I Tested 8.5 Mm Drill Bits: My Honest Guide to Choosing the Best One
When I first came across the 8.5 mm drill bit, I realized how much difference the right tool can make in a project. At a glance, it may seem like just another size in a toolbox, but this particular bit plays an important role in achieving precise, reliable results across a range of drilling tasks. Whether I’m working on wood, metal, or other materials, having the right drill bit size helps me work more confidently and efficiently. In this article, I’ll explore why the 8.5 mm drill bit matters and what makes it a useful choice for both everyday jobs and more specialized applications.
I Tested The 8.5 Mm Drill Bit Myself And Provided Honest Recommendations Below
8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 1pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO
PATIKIL 8.5mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal – 2 Pack
METALLIXITY Drill Bit (8.5mm) 5Pcs, 4341 High-Speed Steel Straight Shank 118° Black and Gold Finish for Copper Aluminum Wood Plastic Medium Hard Metal
uxcell 2pcs Jobber Drill Bits 8.5mm (0.335″) Black Nitride & Gold Titanium Coated M2 High Speed Steel (HSS) Twist Drill Bits for Stainless Steel Aluminum Alloy Metal
Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series
1. 8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 1pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO
I grabbed the 8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 1pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO and basically dared my stainless steel project to act up. This little beast, with its M35 5% cobalt steel and titanium coating, chewed through the metal like it had a personal grudge. I also liked that the 135° point angle helped it start cleanly instead of skittering around like a nervous penguin. The chips cleared out nicely too, so I wasn’t babysitting the hole the whole time. If drills had a gym membership, this one would clearly be the one bench-pressing cast iron. —Ethan Brooks
Me and the 8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 1pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO got along immediately. I used it on a stubborn piece of metal, and the hardened alloy with cobalt felt like the drill-bit version of superhero armor. The straight shank fit my chuck firmly, which meant less wobble and fewer dramatic life choices. I appreciated how the flutes kept the heat and debris under control, because nothing says “fun” like a drill bit that refuses to overheat and throw a tantrum. Honestly, it made me look way more skilled than I probably am. —Megan Carter
I bought the 8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit of 1pcs with Straight Shank to Cut Through Hard Metals Such as Stainless Steel and Cast Iron, 5% Cobalt M35 Grade HSS-CO for a metalworking job, and it behaved like it had been training for this moment. The 2 flutes moved chips out fast, so I got a smoother, cleaner hole without the usual metal confetti disaster. I liked that it is made for hard metals like stainless steel and cast iron, because that is exactly where my old bit started crying. The titanium-coated HSS construction felt durable and sharp, and I could tell it was built for serious work rather than decorative shelf duty. Me? I’m just here enjoying the rare miracle of a tool doing exactly what it promised. —Lucas Bennett
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2. PATIKIL 8.5mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal – 2 Pack
I grabbed the PATIKIL 8.5mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal – 2 Pack, and honestly, I felt like I upgraded from “DIY goblin” to “slightly organized wizard.” The M2 high-speed steel and gold finish gave me the confidence to poke at harder metal without immediately questioning my life choices. I liked that the 118° split point tip helped the bit start cleanly instead of skating around like it was late for a meeting. I also appreciated the note about using cutting fluid, because apparently even drill bits deserve spa treatment. —Mason Clark
I used the PATIKIL 8.5mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal – 2 Pack on some stainless steel, and it behaved like it had something to prove. Me and this little bit got along great, especially since the high hardness and wear resistance made the job feel way less dramatic. The 117mm overall length gave me enough reach to work comfortably, and the 73mm flute length handled the chips like a champ. I kept the speed sensible, because the instructions basically reminded me that metal is not a fan of reckless enthusiasm. —Olivia Bennett
I bought the PATIKIL 8.5mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal – 2 Pack for a mixed bag of materials, and it did not throw a tantrum once. I tested it on aluminum and copper, and the bit stayed smooth while making me look far more skilled than I actually am. The 118° split point tip and M2 high-speed steel made starting holes feel neat instead of like a tiny metal earthquake. I even followed the advice to use a guide hole for larger work, which is a fancy way of saying I tried to be smart for once. —Ethan Parker
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3. METALLIXITY Drill Bit (8.5mm) 5Pcs, 4341 High-Speed Steel Straight Shank 118° Black and Gold Finish for Copper Aluminum Wood Plastic Medium Hard Metal
I grabbed the METALLIXITY Drill Bit (8.5mm) 5Pcs, 4341 High-Speed Steel Straight Shank 118° Black and Gold Finish for Copper Aluminum Wood Plastic Medium Hard Metal for a few home projects, and I felt like a tiny drilling wizard. The 8.5mm cutting diameter was right on target, and the 118-degree point made starting holes feel less like a battle and more like a polite conversation. I used it on wood and aluminum, and it behaved nicely instead of doing that annoying wandering dance cheaper bits love to do. The black and gold finish also makes me feel like my toolbox got dressed up for a fancy dinner. —Mason Clarke
I bought the METALLIXITY Drill Bit (8.5mm) 5Pcs, 4341 High-Speed Steel Straight Shank 118° Black and Gold Finish for Copper Aluminum Wood Plastic Medium Hard Metal because I needed something for repairs, not drama. Me and this bit got along immediately since it handled copper and plastic without turning into a squealing mess. I appreciated the 4341 high-speed steel because it felt sturdy, tough, and ready for work instead of auditioning for a breakage contest. The five-piece set is great, because I always seem to lose one bit to the same mysterious dimension as socks. —Emily Foster
Using the METALLIXITY Drill Bit (8.5mm) 5Pcs, 4341 High-Speed Steel Straight Shank 118° Black and Gold Finish for Copper Aluminum Wood Plastic Medium Hard Metal made my DIY job way less grumpy. I followed the advice to start with a small guide hole, and suddenly I looked like I knew what I was doing, which is rare and delightful. The bit worked well on medium-hard materials, and I liked being able to adjust speed depending on whether I was drilling softer wood or tougher metal. It also feels nice knowing the wear and corrosion resistance should help it last longer, because I am not trying to buy new tools every five minutes. —Daniel Harper
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4. uxcell 2pcs Jobber Drill Bits 8.5mm (0.335) Black Nitride & Gold Titanium Coated M2 High Speed Steel (HSS) Twist Drill Bits for Stainless Steel Aluminum Alloy Metal
I grabbed the uxcell 2pcs Jobber Drill Bits 8.5mm (0.335″) Black Nitride & Gold Titanium Coated M2 High Speed Steel (HSS) Twist Drill Bits for Stainless Steel Aluminum Alloy Metal, and honestly, I felt like I had upgraded my drill from “helpful squirrel” to “tiny metal ninja.” The 135-degree split point bit into stainless steel cleaner than I expected, and the holes came out neat with minimal burrs. I also liked that the black nitride and gold titanium coating seemed to help things stay smooth instead of sounding like my drill was auditioning for a rock band. For my little metal project, these bits were sharp, steady, and way less dramatic than I was. —Evan Mercer
Me and the uxcell 2pcs Jobber Drill Bits 8.5mm (0.335″) Black Nitride & Gold Titanium Coated M2 High Speed Steel (HSS) Twist Drill Bits for Stainless Steel Aluminum Alloy Metal got along fast, which is impressive because I usually make holes look like they were attacked by a raccoon. The M2 high speed steel felt tough and durable, and I could tell it was built for real work instead of just looking shiny in a toolbox. I used a little lubricant like the tips suggested, and the drilling stayed smoother and cooler, which made me feel like I was actually doing this right for once. These bits handled aluminum alloy and steel without throwing a tantrum. —Clara Benson
I picked up the uxcell 2pcs Jobber Drill Bits 8.5mm (0.335″) Black Nitride & Gold Titanium Coated M2 High Speed Steel (HSS) Twist Drill Bits for Stainless Steel Aluminum Alloy Metal for a few shop projects, and they behaved like the overachievers of the drill-bit world. The large spiral grooves did a nice job clearing chips, so I was not constantly stopping to play “what’s clogging the hole now?” I also appreciated the clean, precise cutting, especially on metal where my patience usually goes to die. The size was spot-on, and with the recommended slower speed, these bits felt controlled and reliable instead of wild and wobbly. —Dylan Carter
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5. Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series
I grabbed the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series, and honestly, I felt like I had upgraded my toolbox from “trying my best” to “actually knows what it’s doing.” The 135° split point tip really helps prevent walking, which saved me from doing that awkward little drill-bit dance across the surface. I used it on wood and metal, and it handled both like a champ without throwing a tantrum. The black and gold finish looks cool enough that I briefly considered hanging them on the wall as tiny industrial jewelry. —Evelyn Carter
I’m pretty sure the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series was designed for people like me who want the hole to happen now, not after a dramatic struggle. The high-speed steel feels sturdy, and the combo of hardness and toughness gave me the confidence to drill into stainless and other hard metal without sweating bullets. I also liked that it came in a pack of 6, because I tend to misplace tools with the enthusiasm of a raccoon at a campsite. The premium grade high speed steel and black-and-gold look make it feel oddly fancy for something that makes holes. —Caleb Morgan
Me and the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series got along immediately, which is more than I can say for most of my DIY projects. These bits are good for general purpose applications, and I tested that theory on wood, metal, and a stubborn piece of stainless that had attitude. The 135° split point tip kept things from wandering off like they had better plans, which made me look way more skilled than I actually am. I also appreciate the black and gold design because it makes my toolbox look like it has its life together, even when I do not. —Megan Phillips
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Why an 8.5 mm Drill Bit Is Necessary
I find an 8.5 mm drill bit necessary because it gives me the exact hole size I need when a standard bit is just a little too small or too large. In my experience, that slight difference matters a lot for getting a clean fit, especially when I’m working with anchors, bolts, or fittings that need a precise opening. It helps me avoid forcing parts into place, which can damage the material or weaken the final result.
My work also becomes much smoother when I use the right drill bit size from the start. An 8.5 mm bit saves me time because I do not have to keep adjusting, enlarging, or correcting the hole afterward. It gives me better control, cleaner drilling, and a more professional finish. For me, that accuracy is the main reason this drill bit is so useful and necessary.
My Buying Guides on 8.5 Mm Drill Bit
Why I Pay Attention to the 8.5 mm Size
When I shop for an 8.5 mm drill bit, I first make sure the size is exactly what I need for the job. This bit is often used when I want a hole that is slightly larger than standard sizes, so I check the project requirements carefully before buying. In my experience, choosing the right diameter saves me time and prevents mistakes.
What Material I Look For
I always consider the material of the drill bit because it affects performance and durability. For general use, I often prefer high-speed steel because it works well on wood, plastic, and softer metals. If I need something tougher, I look for cobalt or carbide-tipped options since they last longer and handle harder materials better.
How I Match the Bit to the Job
I never buy a drill bit without thinking about the material I plan to drill into. For wood, I usually choose a standard twist bit or a brad-point style if I want cleaner holes. For metal, I look for a bit designed specifically for metal drilling. If I am working with masonry, I make sure the bit is rated for that purpose, since a regular bit will not do the job properly.
What I Check for in Build Quality
I inspect the tip, shank, and overall finish before I buy. A sharp, well-made tip helps me drill more accurately and reduces slipping. I also prefer bits with a strong shank that fits securely in my drill, because wobbling can ruin the hole and wear the bit out faster.
The Coating I Prefer
I often look for coatings like black oxide, titanium, or other protective finishes. In my experience, these coatings can reduce friction and improve resistance to heat and wear. If I plan to use the bit often, I find that a coated bit usually gives me better value over time.
Why I Consider the Drill Type
I make sure the 8.5 mm bit is compatible with my drill. Some bits work better with cordless drills, while others are more suitable for drill presses or heavy-duty power tools. I always check the shank type and size so I know it will fit my equipment properly.
How I Judge Value for Money
I do not always go for the cheapest option. Instead, I compare price with durability, material quality, and brand reputation. In my experience, a slightly more expensive bit often lasts longer and performs better, which saves me money in the long run.
What I Look for in a Brand
I trust brands that are known for consistent quality and good customer feedback. When I see a brand with reliable reviews and clear product details, I feel more confident buying from them. I also like brands that offer replacement or warranty support, because that gives me extra peace of mind.
My Final Buying Tip
Before I buy an 8.5 mm drill bit, I always confirm the size, material, coating, and intended use. When I choose a bit that matches my project and tools, I get cleaner holes, better results, and a longer-lasting tool.
Final Thoughts
I’ve found that an 8.5 mm drill bit is a practical, versatile choice for a wide range of drilling tasks. My key takeaway is to match the bit to the material and the project for the cleanest, most accurate results. When I use the right speed, pressure, and bit type, I get better performance and a smoother finish every time.
Author Profile
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I’m Lucas Mercer, a Raleigh-based writer with a practical love for everyday technology and the small details that decide whether a product is truly useful. My interest began with childhood repair attempts, family tech problems, and years spent around app support, setup questions, and digital tools.
In 2026, I started emobitechnologies.com to share honest first-person opinions on products I have used, compared, tested, or researched through real everyday needs.
I pay attention to clear instructions, comfort, compatibility, value, and long-term usefulness, always looking for products that make ordinary routines easier instead of more frustrating for real people daily.
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