Metallics JTSS28SS 10 x 1 in. Pan Head Square Drive Tapping Screws - 18-8 Stainless - Each

A #2 square (Robertson) bit. The recess is specified as driver size 2R, measuring 0.112 inch across the flats with a gaging depth of 0.060 to 0.075 inch. The square recess has slightly tapered side walls and a conical bottom, so a well-seated #2 square bit holds without cam-out. Keep a spare bit on hand if you are driving a full jar of 100.

It forms its own thread in sheet metal, but it is not a self-drilling screw. The JTSS28SS is a Type A tapping screw with a gimlet point and 12 threads per inch, so it needs a punched or drilled pilot hole in the sheet and then taps its own mating thread as it drives. If you want a screw that drills and taps in one pass, you need a self-drilling (Type TEK) screw instead.

They can. Fastening 18-8 stainless parts to aluminum or steel sets up a galvanic couple in some environments, which corrodes the less noble metal (the aluminum or the steel, not the screw). Outdoors, in wash-down areas, or anywhere salt or standing moisture is present, that matters. In dry indoor electrical work it generally does not. If galvanic action is a concern on your job, use a fastener of the same metal family as the base material.

No. The JTSS28SS is not Buy American compliant and is not ARRA compliant, and country of origin is listed as multiple. If your contract carries a domestic sourcing clause, this part will not satisfy it and you need a documented domestic fastener instead.

48 lb-in minimum torsional strength. Stainless is softer than hardened carbon steel, so the practical limit is the screw body, not the recess. Set an impact or driver clutch well under that figure when running these into heavier gauge metal, and back off as soon as the pan head seats.

The head measures 0.357 to 0.373 inch across and stands 0.122 to 0.133 inch above the surface. That is a rounded, non-countersunk profile, so plan on roughly an eighth of an inch of head height clearance. If the mating part has to sit flush against the sheet, a pan head is the wrong choice and you want a flat head in a countersunk hole.

They ship in a jar of 100, which is the order minimum. There is no smaller count, so a single part number gets you a full jar. Metallics notes that other sizes and quantities can be had by request.

Head and recess dimensions follow ASME B18.6.3-2013, and the thread conforms to ASME B18.6.4, the tapping screw standard. So a #10 pan head square drive from this series interchanges dimensionally with any other B18.6.3/B18.6.4 #10 Type A screw. Note that Metallics calls out #9 diameter dimensions as independent of ASME B18.6.4, which does not affect this #10.

Metallics lists them for the electrical, plumbing, and heating and air conditioning trades: fastening panel covers, device plates, duct and sheet metal components, hanger and bracket work. The 1 inch length with 12 threads per inch handles thin sheet into light structure, and 18-8 stainless suits damp or exposed interior locations better than plated carbon steel.

Cam-out. The square recess on the JTSS28SS has a tapered wall and conical bottom that grips a 2R bit, so the bit stays in the head when you lean on it overhead or one-handed in a panel. Phillips recesses are designed to slip at torque, which chews up the head and, in stainless, leaves you drilling the screw out. If you are driving by hand in tight gear, square drive is the easier head to keep loaded.