Metallics QDS153 8 x 3/4 in. 1/4 Hex Head Quadrive Sharp Point Tapping Screws - Steel Zinc - Each

The QDS153 is a #8 diameter by 3/4 inch long tapping screw with a 1/4 inch hex head. The head is a Quadrive design, so besides a 1/4 inch hex driver or socket it also accepts a slotted, Phillips, or square bit. Handy on overhead work where a socket will not reach but a cordless driver bit will.

Sharp point is the key detail. The QDS153 pierces and taps its own thread in thin material such as light gauge sheet metal boxes, covers, and plates, but it has no drill flute, so it will not start its own hole in heavier steel. For thicker channel or structural steel you want a self-drilling (TEK style) screw instead, or pre-drill a pilot hole for the QDS153.

It is steel with a zinc plating, which handles interior and dry or occasionally damp locations. Zinc plating is a sacrificial coating, not stainless, so for wet, coastal, or corrosive exposure specify a stainless or hot dip galvanized fastener instead.

At 3/4 inch, the QDS153 has enough shank to pass through a cover, strap, or clip and still engage several threads in sheet metal behind it, which is the usual case for mounting to boxes and enclosures. If your stack of material is thicker than about half an inch you will run out of thread engagement and should step up to a longer screw in the same #8 size.

Order by Metallics part number QDS153. It is made in the USA.

It is a tapping screw with a sharp point, intended to cut threads in thin metal. It will bite into wood, but the thread pitch and point are not designed for holding power in wood or for drywall, where a coarse thread wood screw or a drywall screw holds better. For metal to metal and metal to light substrate work in an electrical install, the QDS153 is the right type.