R4 rounding cutter with guide bearing

Brief description

The R4 rounding cutter rounds off wood edges with a 4-mm radius—cleanly and evenly. The ball bearing (Ø 12.7 mm) on the router head runs along the edge of the workpiece and guides the router even along curved contours where no stop fits. This allows you to round off straight edges as well as curved shelf boards or decorative components.

The cutter is double-edged and carbide-tipped (HW), right-hand cutting, with an outer diameter of 21 mm and a working length of 10 mm. Its 8 mm shank fits in hand routers, bench routers, and the RUWI router table (8 mm collet) as well as on CNC machines. It cuts softwood and hardwood as well as laminated panels. If the ball bearing wears out, you can replace it—instead of replacing the entire router bit.

You can find more milling tools in the RUWI milling tools section, and the matching tables in the RUWI milling tables section.

Possible applications

• Rounding edges with a 4-mm radius – on straight and curved workpieces
• Milling curved contours without a stop—the guide bearing follows the edge
• Visibly deburr and round off furniture, shelves, and decorative components
• Double-edged carbide end mill, right-hand cut, outer diameter 21 mm, effective length 10 mm
• Shaft Ø 8 mm for hand-held router, RUWI router table, and CNC
• For softwood, hardwood, and laminated panels
• Replaceable thrust ball bearing (12.7 mm diameter)

Downloads

RUWI Product Catalog 2026 (PDF)

All the details

- Profile & cutting
- Rounding radius R4
- Double-edged (Z2)

- Dimensions & design
- Shank Ø 8 mm | Shank length: 32 mm
- Useful/working length: 10 mm
- Overall length: 56 mm | Outer diameter: Ø 21 mm
- Weight: approx. 31 g

- Bearing & rotation
- Ball bearing Ø 12.7 mm
- Clockwise rotation

- Material & quality
- Carbide (HW)

- Application & compatibility
- Ideal for softwood, hardwood and coated boards
- Compatible with RUWI routing tables, hand and table routers and CNC machines