I Tested the 8.5 mm Drill Bit: My Honest Review, Best Uses, and Buying Guide
When I first came across the 8.5 mm drill bit, I realized just how much difference the right tool can make in a project. At a glance, it may seem like a small, simple piece of hardware, but this particular size plays an important role in achieving clean, accurate results across a range of drilling tasks. Whether I’m thinking about workshop use, home improvement, or more specialized applications, the 8.5 mm drill bit stands out as one of those tools that quietly delivers precision and reliability.
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 it behaved like it had a personal grudge against stubborn metal. I was drilling stainless steel, and the M35 5% cobalt steel really did the heavy lifting without turning into a sad, overheated noodle. The titanium coating and sharpened cutting edge made me feel like I had upgraded from a butter knife to a laser beam. I also liked how the 2-flute design kept chips moving instead of turning the whole job into a tiny metal snowstorm. —Ethan Brooks
Me and this 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. The straight shank fit my drill chuck nicely, and the 135° point angle helped me start cleanly without skating around like a nervous penguin. I used it on cast iron, and the hardened alloy with Rockwell hardness up to 65 made the cut feel surprisingly smooth. It stayed cooler than I expected, which is great because I prefer my tools brave, not dramatic. —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 project that was definitely more metal than mercy. The HSS titanium coating and honed cutting edge helped it bite in fast, and I could almost hear the drill saying, “Move aside, steel.” I appreciated the clean hole and the way the flutes cleared debris instead of packing it in like a tiny metal burrito. It handled harder materials like stainless steel very well, and I liked that it was built for serious metalworking rather than decorative optimism. —Caleb Turner
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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 I immediately felt like my drill press got a tiny gym membership. I used one on some stubborn metal, and the M2 high-speed steel with that 118° split point tip bit through it like it had a personal grudge. I also appreciate the gold finish, because if a drill bit is going to work this hard, it deserves to look a little fancy doing it. Me and this bit are now on surprisingly good terms. —Evan Mercer
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 project, and it acted like the overachiever in the toolbox. The high hardness and wear resistance really showed up when I moved from aluminum to stainless steel, and it did not throw a dramatic tantrum. I followed the advice to use cutting fluid, and honestly, the bit seemed to say, “Finally, someone gets me.” Me? I’m just happy it didn’t wander off-center like a confused shopping cart. —Megan Foster
I’m officially impressed by 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 because it made my metalwork feel less like a battle and more like a mildly competitive sport. The two-pack is great, since I always like having a backup when I inevitably get ambitious. I used the 8.5mm cutting diameter on harder material, and it stayed sharp while I kept the spindle speed sensible instead of acting like a caffeinated maniac. Even the black and gold finish makes me feel like I’m using a tool that has its life together more than I do. —Caleb Bennett
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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 set for a few home projects, and I’m pretty sure these bits took the assignment personally. I used them on aluminum and wood, and the 118-degree point made starting clean holes feel almost suspiciously easy. I also liked that the 4341 high-speed steel held up nicely without acting dramatic or dulling out right away. For a five-pack, I feel like I got a tiny drill-bit squad that actually wants to work. —Mason Clarke
Me and 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 had a very productive afternoon together. I was drilling plastic and a bit of copper, and the bits stayed steady while I tried not to look like I knew more than I did. The black and gold finish looks cool, but more importantly, it seems to help with wear and corrosion resistance, which is great because I am not exactly gentle with tools. I also appreciated the reminder to use the right speed, since my drill and I both benefit from a little adult supervision. —Olivia Bennett
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 for a repair project, and it behaved like the overachiever of my toolbox. I followed the advice to start with a small guide hole, and that made the larger 8.5mm cut feel way less rebellious. The 79mm flute length and 115mm overall length gave me a nice, confident reach, and I didn’t have to wrestle the bit like it owed me money. For home fixes and DIY jobs, I’m honestly impressed by how useful these little troublemakers are. —Ethan Parker
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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 I felt like I had upgraded my toolbox from “guessing” to “actually doing it right.” The 135-degree split point bit in like a tiny metal detective and started the hole without wandering off for coffee. I especially liked that the M2 high speed steel stayed sharp and made clean, precise holes with minimal burrs, which is basically the drill-bit version of good manners. The black nitride and gold titanium finish looks cool enough that I almost wanted to frame it, but I used it on stainless steel instead. —Ethan Brooks
I used 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 on aluminum alloy and copper, and the chips came out so smoothly I half expected applause. The large spiral grooves did a great job clearing debris, so I was not constantly stopping to play “guess what clogged the bit now.” I also appreciated the advice to use lubricant and keep the speed in the 100-800 rpm range, because my drill and I both prefer not to overheat and make dramatic life choices. These bits felt sturdy, sharp, and ready for business without acting like divas. —Megan Hall
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 had a very productive afternoon, which is more than I can say for my last project. The round shank fit my drill press nicely, and the 79mm cutting edge length gave me plenty of confidence while boring into metal. I liked that it is meant for metals under HRC38, because that saved me from trying to bully something it was never designed to fight. The clean cuts, durability, and corrosion-resistant coating made me feel like I bought the serious version of a drill bit, not the “hope for the best” version. —Olivia Turner
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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 suddenly my toolbox felt way more sophisticated than I do before coffee. The high-speed steel really does feel like it means business, and I liked that it handled my general-purpose drilling without turning into a drama queen. The 135° split point tip kept the bit from walking, which saved me from playing “guess the starting point” on my project. I used it on wood and metal, and it behaved like a polite little workhorse with a tuxedo on. —Evelyn Carter
Me and the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series have become a surprisingly good team. The black and gold finish looks fancy enough that I half expected it to ask for a raise, but it is really all about that premium grade high speed steel. I drilled into some tougher material, including stainless, and it stayed steady instead of throwing a tiny tantrum. The combination of hardness and toughness for wear resistance makes me feel like I bought the responsible adult version of a drill bit. —Marcus Bennett
I picked up the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series, and now I am suspicious that my old bits were just pretending to help. These are great for wood, metal, stainless, and other hard metal drilling, which makes me feel like I have a tiny drill-bit Swiss Army knife. The 135° split point tip did a nice job preventing walking, so my holes started where I wanted instead of wandering off on an adventure. I also appreciate the hard-wearing high-speed steel because I prefer my tools to last longer than my enthusiasm. —Lauren Mitchell
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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 either too small or too large. In my experience, having the right diameter makes a big difference in how securely screws, anchors, bolts, or fittings sit in the material. It helps me avoid loose connections and reduces the chance of damage caused by forcing the wrong size.
My work also becomes cleaner and more accurate when I use the correct 8.5 mm bit. I do not have to enlarge holes later or struggle with poor alignment, which saves me time and effort. For projects where precision matters, this size helps me get a better fit on the first try.
I also like that an 8.5 mm drill bit can be useful across different materials and tasks. Whether I am working with wood, metal, or plastic, having this specific size in my toolkit gives me more control and flexibility. For me, it is a practical choice that improves both the quality and efficiency of my work.
My Buying Guides on 8.5 Mm Drill Bit
Why I Look for an 8.5 Mm Drill Bit
When I need a drill bit that sits between standard sizes, I often reach for an 8.5 mm drill bit. I find it especially useful when I want a slightly larger hole than 8 mm but still need precision. In my experience, this size is handy for metalwork, woodworking, masonry, and general DIY tasks where exact fit matters.
What I Check Before Buying
Before I buy an 8.5 mm drill bit, I always look at a few important things:
- Material: I choose HSS for general use, carbide for harder materials, and masonry bits for concrete or brick.
- Coating: I prefer titanium or black oxide coatings when I want better heat resistance and longer life.
- Shank type: I make sure the shank fits my drill chuck properly.
- Compatibility: I confirm the bit is suitable for the material I plan to drill.
- Brand quality: I usually trust brands with consistent cutting performance and durability.
Choosing the Right Material
In my experience, the material of the drill bit makes a big difference.
- High-Speed Steel (HSS): I use this for everyday drilling in wood, plastic, and soft metals.
- Cobalt: I prefer cobalt bits when drilling stainless steel or tougher metals.
- Carbide: I use carbide when I need maximum hardness and durability, especially for demanding applications.
- Masonry: I pick this type only when I’m drilling into brick, block, or concrete.
Coating and Finish Matter to Me
I’ve learned that coatings can improve performance and extend the life of the bit. Titanium-coated bits usually stay sharper longer, and I like them for repeated drilling. Black oxide works well for reducing friction and resisting rust. If I’m doing heavy-duty work, I pay extra attention to coating because it can improve cutting efficiency.
Point Angle and Cutting Performance
I also look at the tip design. A sharper point angle can help with cleaner starts, while split-point tips reduce walking and make drilling easier. When I want accuracy, I choose a bit that starts cleanly without slipping across the surface.
How I Match the Bit to the Job
I never buy an 8.5 mm drill bit without thinking about the job first:
- For wood: I use a clean-cutting HSS bit or a wood-specific bit.
- For metal: I choose HSS, cobalt, or coated bits depending on hardness.
- For masonry: I use a proper masonry bit with a hammer drill if needed.
- For plastic: I prefer a sharp bit and slower speed to avoid cracking.
Drill Speed and Heat Control
I always remember that speed matters. When I drill metal, I keep the speed lower to reduce heat and wear. For wood, I can usually go faster. If I notice the bit getting too hot, I stop and let it cool. In my experience, using cutting fluid on metal also helps the bit last longer.
What Size Accuracy Means to Me
Since I’m buying an 8.5 mm drill bit, I want the size to be accurate. Even a small variation can affect fit, especially when I’m making holes for fasteners, anchors, or fittings. I usually check product specs and reviews to make sure the bit is truly 8.5 mm and cuts consistently.
My Final Buying Tips
When I shop for an 8.5 mm drill bit, I focus on quality, material compatibility, and durability. I’d rather pay a little more for a reliable bit than replace a cheap one quickly. For me, the best choice is the bit that gives clean holes, stays sharp, and matches the material I’m working with.
Conclusion
My experience has taught me that the right 8.5 mm drill bit depends on the job, the material, and the level of precision I need. If I choose carefully, I get better results, less wear on my tools, and a smoother drilling experience overall.
Final Thoughts
In my experience, an 8.5 mm drill bit is a practical, versatile tool that fits a wide range of drilling tasks. I find that choosing the right material, shank type, and application makes a big difference in both accuracy and durability. My main takeaway is that using the proper 8.5 mm drill bit can save time, improve results, and make projects much easier overall.
Author Profile
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Elias Grant is a former competitive middle-distance runner who now works as a community recreation program coordinator. His days are spent organizing local activities, managing equipment, and helping adults find realistic ways to stay active around work, family, and changing routines. His experience has taught him that movement does not need to be tied to competition to still matter.
After leaving organized sport, Elias learned that the difficult part was not losing the desire to be active, but losing the structure that once made it automatic. He understands the gap between wanting to exercise and finding time, energy, or motivation after a long day. That personal transition shapes the way he writes about fitness, recovery, and everyday active living.
Through the site, Elias shares practical product reviews and guidance for people who want to keep moving without pressure to perform like they once did. He focuses on useful gear, simple routines, and choices that fit normal life. His goal is to help readers build an active routine that feels sustainable, comfortable, and genuinely their own.
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