Why I Recommend the 8.5 mm Drill Bit: My Expert Experience and Tips

When I first picked up an 8.5 mm drill bit, I didn’t realize just how versatile and essential this seemingly simple tool would become in my projects. Whether you’re a seasoned DIY enthusiast or just starting to build your toolkit, understanding the value of the right drill bit size can make all the difference. The 8.5 mm drill bit strikes a perfect balance between precision and strength, opening up a world of possibilities for drilling through various materials with ease. In this article, I want to share why this particular size has earned a special place in my collection and how it can elevate your drilling experience too.

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

When I first came across the 8.5mm Metric M35 Cobalt Steel Extremely Heat Resistant Twist Drill Bit, I was immediately intrigued by its promise to cut through tough metals like stainless steel and cast iron. As someone who often works with hard metals and requires reliable drill bits that can withstand intense use, this product caught my attention because it combines advanced materials and thoughtful design features to deliver superior performance. The use of M35 grade HSS-CO with 5% cobalt is particularly appealing since cobalt steel is well-known for its exceptional heat resistance and durability, making it a strong candidate for heavy-duty drilling tasks.

One of the standout aspects of this drill bit is its material composition. Manufactured from M35 5% cobalt steel alloyed with molybdenum and cobalt, it offers a Rockwell hardness rating of up to 65. This level of hardness is significant because it allows the bit to maintain sharpness and resist wear much longer than standard high-speed steel (HSS) bits. From my experience, standard HSS drill bits tend to dull quickly when used on hard metals, but this M35 cobalt alloy is designed to last up to 10 times longer, which means fewer replacements and more efficiency in the long run.

The bit also features a classic HSS construction with a titanium coating, which further enhances its durability and cutting capability. The titanium coating helps reduce friction and heat buildup during drilling, making the process smoother and less prone to overheating. The cutting edge is hardened and precisely honed, which means it stays sharp and cuts cleanly through metal without excessive force. For me, this translates into more precise holes and less frustration from drill bits that wander or produce rough edges.

Another important design feature is the 2-flute form. This flute design is excellent for clearing chips and debris away from the drilling area, which decreases friction and heat generation. In practice, I have found that bits with good chip evacuation perform better because they stay cooler and reduce the risk of bit damage or workpiece burning. Additionally, the staggered cutting teeth and chatter-free design contribute to a smooth drilling experience, providing precise countersinking and clean holes. These features are critical for metalworking applications where accuracy and finish quality matter.

The straight shank and 135° point angle make this drill bit compatible with standard drill chucks and collet chucks, ensuring a firm grip and accurate centering. This is a practical advantage for anyone using standard drilling equipment, as it guarantees stability and reduces wobbling during drilling. The helical flute design also facilitates easy swarf removal, which is essential for maintaining efficiency when drilling through tough materials.

As for its application scope, this drill bit is particularly well-suited for cutting through hard metals with hardness less than HRC 38°, such as stainless steel and cast iron. However, it is versatile enough to handle softer metals like copper and aluminum as well. I do note that it is not intended for hardened steel or high carbon steel, which is an important consideration depending on your specific projects. For my needs, which often involve stainless steel and cast iron, this bit fits perfectly and offers a reliable solution for demanding tasks.

Feature	Description	Benefit to User
M35 Cobalt Steel (5% Cobalt)	Hardened alloy with molybdenum and cobalt, Rockwell hardness up to 65	Significantly longer lifespan and faster cutting on hard metals
HSS Titanium Coating	Classic HSS base with titanium coating for durability	Reduced friction and heat, sharper cutting edge, improved durability
2-Flute Design with Staggered Teeth	Efficient chip clearance and chatter-free cutting	Cleaner holes, cooler drilling process, less bit wear
Straight Shank & 135° Point Angle	Fits standard drill chucks, ensures accurate centering	Stable drilling, precise hole placement
Material Compatibility	Ideal for stainless steel, cast iron, copper, aluminum	Versatile for various metalworking projects

Overall, I find this drill bit to be an excellent choice if you frequently work with hard metals and need a reliable, long-lasting tool that performs consistently. While it may

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2. uxcell Straight Shank Twist Drill Bits 8.5mm High Speed Steel 4341 with 8.5mm Shank 2 Pcs for Stainless Steel Alloy Metal Plastic Wood

When I first came across the uxcell Straight Shank Twist Drill Bits 8.5mm High Speed Steel 4341, I was immediately intrigued by their promise of versatility and durability. As someone who frequently works with a variety of materials—from stainless steel to wood—I needed drill bits that could handle different tasks without compromising performance. These drill bits caught my eye because they are specifically designed with a high-speed steel (HSS) 4341 composition, known for its excellent hardness and toughness, which means they are built to withstand wear and tear over time.

One of the standout features for me is the precise sizing an 8.5mm cutting edge diameter paired with an 8.5mm shank diameter ensures a perfect fit for many standard drill chucks. The cutting edge length of 76mm and total length of 115mm make these bits long enough for deeper drilling tasks while still maintaining control and stability. The right-hand cutting direction is standard, making them compatible with most drills and familiar to use.

The sharp spiral flutes impressed me, as they are designed to provide neat and smooth cuts. This is crucial because a clean cut reduces the risk of material damage and ensures a better finish on my projects. Additionally, the spiral groove’s role in efficiently ejecting metal chips cannot be overstated; it saves me time and effort by preventing clogging and overheating during prolonged use. This feature alone enhances the overall drilling experience significantly.

Another notable aspect is the black and gold oxide finish. This dual coating of premium gold titanium and black nitride not only looks professional but also serves a functional purpose by improving lubrication during drilling. This results in smoother operation and increased durability, as the coating helps prevent corrosion and wear. For me, this means these bits can maintain their sharpness and effectiveness over multiple uses without needing frequent replacements.

Versatility is key with these drill bits. They are suitable for drilling through stainless steel, aluminum alloy, iron, copper, brass, wood, plastic, and other metals. This wide range of applications means I don’t need to switch between multiple types of drill bits for different materials, making my toolkit simpler and more efficient. The stable round shank design ensures a tight grip in the drill chuck, reducing wobble and slippage during operation. This stability translates into better precision and safety while working.

To give you a clearer overview, here’s a quick comparison table highlighting the key specifications and benefits

Feature	Specification	Benefit
Cutting Edge Diameter	8.5mm / 0.33″	Ideal size for various general-purpose drilling tasks
Shank Diameter	8.5mm / 0.33″	Ensures compatibility and firm grip in drill chucks
Cutting Edge Length	76mm / 3″	Allows for deeper drilling without sacrificing control
Total Length	115mm / 0.59″	Provides reach for a variety of drilling depths
Material	High-Speed Steel 4341	Balances hardness and toughness for long-lasting use
Coating	Black & Gold Oxide (Titanium & Nitride)	Enhances lubrication, durability, and corrosion resistance
Spiral Flutes	Sharp, right-hand spiral	Ensures smooth cutting and efficient chip removal
Compatibility	Stainless Steel, Aluminum, Wood, Plastic, etc.	Versatile use for multiple materials and drill types
Shank Design	Stable round shank	Prevents slipping and wobbling during drilling

Overall, I find the uxcell 8.5mm Straight Shank Twist Drill Bits to be a reliable and efficient choice for anyone needing a high-quality drill bit that performs well across

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3. HARFINGTON Brad Point Drill Bit 8.5mm(21/64″) Dia Straight Round Shank Drill Metric Brad Point Spiral Twist Drill Bits for Carpenter Woodworking Plastic Rubber, Golden

When I first came across the HARFINGTON Brad Point Drill Bit 8.5mm (21/64″) Dia, I was immediately drawn to its precise specifications and thoughtful design tailored for woodworking and other soft materials. The 8.5mm diameter combined with a straight round shank ensures compatibility with most standard drill chucks, making it a versatile addition to my toolkit. The overall length of 117mm with a maximum cutting depth of 75mm means I can tackle a variety of project depths without changing bits frequently, which is a real time-saver.

One of the standout features for me is the material quality. Being made from High-Speed Steel 4241 and coated with titanium significantly boosts durability. This combination means the bit can withstand higher temperatures generated during prolonged drilling without losing sharpness or breaking easily. As someone who values tools that last, this durability gives me confidence that the drill bit will perform reliably over many projects, saving me money and frustration in the long run.

The design of the brad point tip is another major plus. It offers precise locating, which is crucial when I need exact holes without wandering or slipping on the surface. The widened and deepened chip removal grooves are smart engineering because they clear debris quickly, keeping the drilling smooth and efficient. This not only improves my productivity but also results in cleaner holes, which enhances the overall finish of my woodworking or plastic projects.

In terms of application, the bit’s versatility truly shines. It works perfectly with a range of drill drivers—from bench drills to cordless models—which means I’m not limited by the type of drill I have. Whether I’m working on softwood, hardwood, plywood, plastic, rubber, or polyurethane, this bit performs consistently well. However, it’s important to note that it’s not designed for metal, concrete, or glass, so I appreciate the clear guidance to avoid misuse and maintain safety.

Overall, the HARFINGTON Brad Point Drill Bit strikes a great balance between precision, durability, and versatility for anyone involved in carpentry or crafting with soft materials. If you’re looking for a reliable drill bit that can handle a variety of tasks with accuracy and longevity, this is a solid choice. I’d recommend it especially if you want to improve your drilling accuracy and efficiency without constantly replacing worn-out bits.

Feature	Details
Diameter	8.5mm (21/64″)
Shank Type	Straight Round Shank, 8.5mm (21/64″)
Overall Length	117mm (4.61″)
Maximum Cutting Depth	75mm (2-61/64″)
Material	High-Speed Steel 4241 with Titanium Coating
Applications	Softwood, Hardwood, Plywood, Plastic, Rubber, Polyurethane
Not Suitable For	Metal, Walls, Rocks, Glass, Concrete

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4. uxcell M10 x 1.5 Spiral Point Thread Tap and 8.5mm Twist Drill Bit Set, Metric Titanium Plated 6542 High Speed Steel Machine Screw Thread Tap Threading Tool

When I first came across the uxcell M10 x 1.5 Spiral Point Thread Tap and 8.5mm Twist Drill Bit Set, I was immediately drawn to its promise of precision and durability. The set combines a metric titanium-plated 6542 high-speed steel machine screw thread tap with a perfectly matched 8.5mm drill bit, which signals that it’s tailored for those who need reliable threading and drilling tools for professional or hobbyist use. The M10 x 1.5 tap size is a very common thread size, making this set highly versatile for many general-purpose applications. This alone makes it a practical addition to anyone’s toolbox who frequently works with machine screws or needs to create precise threaded holes.

The high-speed steel (HSS) construction with titanium plating is a feature I particularly appreciate. HSS is known for its hardness and toughness, so it resists wear and tear well. Adding titanium plating elevates corrosion resistance and wear resistance, ensuring the tools remain sharp and effective for longer periods. This means fewer replacements and consistent performance, which is essential if you are working on multiple projects or in environments where tool longevity matters. I find this combination reassuring because it reflects quality and durability, traits that are critical when investing in threading tools.

One of the standout features is the spiral point tap design. The spiral point flute is engineered to push chips downward, which effectively clears debris away from the cutting area. This design not only speeds up the tapping process but also enhances accuracy. From my experience, taps that efficiently remove chips reduce the risk of jamming or damaging the threads, which is a common frustration with lesser tools. The right-hand thread cutting aligns with standard threading conventions, making it straightforward to use. Additionally, the spiral point tap’s suitability for through-hole threads and materials like aluminum, die steel, stainless steel, bronze, and even hard plastics makes it incredibly versatile for different machining tasks.

The twist drill bit included in this set features a spiral chip space design, which complements the tap’s ability to remove chips quickly and cleanly. The sharp cutting edge ensures smooth cuts without glitches, which is important for maintaining precision and avoiding material damage. The titanium coating here again plays a role in corrosion and wear resistance, supporting long-term use even under demanding conditions. For me, having a drill bit that matches the tap’s quality means I can count on accurate hole preparation, which is the foundation of successful threading.

In terms of usability, the set is compatible with drilling machines, tapping machines, CNC, and milling machines, which makes it highly adaptable to various workshop setups. I also appreciate the recommendation to use tapping oil, as it significantly improves thread quality and tap durability—this is a practical tip that shows the product is designed for serious users who want the best results. Using machine taps with tap collets that have overload protection is another thoughtful suggestion, as it helps prevent tap breakage and extends tool life, something I’ve learned the hard way when cutting corners.

Finally, the drill bit tips are designed to benefit from suitable lubricants, which facilitate cutting and cooling. This not only makes the cutting process smoother but also improves dimensional accuracy and tool longevity. Choosing the right feed rate and cutting speed, as advised, can further enhance performance. For anyone who values precision and efficiency, these small but important details in the product features indicate that this set is engineered for optimal results.

Feature	Description	Benefit to User
Tap Thread Size	M10 x 1.5	Common size suitable for many general-purpose threading tasks
Drill Bit Diameter	8.5mm / 0.33″	Perfectly matched size for creating precise pilot holes for the tap
Material	Titanium plated 6542 High Speed Steel	High hardness, toughness, corrosion and wear resistance for durability
Spiral Point Tap	Downward chip removal, right hand thread cutting	Fast, accurate tapping with reduced risk of chip clogging
Twist Drill Bit Design	Spiral chip space and sharp cutting edge	Efficient, clean cutting with smooth finish and minimal glitches
Usage Compatibility	Get It From Amazon Now: Check Price on Amazon & FREE Returns How an 8.5 mm Drill Bit Has Helped Me I’ve found that having an 8.5 mm drill bit in my toolkit is incredibly useful for a variety of projects. Its size is just right for creating precise holes for medium-sized bolts and anchors, which I often need when mounting shelves or assembling furniture. The bit gives me confidence that the holes will be clean and accurate, making my work look professional. Another reason I rely on my 8.5 mm drill bit is its versatility. It works well on different materials like wood, metal, and plastic, so I don’t have to keep switching bits for most home improvement tasks. This saves me time and effort, especially when I’m in the middle of a project and want to keep a steady workflow. Overall, the 8.5 mm drill bit has become one of my go-to tools because it strikes the perfect balance between precision and practicality. It helps me complete tasks efficiently and with better results, which makes DIY work much more enjoyable. Buying Guide for an 8.5 mm Drill Bit Understanding the Size and Its Uses When I first looked for an 8.5 mm drill bit, I realized the size is quite specific and useful for certain tasks. This diameter is ideal for creating medium-sized holes, often needed in woodworking, metalworking, or even masonry projects. Knowing what material I plan to drill into helps me choose the right type of drill bit. Material of the Drill Bit Choosing the material was crucial for me because it determines durability and performance. Common materials include high-speed steel (HSS), cobalt, carbide, and titanium-coated bits. For example, HSS bits worked well on softer metals and wood, while cobalt bits are better for tougher metals. I matched the drill bit material to the job to ensure longevity and efficiency. Type of Drill Bit There are various types of drill bits like twist bits, masonry bits, spade bits, and more. For an 8.5 mm size, twist drill bits are the most common and versatile. But if I was working with concrete or brick, I would opt for a masonry bit. Identifying the right type based on the material saved me time and prevented damage to both the bit and the surface. Shank Compatibility I always checked the shank type and size because it needs to fit securely in my drill chuck. Most 8.5 mm bits come with a round shank, but some have hex shanks for better grip and torque. Making sure the shank matches my drill ensures safety and precision during use. Coating and Finish The coating on a drill bit can extend its life and improve performance. I looked for coatings like titanium nitride or black oxide, which reduce friction and heat buildup. This was especially important for prolonged drilling sessions or tougher materials. Price vs. Quality I found that while cheaper drill bits might seem appealing, investing in higher quality ones paid off in the long run. A well-made 8.5 mm drill bit holds its sharpness longer and reduces the risk of breaking. Balancing cost and quality helped me get the best value. Additional Tips It’s helpful to have a set of drill bits including the 8.5 mm size for versatility. Also, using the correct drilling speed and applying steady pressure improved my results and extended the bit’s lifespan. Proper storage and maintenance, like cleaning after use, kept the drill bits in good condition. Final Thoughts Selecting the right 8.5 mm drill bit depends on understanding your project needs, the material you’re working with, and your drill’s compatibility. Taking the time to choose carefully made my drilling tasks smoother and more efficient. Author Profile Ilyes Marques My name is Ilyes Marques, though some people still associate me with my earlier work in France’s vaporizer space. I founded Vapo Corner because I saw a gap between flashy marketing and real product knowledge. Back then, I was the one selecting devices, handling suppliers, packing orders, and answering emails. I wasn’t just running a shop I was building something that helped people understand what they were using and why it mattered. In 2025, I took that mindset in a new direction. I started writing. Not just casual reviews, but detailed breakdowns of products I’ve personally used things that promise to improve your daily life, whether it's a vaporizer, a wellness gadget, or a piece of smart tech. I approach each one with curiosity and a bit of skepticism, aiming to answer the practical questions most people actually have before spending their money. 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