Metallics JTEKD8M 12 x 1 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - Steel Zinc - Each

The Metallics JTEKD8M is rated for panel thickness of 0.110 to 0.210 in. That is the combined metal the #3 drill point will drill and tap without a pilot hole, so it suits heavier gauge steel framing, strut, and plate rather than thin sheet. Below about 0.110 in. you want a finer point; above 0.210 in. you need a pilot hole and a machine screw.

Torsional strength is 92 lb-in minimum, with case hardness of Rockwell C32-40. That is enough to drive through the rated 0.110 to 0.210 in. panel range, but an uncontrolled impact driver can exceed it. Use a clutched screw gun or back off the impact setting once the washer seats. Drill time runs about 2.5 seconds through a 1 mm plate.

It takes a 5/16 hex driver. The indented hex washer head measures 0.305 to 0.312 in. across the flats and 0.34 in. across the corners, with a head height of 0.139 to 0.155 in. A standard 5/16 magnetic nut setter in an impact or screw gun drives it.

The washer is part of the head. The JTEKD8M is an indented hex washer head screw with a washer outside diameter of 0.398 to 0.432 in. and washer thickness of 0.022 to 0.039 in. Nothing loose to handle on the ladder, and the wider bearing surface spreads load on sheet metal and strap.

The JTEKD8M is carbon steel with a zinc finish, silver in appearance. Zinc plating is a dry indoor and protected service coating. For exposed exterior, coastal, or wet duty, specify a stainless or coated exterior self-drill screw instead, because zinc plate will eventually bloom and rust in standing moisture.

The JTEKD8M is flagged as both Buy American compliant and ARRA compliant in the manufacturer data. Country of origin is listed as multiple, so if your contract requires a single documented origin, request the certification for the specific lot.

That is what a Type BSD self-drilling and tapping screw with a hex washer head is for. It drills its own hole and taps its own thread in steel from 0.110 to 0.210 in. thick, so no pre-drilling for box mounting, strap, conduit clips, or strut attachment to structural steel and heavier studs. The 1 in. length gives you fastener left over after the panel, so check your stack-up against that length.

They ship in a jar, with an order minimum of 1,000 pieces. Plan the buy in full thousands rather than by the handful.

Carbon steel to AISI 1016 - 1024, heat treated to Rockwell C32-40. That is the standard case-hardened self-drill screw stock, hard enough at the point to cut steel while the core stays tough enough to carry the 92 lb-in minimum torsional load.