Metallics QK178M 8 x 1-1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

No pilot hole is needed. The QK178M is a sharp point self-piercing and tapping screw, so the point pierces thin material and the thread taps its own mating thread as it drives. Twin lead threads cut driving torque, which matters when you are running hundreds of them into metal studs or sheet metal by hand or with a screwgun.

Either works. The head is a 1/4 inch hex with a slotted drive across the top, so you can run it with a 1/4 inch hex driver or socket, or back it out with a flat blade screwdriver. Head width measures 0.244 to 0.25 in. and the slot is 0.045 to 0.054 wide by 0.052 to 0.074 deep, so a standard cabinet-tip blade seats properly.

They ship in a box of 8,000 pieces, which is the order minimum. Plan on that volume count if you are buying for a job, not a handful of screws.

Not necessarily. Metallics notes that head dimensions on self-piercing screws differ from standard tapping screws, and that there is no single industry standard for self-piercing screw dimensions, so the published figures are a guide and deviations can occur. If you are seating the head into an existing punched hole or a fixture recess, check against the actual head width of 0.244 to 0.25 in. and head height of 0.096 to 0.11 in. rather than assuming a standard #8 hex head.

Yes, the head carries a washer face with a 0.322 to 0.348 in. outside diameter and 0.019 to 0.031 in. thickness, giving more bearing surface than a plain hex head. There is also an undercut beneath the head, which lets more of the thread engage the material instead of being wasted under the washer.

They are heat treated to Rockwell C28-38 and made from AISI 1018 to 1022 steel, which is the hardness range a self-tapping screw needs to form threads in light gauge steel without the point rolling over. Thread pitch is 15 threads per inch on a #8 diameter, 1-1/2 in. long.

The finish is zinc plating over steel, which is a general indoor and dry-location corrosion coating. It handles normal interior construction and electrical work fine, but zinc plated steel is not a substitute for hot-dip galvanized or stainless in wet, exterior, or corrosive service.

Metallics lists the QK178M as both Buy American compliant and ARRA compliant. Country of origin is listed as multiple, so the specific origin can vary by production lot. For federally funded projects with documentation requirements, that compliance flag is what your submittal package needs.

A box runs 52.72 lbs, with carton dimensions of 11.5 x 10.75 x 11.5 inches. Worth knowing before you have someone carry one up a ladder or onto a scaffold.