Metallics JTSS12 8 x 2 in. Pan Head Square Drive Tapping Screws - Steel Zinc - Each

A #2 square (Robertson) bit. The recess on the JTSS12 is spec'd at a 2R driver size, 0.112 in. across flats, with a gaging depth of 0.060 to 0.075 in. Run a clean, undamaged #2 square bit and the driver stays seated; the screw is rated to 39 lb-in minimum torsional strength, so an impact driver set too aggressively will twist the head off before the point stops turning.

Type A tapping screws like the Metallics JTSS12 have a gimlet point, which is the sharp tapered point that starts its own hole in thin sheet metal and forms the thread as it drives. In light gauge steel and in wood or composite, no pilot is needed. In heavier gauge stock, drill a pilot, because the coarse 15 threads per inch on a Type A is meant for thin material, not structural steel.

That is the intended work. Metallics lists the JTSS12 for the electrical, plumbing, heating and air conditioning trades. The pan head is a low, flat-bearing head, 0.306 to 0.322 in. across and 0.105 to 0.115 in. tall, so it seats flat against a box ear or a bracket without needing a countersink. At 2 in. long it will pass through a mounting flange and still get plenty of thread into wood framing.

No. The JTSS12 is not Buy American compliant and is not ARRA compliant, and country of origin is listed as multiple. If your spec carries a domestic sourcing clause, this is not the screw for that package.

They ship 100 to a jar, and 100 is the order minimum, so the smallest quantity you can buy is one 100-count jar. Jar weight is listed at 0.92 lbs.

They case harden to Rockwell C28-38 from AISI 1016-1024 steel, which is the standard case-hardened tapping screw range and is enough to cut threads in light gauge steel stud and sheet. It is not a self-drilling screw, though. There is a gimlet point, not a drill point, so heavier stock still wants a pilot hole.

The JTSS12 is steel with a zinc plated finish, which is a dry-location and general indoor coating. It handles incidental moisture but it is not a marine or sustained-wet finish, so for exterior, coastal, or wet process areas specify a stainless or hot dip galvanized fastener instead.

Head and recess dimensions follow ASME B18.6.3-2013, and the thread form follows ASME B18.6.4, the tapping screw standard. If a submittal calls out a B18.6.4 Type A screw, the JTSS12 answers it. One caveat Metallics states: dimensions for the #9 diameter are independent of ASME B18.6.4.

The square recess holds the bit on the driver without a second hand, which is the reason it gets specified for overhead and one-handed work in panels and ceilings. The JTSS12 recess has a square center opening with slightly tapered side walls and a conical bottom, and it takes a 2R bit. A Phillips of the same size is more prone to cam-out under the 39 lb-in of torque this screw is rated to carry.