DUO System 90 x 20 – Heavy-Duty Concealed Bed Frame Connector

The DUO 90×20 is a heavy-duty connector in the DUO-System, engineered for robust frame joints that demand both strength and a clean, concealed finish. With its wider and longer profile, it delivers excellent holding power while maintaining the fast, non-visible, and self-tightening design of the DUO family.

Certified with a load value of 2.37 kN (transverse force, insertion direction), the DUO 90×20 is well-suited for demanding furniture and timber joinery applications, offering a secure and adjustable connection that can be disassembled if needed.

Features and Benefits

• High load-bearing capacity for heavy-duty connections

• Concealed design – no visible fasteners on finished pieces

• Self-tightening system keeps joints secure over time

• Adjustable screws allow re-tightening as wood shrinks or swells

• Quick installation with CNC or hand tools

• Certified strength and reliability by Holzforschung Austria

• Heavy furniture frames

• Bed rails and structural bed assemblies

• Timber construction joints

• Architectural joinery requiring robust concealed fasteners

• Size: DUO 90×20 mm

• Material: Blue-galvanized, weather-resistant steel

• Load Value: 2.37 kN (transverse force, insertion direction)

• Mounting: Install with CS-screws Ø 5–6 mm (recommended: 5×40, 5×60, 6×40, or 6×60 mm per Ö-Norm M5027)

• Installation Tools: CNC machine, long hole drilling machine, or hand router

• Suitable Materials: Solid wood and plywood panels from 21 mm thickness

• Advantages: Concealed, self-tightening, heavy-duty connector with adjustable screws

Steps

1. Cut the mortise using a 2-Flute Straight Router Bit (13/32″) with a Router Bushing (1″ OD) and the MULTI F Routing Jig.
   Note: Choose the correct Routing Jig size for the DUO 90×20. Optionally, use the Router Base Plate Adapter to hold the Router Bushing (1″ OD).

2. Align the Routing Jig and cut a 13 mm deep mortise into either the end-grain or face of the timber. Mortise width is preset; mortise length corresponds to connector size.

3. Insert one DUO 90×20 connector plate into the mortise and predrill screw holes using the plate as a guide.

4. Secure the first connector plate with the screws provided.

5. Place the second plate over the first and tighten the pan head screws until snug for proper alignment and depth.

6. Fasten the second connector plate with the provided screws.

7. Assemble the workpieces by tapping together with a rubber mallet.

Tips

• The dovetail-like interlock ensures tight, secure joints.

• Connectors allow for natural wood movement and can be re-tightened as needed.