Metallics JTSF18 8 x 1/2 in. Flat Head Phillips Tapping Screws - Steel Zinc - Each

The Metallics JTSF18 is a Type A tapping screw with a gimlet point, meaning it drills its own thread as it goes into a pilot hole in thin sheet metal. At 15 threads per inch it is a coarse, widely spaced thread, which is what you want in sheet steel, electrical boxes, duct and strut-type sheet material rather than solid stock. Metallics lists it for the electrical, plumbing, heating and air conditioning trades.

Yes, if the hole is countersunk. The JTSF18 is a flat head screw with a head width of 0.285 to 0.312 in. and a head height of 0.084 to 0.1 in., so the head is designed to seat down into a countersink and finish flush with the surface. On a flat, non-countersunk plate the head will stand proud by that head height, so use a pan or hex washer head screw there instead.

Yes. The JTSF18 is built to ASME B18.6.4-1998 for dimensions and ASME B18.6.4 for thread, with a gaging diameter of 0.267 in. and a protrusion gaging diameter of 0.023 to 0.039 above. That means a #8 flat head Phillips Type A called out on a drawing is interchangeable with this one. One caveat for mixed orders: Metallics notes that dimensions for its #9 diameter screws are independent of ASME B18.6.4.

No. The JTSF18 is not Buy American compliant and is not ARRA compliant, with country of origin listed as multiple. If your project carries a domestic sourcing requirement you will need a fastener specifically certified as domestic.

A #2 Phillips. The recess on the JTSF18 is 0.182 in. in diameter and 0.11 in. deep, so a #2 bit seats fully and a #1 will cam out and chew the recess. Keep a few #2 bits on the truck if you are running a full jar of 100.

They ship in a jar of 100, and 100 is the order minimum. If you need a different length or diameter in the same flat head Phillips Type A pattern, Metallics makes other sizes and quantities available by request.

The JTSF18 is carbon steel with a zinc finish, which is a plated coating meant for dry interior service. It handles normal indoor humidity, but for exterior, wet locations, or corrosive environments you want stainless or a hot dip galvanized fastener instead, since plated zinc will eventually rust through on continuous exposure.

They are heat treated to Rockwell C28-38 with a minimum torsional strength of 39 lb-in, made from AISI 1016 to 1024 carbon steel. That is enough case hardness for the gimlet point to form thread in sheet metal. Driving them with an impact driver or over-torquing past that 39 lb-in figure is what shears heads off, so set the clutch on your drill rather than running it wide open.