Core Drill Bit Sets

Core Drill Bit Sets

Core drills (hole enlargers or step drills for metal) are designed to enlarge existing holes to a precise finished size — removing only the annular material from the existing bore without removing the full slug from a solid workpiece. AIMS Industrial stocks core drill sets in HSS and TCT for use in drill presses and magnetic drill presses on steel plate and structural sections.

Core Drills vs Twist Drills for Hole Enlargement

Enlarging an existing hole with a twist drill is problematic — the chisel point at the tip of a twist drill is designed to cut from the centre out, and when presented to an existing hole it has nothing to cut at centre, causing chatter, tool grab and a poor-quality oversize hole. A core drill has a flat or countersunk centre with cutting edges arranged only on the annular zone, allowing it to enlarge the existing bore cleanly and accurately without chatter. This makes core drills the correct tool for opening punched or pre-drilled holes to a precise bolt or pipe clearance size.

Applications

Core drills are used in structural fabrication to bring punched holes to exact bolt clearance diameters, in plumbing and HVAC installation to open pre-cut holes in steel frames for pipe penetrations, and in any situation where an existing hole needs to be accurately enlarged to a specific size. Step drills (multi-diameter cone drills) serve a related function in thinner sheet materials, cutting clean holes in sizes from 4mm to 30mm from a single tool.

Set Coverage

Core drill sets typically cover hole enlargement from 14mm to 60mm diameter, addressing structural and mechanical fastening applications. For help selecting the right core drill for your material and application, contact our team. AIMS Industrial has been supporting Australian industry since 1988.