The Benchmark Abrasives SK-5 90° Countersink Premium Tungsten Carbide Burr is built for fabricators, machinists, welders, and metalworkers who expect professional-grade cutting performance and dependable construction. Unlike lower quality burrs that may use hollow heads or inconsistent brazing, Benchmark carbide burrs feature a solid carbide head with a silver-brazed connection to the shank. The result is a strong, stable cutting tool made for demanding deburring, chamfering, countersinking, and material-removal applications.
The SK-5 combines that premium construction with a larger 1/2" diameter, 90° countersink profile and double-cut tooth pattern for controlled work around holes, openings, and angled edges. Its conical geometry is designed specifically for chamfering edges and refining 90° included-angle countersinks, while the intersecting double-cut flutes divide removed material into smaller chips for a more manageable cutting action and smoother result than a comparable single-cut burr.
Whether you're breaking sharp edges around holes, refining an existing 90° countersink, chamfering larger openings, or performing general fabrication and maintenance work, the SK-5 provides more cutting surface than the smaller SK-3 while maintaining the same purpose-built 90° geometry. The 1/4" shank fits compatible die grinders and rotary tools with a matching collet, while the standard-length 1/2" head is rated for a maximum speed of 50,000 RPM.
Features
- Premium tungsten carbide construction
- Double-cut design for efficient, controlled material removal
- 90° countersink geometry for chamfering and countersinking
- 1/2" head diameter for larger holes and openings
- Suitable for breaking sharp edges and refining angled features
- Produces smaller chips than comparable single-cut burrs
- Suitable for fabrication, machining, deburring, and maintenance work
- 1/4" shank for compatible die grinders
- Sold individually
Applications
The SK-5 90° countersink profile is well suited for:
- 90° countersinking
- Chamfering with a 90° included-angle profile
- Breaking sharp edges around holes
- Refining existing countersinks
- Deburring drilled or machined openings
- Edge preparation around larger circular features
- Localized angled material removal
- General fabrication and maintenance work
Materials
Recommended primarily for:
- Steel
- Stainless steel
- Cast iron
Also suitable for additional materials when the correct operating speed and technique are used, including titanium, nickel, wrought iron, copper, fiberglass, plastic, hard rubber, wood, and stone.
Machine Compatibility
Designed for die grinders and other rotary tools equipped with a properly sized 1/4" collet.
Compatible examples include:
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Benchmark Straight Pneumatic Die Grinder (BMT-DGST_1) — 1/4" collet, up to 25,000 RPM.
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DEWALT DCG426B — 1/4" collet, variable speed up to 25,000 RPM.
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Milwaukee 3485-20 — 1/4" collet, variable speed up to 20,000 RPM.
Always confirm the burr shank is securely seated in the correct collet and that the machine speed is appropriate for the burr diameter, workpiece material, and application.
Cutting Performance
The SK-5 uses a 90° conical cutting profile designed specifically for chamfering and countersinking. Its larger 1/2" head and 1/4" cut length provide more cutting surface than the SK-3, making it better suited for larger openings and broader 90° features while maintaining the same controlled angled geometry.
The double-cut pattern divides removed material into smaller chips, providing controlled cutting and a smoother working feel than a comparable single-cut burr. Carbide burrs are primarily cutting and shaping tools; applications requiring a refined cosmetic finish should be followed with the appropriate abrasive finishing process.
Use the chart above as a starting guide to operating speed based on the 1/2" burr head diameter and workpiece material. These are suggested cutting ranges, not minimum machine speeds; conventional die grinders commonly run at 20,000–29,000 RPM.
Do not exceed the 50,000 RPM maximum speed for this standard-length 1/2" carbide burr. Always operate within the lower maximum speed of the burr, machine, collet, or accessory system.
Safety Tips
- Always wear appropriate eye, hearing, respiratory, and hand protection.
- Secure the workpiece before beginning operation.
- Confirm the 1/4" shank is properly seated and securely tightened in the correct collet.
- Use light, controlled pressure and allow the carbide cutting edges to remove the material.
- Keep the burr centered and controlled when forming or refining a countersink.
- Avoid excessive force, which can increase heat, vibration, and premature cutting-edge wear.
- Select operating speed according to burr diameter, workpiece material, machine requirements, and the recommended operating-speed chart.
- Never exceed 50,000 RPM.
- Stop immediately if excessive vibration, chatter, unusual noise, or visible damage occurs.
- Do not use a damaged, chipped, bent, or improperly mounted carbide burr.
