Metallics QK55M 8 x 1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

No pilot hole needed. The QK55M is a self-piercing, self-tapping screw with a sharp point, so it pierces and forms its own thread in sheet metal as you drive it. Twin lead threads cut the driving torque, and the undercut under the head gives you more thread engagement in thin material.

Either works. The head is a 1/4 inch hex measuring 0.244 to 0.25 inch across, so a 1/4 inch hex driver or nutsetter 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 cannot get a driver in. Head height runs 0.096 to 0.11 inch.

The QK55M is flagged compliant for both ARRA and Buy American, which is what institutional and public-works procurement typically asks for on fasteners. Country of origin is listed as multiple.

It's a #8 diameter by 1/2 inch long screw with 15 threads per inch. The 1/2 inch length keeps it short enough for stud and sheet metal work where a longer screw would bottom out or protrude behind the material.

Yes, there's a washer face under the hex head with an outside diameter of 0.322 to 0.348 inch and a thickness of 0.019 to 0.031 inch. That bearing surface spreads the clamp load so the head doesn't pull through light-gauge sheet metal.

It's case hardened to Rockwell C28-38 and made from AISI 1018 to 1022 steel, which is what lets the sharp point pierce and tap sheet steel rather than skating or snapping. Material is steel with a zinc finish.

They ship as a box of 5,000, which is the order minimum. Plan the buy as a bulk pack rather than a small count, so it suits crews doing repetitive sheet metal, hanger, or strap work rather than a single service call.

Not necessarily. Head dimensions on self-piercing screws differ from standard tapping screws, and there is no single industry standard for self-piercing screw dimensions, so the published values (0.244 to 0.25 inch head width, 0.096 to 0.11 inch head height) are a guide and small deviations can occur. If a cover plate or clip needs a specific head profile, measure before you mix them in.

The QK55M carries a zinc finish, which is a corrosion-resistant plating intended for dry interior and protected use. For sustained outdoor exposure, wet locations, or contact with treated lumber, specify a stainless or heavier coated fastener instead.

Order Metallics QK55M, part of the JQK series of hex head slotted sharp point self-piercing and tapping screws. Other diameters, lengths, and quantities in the same series are available by request if the #8 x 1/2 inch doesn't suit the gauge you're fastening.