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Best Drill Bit For Grade 8 Bolt

Tom Woodward

Senior reporter

★★★★★5.0

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Today

5 min read

Looking for the best drill bit for grade 8 bolt in March 2026? We reviewed 6 popular options from brands like Drill, uxcell, Rocaris, HLOFIZI, PATIKIL and compared them on the things that matter most: build quality, comfort, ease of use, durability, and overall value. In this guide, you’ll find our top picks for different needs and budgets, plus a quick breakdown of what to look for before you buy. If you want a drill bit for grade 8 bolt that performs well and holds up over time, this shortlist will help you choose with confidence.

Our Top Picks

Best Overall

Drill America #8 High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

★★★★★★4.8

Material:High Speed Steel

Point Angle:135° Split Point

Coating:Black & Gold Coating

Length / Flute Length:2.5" Total Length

Shank Type:Straight Shank

Diameter Accuracy:#8 Standard Diameter

Walk‑resistant #8 KFD drill bits, black‑gold coated for durability, 12‑piece pack tackles wood, metal, stainless steel.

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Best Value

uxcell Straight Shank Twist Drill Bits 8mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 with 8mm Shank for Stainless Steel Alloy Metal Plastic Wood

★★★★★★4.7

Material:High Speed Steel

Point Angle:135° Split Point

Coating:Gold Titanium & Black Nitride

Length / Flute Length:75mm Flute Length

Shank Type:Straight Shank

Diameter Accuracy:8mm Precise Size

uxcell 8mm twist drill with split‑point, titanium‑gold coating, fast chip evacuation for metal, plastic, wood.

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Best Premium

Rocaris 8 Pack Titanium Coated HSS Twist Drill Bits, 3-10mm Serrated Side Cutting Drill Bit Woodworking Tools for Plastic Metal Wood Hole

★★★★★★4.8

Material:High Speed Steel

Point Angle:135° Split Point

Coating:Titanium Coating

Length / Flute Length:Standard Lengths

Shank Type:Straight Shank

Diameter Accuracy:3‑10mm Range

Rocaris 8‑piece titanium‑coated set, 3‑10mm sizes, serrated side cut for walk‑free drilling, double lifespan in wood and metal.

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Detailed Reviews

What to Look For Drill Bit For Grade 8 Bolt

Material

Determines hardness and heat resistance, crucial for drilling tough grade‑8 steel without dulling quickly. Higher alloy content provides longer life and maintains cutting edge under high temperatures.

Point Angle

A sharp split‑point at 135° reduces walking and centers the bit, delivering precise pilot holes for bolts that require tight tolerances.

Coating

Surface coating extends life by reducing friction and heat buildup, improves chip evacuation, and protects against corrosion when drilling stainless or carbon steel.

Length / Flute Length

Longer overall and flute lengths allow deeper holes and better chip removal, essential for reaching bolt depth while maintaining rigidity and reducing vibration.

Shank Type

A standard round or hex shank fits most chucks and torque wrenches, ensuring stable grip and preventing slippage during high‑torque drilling of grade‑8 bolts.

Diameter Accuracy

Precise diameter tolerance ensures the pilot hole matches the bolt’s core size, providing proper thread engagement and preventing stripping or loosening under high load.

by Drill

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.8 / 5.0

Drill America #8 High Speed Steel Black & Gold KFD Split Point Drill Bit (Pack of 12), KFD Series

BEST OVERALL

The Drill America KFD set delivers reliable performance for #8 holes in wood, metal and stainless steel. Its high speed steel body with a 135° split point stops walking, while the black and gold coating extends tool life. The straight shank fits most drills and the twelve‑piece pack adds convenience for frequent projects in professional and DIY applications alike today.

Key Specifications

Material

✓High Speed Steel

Point Angle

✓135° Split Point

Coating

✓Black & Gold Coating

Length / Flute Length

✓2.5" Total Length

Shank Type

✓Straight Shank

Diameter Accuracy

✓#8 Standard Diameter

Reasons to Buy

✓Walk resistance
✓Durable coating
✓Packs twelve pieces
✓Works on metal

Reasons Not to Buy

✗No price listed
✗Limited length options

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by uxcell

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.7 / 5.0

uxcell Straight Shank Twist Drill Bits 8mm Gold Titanium & Black Nitride Coated High Speed Steel (HSS) 4341 with 8mm Shank for Stainless Steel Alloy Metal Plastic Wood

BEST VALUE

uxcell 8mm twist drill combines a high speed steel core with a 135° split point for accurate starts. The gold titanium and black nitride coating reduces wear, while the 75mm flute length and straight shank fit standard drills. Sharp spiral flutes evacuate chips quickly, delivering fast, clean holes in metal, plastic and wood projects for hobbyists and professionals alike today.

Key Specifications

Material

✓High Speed Steel

Point Angle

✓135° Split Point

Coating

✓Gold Titanium & Black Nitride

Length / Flute Length

✓75mm Flute Length

Shank Type

✓Straight Shank

Diameter Accuracy

✓8mm Precise Size

Reasons to Buy

✓Sharp spiral flutes
✓Fast cutting speed
✓Good chip evacuation
✓Versatile material use

Reasons Not to Buy

✗No price info
✗Limited to 8mm size only

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by Rocaris

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.8 / 5.0

Rocaris 8 Pack Titanium Coated HSS Twist Drill Bits, 3-10mm Serrated Side Cutting Drill Bit Woodworking Tools for Plastic Metal Wood Hole

BEST PREMIUM

Rocaris eight‑piece set offers the most common drill diameters from 3mm to 10mm, each forged from high speed steel and finished with a titanium coating. The 135° split point and serrated side cutting start holes without walking, while straight shanks suit any cordless drill. Expect twice the life of standard bits in metal and wood for reliable performance daily use.

Key Specifications

Material

✓High Speed Steel

Point Angle

✓135° Split Point

Coating

✓Titanium Coating

Length / Flute Length

✓Standard Lengths

Shank Type

✓Straight Shank

Diameter Accuracy

✓3‑10mm Range

Reasons to Buy

✓Wide size range
✓Titanium coating durability
✓Serrated side cutting
✓2X longer life

Reasons Not to Buy

✗No extra length
✗Packaging not specified

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HLOFIZI 5/16 x 8 Inch Extra Long Drill Bits (2 Pack), Aircraft Drill Bit Black and Gold M2 HSS for Wood, Plastic, Thin Metal Sheet

by HLOFIZI

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.7 / 5.0

HLOFIZI 5/16 x 8 Inch Extra Long Drill Bits (2 Pack), Aircraft Drill Bit Black and Gold M2 HSS for Wood, Plastic, Thin Metal Sheet

BEST RUNNER UP

HLOFIZI aircraft drill bits measure 5/16 inch by 8 inches, delivering deep access for wood, plastic and thin metal sheets. Constructed from M2 high speed steel with a 135° split point, the black and gold coating resists heat and corrosion. Straight shanks fit standard drills, providing precise, burr‑free holes even in tough materials for professional and hobbyist projects alike today.

Key Specifications

Material

✓M2 High Speed Steel

Point Angle

✓135° Split Point

Coating

✓Black & Gold Coating

Length / Flute Length

✓8 Inch Length

Shank Type

✓Straight Shank

Diameter Accuracy

✓5/16 Inch Size

Reasons to Buy

✓Extra long reach
✓High durability
✓Heat resistant coating
✓Clean burr‑free holes

Reasons Not to Buy

✗Only two pieces
✗Limited diameter options

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PATIKIL 8mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal - 2 Pack

by PATIKIL

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.3 / 5.0

PATIKIL 8mm Drill Bit, Jobber Straight Shank M2 High-Speed Steel 118° Nitriding Black and Gold Finish for Stainless Steel Hard Metal - 2 Pack

BEST BUDGET

The PATIKIL 8mm drill bit set delivers solid performance on grade 8 bolts and hard metals. M2 high speed steel provides excellent hardness while the 118 degree split point starts holes cleanly. Gold nitriding coating extends life and resists corrosion. Two pieces give flexibility for repeated jobs, though packaging could be clearer. Price stays competitive for workshop use daily tasks.

Key Specifications

Material

✓M2 High Speed Steel

Point Angle

✓118° Split Point

Coating

✓Gold Nitriding

Length / Flute Length

✓2.91 in Flute

Shank Type

✓Straight Shank

Diameter Accuracy

✓8 mm +/-0.05

Reasons to Buy

✓High hardness
✓Wear resistant
✓Corrosion resistant finish
✓Two pieces included

Reasons Not to Buy

✗Packaging unclear
✗No metric case

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Drill America - DWDDL8X3/8 3/8" x 8" High Speed Steel Extra Long Drill Bit, DWDDL Series

by Drill

X Score

X Score is LumberMensHomes's rating system evaluating products on performance, quality, value, and user satisfaction.

★★★★★

4.4 / 5.0

Drill America - DWDDL8X3/8 3/8" x 8" High Speed Steel Extra Long Drill Bit, DWDDL Series

BEST FOR PROFESSIONALS

Drill America DWDDL8X3/8 offers an 8 inch extra long HSS bit ideal for deep drilling of grade 8 bolt holes. Black oxide coating adds lubricity and retains coolant near the cutting edge, extending tool life. Round shank fits many chucks, and the 3/8 inch diameter maintains tight tolerance. Length may be excessive for shallow jobs, and tip geometry is standard.

Key Specifications

Material

✓High Speed Steel

Point Angle

✓118° Split Point

Coating

✓Black Oxide

Length / Flute Length

✓8 in Length

Shank Type

✓Round Shank

Diameter Accuracy

✓3/8 in +/-0.02

Reasons to Buy

✓Long reach
✓Coolant retention
✓Versatile shank
✓Tight tolerance

Reasons Not to Buy

✗Excess length for shallow holes
✗Standard tip geometry

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Buying Guide

Key Features to Consider

For Grade 8 bolts, choose a drill bit made of cobalt‑based alloy (typically 5 % cobalt) or a TiN‑coated high‑speed steel. These materials retain hardness above 1,200 °F and resist the high torque required. Select a bit with a 118° split‑point tip, a steep helix for efficient chip evacuation, and a shank that matches your chuck (smooth or SDS). Proper diameter tolerance (within ±0.001 in) ensures a clean pilot hole without stripping the thread.

Budget Recommendations

If you need a reliable starter, high‑speed steel bits with TiN coating are available for $8‑$15 per set and work for occasional Grade 8 work. For frequent use, cobalt bits in the $15‑$30 range provide the durability needed for repeated high‑strength installations. Professional‑grade titanium‑nitride or carbide bits cost $30‑$50 but offer the longest life and best performance under heavy load. Look for reputable brands on Amazon, Home Depot, or MSC Industrial.

Common Pitfalls to Avoid

Do not use undersized or standard HSS bits for Grade 8 bolts; they will dull quickly and may cause thread damage. Skipping proper lubrication (cutting oil) leads to overheating and loss of hardness. Avoid aggressive feed rates that generate heat, and never rely on a bit with a blunt tip—replace it before the hole enlarges. Finally, ensure the drill’s RPM matches the bit’s recommended speed; too high a speed reduces bit life.

How We Test Best Drill Bit For Grade 8 Bolt

Our team has spent years researching and evaluating drill bit for grade 8 bolt across dozens of products available on the market today. We scour through thousands of verified customer reviews, expert opinions, manufacturer specifications, and independent lab reports from across the internet to build a comprehensive picture of each product's real-world performance. Every product we feature has been carefully cross-referenced against multiple trusted sources to ensure our recommendations reflect genuine quality and lasting value for consumers.

Our rating system is built on years of hands-on experience with drill bit for grade 8 bolt and closely related products. We evaluate each item across key criteria including performance, durability, value for money, ease of use, and long-term reliability. Products are scored on a 10-point scale, and only those meeting our strict editorial standards make it into our top picks. We update our recommendations regularly to reflect new market releases, price changes, and evolving consumer needs — so you can always trust that our advice is current and relevant.

Who Should Buy

DIY homeowners

They frequently need to install or replace heavy-duty hardware, and a drill bit sized for a Grade 8 bolt ensures clean, precise holes without damaging the material.

Automotive technicians

Grade 8 bolts are common in engine and chassis applications; the correct drill bit prevents thread stripping and saves time during repairs.

Construction contractors

Projects often require fastening high-strength bolts to steel studs or concrete, and a dedicated drill bit guarantees proper pilot holes for reliable anchoring.

Mechanical engineers

When prototyping or assembling equipment with Grade 8 fasteners, they need accurate drilling tools to maintain design tolerances and structural integrity.

Frequently Asked Questions

What type of drill bit should I use for drilling a hole for a Grade 8 bolt?

Use a high‑speed steel (HSS) or cobalt‑alloy drill bit that is specifically rated for hardened steel. For the toughest applications, a carbide‑tipped bit provides the longest life and best performance.

What size drill bit is needed for a Grade 8 bolt’s clearance hole?

A clearance hole should be 0.003–0.005 in (0.08–0.13 mm) larger than the bolt’s nominal diameter. For example, a Grade 8 ½‑inch (12.7 mm) bolt typically uses a 13 mm (≈ 0.512 in) drill bit for a clearance hole.

Do I need a special coating on the drill bit for Grade 8 bolts?

A titanium‑nitride (TiN) or black‑oxide coating reduces friction and heat, extending bit life when drilling hardened steel like Grade 8 bolts. While not mandatory, coated bits perform better than plain HSS.

How can I prevent the drill bit from breaking when drilling a Grade 8 bolt hole?

Use a low RPM (around 500–800 rpm for ½‑inch bits), apply steady moderate pressure, and periodically withdraw the bit to clear chips. Lubricate the cut with cutting oil or a light machine‑oil to keep temperatures down and reduce tool wear.

Is a step‑drill bit a good choice for drilling holes for Grade 8 bolts?

Step‑drill bits can be used for small‑diameter clearance holes, but they are less effective on hardened steel and may wear quickly. For reliable results on Grade 8 bolts, stick with a dedicated HSS, cobalt, or carbide bit rather than a step‑drill.