Step drill bit Irwin 10502854 — stepped diameter up to 35 mm, for drilling sheet metal and plastics

Irwin 10502854 is a step drill bit designed to cut progressively larger holes up to 35 mm in thin materials such as sheet metal and plastics. The single-flute geometry and self-centring point enable controlled cutting and accurate hole positioning without the need for a separate centre punch. Manufactured from industrial-grade M7 high-speed steel and fitted with a flatted shank, this stepped bit is intended for use with standard handheld drills and drill drivers where multiple hole sizes are required without frequent bit changes.

Advantages

The single-flute design provides smooth chip evacuation and improved control when drilling into sheet metal, while the unique flute profile supports the formation of round holes. The self-centring tip reduces walking at the start of drilling, improving accuracy and reducing the need for pre-marking. Constructed from M7 high-speed steel, the bit offers wear resistance suitable for repeated use in metal and plastic, and the flatted shank improves grip in the chuck to minimise slipping during operation.

Suitable for

• Drilling holes in sheet metal panels and enclosures
• Creating openings in plastic panels and thin polymer sheets
• Electrical and HVAC installations where multiple hole sizes are required
• Fabrication or maintenance tasks that need progressive hole enlargement

Key specifications

• Maximum drilled diameter: up to 35 mm
• Material: M7 high-speed steel
• Flute type: single flute with unique profile for round holes
• Tip: self-centring point to reduce walking
• Shank: flatted shank to prevent slipping in the chuck
• Suitable substrates: sheet metal and plastics (thin materials)

How to use

Mark the desired hole centre and secure the workpiece to prevent movement. Fit the step drill bit into a compatible drill or drill driver, ensuring the flatted shank seats firmly in the chuck. Start drilling at low speed to engage the self-centring tip, apply steady axial pressure, and increase speed as the bit progresses through successive steps. Use moderate cutting force and allow the single flute to evacuate chips; withdraw periodically if chips accumulate. For metal applications, use appropriate cutting lubricant to extend bit life and improve cutting performance.

Usage recommendations

For best results when drilling sheet metal, clamp the workpiece, use a light cutting fluid for heat management, and operate at controlled speeds. Avoid excessive axial force which can reduce hole quality and increase wear. The bit is intended for thin materials—do not attempt deep plunging in thick stock beyond the specified stepped diameter.