Set of Koelner/Rawlplug construction screws 4.0x50 mm with partial thread and countersunk head, supplied as a pack of 18 screws divided into five blister packs. These screws are intended for joining wooden elements and light structural components where a flush, conical head finish is required. The 4.0 mm shank diameter and 50 mm length provide a balance between holding power and ease of installation for typical carpentry and light construction tasks.
Advantages
The partial-thread design allows secure clamping of two wooden elements while reducing the risk of over-drilling or splitting the material. The countersunk (conical) head sits flush with or below the work surface when properly driven, giving a neat finish and accommodating screw-top cover caps or filling. Packaged in five small blisters, the set supports controlled consumption and straightforward storage, reducing waste and keeping the fasteners separated for different tasks.
Suitable for
- Joining timber-to-timber connections in carpentry and furniture assembly
- Fixing battens, frames, and rails where a flush head is preferred
- General light-construction fastening tasks in renovations and DIY projects
When it may not be suitable
These screws are intended primarily for wood and light construction uses. They are not designed for heavy structural loads or applications requiring full-thread fasteners for maximum withdrawal resistance. For use in metal-to-metal connections, masonry, or where specific corrosion resistance is required, alternative fasteners or additional anchors should be selected.
Key specifications
- Diameter: 4.0 mm
- Length: 50 mm
- Thread type: partial (incomplete) thread
- Head type: countersunk (conical) head
- Quantity: 18 screws per pack, supplied in five blister packs
How to use
Pre-drill pilot holes appropriate to the wood type and screw diameter to reduce splitting in hardwoods; use a suitable countersink if a fully flush finish is required. Drive the screw with a compatible screwdriver bit or drill/driver set at moderate speed to avoid damaging the head or the material. Tighten until the head is flush with the surface or just below, taking care not to over-torque which can strip the wood or the screw seating.
What to consider before purchase
- Check material compatibility — optimized for wood and light structural timber, not for masonry or metal without appropriate anchors
- Confirm the required length and diameter for sufficient penetration and holding power in your application
- Consider corrosion requirements for outdoor or humid environments and choose coated or stainless alternatives if needed
Usage recommendations
For best results, match the pilot hole diameter to the screw core for the wood species being used, and employ a proper countersink for a clean, flush finish. Store blister packs in a dry place and use screws from one blister at a time to maintain organization on job sites.
