Metallics JTSS8SS 8 x 3/4 in. Pan Head Square Drive Tapping Screws - 18-8 Stainless - Each

A #2 square (Robertson) bit. The recess is spec'd at driver size 2R, with 0.112 across the flats and a gaging depth of 0.060 to 0.075 inch. The square recess has slightly tapered side walls and a conical bottom, so a correctly seated #2R bit resists cam-out when you are driving into sheet metal overhead.

It will not drill its own hole. The JTSS8SS is a Type A tapping screw with a gimlet point, which means it needs a pilot or punched hole in sheet metal and then forms its own thread as it goes. At 15 threads per inch it is the coarse Type A thread meant for thin-gauge sheet metal, not for thick plate or for masonry.

You can, but watch the environment. 18-8 stainless fasteners in contact with aluminum or steel can set up a galvanic couple and corrode the lighter metal, which matters on exterior, roof, and wet-location work. Indoors and dry, it is a non-issue. If the connection is outdoors or in a damp mechanical space, isolate the joint or use a fastener matched to the base metal.

No on both counts. The JTSS8SS is not Buy American compliant and is not ARRA compliant, and country of origin is listed as multiple. On a federally funded project with domestic-sourcing language in the spec, this fastener will not satisfy it.

39 lb-in minimum torsional strength. Stainless twists off sooner than hardened carbon steel, so set your impact or clutch driver low and finish the last turn by feel. If you are breaking heads, the pilot hole is too small for the 15 TPI thread rather than the screw being underspec'd.

Pan head, 0.306 to 0.322 inch across the head and 0.105 to 0.115 inch high. That low crown is what lets it sit against a device bracket, box ear, or strap without fouling a cover plate, and the broad bearing surface spreads load on thin sheet metal better than an oval or round head.

Head and recess geometry follow ASME B18.6.3-2013, and the thread follows ASME B18.6.4, the tapping screw thread standard. That means the #2R square recess and the pan head profile are to published dimensions, so a spec'd fastener callout on a drawing is satisfied by dimension, not by a trade name.

They come in a jar, with a 100-piece minimum per jar. Pack weight is 0.59 lbs. Other sizes and quantities are available by request if your job needs a different length or count.

Metallics lists it for electrical, plumbing, heating and air conditioning work. In practice that is sheet metal duct, strut and strap, enclosure and box mounting, and anywhere a stainless screw is wanted for a damp or washdown location. The square drive is the reason techs favor it on ladders, since the bit holds the screw one-handed.