Metallics QK16WM 8 x 1-1/4 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Gray - Steel Zinc - Each

No pilot hole needed in thin sheet metal. The QK16WM is a sharp point self-piercing and tapping screw, so the point pierces the sheet and the twin lead threads cut their own thread as you drive. The twin leads also cut driving torque, which matters when you are running a few hundred of them into hat channel or outlet box ears.

It is a #8 diameter screw, 1-1/4 inches long, with 15 threads per inch. The 15 TPI twin lead thread is a coarse pitch meant for sheet metal and light gauge steel rather than machine thread work, so it will not mate with a #8-32 tapped hole.

The screw is case hardened to Rockwell C28-38 and made from AISI 1018 to 1022 carbon steel. That hardness suits piercing light gauge sheet steel; it is not a self-drilling point for heavy structural stock. For thicker steel you want a drill point (Tek style) screw instead of this sharp point.

It takes a 1/4 inch hex nut driver or socket, with a slotted drive in the head as a backup for a flat blade. Head width measures 0.244 to 0.25 inches across, head height 0.096 to 0.11 inches, and the slot is 0.045 to 0.054 inches wide and 0.052 to 0.074 inches deep. Most people run these with a 1/4 inch magnetic nutsetter on a screwgun.

Yes, it has an integral washer under the hex head with an outside diameter of 0.322 to 0.348 inches and a washer thickness of 0.019 to 0.031 inches. That spreads the clamp load over a wider footprint than a plain hex head, useful on soft or thin material where a bare head would pull through. There is also an undercut beneath the head that gives you more thread engagement in the workpiece.

The QK16WM is zinc plated carbon steel. Zinc plating handles indoor and protected use fine, but it is not stainless and not hot dip galvanized, so direct weather exposure, wet locations, or treated lumber contact will corrode it. For exterior or damp work, specify a stainless or galvanized fastener.

Both the Buy American and ARRA compliance flags on the QK16WM are marked compliant. Country of origin is listed as multiple, so if your specification requires a single named country of manufacture on the submittal, confirm the origin on the lot you receive.

Not necessarily. Head dimensions on self-piercing screws differ from standard tapping screws, and there is no single industry standard for self-piercing screw head geometry. The published figures (0.244 to 0.25 inch head width, 0.096 to 0.11 inch head height) are a guide and small deviations can occur, so if a clearance hole or a cover plate counterbore is tight, check one screw before running the whole box.

They ship boxed, with a minimum order of 1,000 pieces (one thousand-count box). Box weight is 6.08 lbs and the carton measures 7.25 x 6.75 x 3.25 inches. If you only need a handful for a service call, this is a bulk box, not a small pack.