Metallics JTEKD92SS 14 x 1-1/2 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - 410 Stainless Steel - Each

A 5/16 inch hex driver. The JTEKD92SS has an indented hex washer head with a hex drive, and the head measures 0.367 to 0.375 inch across the flats with 0.409 inch across the corners, so a standard 5/16 magnetic nutsetter in a screw gun seats it properly. There is no Phillips or square recess to strip.

Two standards are called out on the JTEKD92SS: head and body dimensions to ASME B18.6.3-2010, and threads to SAE J78-2013. Thread form is UNC at 14 threads per inch. The part is also flagged ARRA compliant and Buy American compliant, with country of origin listed as multiple, which matters on federally funded work where you have to document the sourcing.

It is the right type for that kind of work. A Type BSD self-drilling and tapping screw cuts its own hole and forms its own thread in one pass, so you fasten to steel without pilot drilling or a nut on the back side, which is the usual reason electricians reach for it on strut, clamps, boxes and brackets. With a #3 point and a 1-1/2 inch length, it is sized for heavier gauge steel. Where you cannot reach the back of the member or the base metal is masonry or concrete, this is the wrong fastener and you need an anchor instead.

410 stainless is the grade used for self-drillers because it can be hardened enough to cut its own hole, and the JTEKD92SS is heat treated to Rockwell C38-46 for that reason. It gives you corrosion resistance well beyond plain zinc-plated carbon steel and suits damp interior and sheltered exterior work. It is a martensitic stainless, not 300 series, so for salt spray or coastal exposure specify a 300 series fastener with a carbon steel drill tip instead.

They sell in a jar of 100. The order minimum on the JTEKD92SS is 100 count, and the packed jar weighs about 2 lbs. Metallics notes other sizes and quantities are available by request if 14 x 1-1/2 inch is not the length you need.

Driving torque is comparable. Metallics states minimum torques are the same for stainless and steel self-drill screws, with a 2.5 second drill time through 1 mm plate, so the JTEKD92SS runs on the same screw gun setup you would use for a zinc self-driller. Keep steady axial pressure and avoid over-spinning, since a hardened 410 point dulls if you let it spin without biting.