Double Thread range of Welfast Self Drilling Screws offers following additional features to that of a Bright Zinc and Dacromet Coated series of Self Drilling Screws:

• Upper Thread under the head prevents strip-out
• High performance in exterior roofing environment
• Prevents water entry through the roof sheet

In addition to the applications of Bright Zinc and Dacromet Self Drilling Screws, Welfast Double Thread Self Drilling Screws also specialize in the following applications:

• Fastening insulated composite panels to steel purlins and timber structures.
• Roofing structures
• Insulated cladding to steel purlins and wood strucutres

How to Install :

• 1) Insert the 8 or 10 mm (according to required size) hex head adapter into the drill motor. Center the adapter into the drill’s chuck to ensure that adaptor does not wander.
• Put on the safety glasses to protect your eyes.
• Inspect the hex end of the adaptor for cleanliness. If metal shavings are built up inside the tip, insert the drilling end of the screw into the cavity of the hex head while holding the trigger of the drill.
• Place a self-drilling screw into the hex head adapter.
• Depress the trigger of the drill slowly, while the drilling tip of the screw rests against the metal. Increase the speed of the drill when the screw finds its center.
• Stop drilling when the head of the self drilling screw tightens against the surface of the metal. If the drill you are using does not have a clutch, pay close attention to the screw head, as too much pressure will either snap the screw of strip the threads formed in the metal by the screw.
• Perform Step 3 before you install another self drilling screw.

Double Coarse Thread

Double Coarse Thread

Double Fine Thread

Hex Washer Head with Black Washer - Double Coarse Thread :