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Unibor 25428 M42 cobalt annular cutter with pilot pin

Unibor

Unibor 25428 7/8in x 4in Premium M42 Cobalt Annular Cutter with Pilot Pin pneumatic accessory

SKU CH-4ZCF-JQ4PP

Cuts softer metals, mild and stainless steels with a 4in depth and 30% longer life than HSS

  • 30% longer life with M42 cobalt alloy
  • 4 inch depth of cut for thick materials
  • Cuts mild and stainless steels efficiently
  • Includes pilot pin for accurate starts
  • Premium annular cutter built for durability

Premium M42 Cobalt Annular Cutter

The Unibor 25428 annular cutter is built for metalworkers who need reliable hole-making in structural steel and pipe. Its M42 cobalt alloy construction provides a 30% longer life than standard high-speed steel cutters. The tool handles softer metals, mild steel and stainless steel in fabrication and maintenance tasks. A pilot pin is included to ensure accurate centring at the start of each cut.

Thermals noise and power draw

As a non-powered cutting accessory, the cutter generates no electrical noise or power consumption of its own. Heat produced during cutting depends entirely on the magnetic drill or press used and the material being machined. Operators should follow the host machine's cooling recommendations to manage temperatures during deep cuts. Proper lubrication further reduces friction and extends the cobalt alloy's working life.

Pilot pin and cobalt alloy benefits

The supplied pilot pin centres the cutter instantly, reducing setup time and preventing wander on curved or uneven surfaces. M42 cobalt alloy retains hardness at elevated temperatures, allowing the 4in depth of cut to be reached in tougher alloys without premature wear. This combination means fewer tool changes and consistent hole quality across production runs. The accessory fits standard magnetic drill arbors for immediate use.

How it compares

Measured against everything we stock in Bits, Hole Saws & Accessory Kits, at today’s prices. Recalculated every night.

Price $131.99
Pricier than about 89% of the 5,493 comparable items (median $27.99).

Specifications

Product
Brand nameUNIBOR

Questions about this item

How do I install the pilot pin correctly so it does not fall out during the first cut?

Insert the supplied pilot pin into the centre hole of the annular cutter until it clicks into the internal groove; the pin must protrude past the cutting edges to start the hole and eject the slug.

When will the cobalt alloy teeth need replacement compared with standard HSS cutters?

The M42 cobalt alloy delivers roughly 30% longer life than HSS, so expect to replace the cutter after noticeably more holes in mild or stainless steel.

What cutting-depth limit stops me from drilling deeper in a single pass?

The cutter is designed for a maximum 4" depth of cut; attempting to go deeper requires withdrawing the tool and clearing chips before continuing.

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