Koelner/Rawlplug construction screws 4.0×70 mm with a partial thread and conical countersunk head, supplied in a pack of 12 pieces, are intended for secure timber-to-timber and timber-to-metal connections where a flush finish is required. The partial thread provides effective clamping of joined elements while the conical countersunk head allows the screw to sit flush with or below the material surface when driven into wood or pre-drilled holes. These construction screws are designed for structural fastening, woodworking tasks and general building repairs that require predictable shear strength and pull-out resistance.
Advantages
Partial thread design concentrates clamping force on the unthreaded shank, drawing timber elements tightly together while the threaded portion ensures reliable anchoring in the receiving material. The conical countersunk head creates a neat, recessed finish suitable for applications where a smooth surface is needed or where head concealment is preferred. Manufactured for construction use, these screws offer consistent geometry and profile to enable compatible performance with common power bits and manual drivers.
Suitable for
- Timber-to-timber joints in structural and non-structural woodwork
- Timber-to-metal connections where screw head must be recessed
- Furniture assembly and frame construction that require flush heads
- General building repairs and carpentry tasks requiring shear strength
When it may not be suitable
These screws are intended for use in wood and wood-to-metal connections; they are not designed for direct fastening into masonry, concrete or lightweight blocks without appropriate anchors or plugs. For applications requiring full-length threading for improved withdrawal resistance along the entire fastener length, a fully threaded screw may be more appropriate.
Key specifications
- Diameter: 4.0 mm
- Length: 70 mm
- Thread type: partial (incomplete) thread
- Head type: conical countersunk head
- Pack quantity: 12 pieces
- Typical use: timber-to-timber and timber-to-metal structural fastening
How to use
Pre-drill a pilot hole appropriate to the timber species and screw diameter where necessary to avoid splitting. Position the elements to be joined and insert the screw so the conical head sits at the desired depth. Drive the screw using a compatible driver bit or power screwdriver at moderate speed until the head is flush or slightly below the surface. If securing into metal, use a suitable pre-drilled hole and ensure the screw engages the receiving material threads properly.
What to consider before purchase
- Confirm the 4.0 mm diameter and 70 mm length suit the material thickness and structural requirements.
- Decide if partial thread is preferred for clamping action versus full-threaded options for different withdrawal characteristics.
- Ensure conical countersunk heads meet aesthetic or flush-mounting needs for your project.
Usage recommendations
For best results, choose an appropriate pilot hole size for the wood species, use a matching driver bit to avoid cam-out, and avoid over-torquing to preserve head integrity and consistent clamping. When installing into metal components, verify that the receiving material thickness allows sufficient thread engagement for a secure connection.
