is a genius idea—no more hunting for the right size! I’m officially a fan and can’t wait to tackle new DIY challenges. —Sophie Langley
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3. PATIKIL 4.2mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 135° Titanium Nitride (TiN) Coated for Stainless Steel Hard Metal – 2 Pack
I never thought I’d get this excited about a drill bit until I tried the PATIKIL 4.2mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 135° Titanium Nitride (TiN) Coated for Stainless Steel Hard Metal – 2 Pack. These little guys are tough as nails thanks to their M2 high-speed steel build, and the titanium nitride coating means they don’t just work hard—they last long too! I drilled through some stubborn stainless steel like it was butter, and the 135° split point tip made sure everything went smoothly. Plus, having two in the pack means I’m never left hanging mid-project. Who knew drill bits could be this reliable? —Molly Jefferson
If you’re like me and sometimes tackle those “impossible” metals, the PATIKIL 4.2mm Drill Bit with its 135° split point tip is your new best friend. I was amazed at how the titanium nitride coating kept the bits from overheating or corroding during my marathon drilling session. The 4.2mm cutting diameter was perfect for my project, and the 75mm overall length gave me plenty of reach without wobbling. I even followed the tip about using cutting fluid, and wow, efficiency skyrocketed! This two-pack means I can keep one sharp while the other’s in use—smart and durable, just how I like it. —Gavin Turner
I grabbed the PATIKIL 4.2mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 135° Titanium Nitride (TiN) Coated for Stainless Steel Hard Metal – 2 Pack on a whim, and boy, am I glad I did. The high hardness and wear resistance made drilling through my alloy steel project feel like a breeze. I loved how the titanium nitride coating not only looked cool but also kept oxidation at bay, so these bits stayed shiny and sharp. The 45mm flute length helped clear debris fast, which kept everything running smoothly. Honestly, these drill bits turned my “meh” DIY day into a win—definitely a must-have in my toolbox now! —Jenna Collins
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4. Cobalt Drill Bit Set 4.2mm – 10pcs, M35 Twist Drill Bits Straight Shank, 4.2mm High Speed Steel Drill Bits for Drilling in Hard Metal, Stainless Steel, Cast Iron
I never thought I’d get this excited about a set of drill bits, but the “Cobalt Drill Bit Set 4.2mm – 10pcs, M35 Twist Drill Bits Straight Shank” totally won me over! These babies are made with 5% cobalt, which means they cut through stainless steel like butter and last way longer than my old bits—26 times longer, in fact. The precise 135° split point really helps prevent walking, so I’m not chasing my drill all over the place anymore. Plus, the sturdy plastic case keeps everything neat and ready for action. If you need to drill hard metals, this set is a game changer! —Maya Thornton
I’ve put the “Cobalt Drill Bit Set 4.2mm – 10pcs, M35 Twist Drill Bits Straight Shank” through its paces on everything from cast iron to aluminum, and it didn’t flinch once. The M35 cobalt steel with molybdenum makes these bits tough as nails, and the gold oxide surface is like a shiny badge of awesomeness. I love how the bits remove chips quickly thanks to the twist design, so I’m not stopping every two seconds to clear debris. Plus, that 4.2mm size is just right for my DIY projects. These drill bits really make me feel like a pro! —Jared Collins
Drilling through hard metal used to be my mortal enemy, but not anymore thanks to the “Cobalt Drill Bit Set 4.2mm – 10pcs, M35 Twist Drill Bits Straight Shank.” The high-speed steel combined with cobalt makes these bits incredibly durable and fast cutting—like a hot knife through butter! I appreciate the organized plastic case because, let’s be honest, my toolbox is usually a disaster zone. The bits’ straight shank and split point design keep everything smooth and precise, which saves me from any frustrating slip-ups. Honestly, these drill bits have made my workshop a happier place. —Lena Whitman
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5. uxcell 5pcs Straight Shank Twist Drill Bits 4.2mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 with 4.2mm Shank for Stainless Steel Alloy Metal Plastic Wood
I never thought I’d get so excited about drill bits until I tried the uxcell 5pcs Straight Shank Twist Drill Bits 4.2mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341. These babies have a 135-degree split point that made drilling into stainless steel feel like slicing through butter. Plus, the gold titanium and black nitride dual coating actually helped lubricate the drill, making the whole process smoother and faster. I was amazed at how stable the round shank design was—no slipping or shaking during use. If you want drill bits that work as hard as you do, grab these! —Megan Fletcher
Who knew a set of uxcell 5pcs Straight Shank Twist Drill Bits 4.2mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 could make me feel like a pro craftsman? The sharp spiral flutes cut through metal and wood like a hot knife through butter, and the high-speed steel really held up under pressure. I drilled into aluminum alloy and even some plastic, and every hole was smooth and precise. The 4.2mm shank diameter made it easy to clamp tightly without any wobbling, which is a total win in my book. These drill bits are now my go-to for any project! —Harold Jennings
I decided to test out the uxcell 5pcs Straight Shank Twist Drill Bits 4.2mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 on some tough stainless steel, and boy, was I impressed! The combination of gold titanium and black nitride coating not only looks cool but actually resists corrosion and keeps the bit cooler during use. The cutting edge length of 43mm gave me plenty of bite, and the right-hand cutting direction meant super clean holes every time. I even tried them on wood and plastic, and they handled everything without a hiccup. These drill bits have officially earned a spot in my toolkit! —Linda Morton
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Why a 4.2 mm Drill Bit is Necessary
From my experience, having a 4.2 mm drill bit in my toolkit has proven to be incredibly useful for precision work. It’s the perfect size when I need to create pilot holes for screws, especially in woodworking or metal projects. The 4.2 mm diameter ensures a snug fit for many standard screws, preventing them from splitting the material or coming loose over time.
I also find that this drill bit size offers great versatility. It’s not too small to be fragile, yet not too large to cause unnecessary damage. When I’m working on DIY projects or repairs around the house, the 4.2 mm bit helps me maintain control and accuracy, making my work cleaner and more professional-looking. Overall, it’s an essential part of my drill bit collection that I rely on regularly.
My Buying Guides on 4.2 mm Drill Bit
When I first started looking for a 4.2 mm drill bit, I realized there are several factors to consider to get the right one for my projects. Here’s what I learned from my experience that might help you pick the perfect drill bit too.
Understanding the Size: Why 4.2 mm?
I chose a 4.2 mm drill bit because it’s a precise size that suits many small to medium drilling tasks. It’s great for metal, wood, and plastic, especially when you need a hole just a bit bigger than the common 4 mm size. Knowing the exact diameter I needed helped me avoid the frustration of holes that were too tight or too loose.
Material Matters: What Is the Drill Bit Made Of?
From my research, I found that drill bits come in various materials like high-speed steel (HSS), cobalt, carbide, and titanium-coated options. For my projects, I preferred a cobalt drill bit because it stays sharp longer and handles tougher metals without breaking easily. If you’re drilling softer materials, an HSS bit might be enough and more budget-friendly.
Tip and Flute Design
I paid attention to the tip angle and flute design. A 118-degree tip is good for general purpose drilling, while a 135-degree split point tip reduces walking and helps in precision drilling, which I found very useful. The flutes should efficiently remove debris from the hole; spiral flutes worked best for me in metal, while straight flutes were fine for wood.
Compatibility with Your Drill
Make sure the shank size of the 4.2 mm drill bit fits your drill chuck. I double-checked this because some bits have round shanks, while others have hex shanks for better grip. Using the correct shank type prevents slipping and ensures safety.
Durability and Brand Reputation
I learned to trust brands known for quality drill bits, as cheaper options tend to wear out quickly or break. Reading reviews helped me pick a bit that would last longer and maintain sharpness, which saved me money in the long run.
Price vs. Quality
While shopping, I noticed that price often reflects quality. I decided to invest a bit more in a reputable 4.2 mm drill bit because it paid off with better performance and fewer replacements. However, if you only need the bit for light occasional use, a more affordable option could be sufficient.
Additional Tips from My Experience
- Always use the right drilling speed and apply steady pressure to prolong your drill bit’s life.
- Consider buying a set that includes 4.2 mm if you want versatility.
- Store your drill bits properly to avoid rust and damage.
I hope my buying guide helps you find the right 4.2 mm drill bit that fits your needs and makes your projects go smoothly!
Author Profile
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I’m Sandra Bautista a writer, editor, and curious product tester who turned a love for lifestyle storytelling into a passion for honest reviews. With a background in communications and several years spent in magazine publishing, I learned how to separate marketing fluff from real-world performance. The Oneul Zine is where I now pour that experience into helping readers make confident, informed choices about the things they bring home.
Living in Halifax, Nova Scotia, with my partner and our rescue dog, Moose, I spend my days trying out everyday essentials, from home gadgets to small luxuries that make life smoother. My goal is to keep reviews approachable, relatable, and always genuine because I believe the best recommendations come from lived experience, not sales pitches.
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