Wood construction screw Koelner TS-4020 4x20 mm countersunk head Torx drive

Koelner TS-4020 is a 4x20 mm wood construction screw with a countersunk (conical) head and Torx (TX) drive designed for joining timber and wood-based materials. Its 4 mm shank diameter and 20 mm length make it suitable for light- to medium-duty woodworking tasks where a flush surface is required. The countersunk head allows the fastener to sit level with or below the material surface for clean finishes in furniture assembly, trim work and general carpentry.

Advantages

The Torx drive provides improved torque transfer and reduces cam-out compared with slotted or Phillips drives, allowing faster and more controlled installation. The countersunk head design minimizes protrusion and helps prevent snags or interference with adjacent parts. Its dimensions and thread profile are selected to reduce splitting in typical timber and engineered wood panels while maintaining firm clamping force between joined elements.

Suitable for

• Furniture assembly and fittings
• Interior carpentry and trim
• Framing of lightweight structures
• Fixing wood-based panels and laminates

Key specifications

• Diameter: 4 mm
• Length: 20 mm
• Head type: Countersunk (conical)
• Drive type: Torx (TX)
• Material: Steel (typical for wood construction screws)
• Typical finish: Corrosion-resistant coating (dependent on variant)

How to use

Select an appropriate pilot hole size if working with dense hardwoods or near edges to further reduce splitting; for softer woods pilot drilling is often unnecessary. Use a matching Torx bit in a manual screwdriver or powered driver, apply steady pressure and drive at a controlled speed until the head is flush or slightly countersunk with the workpiece. Avoid over-torquing which can strip the drive or damage the material.

Usage recommendations

For best results, choose screw length so that at least two-thirds of the screw penetrates the receiving member. When installing into engineered boards, consider pre-drilling when close to board edges or ends. Use compatible Torx bits to preserve bit and drive life, and select a corrosion-resistant finish variant for any application exposed to humidity.