Metallics JQK5 8 x 1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

Either works. The JQK5 has a hex head measuring 0.244 to 0.250 inch across, so a 1/4 inch hex driver or nut setter seats on it, and the head is also slotted (slot width 0.045 to 0.054 inch, depth 0.052 to 0.074 inch) for a flat blade when you are working in a tight spot and cannot get a socket on it. Electricians usually run them with the hex and keep the slot as a backup.

That is exactly what the sharp point is for. The JQK5 is a #8 diameter, 1/2 inch long sharp point self-piercing and tapping screw, so it pierces and forms its own thread in thin sheet metal without a pilot hole. Twin lead threads at 15 threads per inch keep the driving torque down. On heavier gauge or structural steel you want a drill point screw instead, not a sharp point.

No. The JQK5 screws are not Buy American compliant and are not ARRA compliant, with country of origin listed as multiple. If your contract carries a domestic sourcing clause, these will not clear it and you need a domestically manufactured fastener instead.

It is a hex washer head. The washer outside diameter runs 0.322 to 0.348 inch with a washer thickness of 0.019 to 0.031 inch, and overall head height is 0.096 to 0.110 inch. That flange spreads the clamp load over sheet metal and over slotted strut or box flanges so the head does not pull through. There is also an undercut beneath the head, which lets more of the thread engage the material.

The JQK5 is carbon steel with a zinc plated finish, which is a mild corrosion barrier meant for dry interior work: panel boxes, raceway, duct, interior strut. Zinc plating is not a marine or sustained wet-location coating, so for exterior, roof, or damp duty step up to a stainless or a heavier coated fastener. The base steel is AISI 1018 to 1022, case hardened to Rockwell C28-38.

They come in a jar of 100, and 100 is the order minimum, so a single jar is the smallest quantity. Jar weight is 0.35 lbs. Metallics does offer other sizes and quantities of this screw by request.

No, and Metallics flags it on this product. Head dimensions on self-piercing screws differ from standard tapping screws, and there is no single industry standard for self-piercing screw dimensions. The published values, such as the 0.244 to 0.250 inch head width and 0.322 to 0.348 inch washer OD on the JQK5, are a guide and deviations can occur. If a hole or clearance is tight, measure the actual screw rather than working off a tapping screw table.

Metallics lists it for the electrical, plumbing, and heating and air conditioning trades. In practice that is mounting device boxes, straps, clips, plates and brackets to light gauge metal, plus sheet metal duct work on the mechanical side. The 1/2 inch length keeps the point from protruding far behind thin material.