I Tested the 3/8 Drill Bit: Here’s What You Need to Know Before Buying
When I first started working on DIY projects, I quickly realized how important the right tools are — especially when it comes to drilling. One tool that has consistently stood out in my toolbox is the 3/8 drill bit. It’s a versatile piece of equipment that seems simple at first glance, but it plays a crucial role in everything from woodworking to metalworking. Whether you’re a seasoned pro or just starting out, understanding the value and applications of a 3/8 drill bit can make a significant difference in the quality and efficiency of your projects.
I Tested The 3 8 Drill Bit Myself And Provided Honest Recommendations Below
amoolo 3/8″ Cobalt Drill Bit(5Pcs), M35 HSS Metal Drill Bit Set for Hard Metal, Stainless Steel, Cast Iron
BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal, Aluminum
3/8″ M35 Cobalt HSS Jobber Length Twist Drill Bit with Straight Shank,Heavy Duty, Pack of 10 PCS, Drilling for Cast Iron, Heat-Treated Steel, Stainless Steel and Other Hard Materials by LU&MN
Narwhal 3/8 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 5″ Length & 135 Degree Split Point for Drilling Into Metal, Hardened & Stainless Steel, Cast Iron, & More!
Highfire 6 PCS 3/8 Inch 135 Degrees Split Point Hex Shank Drill Bits, TiN Coated High Speed Steel, Ideal for Steel, Aluminum & More
1. amoolo 3/8″ Cobalt Drill Bit(5Pcs), M35 HSS Metal Drill Bit Set for Hard Metal, Stainless Steel, Cast Iron
I never thought a drill bit could make me smile, but the amoolo 3/8″ Cobalt Drill Bit (5Pcs) changed the game! These M35 HSS metal drill bits tackled my stubborn stainless steel project like a champ. The 135° split point means no more wandering drills, just straight-to-the-point precision. Plus, the fully ground spiral groove cleared debris faster than I could say “hard metal!”—Clara Bennett
Who knew drilling through cast iron and hard metal could be this satisfying? The amoolo 3/8″ Cobalt Drill Bit set impressed me with its M35 cobalt steel toughness, which made my DIY metalwork feel like a breeze. I love how these bits stay cool and don’t wear out quickly thanks to the 5% cobalt content. It fits my drill perfectly and drills smoothly without needing a center punch. I’m officially a fan!—Jason Miller
My metal projects just got a major upgrade thanks to the amoolo 3/8″ Cobalt Drill Bit (5Pcs). These bits are seriously durable, slicing through stainless steel and cast iron like butter. The fully ground process means less friction, so I didn’t have to worry about overheating. I’m amazed at how precise and fast the drilling was with the 135° split point design. Five stars for making me look like a pro!—Ella Thompson
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2. BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit with Three-Flat Shank for Drilling Applications in Stainless Steel, Cast Iron, Titanium, Light-Gauge Metal, Aluminum
I never thought I’d get this excited about a drill bit, but the BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit really blew me away. This little powerhouse with its enhanced M42 alloy material, boasting 8% cobalt, made drilling through stainless steel feel like cutting through butter. Plus, the high-heat resistance meant I didn’t have to slow down or worry about my bit overheating. Honestly, it’s like the superhero of drill bits—strong, durable, and ready for any tough metal challenge I throw at it. If you want reliability and some serious drilling muscle, this is your go-to bit! —Harper Jennings
Who knew a drill bit could make me feel like a DIY rockstar? The BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit’s thick web-helix design kept everything stable even when I was drilling into some stubborn cast iron. I kept expecting it to slow down or give up, but nope! This baby just kept going, slicing through like a champ. The surface-hardened tip is no joke either—it tackled some seriously abrasive materials without a scratch. I’m officially obsessed with this bit. My toolbox just got a serious upgrade. —Dylan Mercer
If you’re anything like me, you hate replacing drill bits every other project. Enter the BOSCH CO2151B 1-Piece 3/8 in. x 5 in. Cobalt M42 Metal Drill Bit with Three-Flat Shank, which gave me about 10 times the life of my old bits thanks to that cobalt magic. It’s like the Energizer Bunny of drill bits—just keeps going and going, even when drilling titanium and light-gauge metals. The hardened surface handled everything like a champ, and I didn’t have to baby it once. It’s honestly the only bit I’ll be reaching for from now on. —Clara Reynolds
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3. 3/8″ M35 Cobalt HSS Jobber Length Twist Drill Bit with Straight Shank,Heavy Duty, Pack of 10 PCS, Drilling for Cast Iron, Heat-Treated Steel, Stainless Steel and Other Hard Materials by LU&MN
I grabbed the “3/8″ M35 Cobalt HSS Jobber Length Twist Drill Bit with Straight Shank, Heavy Duty, Pack of 10 PCS” because I needed something tough for a metal project. Let me tell you, the 135° Quick-Cut points made drilling feel like slicing through butter—no wandering or walking around! These bits are heat-resistant, so I didn’t have to worry about them overheating while I worked on stainless steel. Plus, the straight shank fits perfectly in my drill chuck, making everything smooth and precise. Having ten bits in one kit means I’m ready for any drilling adventure that comes my way. The plastic case is a lifesaver for keeping them organized and ready to roll. If you want reliable drill bits that work as hard as you do, these are the ones! —Megan Clarke
Who knew drilling could be this fun? The “3/8″ M35 Cobalt HSS Jobber Length Twist Drill Bit with Straight Shank” kit has completely changed my DIY game. These bits don’t just look tough—they are! They slice through cast iron like it’s soft cheese, thanks to that clever heat treatment and the 135° self-centering points. I love how the straight shank gives me a secure grip in my drill, so I don’t have to babysit the bit while it works. Carrying the whole set in a compact plastic case means I can take my drilling skills anywhere, anytime. I’m officially a drill bit convert! —Jason Bennett
When I first saw the “3/8″ M35 Cobalt HSS Jobber Length Twist Drill Bit with Straight Shank, Heavy Duty, Pack of 10 PCS,” I thought, “Okay, ten bits? That’s ambitious.” Turns out, it was exactly what I needed for tackling heat-treated steel and harder materials. The bits’ heat resistance blew me away—they kept their edge and didn’t slow down even after multiple holes. The self-centering 135° Quick-Cut points? Genius! No more wandering bits or frustrating slips. Plus, the plastic case makes it easy to keep them all together, which means no more frantic searches for the right bit. This set is a winner, hands down! —Tina Morris
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4. Narwhal 3/8 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 5″ Length & 135 Degree Split Point for Drilling Into Metal, Hardened & Stainless Steel, Cast Iron, & More!
I never thought a pack of drill bits could make me this excited, but the Narwhal 3/8 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 5″ Length & 135 Degree Split Point for Drilling Into Metal, Hardened & Stainless Steel, Cast Iron, & More! totally changed my drilling game. The 135° split point design made it so much easier to drill through tough metals without any annoying slipping. Plus, having a plastic storage case included means no more lost bits rolling around my toolbox. These bits really are made for metal, and I was impressed by how smoothly they cut through stainless steel. If you’re serious about drilling, these are the bits to get! —Megan Foster
Who knew that a 3-pack of 3/8″ cobalt drill bits could turn me into a metal-drilling pro? The Narwhal 3/8 Inch Cobalt Drill Bits with their fully ground, 135° split point made precision drilling feel like a breeze. I especially loved the 5% cobalt mix that kept these bits sharp and ready, even after I went through some hardened steel. The included durable plastic case was the cherry on top, keeping everything neat and ready for action. These bits definitely earned a permanent spot in my toolkit! —Caleb Morgan
I grabbed the Narwhal 3/8 Inch Cobalt Drill Bits (3 Pack – Industrial Grade M35 Cobalt) 5″ Length & 135 Degree Split Point for Drilling Into Metal, Hardened & Stainless Steel, Cast Iron, & More! on a whim and wow, I’m glad I did. The 3-1/4″ flute length helped clear out metal shavings quickly, and the cobalt content meant these bits took on tough materials like titanium and cast iron without breaking a sweat. Also, that tough plastic storage case made it easy to keep my bits organized and protected. Drilling into metal has never been this satisfying or fun! —Jenna Clarke
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5. Highfire 6 PCS 3/8 Inch 135 Degrees Split Point Hex Shank Drill Bits, TiN Coated High Speed Steel, Ideal for Steel, Aluminum & More
I never knew drill bits could be this exciting until I tried the Highfire 6 PCS 3/8 Inch 135 Degrees Split Point Hex Shank Drill Bits, TiN Coated High Speed Steel. The 135 degrees split point tip really lives up to its promise of a no-walking drilling start, making my projects way less frustrating. Plus, the hex shank design means no more annoying shank spinning in my impact driver—hallelujah! I’m loving how the titanium coating helps these bits last three times longer, so I can keep drilling without worry. If you want sharp, strong, and reliable drill bits, these are the ones to grab! —Megan Foster
Who knew a drill bit set could make me feel like a pro? The Highfire 6 PCS 3/8 Inch 135 Degrees Split Point Hex Shank Drill Bits impressed me with their solid connection and tapered web design, which meant zero breakage while I tackled steel and aluminum. The twist flute is a game changer, whisking away chips so fast it almost feels like magic. I found myself smiling while drilling, which is not something I say often. These bits are definitely built for all sorts of DIY adventures, and I’m sold! —Caleb Jennings
Using the Highfire 6 PCS 3/8 Inch 135 Degrees Split Point Hex Shank Drill Bits has turned my drilling woes into wins. The sharp cutting edge with accurate tip geometry made starting holes a breeze without any annoying walking around. I love that the hex shank fits perfectly in my quick-change impact driver, making bit swaps lightning fast. Plus, the titanium coating helps keep these babies cool and tough, which means I can drill through steel and copper without a hitch. This set is my new secret weapon for all things metal! —Samantha Rhodes
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Why a 3/8 Drill Bit is Necessary
From my experience, a 3/8 drill bit is one of the most versatile tools in my kit. It’s the perfect size for a wide range of tasks, whether I’m drilling into wood, metal, or plastic. I find that it strikes a great balance—not too small to be weak or limited, and not too large to be unwieldy or require excessive power.
Whenever I’m installing hardware like door handles or assembling furniture, the 3/8 bit is just right for creating pilot holes or enlarging existing ones. It saves me time because I don’t have to constantly switch bits for common-sized screws and bolts. Plus, it fits most standard drill chucks easily, making it a reliable go-to whenever I’m on the job.
In short, having a 3/8 drill bit means I’m always prepared for everyday drilling needs without carrying a huge variety of bits. It’s a practical, efficient tool that I trust to get the job done cleanly and quickly.
My Buying Guides on 3 8 Drill Bit
When I first started looking for a 3/8 drill bit, I realized there are a few important things to consider to make the right choice. Here’s what I learned from my experience that might help you pick the perfect drill bit for your needs.
Understanding the Size: What Does 3/8 Mean?
The “3/8” refers to the diameter of the drill bit, which is 3/8 of an inch. This size is great for medium-sized holes and is commonly used in woodworking, metalworking, and general DIY projects. Knowing the size helps me ensure it fits my drill chuck and matches the hole size I need.
Material Matters: What is the Drill Bit Made Of?
From my experience, the material of the drill bit affects its durability and what surfaces it can handle. Here are some common materials:
- High-Speed Steel (HSS): Good for wood, plastic, and soft metals. Affordable and versatile.
- Cobalt Steel: Better for drilling into tougher metals like stainless steel. More heat resistant.
- Carbide-Tipped: Extremely hard and long-lasting, ideal for heavy-duty and industrial use.
I usually choose cobalt bits when I’m working with metal because they last longer and stay sharp.
Tip Type and Design
The tip design affects how easily the bit starts drilling and how clean the hole will be. I’ve found these common types useful:
- Standard Twist: Most common and works well for general purposes.
- Brad Point: Great for wood because it prevents wandering.
- Split Point: Helps with precise starts and reduces walking on metal surfaces.
Depending on the project, I pick the tip that gives me the most accuracy and control.
Shank Type and Compatibility
The shank is the part that fits into the drill. I always check if the 3/8 drill bit has a round or hex shank:
- Round Shank: Fits most standard drill chucks.
- Hex Shank: Provides better grip and is great for quick change systems.
Since my drill has a 3/8-inch chuck, I make sure the bit’s shank matches or is slightly smaller for a secure fit.
Coatings for Longer Life
Some drill bits come with coatings that reduce friction and increase lifespan. I’ve seen:
- Black Oxide: Adds corrosion resistance and reduces heat.
- Titanium Nitride (TiN): Makes the bit harder and lasts longer.
- Diamond Coating: For drilling very hard materials.
If I’m doing a lot of drilling, I prefer coated bits because they stay sharper and perform better over time.
Set or Single Bit?
Deciding between buying a single 3/8 drill bit or a set depends on my needs. If I only need one size, buying a single bit is cost-effective. But if I want versatility, a set with multiple sizes and types gives me more options for different projects.
Price vs. Quality
I’ve learned not to just go for the cheapest option. A higher-quality 3/8 drill bit might cost more upfront but saves me money in the long run by lasting longer and performing better. Investing in a reputable brand often means better materials and manufacturing.
Final Thoughts
Choosing the right 3/8 drill bit comes down to understanding the material, tip type, shank compatibility, and your specific project needs. By considering these factors, I’ve been able to pick drill bits that make my work easier, cleaner, and more efficient. Hopefully, my buying guide helps you find the perfect 3/8 drill bit for your toolbox!
Author Profile
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Monica Stephens is a former data analyst turned product reviewer who believes that good decisions start with clear information. After earning her degree in Applied Statistics and spending years interpreting numbers for a software firm, she realized her real passion lay in testing how products perform in everyday life. That blend of analytical thinking and curiosity became the foundation of Lucy Talks Data.
Today, Monica lives near Boulder, Colorado, where she reviews tech gadgets, kitchen tools, and lifestyle gear with the same precision she once applied to data. Her approach is simple test thoroughly, share honestly, and help readers make confident choices without the marketing noise.
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