Unibor 25000 Series M42 Cobalt Annular Cutter

Unibor 25000 Series M42 Cobalt Annular Cutter — Extended Life for Tough Materials

The Unibor M42 Cobalt Annular Cutter is manufactured with an increased percentage of cobalt, making it ideal for steel up to a tensile strength of <900N, tough stainless steel, aluminum, and plastics — without compromising on tool life. With up to 30% longer life than standard M2 HSS cutters, the 25000 Series is the professional's choice for demanding applications.

Available in diameters from 7/16" to 3" and depths of cut from 1" to 4", with a 3/4" Weldon shank for use with any magnetic drill. All cutters are supplied with a pilot pin included.

Key Features & Benefits

M42 Cobalt Construction

Increased cobalt percentage delivers extended cutting lifespan and performance on tougher materials including stainless steel, aluminum, copper/brass, and cast iron — outperforming standard M2 HSS in difficult applications.

Up to 30% Longer Tool Life

Engineered to withstand higher temperatures and cutting harder materials, the M42 grade significantly reduces tooling costs and downtime on high-production or difficult-material jobs.

3/4" Weldon Shank

Compatible with all magnetic drills using a 3/4" Weldon shank — the industry standard for annular cutters, ensuring secure, wobble-free mounting and maximum power transfer.

Pilot Pin Included

Every cutter ships with a pilot pin for accurate, centered drilling without punching or pre-drilling. Replacement pilot pins (USP-1 through USP-4) are available separately.

Wide Size Range

Available from 7/16" to 3" diameter and 1" to 4" depth of cut, with tapping sizes also available — covering virtually every structural steel drilling application.

Made in England

Manufactured in England to exacting tolerances, the Unibor M42 series delivers the precision and consistency demanded by professional contractors and fabricators.

Common Applications

Structural Steel Fabrication

Clean, burr-free holes in structural steel beams, columns, and plate up to 4" deep — faster and cleaner than twist drills.

Stainless Steel

The increased cobalt content handles stainless steel up to <900N tensile strength where standard HSS cutters fail prematurely.

HVAC and Mechanical

Precise holes in steel ductwork, pipe flanges, and equipment mounting plates where accuracy and clean edges are critical.

Shipbuilding and Marine

Suitable for marine-grade stainless and aluminum, delivering consistent results in demanding marine fabrication environments.

Technical Specifications

Frequently Asked Questions

Q: What is the difference between M2 HSS and M42 Cobalt?
A: M42 contains a higher percentage of cobalt, which improves hardness at elevated temperatures and provides up to 30% longer tool life — especially important when cutting stainless steel or other tough materials that generate more heat.

Q: Which pilot pin do I need?
A: USP-1 for 1" cutters over 1/2", USP-1A for cutter 25114, USP-2 for 2" cutters over 1/2", USP-2A for cutter 25214, USP-3 for 3" cutters, USP-4 for 4" cutters.

Q: Can I use these with any magnetic drill?
A: Yes — the 3/4" Weldon shank is the universal standard for magnetic drill annular cutters and fits all major brands.

Q: Are sizes up to 4" diameter available?
A: Yes, sizes up to 4" diameter are available — contact us for pricing on sizes above 3".