Metallics JDS173V 12 x 1-1/2 in. 5/16 Indented Hex Head Slotted Sharp Point Tapping Screws - Steel Zinc - Each

The Metallics JDS173V is a Type A tapping screw with a gimlet (sharp) point and 11 threads per inch. Type A threading with a sharp point is for thin sheet metal, sheet metal boxes, and similar light-gauge work where the screw forms its own thread as it drives. The coarse 11 TPI spacing is what gives it bite in thin stock. For thicker steel or machine-screw threading you want a different thread type.

Either works. The head is an indented hex with a slot, so it takes a 5/16 nut driver across the flats (head width measures 0.305 to 0.312 in., 0.34 across the corners) or a flat blade in the slot, which runs 0.056 to 0.067 in. wide and 0.077 to 0.093 in. deep. Electricians usually run them with a nut driver in a drill and keep the slot as a backup for tight spots where a driver socket will not sit square.

The JDS173V is heat treated to Rockwell C28-38 with a minimum torsional strength of 83 lb-in, made from AISI 1016-1024 steel. That is enough to tap its own thread in sheet metal without shearing when driven at sensible speed, but 83 lb-in is a hard ceiling. An impact driver will exceed it easily. Run them with a clutched drill or a nut driver and stop at seating.

At 1-1/2 in. the JDS173V leaves a lot of thread past thin sheet, so the tip will protrude well behind the material. That is fine where there is clear space behind, such as strap or bracket work and attaching into wood blocking or thicker build-ups, but in a shallow enclosure a protruding sharp gimlet point is a wire-damage hazard. For thin-to-thin sheet metal joints, a shorter length in the same JDS series is the better call.

It does. The indented hex head carries an integral washer section measuring 0.398 to 0.432 in. outside diameter and 0.022 to 0.039 in. thick, with overall head height of 0.139 to 0.155 in. That wider bearing surface spreads load on thin sheet metal and helps cover slightly oversized or elongated holes without adding a loose washer to the job.

These are carbon steel with a zinc plated finish, which is a general indoor and protected-location coating. It handles normal interior humidity and mechanical rooms fine, but zinc plating is not a marine or sustained wet-exposure finish. For direct weather or washdown areas, specify stainless.

The JDS173V is flagged compliant for both Buy American and ARRA. Country of origin is listed as multiple, so if your specification requires documented domestic origin on a specific lot, get the origin confirmed against the shipment rather than relying on the catalog flag alone.

They ship in a jar of 500, and 500 count is the order minimum, so this is a bulk-consumption item rather than a small blister pack. A full jar weighs 6.6 lbs. If you need a different size or count, Metallics offers other sizes and quantities by request.

Head and body dimensions follow ASME B18.6.3-2010, and the threading follows ASME B18.6.4. One caveat worth knowing if you cross-reference sizes: dimensions for #9 diameter in this family are independent of ASME B18.6.4. This #12 x 1-1/2 in. size is covered by the stated standards.