Metallics QK16GR8M 8 x 1-1/4 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Gray - Steel Zinc - Each

The QK16GR8M is a #8 diameter by 1-1/4 inch self-piercing and tapping screw with 15 threads per inch. It ships boxed, with a minimum order of 8,000 pieces, so this is a bulk production item rather than a handful for a single repair.

Either works. The head is a 1/4 inch hex with a slot cut across it, measuring 0.244 to 0.25 inch across and 0.096 to 0.11 inch high, so a 1/4 inch nut driver or hex socket seats on it, and the slot (0.045 to 0.054 inch wide, 0.052 to 0.074 inch deep) takes a flat blade in tight spots where a driver will not fit.

No pilot hole is needed. The sharp point pierces thin metal and the twin lead threads tap their own threads while cutting driving torque, which is the whole point of a self-piercing screw. For heavier stock a self-drilling point screw is the better choice.

They are case hardened to Rockwell C28-38 and made from AISI 1018-1022 steel with a zinc finish, which is the standard hardness range for a point that has to form its own thread in light gauge steel. The zinc plating gives basic corrosion resistance for interior work; it is not a stainless or exterior coated fastener.

Yes, the hex head sits on a built-in washer measuring 0.322 to 0.348 inch outside diameter and 0.019 to 0.031 inch thick. That spreads bearing load over thin material and covers a slightly oversized hole. There is also an undercut under the head so more thread engages the workpiece.

Metallics lists the QK16GR8M as both ARRA compliant and Buy American compliant. Country of origin is recorded as multiple, so if your specification requires a single documented source, ask for the certification covering the specific lot.

They won't. Self-piercing screw heads are dimensioned differently from standard tapping screws, and there is no single industry standard governing them. Metallics publishes the QK16GR8M figures (0.244 to 0.25 inch head width, 0.322 to 0.348 inch washer OD) as a guide, and small deviations can occur lot to lot. If you are matching an existing fastener for appearance, check a sample before committing to 8,000.

The 8,000 piece box weighs 45.57 lbs and measures 11.5 x 10.75 x 11.5 inches. Worth knowing if you are staging material on a floor by hand or allocating shelf space in a shop.

The heads are gray over the zinc plated steel, which reads close to galvanized boxes, raceway and strut. It is a standard color choice for electrical rough-in where fasteners are visible but not meant to stand out.