Cone & Stepped Drill Bits

About Cone & Stepped Drill Bits

Cone and stepped drill bits are specialised cutting tools that enable tradespeople to drill multiple hole sizes with a single bit, eliminating constant bit changes on site. Featuring a distinctive pyramid or conical shape with graduated cutting edges, these versatile bits are essential for electricians, plumbers, HVAC engineers and sheet metal workers who regularly drill holes in thin materials such as sheet metal, plastic, aluminium and copper. Unlike conventional twist drills limited to one diameter, stepped bits progressively enlarge holes with exceptional accuracy and minimal burr formation.

MyToolShed.co.uk stocks over 45 cone and stepped drill bits from trusted manufacturers including Bosch Professional, Sealey, Milwaukee, Makita and Faithfull. The range encompasses individual bits in various size configurations alongside convenient 3-piece sets covering the most common drilling requirements. Many feature premium coatings such as titanium nitride (TiN) or aluminium titanium nitride (AlTiN) that significantly extend tool life and enhance cutting performance. With high-speed steel (HSS) construction, hex shank compatibility for cordless drills and impact drivers, and step increments typically ranging from 2mm to 4mm, these bits deliver professional results from 4mm up to 32mm diameters.

Applications

Cone and stepped drill bits serve numerous trades and applications across professional and DIY projects:

• Electricians: Creating cable entry points in consumer units, junction boxes and electrical enclosures
• Plumbers and heating engineers: Drilling holes for pipework, radiator valves and mounting brackets in sheet metal
• HVAC installers: Making ductwork connections and ventilation system mounting holes
• Metal fabricators: Precision hole drilling and enlarging in steel, aluminium and copper sheet
• Automotive technicians: Custom installations, bodywork modifications and electrical system upgrades
• Shop fitters and signage installers: Creating mounting points in plastics and composite panels
• General builders: Versatile hole drilling across multiple site applications requiring clean, accurate results

Choosing The Right Cone & Stepped Drill Bits

Material and coating: Standard HSS bits suit occasional use and softer materials, whilst titanium-coated options from Bosch Professional or Milwaukee offer extended lifespan for demanding professional applications. TiN coatings reduce friction and heat build-up, particularly important when drilling stainless steel.

Size range requirements: Consider your typical hole diameters. Starter sets from Blue Spot or Draper typically cover 4-12mm, 6-20mm and 10-32mm ranges. Individual bits from Sealey or Faithfull may prove more economical if you regularly work with specific sizes.

Step increments: Smaller increments (2mm) provide more sizing options but take longer to reach larger diameters. Larger increments (4mm) work faster but offer fewer intermediate sizes. Match the increment to your precision requirements.

Shank compatibility: Hex shanks are standard and work perfectly with modern 240v corded drills, cordless drills and impact drivers. Ensure compatibility with your existing equipment, particularly quick-change systems.

Single bits versus sets: Three-piece sets from manufacturers stocked at MyToolShed.co.uk offer excellent value and cover most common requirements. Professional tradespeople drilling hundreds of holes weekly should invest in premium coated sets for superior durability.

Safety Information

Always wear safety glasses or a face shield when drilling metal, as hot swarf can cause serious eye injuries. Secure workpieces with clamps – never hold sheet material by hand, as stepped bits can grab suddenly when breaking through. Use moderate drill speeds (500-1000 RPM) to prevent overheating and premature wear. Check for hidden electrical cables, gas pipes or other services before drilling. Inspect bits before use for damage or coating deterioration, replacing worn bits promptly rather than forcing them to continue cutting. Consult HSE guidance on safe operation of portable power tools.

Frequently Asked Questions

Can I use stepped drill bits in a cordless impact driver?
Yes, hex shank stepped bits work excellently in impact drivers, particularly when drilling harder materials like stainless steel. The percussive action can improve cutting performance and reduce binding. Use lower speed settings and ensure your impact driver has adequate torque (typically 150Nm+ for larger holes).

What's the difference between cone cutters and stepped drill bits?
Stepped drill bits feature distinct flat platforms at each diameter increment for drilling precise, specific hole sizes. Cone cutters have a smooth conical profile without defined steps, making them ideal for deburring, chamfering or creating tapered holes rather than specific diameters.

Why do my stepped bits wear quickly?
Premature failure usually results from excessive speed, insufficient lubrication or drilling materials too thick or hard. Most stepped bits are designed for sheet materials up to 3-4mm thick. Use cutting fluid, moderate speeds and allow the bit to cut rather than forcing it through material for optimal longevity.