STAINLESS STEEL PHILLIPS COUNTERSUNK BI-METAL WING DRILL TIMBER TEK 5 SCREWS

Phillips Countersunk Bi-Metal Wing Drill Timber Tek 5 Screws — This is the heavier-duty version of the wing-drill timber screw, sharing the same wing-drill point principle as the Tek 3 range but paired with a Tek 5 point for timber fixed over thicker steel purlins or structural sections. The wings ream a clearance path through the timber layer ahead of the thread and shear off on contact with the steel, so the Tek 5 point can self-drill cleanly into thicker steel without the timber binding it first and generating heat or causing a failed start. It suits the same family of applications as the Tek 3 version - timber battens, boards, or packers fixed directly to steel structure in a single pass - but specifically where that structure is heavier gauge steel, larger purlins, or structural sections that a Tek 3 point isn't rated to clear efficiently. As with the rest of the bi-metal range, the stainless body and thread carry corrosion resistance for the timber-facing, weather-exposed part of the fixing, while the hardened carbon-steel point, wings and Tek 5 flute included, does the mechanical work of clearing timber and drilling thick steel that a solid stainless point simply isn't capable of. The decision to specify Tek 5 over Tek 3 in this wing-drill range follows the same logic as elsewhere in the Tek family: heavier steel behind the timber needs the longer point and flute Tek 5 provides to clear swarf and avoid stalling, and if a Tek 3 wing-drill screw is struggling to complete its drilling stage cleanly, that's the sign to move up rather than force it. Length remains the most important sizing decision on any wing-drill screw - it has to clear the timber thickness fully, let the wings shear at the right point, and still achieve solid thread engagement in the steel beyond, so it should always be selected against the actual timber and steel build-up rather than a generic length.

FAQs
How does Tek 5 differ from Tek 3 in this wing-drill range?
Tek 5 has a greater drilling capacity and a longer flute to clear swarf from thicker steel, where Tek 3 is matched to medium-gauge sections, once the wings have cleared the timber layer in either case.

Why not use a standard Tek 5 screw for timber-over-steel fixing?
Without the wings, the point can bind in the timber layer before reaching the steel, generating heat and risking a poor or failed drilling start; the wing design clears the timber first to prevent this.

What's the sign a Tek 3 wing-drill screw should be upgraded to this Tek 5 version?
If the point struggles, stalls, or takes noticeably longer to complete its drilling stage once past the timber, the steel structure is likely heavier gauge than Tek 3 is rated to clear efficiently.