Metallics JTSF7SS 6 x 3/8 in. Flat Head Phillips Tapping Screws - 18-8 Stainless - Each

A #2 Phillips bit. The JTSF7SS has a Phillips drive with a recess 0.168 in. in diameter and 0.094 in. deep, so a #2 seats fully. Going to a #1 or #3 risks cam-out, and with a stated torsional strength of 24 lb-in minimum these screws will snap before they strip out a pilot hole in heavier gauge metal, so keep the driver clutch low.

Yes, if the hole is countersunk. Flat head means the head is designed to seat below the surface, and the head measures 0.238 to 0.262 in. across with a head height of 0.069 to 0.083 in. Cut or punch the countersink to match that head diameter. In a plain drilled hole with no countersink the head will stand proud.

Mechanically yes, but watch the metals. These are 18-8 stainless, and Metallics notes that fastening stainless parts to aluminum or steel can set up a galvanic couple in some environments, meaning the aluminum or steel corrodes around the fastener. Outdoors, in damp mechanical rooms, or anywhere coastal, either isolate the joint or match the fastener material to the base metal.

The JTSF7SS is a Type A tapping screw with a gimlet point, which means it needs a pilot hole or a soft substrate. It cuts its own thread in sheet metal, resinous plywood, and asbestos board type materials, but it will not drill through steel on its own. If you are fastening straight into steel with no pre-drilled hole, you want a self-drilling point instead.

18 threads per inch, to ASME B18.6.4, with a gaging diameter of 0.22 in. That is the coarse Type A pitch, so it bites in thin sheet with fewer turns than a machine screw would. If you are matching an existing hole already tapped by a #6 Type A screw, this will thread back into it.

They ship in a jar of 100, and 100 count is the order minimum. For a service van or a panel shop that is a single jar per order rather than loose counts.

The JTSF7SS is flagged ARRA compliant and Buy American compliant in Metallics' own data, which is what a public-works or federally funded procurement file usually needs on the fastener line. Country of origin is listed as multiple, so if your contract requires a single named origin, ask for origin documentation on the lot you receive.

Yes. The JTSF screws are built to ASME B18.6.4-1998 for both dimensions and threads, so head size, recess geometry, and pitch are all to that standard. Metallics does note that dimensions for #9 diameter screws fall outside B18.6.4; the #6 size is within it.