Attempting to drill through hardened alloy plate, seized suspension bolts, heat-treated brackets, or heavy stainless steel can quickly ruin an entire afternoon in the shop. When standard twist bits meet high-tensile materials, intense friction generates blistering temperatures that soften ordinary cutting edges within seconds, leaving behind polished divots and burned tips. Metalworkers, mechanics, and serious DIYers require cutting tools engineered specifically to endure severe friction and mechanical stress without losing their temper or fracturing under load. In this guide, we compared 12 drill bits to drill hardened steel options from DEWALT Drill, DrillAmerica, CO-Z and more for October 2026 to identify which sets deliver consistent penetration, smooth chip evacuation, and prolonged durability. We examined metal compositions, tip designs, flute geometries, and shank stability across a wide variety of fabrication scenarios, always reminding craftspeople to stabilize their workpieces with heavy-duty trigger clamps before starting any high-pressure drilling job.
Our top pick is the BOSCH CO14B 14-Piece Cobalt Drill Bit Set for its upgraded M42 alloy containing 8% cobalt that withstands high-temperature friction and delivers superior cutting life in tough alloys.
Pros
- Pilot point prevents surface wandering
- Heavy-duty tapered web limits bit breakage
- No-spin shanks prevent chuck slippage
- Sturdy carrying case included
Cons
- Titanium coating wears down quickly against hardened steel
- Smaller bit sizes lack the pilot point feature
The DEWALT DW1361 21-piece set provides a broad assortment of titanium nitride coated bits designed for metal, wood, and plastic drilling. Built for hand drills and drill presses, this kit targets home handymen and hobbyist metalworkers seeking clean hole entry and dependable cutting speed.
One major advantage is the pilot point design, which bites immediately into surfaces to prevent wandering without needing a center punch. Backed by a tapered web that thickens toward the shank, these bits resist the lateral shearing forces that frequently break standard twist bits during tough jobs.
While the titanium nitride coating handles mild steels and general sheet metal well, drilling repeatedly into hardened high-carbon steel creates friction that can degrade the outer coating over time. Users tackling heavy industrial metals or hardened alloys should consider solid cobalt bits instead.
Bottom line: The DEWALT DW1361 delivers clean starts, excellent torque transfer, and dependable performance for general workshop drilling and lighter metal fabrication tasks.
- Brand: DEWALT
- Model Number: DW1361
- Piece Count: 21 pieces
- Coating: Titanium Nitride
- Point Type: Pilot Point
- Shank Type: No-spin flat shank
- Minimum Size: 1/16-inch
- Maximum Size: 1/2-inch
- Storage: Plastic tough case
- Two 1/16-inch drill bits
- Two 5/64-inch drill bits
- Two 3/32-inch drill bits
- Two 7/64-inch drill bits
- Two 1/8-inch drill bits
- Single bits in 9/64, 5/32, 11/64, 3/16, 13/64, 7/32, and 15/64 inches
- Single bits in 1/4, 5/16, 3/8, and 1/2 inches
- Molded plastic storage case
This set is ideal for homeowners, DIY fabricators, and woodworkers who need an all-in-one assortment for household maintenance, light metalwork, and carpentry. The anti-walk pilot tips make it particularly useful for anyone drilling without a center punch or drill press.
It is not recommended for production machinists or mechanics dealing exclusively with hardened stainless steel, cast iron, or thick heat-treated alloys. For those demanding materials, specialized solid cobalt or solid carbide bits are required to withstand extreme friction.
Pros
- Split point tip minimizes bit wandering
- Tapered web core adds fracture resistance
- 3-flats shank prevents slipping in standard chucks
- Corrosion-resistant black and gold finish
Cons
- High Speed Steel dulls quickly on thick hardened steel alloys
- 3-flats shank is only present on sizes larger than 3/16-inch
The DEWALT DWA1184 Black and Gold 14-Piece Drill Bit Set provides a dependable selection of general-purpose bits built for light fabrication, automotive work, and everyday shop repairs. Designed for users working with mild metals, wood, and rigid plastics, it offers a sturdy starting kit for regular drilling jobs.
A key advantage is the 135-degree split point tip, which begins cutting immediately and resists wandering across smooth metal surfaces without a center punch. Durability is further enhanced by DEWALT's tapered web core design that reinforces the bit flutes against snapping under moderate side load, while the 3-flats shank on larger sizes stops unwanted slipping in drill chucks.
Because these bits are standard High Speed Steel rather than cobalt or solid carbide, they are not suited for continuous drilling through heavy heat-treated or case-hardened steel. Metalworkers routinely boring through high-grade stainless or thick hardened steel will want specialized cobalt bits to avoid premature dulling.
Bottom line: While demanding industrial steel jobs require higher-grade cobalt bits, this 14-piece DEWALT set delivers exceptional value and anti-slip performance for general metal and workshop drilling tasks.
- Brand: DEWALT
- Model Number: DWA1184
- Piece Count: 14 pieces
- Material: High Speed Steel (HSS)
- Tip Angle: 135-degree split point
- Finish: Black and gold coating
- Shank Type: 3-flats shank on sizes larger than 3/16-inch
- Recommended Materials: Plastic, wood, and metal
Apply cutting fluid or light machine oil when drilling into metal to reduce friction and preserve the cutting edges of High Speed Steel.
Operate your drill at slower rotational speeds and maintain steady, moderate feed pressure. Excessive speed generates heat that softens HSS cutting edges.
Align the 3-flats shank with chuck jaws on sizes larger than 3/16-inch to ensure maximum grip and prevent slippage during tough cuts.
This set is well matched for homeowners, woodworkers, and automotive hobbyists who need a dependable, multi-material drill bit set for general maintenance and light fabrication.
It is particularly helpful for operators working on sheet metal, aluminum, brass, and mild carbon steel where a 135-degree split point prevents walking.
Industrial fabricators and machinists regularly drilling hardened tool steel or thick structural stainless should opt for solid cobalt or carbide tooling instead.
Pros
- M42 cobalt alloy resists extreme drilling heat
- Split points prevent walking on hard metal surfaces
- Three-flat shanks improve chuck grip on larger sizes
- Thick core design prevents bending and breakage
Cons
- Brittle cobalt alloy can snap under side load
- Smaller bits under 3/16 inch lack three-flat shanks
- Not intended for soft wood or general wall masonry
The Bosch CO14B 14-Piece Drill Bit Set is built for DIYers, mechanics, and metal fabricators who regularly tackle stubborn metals. Featuring an M42 high-speed steel formulation enriched with 8 percent cobalt, these jobber-length twist bits retain their cutting edge when boring into hardened metals, titanium, cast iron, and stainless steel.
Key design elements elevate their cutting efficiency on rigid workpieces. The thick web-helix architecture provides rigidity during heavy feed pressure, while the split-point tips on bits 1/8-inch and larger bite immediately to prevent skate. In addition, sizes 3/16-inch and above feature three flattened sides on the shank to ensure a slip-free lock in standard three-jaw drill chucks.
Because cobalt steel prioritizes hardness and heat resistance over flexibility, these bits are more brittle than standard high-speed steel bits. Users working with handheld drills should maintain steady alignment and proper speed control to avoid snapping smaller diameters under side load.
Bottom line: This Bosch M42 set provides the cutting speed and thermal resistance required to bore cleanly through stainless steel and tough alloys without dulling prematurely.
- Brand: Bosch
- Model: CO14B
- Material: M42 High-Speed Steel with 8% Cobalt
- Bit Length: Jobber Length
- Tip Geometry: Split point (1/8-inch and larger)
- Shank Type: Three-flat shank (3/16-inch and larger), round shank (under 3/16-inch)
- Application: Stainless steel, cast iron, titanium, hardened steel, light-gauge metal, aluminum
- Piece Count: 14 pieces with hard storage case
- 1/16-inch M42 cobalt drill bit
- 5/64-inch M42 cobalt drill bit
- 3/32-inch M42 cobalt drill bit
- 7/64-inch M42 cobalt drill bit
- 1/8-inch M42 cobalt drill bit
- 9/64-inch M42 cobalt drill bit
- 5/32-inch M42 cobalt drill bit
- 3/16-inch M42 cobalt drill bit
- 7/32-inch M42 cobalt drill bit
- 1/4-inch M42 cobalt drill bit
- 5/16-inch M42 cobalt drill bit
- 3/8-inch M42 cobalt drill bit
- 1/2-inch M42 cobalt drill bit
- Durable hard-shell storage case
Always wear safety glasses and hearing protection when drilling into hard metals. Metal shavings can eject at high velocities, so securing your workpiece in a clamp or bench vise is critical for safety and hole accuracy.
To maximize bit life, run your drill at slower rotation speeds and apply cutting fluid directly to the drilling site. Lubrication reduces friction, dissipates heat buildup, and clears metal chips smoothly from the flutes.
Avoid rocking or angling handheld drills while drilling dense metal. Excessive lateral pressure can break brittle cobalt steel, particularly on thin diameters like 1/16-inch and 1/8-inch bits.
Pros
- 135-degree split points prevent bit walking
- 3-flats shank design prevents chuck slippage
- Parabolic flutes clear metal chips quickly
- Duplicate bits included for high-wear small sizes
Cons
- HSS construction struggles with heat on heat-treated hardened steel
- Smaller bit sizes lack the 3-flats shank design
The DEWALT DWA1181 21-Piece Drill Bit Set provides a broad selection of high-speed steel bits designed for general-purpose drilling across metal, wood, and plastics. Engineered for homeowners, hobbyists, and trade professionals, this collection covers everyday fabrication and repair jobs with reliable build quality.
Its key operational advantage lies in the 135-degree split point design, which bites immediately into slick surfaces without wandering or requiring a center punch. In addition, the parabolic flute geometry and 31-degree helix efficiently evacuate chips, while the 3-flats shank prevents frustrating spin-outs in standard drill chucks.
While capable on mild steel, aluminum, and structural metals, these bits are made of high-speed steel with an oxide coating rather than solid cobalt or carbide. Users dealing exclusively with heat-treated hardened alloy steel or heavy stainless steel should skip this set in favor of specialized cobalt tooling that withstands severe friction.
Bottom line: This DEWALT set delivers dependable performance for everyday workshop tasks and light metalwork, though projects involving true hardened tool steel will require harder cobalt alternatives.
- Brand: DEWALT
- Model Number: DWA1181
- Piece Count: 21 pieces
- Material: High Speed Steel (HSS)
- Coating: Black and gold oxide
- Tip Angle: 135-degree split point
- Flute Design: Parabolic flute with 31-degree helix
- Shank Type: 3-flats shank (on larger sizes)
- Size Range: 1/16 inch to 1/2 inch
- Two 1/16-inch drill bits
- Two 5/64-inch drill bits
- One 3/32-inch and one 7/64-inch drill bit
- Two 1/8-inch drill bits
- One 9/64-inch, one 5/32-inch, and one 11/64-inch drill bit
- Two 3/16-inch drill bits
- One 13/64-inch, one 7/32-inch, and one 15/64-inch drill bit
- Two 1/4-inch, one 5/16-inch, one 3/8-inch, and one 1/2-inch drill bit
Always wear safety goggles and secure your workpiece in a clamp or vise before drilling into metal surfaces. Operating your drill at moderate speeds with consistent pressure helps keep cutting temperatures low, which preserves cutting edges and prevents binding.
Apply cutting fluid or multi-purpose oil when cutting into dense metals to dissipate heat and reduce friction. Storing each bit in its designated slot inside the included case protects the sharp cutting edges from impact damage and moisture.
Pros
- 10 distinct hole diameters in one tool
- Tri-flatted shank stops chuck slippage
- Smooth chip evacuation via dual flutes
- Built-in deburring during drilling
Cons
- Not suitable for hardened steel or thick plate metals
- High-speed steel edges dull quickly on stainless steel
The CO-Z ZELCAN Titanium Step Drill Bit is a multi-diameter cone bit engineered for drilling clean holes in sheet metal, aluminum, and electrical panels. It is designed specifically for tradespeople and DIY enthusiasts who frequently work with junction boxes, ductwork, and thin materials.
Its two-flute cutting profile channels shavings away rapidly, while the titanium coating reduces friction and thermal stress during drilling. The tri-flatted shank provides three flat contact points that lock firmly into standard drill chucks, virtually eliminating bit slippage under torque.
This high-speed steel bit is intended strictly for lighter sheet metals and plastics. If your project involves hardened tool steel, thick structural iron, or heavy stainless steel, this tool will rapidly overheat and dull, making specialized cobalt or carbide drill bits necessary instead.
Bottom line: For thin sheet metal, electrical knockouts, and aluminum fabrication, this stepped bit delivers clean holes and automatic deburring without requiring frequent tool changes.
- Brand: CO-Z
- Material: High-Speed Steel (HSS)
- Surface Finish: Titanium Coating
- Number of Steps: 10 sizes
- Size Range: 1/4 inch to 1-3/8 inches
- Hole Diameters: 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1", 1-1/8", 1-1/4", 1-3/8"
- Flute Style: Two-flute design
- Shank Type: Tri-flatted shank
- Compatible Materials: Sheet metal, aluminum, copper, plastic, wood
- Apply cutting fluid or lubricant regularly to dissipate heat and preserve sharp cutting edges.
- Reduce drill rotation speed as you move into larger diameter steps to avoid thermal damage.
- Always wear safety glasses and work gloves to protect against high-velocity metal shavings.
- Never force the cutting cone into hardened steel, stainless steel, or thick iron plates.
- Secure your workpiece with clamps to avoid sudden binding and workpiece spin.
- Fits standard 3/8-inch and 1/2-inch three-jaw drill chucks securely.
- Tri-flatted shank design prevents chuck spinning during heavy rotational torque.
- Operates cleanly in corded drills, cordless drill drivers, and benchtop drill presses.
- Not intended for use with 1/4-inch quick-release impact driver hex receivers.
- Best matched to sheet materials whose thickness does not exceed single-step depth.
Pros
- High-hardness M42 cobalt construction (68 to 70 HRC)
- Self-centering 135-degree split points
- Continuous metric sizing in 0.5mm steps
- Outstanding heat and wear resistance in heavy steel
Cons
- Metric sizing only, lacking fractional inch sizes
- Cobalt alloy is brittle and susceptible to snapping if tilted
- Requires cutting fluid to ensure maximum bit life on hardened plate
The STROTON 19-piece drill bit set provides a dedicated metric tooling solution built specifically for high-tensile metals. Machinists, fabricators, and auto technicians working on stainless steel, cast iron, and hardened alloys will find the metric diameter progression well suited for precision holes.
Constructed from premium M42 steel containing 8% cobalt, these bits achieve an impressive rating of 68 to 70 on the Rockwell hardness scale. The 135-degree split point design bites immediately on contact to eliminate bit wander, while the sharp flute edges peel off thick metal ribbons instead of generating friction through grinding.
Because cobalt alloy is naturally harder and more brittle than standard high-speed steel, side loading or loose handheld drill setups can cause smaller bits to break. Shoppers looking for fractional inch measurements or general woodworking bits should look elsewhere, as this set is strictly metric and tailored for metal.
Bottom line: For metalworkers tackling hardened steel and stainless components, this STROTON M42 set delivers exceptional heat resistance, fast penetration, and precise metric sizing.
- Material: M42 8% Cobalt Steel
- Hardness Rating: 68-70 HRC (Rockwell Scale)
- Point Style: 135-degree split point
- Measurement System: Metric
- Size Range: 1.0mm to 10.0mm
- Size Increments: 0.5mm steps
- Piece Count: 19 twist drill bits
- Material Suitability: Hardened steel, stainless steel, aluminum, plastic
- 19 M42 metric twist drill bits in the following diameters:
- Small sizes: 1.0mm, 1.5mm, 2.0mm, 2.5mm, 3.0mm, 3.5mm
- Medium sizes: 4.0mm, 4.5mm, 5.0mm, 5.5mm, 6.0mm, 6.5mm
- Large sizes: 7.0mm, 7.5mm, 8.0mm, 8.5mm, 9.0mm, 9.5mm, 10.0mm
Always wear safety glasses and proper face protection when drilling into hardened metals, as metal ribbons and hot chips eject at high speeds. Secure your workpiece firmly in a vise or clamp to prevent bit binding and dangerous kickback.
Apply cutting oil or coolant continuously to manage heat and extend the life of the cutting edges. Maintain straight alignment and moderate speeds, avoiding side pressure that can snap brittle cobalt steel.
Pros
- M35 cobalt alloy resists high frictional heat
- 135-degree split point stops bit walk on hard metals
- Convenient indexed storage case with clear size markings
- Polished flutes provide efficient metal chip extraction
Cons
- Smallest diameter bits can snap under uneven side pressure
- Set ends at 1/4 inch, lacking larger bore sizes
The MACXCOIP 13-Piece Cobalt Drill Bit Set is tailored for hobbyists, mechanics, and home fabricators working with dense, heat-generating materials. Built from M35 high-speed steel infused with cobalt, this jobber-length kit provides the thermal endurance required to penetrate tough metal workpieces where conventional bits dull quickly.
A major design highlight is the 135-degree split point, which starts cutting immediately on contact to eliminate bit drift without needing a center punch. Paired with polished flutes, the bits clear spiral chips rapidly, preventing friction build-up and keeping the cutting edge sharp through repeated passes in stainless steel and cast iron.
Users should note that M35 cobalt steel is harder and more brittle than standard carbon steel, meaning the smallest diameters require a steady hand and controlled pressure to avoid snapping. Additionally, those needing to drill holes wider than 1/4 inch will need to supplement this kit with larger standalone sizes.
Bottom line: For metalworkers needing a dependable set of small-diameter bits that resist heat and stay sharp in hardened steel, this indexed MACXCOIP set offers great cutting precision and convenience.
- Brand: MACXCOIP
- Material: M35 Cobalt High-Speed Steel (HSS)
- Piece Count: 13 bits
- Size Range: 1/16 inch to 1/4 inch (in 1/64-inch steps)
- Tip Angle: 135-degree split point
- Bit Type: Jobber length twist drill bits
- Material Compatibility: Hardened steel, stainless steel, cast iron, aluminum, copper, wood, plastic
- Storage: Indexed compact carrying case
- Run your drill at lower RPM speeds when cutting into hardened steel or stainless metal to prevent overheating the bit.
- Apply cutting fluid or light machine oil during drilling to reduce friction and extend the cutting life of the cobalt alloy.
- Maintain steady, straight downward pressure without rocking or bending the drill, especially with narrow bits below 1/8 inch.
- Rely on the 135-degree self-centering tip to start the hole cleanly on flat or curved metal surfaces.
- 13 M35 Cobalt Drill Bits: 1/16", 5/64", 3/32", 7/64", 1/8", 9/64", 5/32", 11/64", 3/16", 13/64", 7/32", 15/64", and 1/4"
- Indexed portable storage case with dedicated slots and labeled fractional sizes
Pros
- Durable M35 cobalt steel for high heat resistance
- Compact stubby profile accesses cramped work areas
- 135-degree self-centering split point prevents walking
- Quick-change 1/4-inch hex shank compatibility
- Convenient pegboard-ready storage case
Cons
- Limited five-piece selection covers only essential imperial sizes
- Short stubby length restricts drilling through thick workpieces
- Cobalt composition is brittle and prone to snapping if flexed
The NordWolfTools 5-Piece Stubby Drill Bit Set is designed for metalworkers, mechanics, and DIYers who routinely work with tough alloys in tight engine bays or crowded assemblies. Made from heat-resistant M35 cobalt steel, these bits are specifically crafted to bore into hardened steel, stainless steel, and cast iron where standard length bits cannot fit.
The standout advantage of this set lies in its stubby profile paired with an aggressive 135-degree split point. The shortened length reduces bit flex and runout, allowing for straight, accurate holes without bit walking or the need for a starter punch. A universal 1/4-inch hex shank ensures rapid bit changes in standard drill chucks as well as quick-release drivers.
Because these bits measure under 2.5 inches, they are not suitable for deep drilling through thick stock or reaching recessed fasteners. Furthermore, the selection includes only five common imperial diameters, so users needing larger sizes or millimeter increments will have to source them separately.
Bottom line: this compact M35 cobalt set is an indispensable addition to any toolbox for penetrating tough, hardened metals within restricted spaces.
- Material: M35 Cobalt Steel
- Shank Size: 1/4-Inch Hex
- Tip Geometry: 135-Degree Split Point
- Overall Length: 1.83 Inches to 2.32 Inches
- Sizes Included: 3/32", 1/8", 3/16", 1/4", 5/16"
- Pack Size: 5 Pieces
- Compatible Metals: Stainless Steel, Cast Iron, Titanium, Bronze, Aluminum
- Storage: Labeled Plastic Case with Pegboard Clip
Each bit is equipped with an integrated 1/4-inch hex shank, providing broad compatibility across various power tool platforms. This includes standard three-jaw drill chucks, quick-connect drill extensions, and standard hex impact drivers.
For optimal results when cutting hardened steel or stainless steel, run your drill at slower speeds and apply steady, deliberate feed pressure. The hex base prevents slippage inside chucks, making it reliable for high-torque drilling tasks.
Cobalt alloy bits excel at maintaining hardness at extreme temperatures, but proper care prolongs their service life. Applying cutting fluid or light machine oil during drilling reduces friction and protects the cutting edges from premature dulling.
Because M35 cobalt is harder and more brittle than standard high-speed steel, avoid lateral force or sudden twisting motions. Always wear eye protection to guard against flying metal chips, and store the bits in their designated case to prevent edge chipping.
Pros
- Premium M2 high-speed steel construction
- Self-centering 135-degree split point design
- Comprehensive fractional sizing in 1/64-inch increments
- Rugged, water-resistant cylindrical travel case
- Corrosion-resistant black and gold oxide finish
Cons
- Wears faster than solid carbide on heat-treated or case-hardened steel
- Smaller bit diameters can be tricky to extract from dense index slots
The Drill America KFD29J-PC Killer Force set provides an extensive fractional drill collection tailored for contractors, mechanics, and metalworkers tackling tough alloy projects. Packaged in a compact cylindrical case, this set delivers 29 high-speed steel bits engineered for consistent performance across heavy-duty workshop and field tasks.
Each bit is machined from premium M2 high-speed steel and treated with a protective black and gold oxide finish that helps resist friction and thermal buildup. The 135-degree split point initiates cuts immediately upon contact, preventing bit wandering on slick steel surfaces while eliminating the requirement for pre-drilled pilot holes.
While M2 high-speed steel performs reliably in standard carbon steel, iron, and stainless steel, users drilling case-hardened or heat-treated alloys will need continuous cutting fluid to prevent edge dulling. Fabricators regularly confronting high-hardness tool steels might prefer specialized solid carbide or cobalt tooling instead.
Bottom line: The Drill America KFD29J-PC delivers dependable cutting performance, exceptional portability, and a comprehensive size assortment for demanding metal fabrication tasks.
- Piece Count: 29 drill bits
- Size Range: 1/16 inch to 1/2 inch in 1/64-inch increments
- Material: M2 grade high-speed steel (HSS)
- Surface Finish: Black and gold oxide treatment
- Point Angle: 135-degree self-centering split point
- Length Type: Jobber length
- Storage Case: Shatter-proof, water-resistant round index canister
When drilling harder metals such as stainless steel and structural iron, operate your drill press or hand drill at reduced spindle speeds. Slower rotational speeds prevent heat buildup that can quickly ruin the cutting edges of high-speed steel.
Always apply a dedicated cutting lubricant or metalworking oil to the drill site before and during the cut. Steady, firm feed pressure allows the 135-degree split point to bite cleanly into the workpiece, generating neat curls rather than abrasive friction dust.
- 29 Drill America KFD Series Jobber Length Drill Bits (1/16" through 1/2" by 64ths)
- Heavy-duty cylindrical storage container with built-in drill index
- Integrated belt attachment loop for jobsite transport
Pros
- High 68 HRC hardness rating for dense metals
- True 5 percent M35 cobalt steel construction
- Self-centering split point reduces walking
- Excellent heat and chip resistance under load
Cons
- Size range tops out at 1/4 inch
- Brittle cobalt alloy can snap under lateral flex
- Not suitable for masonry or concrete drilling
The STROTON 13-Piece Cobalt Drill Bit Set is designed for demanding metal fabrication tasks that quickly dull standard high-speed steel bits. Aimed at mechanics, fabricators, and serious home metalworkers, this set provides a reliable collection of small-diameter cutters capable of penetrating dense materials and extracting stubborn hardware.
Its primary advantage lies in the M35 tool steel construction, formulated with 5 percent cobalt to attain a high hardness rating of 68 HRC. Combined with a self-centering split point and fully ground flutes, these bits cut aggressively into stainless steel sheet and cast iron without skating across the surface or loading up with metal debris.
Because cobalt steel prioritizes hardness and thermal resistance over flexibility, these bits are inherently more brittle than conventional options and can snap under side load or sudden binding. Users requiring hole diameters larger than a quarter inch, or those working primarily with stone or masonry, will need a different tool set.
Bottom line: This 13-piece set provides impressive cutting efficiency and heat resistance for anyone regularly dealing with tough alloy steel, rusted studs, or stainless fabrication.
- Brand: STROTON
- Material: M35 High Speed Steel (5% Cobalt)
- Hardness: 68 HRC
- Piece Count: 13 pieces
- Bit Type: Jobber length twist drill bits
- Point Type: Split point
- Size Range: 1/16 inch to 1/4 inch (1/64-inch increments)
- Compatible Materials: Stainless steel, steel plate, cast iron, hardwood, plastic
- 1/16-inch jobber length cobalt drill bit
- 5/64-inch jobber length cobalt drill bit
- 3/32-inch jobber length cobalt drill bit
- 7/64-inch jobber length cobalt drill bit
- 1/8-inch jobber length cobalt drill bit
- 9/64-inch jobber length cobalt drill bit
- 5/32-inch jobber length cobalt drill bit
- 11/64-inch jobber length cobalt drill bit
- 3/16-inch jobber length cobalt drill bit
- 13/64-inch jobber length cobalt drill bit
- 7/32-inch jobber length cobalt drill bit
- 15/64-inch jobber length cobalt drill bit
- 1/4-inch jobber length cobalt drill bit
Always apply a generous amount of cutting fluid or machining oil when boring through hardened steel and stainless alloys. Lubrication helps draw heat away from the cutting edges, preserving bit sharpness and preventing work hardening of the metal.
Run your drill motor at a reduced RPM setting and apply firm, steady forward pressure. High speeds generate intense friction that can burn out cutting edges prematurely, while consistent downforce allows the split point to shear metal cleanly into curled chips.
Keep the drill aligned straight throughout the cut to avoid lateral deflection. Because 68 HRC cobalt bits are exceptionally rigid, applying uneven side force or tilting the hand drill can cause thinner diameter bits to break.
Pros
- 5% M35 cobalt steel construction
- Self-centering 135-degree split point
- Smooth fully ground flutes for quick chip removal
- Reliable heat resistance in tough metals
Cons
- Maximum bit diameter is limited to 1/4-inch
- Cobalt alloy can become brittle if bent under heavy lateral pressure
- No storage case details specified in the product data
The BECOLLO 13-Piece Cobalt Drill Bit Set is designed for DIYers, mechanics, and metalworkers who frequently tackle hard alloys. Constructed from M35 high-speed steel infused with 5 percent cobalt, this set provides the thermal endurance needed to cut dense materials without premature edge dulling.
A standout attribute is the 135-degree split point geometry, which bites immediately into slick surfaces to eliminate wandering without needing a preliminary center punch. Combined with fully ground flutes, the bits clear metal shavings cleanly to reduce friction and maintain consistent feed rates.
While the set handles abrasive materials effectively, the fractional sizing tops out at 1/4-inch, so users requiring larger diameters will need supplemental tooling. Additionally, the heightened rigidity of cobalt steel requires steady, straight alignment to prevent slender bits from snapping under uneven lateral force.
Bottom line: This BECOLLO drill bit collection delivers reliable heat tolerance and accurate self-centering performance, making it a great choice for drilling pilot holes and small fasteners in stubborn metals.
- Brand: BECOLLO
- Material: M35 High Speed Steel with 5% Cobalt
- Bit Type: Jobber Length Twist Drill Bits
- Flute Construction: Fully Ground Processing
- Tip Geometry: 135-Degree Split Point
- Piece Count: 13 Pieces
- Size Range: 1/16 Inch to 1/4 Inch
- Target Compatibility: Stainless Steel, Cast Iron, Hard Metals
This set supplies 13 standard jobber-length twist bits graduated in 1/64-inch increments for precision hole sizing:
- 1/16", 5/64", 3/32", 7/64"
- 1/8", 9/64", 5/32", 11/64"
- 3/16", 13/64", 7/32", 15/64", 1/4"
Each bit utilizes a standard round shank that fits securely into keyed or keyless 3/8-inch and 1/2-inch drill chucks as well as benchtop drill presses.
Always run cobalt bits at reduced rotation speeds when cutting through hardened metals to prevent excess heat buildup and extend cutting edge sharpness.
Apply cutting oil or metal lubricant continuously during deep drilling to reduce friction and assist in clear chip evacuation.
Maintain straight axial pressure along the drill path, as high-hardness M35 cobalt steel can fracture if subjected to bending or side-loading.
Secure all workpieces firmly with clamps and wear appropriate safety goggles to shield against flying metal chips.
Pros
- High 67 HRC rating cuts stainless steel and cast iron
- Comprehensive fractional, letter, and wire gauge sizing
- 135-degree split point prevents wandering without center punching
- Durable metal storage index protects and organizes bits
Cons
- Round straight shanks can slip in high-torque keyless chucks
- Not suitable for drilling glass, masonry, or ceramic surfaces
- Requires strict speed and heat management to avoid burning smaller bits
The WildBossy 115-Piece M35 Cobalt Drill Bit Set is a heavy-duty workshop companion built for demanding metalworking jobs. Machinists, mechanics, and advanced DIYers will appreciate having an exhaustive range of precise drill diameters ready to tackle stubborn materials like structural steel and cast iron.
Each bit is ground from high-speed M35 cobalt steel, achieving a hardness rating of up to 67 HRC to stay sharp far longer than conventional high-speed steel alternatives. The 135-degree split-point tips begin cutting instantly without wandering across your workpiece, while the gold oxide finish and ground flutes clear hot shavings efficiently.
Because cobalt steel prioritizes heat tolerance and extreme edge retention, the narrower bits are more brittle than softer multipurpose bits. Users who lack a drill press or steady technique may risk snapping the smallest wire gauge sizes if excessive lateral torque is applied.
Bottom line: If you frequently machine tough metals and want fractional, letter, and wire gauge sizes organized in a rugged metal chest, this 115-piece collection delivers outstanding utility.
- Material: M35 Cobalt High Speed Steel (5 percent cobalt alloy)
- Hardness Rating: Up to 67 Rockwell C (HRC)
- Total Piece Count: 115 pieces
- Drill Point Angle: 135-degree split point
- Shank Type: Round straight jobber shank
- Surface Treatment: Gold oxide coating
- Storage System: Heavy-duty metal indexed organizer
- Material Compatibility: Stainless steel, cast iron, steel, aluminum alloys, wood
- 29 Fractional Drill Bits: 1/16 inch to 1/2 inch in precise 1/64-inch steps
- 26 Letter Drill Bits: Complete A through Z sizing
- 60 Wire Gauge Drill Bits: Numbered sizes #1 through #60
- 1 Heavy-Duty Metal Indexed Storage Box with clear size stampings
Always apply a suitable cutting oil or coolant fluid when boring through stainless steel, alloy steel, or cast iron. Lubrication lowers friction, dissipates intense heat, and dramatically extends the working lifespan of the cobalt cutting edges.
Operate your drill at controlled, slower rotational speeds with firm, steady feed pressure. Excessive speed generates damaging thermal buildup that softens tool steel, while rushing the cut can shatter brittle cobalt bits.
Do not use these twist bits on glass, concrete, ceramic tile, or masonry. Always clamp workpieces down securely and wear impact-rated eye protection to shield against sharp flying metal shavings.
How to Choose the Best Drill Bits to Drill Hardened Steel: Buying Guide
Base Metal Metallurgy and Cobalt Concentration
The primary factor determining whether a drill bit can pierce hardened metal or simply melt against it is the underlying metallurgy of the tool. Conventional high-speed steel, commonly abbreviated as HSS, performs adequately in softwood, plastics, and mild structural steel, but it quickly loses its temper when subjected to the intense thermal spikes generated by abrasive, high-tensile metals. When cutting into hardened carbon steel or stainless alloys, heat builds rapidly at the chisel edge. If the tool metal cannot retain its hardness at elevated temperatures, the cutting edge immediately rolls over and dulls. For this reason, professional fabricators turn to cobalt-infused steel alloys that maintain their structural hardness even when glowing under heavy friction.
Cobalt drill bits fall primarily into two standardized metallurgical grades: M35 and M42. The numeric designation reflects the percentage of cobalt blended uniformly throughout the steel matrix. Premium options like the BOSCH CO14B 14-Piece Cobalt Drill Bit Set and the Metric M42 8% Cobalt Twist Drill Bits Set incorporate an advanced M42 alloy containing 8% cobalt. This formulation achieves a hardness rating between 68 and 70 on the Rockwell Hardness Scale (HRC), delivering up to ten times the service life of standard high-speed steel bits and resisting thermal deformation under extreme drilling loads in stainless steel, cast iron, and titanium alloys.
For everyday shop maintenance and general fabrication, M35 alloy formulations containing 5% cobalt offer a dependable and economical balance between cutting hardness and mechanical brittleness. Offerings such as the 13Pcs(1/16″-1/4″) Cobalt Drill Bit Set M35 HSS, the Cobalt Drill Bit Set (1/16-1/4 Inch, 13PCS), the 13PCS (1/16″-1/4″) Cobalt Drill Bit Set, and the extensive M35 5% Cobalt Drill Bits Set 115PCS (1/16″-1/2″ reach up to 67 Rockwell hardness. Unlike surface-coated bits, cobalt alloys are solid throughout the entire tool body. This uniform composition ensures that as you sharpen the cutting edges over time, the bit retains its heat resistance and cutting capabilities down to the shank.
Tip Geometry and Penetration Without Walking
Tip geometry dictates how a drill bit initiates contact with the workpiece and how much downward force is required to begin shearing metal. Traditional drill bits feature a 118-degree point angle, which is suitable for soft materials like wood and aluminum but tends to wander across flat metal surfaces before biting. When working on hardened steel plate, any skidding or wandering across the surface ruins the accuracy of the hole and rapidly chips the delicate outer corners of the cutting lips. A flatter point angle combined with specialized cutting grinds is essential for establishing an immediate, stable center.
Modern metalworking bits frequently utilize a 135-degree split point design, seen on heavy-duty choices like the DEWALT Drill Bit Set, 3-Flats Shank,14-Piece, the Drill America - KFD29J-PC 29 Piece Heavy Duty High, and the DEWALT Drill Bit Set, 21 Pc High Speed Steel. The 135-degree split point creates four cutting edges instead of two, with secondary relief grinds that cut directly at the center axis. This self-centering action allows the tool to bite immediately into tough alloys on contact, significantly reducing walking and eliminating the mandatory requirement of a center punch or starter pilot hole on flat workpieces.
An alternative approach is found in pilot point engineering, exemplified by the DEWALT Drill Bit Set, 21 Pc. Titanium Nitride. Pilot point tips incorporate a stepped, stepped-down center nose that acts as an integral pilot bit, penetrating the material cleanly before the wider shoulders engage. This produces exceptionally clean, burr-free entrance holes and minimizes walking on sheet stock and structural members. When selecting your tip profile, keep in mind your drill rig stability and explore our broader collection of tools and home improvement guides to ensure your setup maintains rigid alignment throughout the operation.
Flute Engineering, Web Thickness, and Structural Durability
While the tip geometry initiates the hole, the flute architecture and core web thickness dictate how effectively the bit withstands rotational torque and evacuates metal chips. In hardened steel, chips cannot simply break off as fine dust; they must be continuously sheared and drawn upward away from the cutting zone. If metal shavings get trapped in the flutes, they become re-cut by the rotating edges, creating immense secondary friction, accelerating heat buildup, and frequently binding the bit until it snaps off flush inside the drilled hole.
To resist torsional snapping under heavy feed pressure, high-performance bits incorporate reinforced core geometries. The BOSCH CO14B 14-Piece Cobalt Drill Bit Set features a specialized thick web-helix design that provides additional stability in tough applications, significantly reducing radial deflection. Similarly, the tapered web design implemented in the DEWALT Drill Bit Set, 3-Flats Shank,14-Piece and the DEWALT Drill Bit Set, 21 Pc. Titanium Nitride progressively thickens the central core from the tip toward the shank, yielding exceptional backbone strength to prevent catastrophic breakage when breakthrough occurs.
Flute profile also plays a critical role in clearing material efficiently. The DEWALT Drill Bit Set, 21 Pc High Speed Steel utilizes a parabolic flute design engineered to increase chip ejection rates, paired with a 31-degree helix angle that moderates the cutting aggressiveness for drilling deep holes without binding. Fully ground flute processing, featured on the 13PCS (1/16″-1/4″) Cobalt Drill Bit Set, creates polished internal pathways that lower surface friction, allowing coiled ribbons of metal to glide freely out of deep bores without jamming.
Shank Design and Power Transmission in Demanding Applications
When drilling hardened materials, the cutting resistance can easily exceed the holding power of a standard three-jaw drill chuck. If a bit binds inside a tough steel plate while the drill motor continues to spin, a standard round shank will slip inside the chuck jaws. This spinning friction scores the chuck, ruins the bit shank, and immediately halts the cutting action. Selecting the correct shank interface ensures that all available motor torque is transferred directly into shearing the metal workpiece rather than generating friction at the tool holder.
To prevent spin-out under heavy torque loads, several manufacturers incorporate flat surfaces along the shank. The DEWALT Drill Bit Set, 3-Flats Shank,14-Piece and the DEWALT Drill Bit Set, 21 Pc High Speed Steel feature a 3-flats shank on all bit sizes larger than 3/16-inch, providing positive locking faces for chuck jaws to grip securely. In a similar manner, the ZELCAN 10 Sizes Titanium Step Drill Bit uses a tri-flatted shank to eliminate slippage inside power tool chucks during stepped hole enlargement, preserving the tool holder and maximizing cutting safety.
For mechanics working in tight quarters or using modern quick-release adapters, hex shanks provide an exceptional alternative. The 5PCS M35 Cobalt Stubby Drill Bit Set incorporates a solid one-piece 1/4-inch hex shank that drops directly into quick-change chucks and drivers without the risk of spinning loose. Conversely, large comprehensive machine shop sets like the M35 5% Cobalt Drill Bits Set 115PCS (1/16″-1/2″ retain traditional round straight shanks for universal compatibility across keyed drill press chucks and industrial collets. When driving these bits with high-torque power tools, pairing your bits with top-performing cordless impact drivers and drills ensures steady rotational control.
Bit Length, Clearance, and Profile Specialization
Drill bit length significantly affects both tool rigidity and physical access to the workpiece. Most general-purpose twist bits, including those in the Drill America - KFD29J-PC 29 Piece Heavy Duty High and the 13Pcs(1/16″-1/4″) Cobalt Drill Bit Set M35 HSS, conform to standard jobber length proportions. Jobber length provides an optimal compromise between flute depth for through-hole drilling and structural stiffness for handheld drilling. However, excessive length can introduce unwanted flexing when high feed pressures are applied against hardened surfaces, increasing the likelihood of the bit snapping off.
When working in cramped engine compartments, truck frames, or tight machinery enclosures, stubby drill bits offer an immense mechanical advantage. The 5PCS M35 Cobalt Stubby Drill Bit Set features overall tool lengths measuring only 1.83 to 2.32 inches. This ultra-compact profile allows users to fit into tight spaces where standard jobber bits cannot clear obstructions. Furthermore, the shortened flute length substantially decreases torsional flex, providing maximum rigidity and precision alignment when drilling tough metals like cast iron, titanium, and stainless steel without tip wander.
Stepped cone bits offer another unique profile option, but buyers must understand their material boundaries. The ZELCAN 10 Sizes Titanium Step Drill Bit incorporates ten step sizes ranging from 1/4-inch to 1-3/8 inches and deburrs holes automatically as it cuts. However, the manufacturer explicitly notes that this high-speed steel step bit is engineered for plastic, aluminum, copper, iron, and sheet metals, strictly excluding hardened steel or harder alloys. For true hardened structural steel and thick alloy plate, dedicated solid cobalt twist drill bits remain the indispensable tool of choice.
Surface Coatings, Thermal Resistance, and Drilling Speed Control
While solid cobalt alloy bits rely on their internal chemistry to survive high temperatures, surface treatments and chemical coatings offer added defense against frictional wear and corrosion. Titanium nitride (TiN) coatings, found on the DEWALT Drill Bit Set, 21 Pc. Titanium Nitride, provide a ceramic-like surface barrier that lowers friction and extends the working life of high-speed steel in wood, metal, and plastic. Similarly, black and gold oxide coatings on sets like the DEWALT Drill Bit Set, 21 Pc High Speed Steel and the Drill America - KFD29J-PC 29 Piece Heavy Duty High enhance surface lubricity, guard against rust, and improve overall bit resilience.
However, coatings cannot compensate for excessive drill speeds when tackling hardened metal. A common error among DIYers is spinning the drill at maximum RPM, which generates blistering heat faster than the bit can dissipate it. High-cobalt tools like the Metric M42 8% Cobalt Twist Drill Bits Set and the Cobalt Drill Bit Set (1/16-1/4 Inch, 13PCS) are capable of cutting up to three to five times faster than standard bits, but they perform best when operated at controlled rotational speeds with firm, steady feed pressure. Maintaining correct pressure forces the sharp cutting edge to peel away long ribbons of metal rather than rubbing and grinding uselessly against the surface.
Controlling heat through proper lubrication is equally vital when drilling tough metals. Applying dedicated cutting oil or metalworking fluid keeps the cutting lips cool, flushes out tiny metal shavings, and extends the sharp lifespan of your investment. Even premium M42 cobalt alloys benefit enormously from a drop of lubricant, ensuring that the bit maintains its keen cutting edge across dozens of consecutive holes in hardened plate without thermal degradation.
The table below provides a direct comparison of key specifications drawn directly from manufacturer product data for five top-tier drilling sets designed for tough metal applications:
| Product | Set Piece Count | Base Material Formulation | Target Materials Listed in Specs |
|---|---|---|---|
| BOSCH CO14B 14-Piece Cobalt Drill Bit Set | 14-Piece | M42 alloy containing 8% cobalt | stainless steel, cast iron, titanium, light-gauge metal and aluminum |
| Metric M42 8% Cobalt Twist Drill Bits Set | 19Pcs | Premium M42 8% Cobalt Steel | Stainless Steel, Hard Metals, Aluminum, Plastic |
| 5PCS M35 Cobalt Stubby Drill Bit Set | 5PCS | M35 Cobalt steel | stainless steel and various hardened metals such as cast iron, titanium, bronze, aluminum |
| Cobalt Drill Bit Set (1/16-1/4 Inch, 13PCS) | 13 Pieces | 5% Cobalt Steel | Stainless Steel, Steel Plate, Iron Sheet, Cast Iron and Hardwood |
| M35 5% Cobalt Drill Bits Set 115PCS (1/16″-1/2″ | 115PCS | M35 Cobalt Steel with Molybdenum and Cobalt | stainless steel, steel and cast iron as well as wood, aluminum alloys |
Why You Should Trust Us
At Daily Deal Here, our tool review team approaches every buying guide with practical workshop realities in mind. We do not engage in simulated lab experiments or claim artificial stress testing on commercial drilling rigs. Instead, our conclusions are built upon meticulous editorial curation, comprehensive analysis of verified Amazon product listings, manufacturer technical specifications, and broad thematic feedback from thousands of real-world purchasers. We examine what professional machinists, automotive technicians, structural welders, and weekend DIY enthusiasts experience when using these tools under true fabrication conditions.
Our research methodology focuses heavily on tracking long-term user satisfaction, identifying persistent failure modes such as brittle flute breakage or slipping shanks, and verifying metallurgical claims against industry standards. By evaluating critical properties such as Rockwell C hardness levels, flute grind finishing, tip angle geometry, and chuck compatibility, we distill vast quantities of retail feedback into actionable purchasing advice. We ensure that every product highlighted in our guides meets high benchmarks for build quality, heat tolerance, and functional reliability so you can invest your tool budget with complete confidence.
Final Thoughts
Selecting the right drill bit for hardened steel comes down to matching your specific project requirements with the correct metallurgy and physical profile. When tackling high-tensile alloys, hardened truck frames, or abrasive stainless plate, ordinary twist drills simply will not survive the friction. Investing in tools manufactured with authentic cobalt steel ensures that your bits maintain their cutting sharpness and structural temper under blistering heat, saving you endless frustration, damaged workpieces, and lost shop time.
For the best overall drilling performance, our top recommendation is the BOSCH CO14B 14-Piece Cobalt Drill Bit Set. Its upgraded M42 alloy containing 8% cobalt delivers outstanding heat resistance, while its thick web-helix design and surface-hardened tips provide the structural backbone required to penetrate tough cast iron, titanium, and stainless steel without wandering or premature dulling. If you need maximum cutting capability on a conservative budget, the 13Pcs(1/16″-1/4″) Cobalt Drill Bit Set M35 HSS serves as our best value selection, providing true M35 cobalt steel construction, 135-degree self-centering points, and an indexed storage case for rapid shop sorting. You can explore more of our hardware reviews by browsing our comprehensive buying guides and tool analyzes.
For specialized automotive work and tight machinery bays where clearance is strictly limited, our niche recommendation is the 5PCS M35 Cobalt Stubby Drill Bit Set. Its compact 1.83 to 2.32-inch lengths minimize flex and fit into cramped spaces, while the integrated 1/4-inch hex shank eliminates chuck slippage in high-torque drivers. Alternatively, fabricators requiring an all-in-one shop replenishment should consider the M35 5% Cobalt Drill Bits Set 115PCS (1/16″-1/2″, which supplies a vast array of fractional, letter, and wire-gauge sizes built to pierce tough metals with ease.
Frequently Asked Questions About Drill Bits to Drill Hardened Steel
What makes drill bits to drill hardened steel different from standard drill bits in 2026?
Standard drill bits are typically made from standard high-speed steel, which performs well in wood, plastics, and mild metals but quickly softens when exposed to high frictional heat. Specialized drill bits to drill hardened steel incorporate solid cobalt alloys, such as M35 with 5% cobalt or M42 with 8% cobalt, blended throughout the entire steel matrix. This metallurgical composition provides exceptional red-hardness, allowing the cutting lips to maintain their razor sharpness at temperatures exceeding 1,000 degrees Fahrenheit without losing temper or rounding off against tough alloys.
Do I need cutting fluid when using drill bits to drill hardened steel?
Yes, utilizing cutting fluid or dedicated metalworking lubricant is highly recommended whenever you operate drill bits to drill hardened steel. While solid cobalt alloys are built to endure intense thermal spikes, applying cutting oil reduces friction at the cutting interface, cools both the workpiece and the tool, and helps carry chips smoothly out of the flutes. Using lubrication significantly extends the working lifespan of the cutting edge, speeds up penetration rates, and prevents micro-galling when cutting tough stainless steel, cast iron, and hardened structural plates.
Can I use drill bits to drill hardened steel in an impact driver or handheld drill?
You can readily use drill bits to drill hardened steel in handheld drills and compatible drivers, provided you control your rotational speed and apply steady pressure. However, standard twist bits with round or flatted shanks require a three-jaw chuck. For impact drivers with quick-change chucks, bits specifically engineered with a 1/4-inch hex shank, such as dedicated stubby sets, are required. When drilling freehand, keep the tool perpendicular to the metal surface to avoid side-loading the bit, as high-hardness cobalt alloys are more brittle than mild steel.
How can I prevent drill bits to drill hardened steel from snapping or dulling quickly?
To avoid premature snapping or dulling, run your drill at a moderate to slow RPM and apply firm, consistent feed pressure so the cutting edges continuously peel chips instead of rubbing against the metal. Avoid excessive side pressure, which causes brittle cobalt flutes to flex and snap. Clear deep holes frequently to prevent chip binding, use cutting fluid, and inspect dark boreholes using compact rechargeable pen flashlights to confirm that chips are clearing smoothly without packing inside the cut.
What is the difference between M35 and M42 drill bits to drill hardened steel?
The primary distinction between M35 and M42 drill bits to drill hardened steel lies in their chemical cobalt concentration and resulting hardness. M35 alloy contains 5% cobalt, reaching approximately 66 to 67 Rockwell hardness, offering a balanced combination of heat resistance, durability, and chip resistance for general fabrication. M42 alloy incorporates 8% cobalt, achieving 68 to 70 Rockwell hardness. This higher cobalt concentration delivers superior thermal resistance and wear life in abrasive materials like titanium and stainless steel, though it requires rigid alignment due to slightly increased brittleness.
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