Metallics QK512M 8 x 1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

No pilot hole needed. The QK512M is a sharp point self-piercing and tapping screw, so it pierces and forms its own thread in sheet metal as it drives. Twin lead threads cut the driving torque, which helps when you are running a lot of them into studs or channel.

The QK512M is a #8 diameter, 1/2 inch long screw at 15 threads per inch, so the usable grip is short, roughly the 1/2 inch of length minus whatever thread has to engage the far side of the metal. That makes it a sheet-metal and light-gauge fastener for things like box mounting, strap and clip work, duct and raceway, not for thick stock. An undercut under the head gives you more thread engagement than a plain tapping screw of the same length.

It sells in a bulk box with a 12,000 piece minimum. That is contractor and MRO volume, so it fits a shop stocking program or a large build-out rather than a one-off repair. Count on about 36.24 lbs for the carton.

Not interchangeably on the head dimension. Metallics notes that 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 are a guide and some deviation occurs. If a clip, strap, or bracket relies on a specific head or washer footprint, go with the self-piercing screw that was called out rather than a tapping screw of the same #8 x 1/2 inch nominal size.

Two options, because the head is a 1/4 inch hex with a slot across it. A 1/4 inch hex driver or nutsetter is the fast way on a screw gun; the slot (0.045 to 0.054 inch wide, 0.052 to 0.074 inch deep) lets you finish or back one out with a flat blade screwdriver when you cannot get a socket in. Measured head width runs 0.244 to 0.25 inch and head height 0.096 to 0.11 inch.

Yes, the head carries an integral washer face measuring 0.322 to 0.348 inch outside diameter with a thickness of 0.019 to 0.031 inch. That spreads the bearing load and will bridge a hole slightly larger than the #8 shank, but it is not a sealing washer and it will not cover a knockout or a badly oversized opening.

Zinc finish over steel is a mild indoor corrosion coating. The QK512M is steel with a zinc plating, which suits dry interior work, panels, and enclosed mechanical spaces. For exposed exterior, coastal, or wet duty, specify a stainless or heavier coated fastener instead rather than relying on this plating.

They are case hardened to Rockwell C28-38 and made from AISI 1018 to 1022 steel, the usual carbon steel range for tapping screws. That gives the sharp point enough hardness to pierce and form thread in light gauge sheet steel. Heavy structural steel is beyond a self-piercing screw; use a drill point self-drilling screw or a drilled and tapped fastener there.

The QK512M is flagged compliant for both Buy American and ARRA requirements, which matters on federally funded institutional and public works jobs. Country of origin is listed as multiple, so if your specification demands a single named origin on the submittal, confirm the origin of the lot you are receiving.

Yes. The QK512M is the #8 x 1/2 inch size in the Metallics JQK series of hex head slotted sharp point self-piercing and tapping screws, and other sizes and quantities are offered by request. Give the diameter, length, and quantity you need and the matching part can be identified.