Flat Drill Bits

About Flat Drill Bits

Flat drill bits, commonly known as spade bits or paddle bits, are indispensable cutting tools designed for boring large-diameter holes quickly and efficiently through wood and similar soft materials. Distinguished by their flat, blade-like cutting surface and central pilot point, these bits excel at rapid material removal where speed takes priority over a perfectly smooth finish. Unlike conventional twist drill bits, flat bits are purpose-built for construction work, cable routing, plumbing installations, and general building tasks where drilling large holes swiftly is essential.

The product range at Tooled-Up.com encompasses an extensive selection of flat drill bits from leading manufacturers including Bosch Professional, DeWalt, Milwaukee, Makita, Bahco, Irwin, and Draper. Available both as individual bits in sizes ranging from 10mm up to 38mm and beyond, and as comprehensive sets offering excellent value, these bits cater to every requirement from occasional DIY projects to demanding professional site work. Many feature hex shanks for secure grip in modern drill chucks and quick-change systems, whilst premium professional-grade options from Bosch Expert incorporate self-cutting spurs and optimised cutting geometry for faster drilling with significantly reduced splintering.

Whether you're a joiner running cables through floor joists, a plumber drilling access holes for pipework, or a homeowner tackling renovation projects, flat drill bits deliver the ideal combination of speed, affordability, and efficiency for creating larger diameter holes without the expense of auger bits or hole saws. Their simple yet effective design has made them a staple in toolkits across the construction industry for generations.

Jargon Buster

• Spade Bit: Alternative name for flat drill bits, referring to their spade or paddle-shaped cutting blade that removes material aggressively through timber and softwood.
• Pilot Point: The central sharp tip that centres the bit precisely and prevents wandering when initiating a hole. Premium bits may feature brad points for enhanced starting accuracy.
• Hex Shank: A six-sided shaft design providing superior grip in drill chucks and quick-change adaptors, preventing slippage under heavy load and enabling rapid bit changes with impact-compatible systems.
• Self-Cut Speed Design: Advanced cutting geometry incorporating sharpened spurs and optimised angles that reduce drilling effort whilst producing cleaner entry and exit holes with minimal splintering.
• Cutting Spurs: Wing-like extensions on the bit's shoulders that score the wood fibres before the main blade removes material, resulting in cleaner holes and improved swarf clearance.
• Long Series: Extended length flat bits engineered for drilling through thick timber sections or reaching into confined spaces where standard bits cannot access.

Who Uses Flat Drill Bits?

• Carpenters and Joiners – Drilling holes for cable runs, dowels, and pipework through timber frames, joists, and studwork
• Electricians – Creating access holes for electrical cables, conduits, and back boxes through wooden studs and beams
• Plumbers – Boring holes for pipe work through floor joists, wall studs, and timber structures during installations
• General Builders – Rough drilling work on construction sites where speed and efficiency matter more than a perfectly finished hole
• Kitchen and Bathroom Fitters – Installing pipework and services behind units, cabinets, and fixtures
• Fencing Contractors – Drilling pilot holes and service access through fence posts, rails, and gates
• Maintenance Engineers – General repair and installation work across commercial and industrial facilities
• DIY Enthusiasts – Home improvement projects requiring larger diameter holes in wooden materials at economical cost

How to Choose the Right Flat Drill Bits

Size Range: Consider which diameters you'll require most frequently in your work. Individual bits are cost-effective for occasional use or specific sizes, whilst comprehensive sets from Bosch, DeWalt, or Bahco deliver better value when you need multiple sizes readily available. Most tradespeople find sizes between 12mm and 32mm cover the majority of typical applications, though larger diameters up to 38mm suit specialist installations.

Shank Type: Hex shanks provide superior grip and compatibility with quick-change systems, making them ideal for professional use with impact drivers and modern cordless drills. Traditional round shanks remain common but may slip under heavy load, particularly when drilling larger diameter holes through hardwoods or dense materials.

Bit Length: Standard length bits (typically 150-200mm) suit most everyday applications, but long series bits or extension shafts become essential when drilling through thick timber sections, double joists, or working in confined spaces requiring extra reach. Bahco and Bosch both manufacture dedicated extension accessories compatible with their flat bit ranges.

Quality Grade: Budget-friendly options from Draper, Faithfull, or Sealey prove adequate for occasional DIY use and light-duty applications, whilst professional ranges such as Bosch Expert, Milwaukee, or Irwin Speedhammer offer superior durability, cleaner cuts, and self-feeding designs that significantly reduce drilling effort and extend service life on busy construction sites.

Cutting Technology: Premium flat bits incorporate self-cutting spurs, double cutting edges, and optimised flute designs for efficient waste clearance. These advanced features justify their higher cost through faster drilling speeds, reduced splintering, cleaner holes, and extended lifespan when drilling repeatedly through demanding materials.

Material Compatibility: Whilst flat bits are primarily engineered for wood, some perform adequately in composite materials, chipboard, MDF, and plastics. Always verify manufacturer specifications and avoid using them on metal, masonry, tiles, or extremely dense hardwoods where specialist bits perform better.

Popular Accessories

• Extension Shafts – Increase effective drilling depth for thick beams, double joists, and awkward access situations where standard bit length proves insufficient
• Quick-Change Adaptors – Enable rapid bit changes with hex shank flat bits, especially valuable when using impact drivers on site
• Drill Bit Sets and Cases – Keep your collection organised, protected, and portable with dedicated storage solutions from Stanley, DeWalt, or Makita
• Cordless Drills and Combi Drills – Adequate power tools for driving flat bits effectively; 18V platforms from Milwaukee, DeWalt, or Makita deliver excellent performance for professional applications
• Hole Saws – Complementary cutting tools for applications requiring cleaner edges or cutting through thicker materials and composites
• Auger Bits – Alternative drilling solution offering greater precision and significantly cleaner holes for fine joinery and visible work
• Countersink Bits – For finishing holes professionally after drilling, particularly when installing fixings or creating recessed fastener heads
• Centre Punches – Help mark drilling locations accurately before starting, preventing bit wander on smooth surfaces

Safety Information

When using flat drill bits, always wear appropriate personal protective equipment including safety glasses or goggles to protect against flying debris, wood chips, and swarf. Ensure your workpiece is securely clamped or held firmly, as flat bits can grab suddenly when breaking through material, potentially causing the workpiece to spin dangerously and resulting in injury.

Be aware that flat bits remove material aggressively and can overheat with prolonged use – allow bits to cool naturally and never touch them immediately after drilling operations. When drilling through existing structures, joists, or walls, always check thoroughly for hidden cables, pipes, and fixings using a cable detector to avoid potentially fatal contact with live electrical wiring or striking water pipes.

Maintain proper drill control throughout the operation, especially at breakthrough points, as resistance suddenly drops and the drill can lurch forward unexpectedly. Never force a dull or damaged bit; sharpen or replace worn bits promptly to maintain safe, efficient operation. Follow HSE guidelines for power tool use on construction sites, and ensure adequate lighting, stable footing, and secure access equipment when working at height or in confined spaces.

Frequently Asked Questions

What's the difference between flat bits and auger bits?
Flat bits are designed primarily for speed and rough construction work, removing material quickly but leaving a relatively rough finish suitable for hidden applications. Auger bits feature a screw thread pilot and helical cutting edges that produce significantly cleaner, more precise holes but drill more slowly. Flat bits are considerably more affordable, making them ideal for construction work where appearance isn't critical, whilst augers are preferred for fine joinery, furniture making, and visible work requiring a superior finish.

Can I use flat drill bits with an impact driver?
Hex shank flat bits work well with impact drivers, particularly for drilling smaller diameter holes up to approximately 20mm. However, for larger diameter bits (above 25mm), a standard drill or combi drill provides better control and is generally recommended by manufacturers. Impact drivers excel at driving smaller flat bits quickly through softwoods but may prove too aggressive for hardwoods or precise work requiring careful control.

Why do my flat bits keep splintering the wood on exit?
Splintering typically occurs at the exit point when the bit breaks through the opposite surface. To minimise this common problem, drill slowly as you approach breakthrough, place a sacrificial backing board behind your workpiece, or drill from both sides meeting in the middle. Upgrading to self-cutting speed bits from Bosch Expert or Milwaukee also significantly reduces splintering through improved cutting geometry and sharpened spurs that score fibres cleanly.

How deep can I drill with a standard flat bit?
Standard flat bits typically offer an effective drilling depth of approximately 100-120mm, though this varies by manufacturer, size, and specific design. For deeper holes through thick beams or multiple joists, use long series flat bits specifically designed for extended reach, or add an extension shaft to your standard bits. Extension accessories are available from brands including Bahco and Bosch, compatible with their respective flat bit ranges.

Do I need different flat bits for hardwood versus softwood?
The same flat bits work effectively for both hardwoods and softwoods, though drilling speed, technique, and bit wear will differ considerably. Hardwoods require slower drilling speeds, sharper bits, and more frequent cooling breaks to prevent overheating, burning, and premature dulling. Professional-grade bits with enhanced heat treatment and superior steel quality, such as those from Irwin, Milwaukee, or Bosch Expert, maintain their cutting edge longer when regularly drilling hardwoods and provide better long-term value for demanding applications.