Metallics JDS153V 8 x 3/4 in. 1/4 Indented Hex Head Slotted Sharp Point Tapping Screws - Steel Zinc - Each

The JDS153V has an indented hex head with a slot, so you have two options: a 1/4 inch nut driver or hex socket across the 0.244 to 0.250 inch flats, or a flat blade in the slot. The slot runs 0.045 to 0.054 inch wide and 0.052 to 0.066 inch deep, so a standard cabinet-tip blade seats properly. Most electricians drive these with a 1/4 inch magnetic nut setter and keep the slot as a backup for tight spots or hand finishing.

A Type A tapping screw with a gimlet (sharp) point is made to pierce and form its own thread in thin sheet metal, so for light gauge steel, sheet metal boxes and strut accessories you generally drive it straight in without a pilot. The JDS153V runs 15 threads per inch, the coarse Type A spacing that gives good hold in thin material. In heavier stock or in hardwood you still want a pilot to avoid snapping the shank.

Minimum torsional strength on the JDS153V is 39 lb-in, with the screw hardened to Rockwell C28-38 from AISI 1016-1024 steel. That is plenty for hand or nut-driver work in sheet metal, but it is well below what a high-torque impact driver can deliver. Run an impact on a low setting or use a clutched drill if you are placing hundreds of them, or you will shear heads.

The JDS153V is zinc plated carbon steel. Zinc handles indoor and normally dry conditions well, but it is a sacrificial coating, not stainless. For exterior exposure, wash-down areas, coastal air or anywhere standing moisture collects, step up to a stainless or hot dip galvanized fastener instead.

Yes, it is an indented hex washer head. The washer face measures 0.322 to 0.348 inch outside diameter and 0.019 to 0.031 inch thick, with head height of 0.096 to 0.11 inch. That bearing surface spreads load across a knockout or an oversized hole in sheet metal, so you usually do not need a separate flat washer.

Head dimensions on the Metallics JDS Series indented hex slotted tapping screw conform to ASME B18.6.3-2010, and the thread conforms to ASME B18.6.4. Material is AISI 1016-1024 steel. One caveat worth noting on submittals: dimensions for the #9 diameter in this family are independent of ASME B18.6.4.

The JDS153V screw is flagged both ARRA compliant and Buy American compliant in the manufacturer's data, which is what procurement on federally funded work normally asks for. Country of origin is listed as multiple, so if your specification requires a single named origin on the submittal, that is the detail to pin down with the order.

These ship as a 500 count jar, and 500 is the order minimum, so it is a full-jar purchase rather than a loose count. The jar weighs 2.25 lbs. Other sizes and quantities in the JDS indented hex slotted family are available by request.

At #8 diameter by 3/4 inch long, the JDS153V leaves roughly a half inch of thread past the sheet once it passes through the panel, so check clearance behind the wall of the enclosure before you commit. In a shallow box or against conduit, wiring or a stud face, that protrusion can foul. For blind or tight-back applications order a shorter length in the same JDS indented hex slotted series.

A 1/4 inch socket or nut driver fits. Across the flats the head measures 0.244 to 0.250 inch, and across the corners it is 0.272 inch, so clearance around the fastener needs to allow for that corner dimension when you are working in a crowded knockout or next to a raceway.