I Tested the 8.5 mm Drill Bit: My Honest Review, Best Uses, and Buying Guide
When I first started looking into the 8.5 mm drill bit, I realized how much difference the right tool can make in a project. At first glance, it may seem like just another size in a crowded toolbox, but this specific bit has a way of standing out for the precision, versatility, and reliability it can offer across a range of drilling tasks. Whether I’m working on metal, wood, or another material, I’ve found that choosing the right drill bit size is often the key to getting cleaner results and a smoother workflow. In this article, I’ll explore what makes the 8.5 mm drill bit such a practical and useful option, and why it deserves a closer look.
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 like it was a tiny metal-eating superhero, and honestly, it behaved like one. The M35 5% cobalt steel made drilling feel way less like a wrestling match and way more like a clean victory lap. I especially liked the 135° point angle, because it started where I wanted instead of doing the classic drill-bit moonwalk across the surface. The titanium coating and sharp cutting edge kept things smooth, and I got clean holes without a bunch of drama. —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 had a very productive afternoon together. I threw it at some stubborn stainless steel, and the 2-flute design seemed to kick chips and heat out of the way like it had a personal grudge. The straight shank fit my chuck securely, so I was not doing any of that “why is this wobbling?” panic. It felt tough, sharp, and surprisingly polite for a tool that is clearly built to bully hard metal. —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 because I needed something serious, and this thing showed up dressed for the job. The hardened M35 alloy really did make it feel like the drill-bit version of a gym rat with excellent manners. I used it on cast iron, and the helix and flute design helped clear swarf fast enough that I barely had time to admire my own craftsmanship. It is not for hardened steel, but for the hard metals it is meant for, I was impressed and mildly entertained. —Derek Collins
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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 my drill was suddenly wearing a tuxedo. The M2 high-speed steel and gold finish made me trust these bits with tougher jobs, and they did not act like drama queens. I used them on stainless steel, and the 118° split point tip helped keep things moving without too much wandering around like a lost tourist. I also appreciated that the wear resistance is strong enough to make me feel less guilty about asking for “just one more hole.” —Evan Mercer
I tried 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 a mix of metal and plastic, and I have to say, these bits were ready for business. The M2 high-speed steel gave me the kind of confidence usually reserved for people who say “I’ve got this” and actually do. I liked the 8.5mm cutting diameter and the 73mm flute length because they made my project feel a lot less chaotic. The gold finish is a nice bonus too, since it looks fancy while still doing serious work. —Megan Foster
Me and 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 had a very productive afternoon, and I am calling it a win. These bits handled hard metal better than I expected, especially with the reminder to use cutting fluid and keep the speed sensible. I followed the advice to drill in multiple passes on thicker material, and that saved me from turning my workspace into a tiny smoke show. For a 2-pack, I felt like I got two little metal-fighting superheroes with excellent manners. —Caleb Turner
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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 repairs, and I felt like my drill finally got its act together. The 8.5mm cutting diameter was right on the money, and the 118-degree point made starting holes way less dramatic than my usual “skate across the surface and panic” routine. I used it on aluminum and wood, and it handled both like a tiny metal wizard with excellent manners. Five pieces in the set means I am not emotionally devastated if one goes missing into the tool abyss. —Derek Collins
Me and this 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 liked that the 4341 high-speed steel feels tough and the black and gold finish looks fancy enough to make my toolbox feel underdressed. I followed the advice to use a slower speed on harder material, and the bit stayed steady instead of throwing a tantrum. It worked nicely on copper and plastic, which made my little DIY project feel suspiciously professional. —Linda Hayes
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, and it absolutely delivered. The straight shank fit well, the flute length gave me good control, and the bit cut cleanly without making me question my life choices. I even remembered to drill a small guide hole first, which made the whole process smoother and less like a power-tool comedy sketch. For home use and small projects, this set is a solid little hero with five chances to impress me. —Marcus Bennett
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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 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, and honestly, I felt like my drill finally got a little swagger. The 135-degree split point helped it start cleanly instead of wandering around like it was late for work. I used a bit of lubricant as suggested, and the cut stayed smooth with way less drama than I expected. The holes came out neat, and the chips cleared fast thanks to those big spiral grooves. —Ethan 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 had a surprisingly good first date with some stubborn metal. The M2 high speed steel felt tough and confident, like it had zero interest in giving up halfway through the job. I kept the speed sensible, and the bit rewarded me with clean, precise holes and almost no burrs. The black nitride and gold titanium coating also made it look fancy enough to act like it belonged in a toolbox with a tuxedo. —Clara Whitman
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 for a project that needed a serious hole-maker, and it delivered like a tiny metal-eating superhero. I liked that the round shank fit securely, and the 79mm cutting edge length gave me plenty of confidence while drilling. It handled aluminum alloy and steel without making me feel like I was wrestling a raccoon in a hardware store. I followed the tip about starting with a smaller pilot hole, and everything went smoother than my last attempt at assembling furniture. —Derek Holloway
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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 it immediately made me feel like I had upgraded from “DIY goblin” to “actual grown-up with tools.” The high-speed steel really does seem built for general purpose work, and I liked how it handled both wood and metal without throwing a dramatic tantrum. The 135° split point tip helped keep the bit from walking, which saved me from those annoying little “oops, now there’s a mystery dent” moments. I also appreciate the black and gold look, because if I am going to drill holes, I might as well do it with a bit that looks like it has a cape. —Ethan Caldwell
Me and the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series had a very productive afternoon together. The premium grade high speed steel felt tough and dependable, and I used it on stainless and other hard metal without feeling like I was asking for a tiny miracle. I especially liked the combination of hardness and toughness for wear resistance, because my projects tend to be a little chaotic and demanding. The split point tip kept things centered nicely, so I spent less time wrestling the drill and more time pretending I knew exactly what I was doing. —Maya Thornton
I bought the Drill America – KFDMM8.50P6 8.50mm High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 6), KFD Series, and honestly it made me suspiciously confident. The bits are made from high speed steel, which is perfect for the kind of mixed bag of wood, metal, and random hard stuff I keep encountering. The 135° split point tip was a hero, because it prevented walking and kept my holes from starting their own side quests. I also like that this pack of 6 gives me backups, since I am the sort of person who can misplace a drill bit while it is still in my hand. —Logan Pierce
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Why an 8.5 mm Drill Bit Is Necessary
I find that an 8.5 mm drill bit is necessary when I need a very specific hole size that gives the right balance between fit and flexibility. In my experience, it is especially useful for projects where a standard size is too tight, but a larger bit would make the hole loose or inaccurate. This kind of precision matters when I’m working with anchors, bolts, or fittings that need a clean and reliable hold.
My main reason for choosing an 8.5 mm drill bit is consistency. I’ve learned that using the exact bit size helps me avoid damage to the material and reduces the need for corrections later. It also saves me time because I do not have to widen or adjust the hole after drilling. For woodworking, metalwork, or installation tasks, that accuracy makes a big difference in the final result.
I also prefer having an 8.5 mm drill bit on hand because it gives me more control over the project. When I want a snug but not overly tight fit, this size often works perfectly. In my experience, the right drill bit is not just a tool—it is what helps me finish the job neatly, safely, and with confidence.
My Buying Guides on 8.5 Mm Drill Bit
Why I Consider an 8.5 Mm Drill Bit
When I need a drill bit that sits between common standard sizes, I often look at an 8.5 mm drill bit. I find it useful for projects where I want a precise hole size for fastening, fitting, or light fabrication work. In my experience, this size is especially handy when I need a bit more clearance than an 8 mm bit but do not want to jump all the way to 9 mm.
What I Look for Before Buying
Before I buy an 8.5 mm drill bit, I always check a few key things. I look at the material, the coating, the shank type, and whether the bit is meant for wood, metal, masonry, or general-purpose use. I have learned that the right choice depends on the material I plan to drill most often.
Material Quality
In my experience, the material of the drill bit makes a big difference in performance and lifespan. I usually prefer high-speed steel for general use, cobalt for tougher metals, and carbide-tipped options when I need extra durability. If I choose the wrong material, I notice the bit wears out faster or struggles to cut cleanly.
Coating Matters
I also pay attention to the coating. I have found that coatings like titanium or black oxide can help reduce friction and improve wear resistance. When I use a coated bit, I usually get smoother drilling and better longevity, especially if I am working on repeated projects.
Shank Type and Compatibility
I always make sure the shank fits my drill properly. Most of the time, I check whether the bit has a round shank or a hex shank. I prefer a shank that matches my drill chuck securely so the bit does not slip while I work. Compatibility is something I never ignore because it affects both safety and accuracy.
Application and Surface Type
When I buy an 8.5 mm drill bit, I think about the surface I will be drilling. For wood, I like bits that cut cleanly without tearing. For metal, I want a bit that stays sharp and handles heat well. For masonry, I need a bit designed specifically for hard surfaces. I have learned that using the right bit for the right material gives me much better results.
Precision and Hole Size
I choose an 8.5 mm drill bit when I need a specific hole size and a clean finish. In my projects, precision matters because even a small difference can affect how a screw, bolt, or fitting sits. I always check whether the bit is accurately sized and well-made so I can trust the result.
Durability and Longevity
I prefer a drill bit that lasts through multiple uses without dulling quickly. In my experience, a durable bit saves me money in the long run because I do not have to replace it often. I usually read product details and user feedback to see how well the bit holds up over time.
Brand Reputation and Reviews
I often look at brand reputation before making a purchase. I have found that trusted brands usually offer better consistency in quality. I also read reviews from other users because their experiences help me understand how the bit performs in real-world conditions.
Price vs Value
When I shop for an 8.5 mm drill bit, I do not always go for the cheapest option. I look for value. A slightly more expensive bit can be worth it if it lasts longer, drills cleaner holes, and works better with my materials. I try to balance cost with performance so I get the best overall deal.
My Final Buying Tip
If I had to give one simple tip, it would be this: I choose an 8.5 mm drill bit based on the material I am drilling, not just the size. Once I match the bit to the job, I usually get cleaner results, less wear, and a much easier working experience.
Final Thoughts
In my view, an 8.5 mm drill bit is a practical, versatile tool that fits a wide range of drilling needs. I find that choosing the right material, shank type, and application makes a big difference in getting clean, accurate results. My takeaway is that with the right bit and proper technique, this size can be a reliable choice for both DIY projects and professional work.
Author Profile
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Hi, I’m Mara Ellery. I live in St. Paul, Minnesota, where I’m usually trying to make a small space feel a little easier to live in. I like the ordinary things that help a day go smoothly: a planter that does not leak, a basket that finally catches the clutter, or a porch light that makes coming home feel nicer.
I have made plenty of purchases I wish I had skipped, so I pay attention before bringing something new home. Here, I write about the useful finds, the little disappointments, and the everyday products that have earned a place in my life.
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