Metallics JTS33M 12 x 3/4 in. Pan Head Combo Sharp Point Tapping Screws - Steel Zinc - Each

Type A is a sharp gimlet point tapping screw, and the JTS33M is built for sheet metal work. The point drills into the material and the 11 threads per inch cut their own thread as the screw drives, so you don't need a nut or a pre-tapped hole, just a pilot hole in heavier gauge. It is the screw electricians reach for on sheet metal enclosures, boxes, raceway and strut covers. For wood or drywall you want a different point and thread.

The JTS33M is flagged compliant for both Buy American and ARRA, which is what a government, school district or healthcare procurement office needs on the submittal. Country of origin is listed as multiple.

Either one. The JTS33M has a combo recess, slotted and Phillips in the same head, so a flat blade works where you can't get a driver square to the work and a Phillips bit works everywhere else. Use a #3 driver. The Phillips recess measures 0.252 inches across with a gaging depth of 0.098 to 0.124 inches, and the slot is 0.056 to 0.067 wide by 0.055 to 0.077 deep, so a worn or undersized bit will cam out before the screw seats.

83 lb-in is the minimum torsional strength on the JTS33M, with the screw case hardened to Rockwell C28 to 38 and made from AISI 1016 to 1024 steel. That is the figure to watch if you're running these with an impact driver or a clutch gun on a big install, set the clutch below it rather than relying on feel.

Zinc plated carbon steel is what the JTS33M carries, which is a mild corrosion coating meant for dry interior service, electrical rooms, enclosures, panel work. It will hold up indoors and in normally dry spaces. For wet locations, exterior runs or anywhere with chemical exposure, specify a stainless tapping screw instead rather than relying on the plating.

Threads on the JTS33M are made to ASME B18.6.4, the tapping screw standard, with UNC thread form at 11 TPI. Head dimensions follow ASME B18.6.3-2013. Because it is a tapping screw thread and not a machine screw thread, don't plan on running a standard #12-24 machine nut onto it. If you need a nut on the back side, use a machine screw and a tapped or clearance hole instead.

The JTS33M is a #12 diameter screw with 3/4 inch of overall length under the pan head. Subtract the thickness of what you're fastening through and the remainder is your thread engagement, so it suits thin to medium sheet metal assemblies, not thick plate or stacked framing. If you're going through a thicker build-up, step up to a longer length in the same series.

They ship 1,000 to a jar, and 1,000 is the order minimum. The jar weighs 7.9 lbs, which is worth knowing if you're staging material by the box on a multi-floor job. Other sizes and quantities can be had by request.