Metallics JTSS81 10 x 3 in. Pan Head Square Drive Tapping Screws - Steel Zinc - Each

A #2 square bit (driver size 2R) drives the JTSS81. The recess measures 0.112 in. across flats with a gaging depth of 0.060 to 0.075 in., so a worn or undersized bit will cam out on a 3 in. screw. Keep a fresh #2 square in the impact driver.

The JTSS81 is a Type A tapping screw with a gimlet point and 12 threads per inch. That gimlet (sharp, wood-screw style) point and coarse pitch is what lets it start in thin sheet metal and bite in wood studs without a pilot hole. It is the screw Metallics lists for electrical, plumbing, and HVAC work, so think strut and box mounting into studs or sheathing rather than structural fastening.

No. The JTSS81 is not Buy American compliant and not ARRA compliant, with country of origin listed as multiple. On federally funded work with domestic sourcing requirements you will need a domestically produced fastener.

The JTSS81 ships in a jar with a 100 piece minimum, so the jar is the order unit. Metallics notes other sizes and quantities are available by request.

The JTSS81 is AISI 1016 to 1024 steel with a zinc finish. Zinc plating is an indoor and protected-location coating, good for dry interior electrical, plumbing, and mechanical work. For exterior, wet, or corrosive environments, specify a stainless or hot dip galvanized fastener instead.

Yes. The pan head measures 0.357 to 0.373 in. across and 0.122 to 0.133 in. high, so it bears on the surface rather than countersinking. That head width gives good bearing on strap, clip, and box flanges, but it stands proud, so it is not the screw for a flush finished surface.

Head dimensions follow ASME B18.6.3-2013 and the thread form follows ASME B18.6.4. Material is AISI 1016 to 1024 steel, hardness Rockwell C28-38, with 48 lb-in minimum torsional strength. That hardness and torque figure is what a submittal reviewer looks for on a tapping screw.

The square recess on the JTSS81 has a square center opening with slightly tapered side walls and a conical bottom, which grips the bit and lets the screw hang on the driver. On overhead box and strap work with a 3 in. screw, that stick-fit is the whole point, since a Phillips cams out and drops. Use a #2 square bit.

A jar of the JTSS81 runs 1.73 lbs, with the package measuring 3.5 x 3.5 x 5.75 in. Useful if you are kitting van stock or batching a shipment of several jars.