Set of Koelner/Rawlplug construction screws with partial thread and conical (countersunk) heads, size 3.5 x 30 mm, 34 pieces. These metal screws are intended for fastening thin panels, trim, and components to wooden or metal substrates where a flush countersunk finish is desired. The partial thread design provides clamping force while allowing the unthreaded shank to draw mating parts together, and the conical head seats flush with the surface after countersinking.
Advantages
The screws combine a partial-thread shank and a conical head to ensure secure clamping and a neat flush finish. Their 3.5 x 30 mm dimensions are suitable for light to medium fastening tasks, and the pack of 34 pieces covers multiple small projects or repairs. The design is compatible with powered screwdrivers or drills with the appropriate tip for efficient installation.
Suitable for
- Fastening thin sheet materials, trims and panels to wood
- Assembly of furniture components requiring a countersunk finish
- Light structural joinery and general construction where partial thread is preferred
- Applications using powered screwdriver or drill for repeatable installation
When it may not be suitable
These screws are not designed for heavy structural loads or primary load-bearing connections in large constructions; larger diameter or fully threaded specialist fasteners may be required in such cases. They may also be unsuitable for outdoor use in corrosive environments unless the specific material and coating are confirmed suitable for exposure to moisture or chemicals.
Key specifications
- Length: 30 mm
- Diameter: 3.5 mm
- Thread type: partial (incomplete) thread
- Head style: conical (countersunk)
- Quantity: 34 pieces
- Intended use: fastening to wood and metal substrates
- Drive type: compatible with powered screwdriver/drill (use appropriate bit)
How to use
Select an appropriate driver bit and set the drill or screwdriver to a controlled speed and torque to avoid overdriving. If a flush finish is required, pre-drill a countersink or pilot hole matched to the head size and material thickness. Insert the screw through the top material into the substrate, driving until the conical head is seated flush with the surface. For thin materials, use a pilot hole to prevent splitting; for metal substrates, select a pilot hole sized to match the screw's minor diameter where necessary.
What to consider before purchase
- Confirm the screw material and surface finish are suitable for the installation environment (indoor vs outdoor)
- Verify 3.5 x 30 mm length and diameter are appropriate for material thickness and substrate
- Ensure you have the correct driver bit and drill/screwdriver settings for controlled installation
- Consider whether partial thread and conical head meet the mechanical requirements of your application
Usage recommendations
Use pilot holes and the correct driver bit to achieve consistent, flush seating and to minimize material damage. For repeated exterior applications verify corrosion resistance before prolonged exposure. Store the pack in a dry place to maintain condition until use.
