Metallics QK17WM 8 x 1-1/2 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Gray - Steel Zinc - Each

No pilot hole needed. The QK17WM is a sharp point self-piercing and tapping screw, 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 the material.

Either. The head is a 1/4 inch hex with a slot cut across it, so you can run it with a 1/4 inch hex driver or a flat blade. Head width measures 0.244 to 0.25 in. and head height 0.096 to 0.11 in. The slot is 0.045 to 0.054 wide and 0.052 to 0.074 deep, so a standard medium flat tip seats in it.

There is an integral washer face on the head, measuring 0.322 to 0.348 in. outside diameter and 0.019 to 0.031 in. thick. It spreads the clamp load over the sheet, but it is plain steel zinc, not a bonded neoprene seal. For a weather-exposed roof or siding penetration you want a screw with an EPDM bonded washer instead.

The screw is case hardened to Rockwell C28-38 and made from AISI 1018-1022 steel, which is what lets the sharp point pierce sheet without a pilot. That hardness range is aimed at light gauge sheet metal work. In structural or heavy plate you should drill and use a machine screw or a self-drilling screw rated for that thickness.

The finish is zinc plating over steel, which is fine for dry interior electrical and sheet metal work. It is not a stainless or hot dip coating, so for sustained exterior exposure, coastal air, or wet locations pick a stainless or heavier coated fastener.

The QK17WM is flagged as both ARRA compliant and Buy American compliant in the manufacturer data. Country of origin is listed as multiple, so if your contract requires documented origin per lot, request the certification with the shipment.

At 1-1/2 inches the #8 QK17WM gives you plenty of length for stacking material ahead of the stud flange, but the point will protrude well past a single 20 gauge stud face. Use it where you need the reach (through furring, strap, or layered sheet) and step down in length where the screw would be left exposed behind the wall.

15 threads per inch on a #8 diameter, with a twin lead thread form. Twin lead means fewer turns to drive and less torque at the gun, which matters when you are running hundreds of fasteners overhead.

It ships in a box with a 1,000 piece minimum. Box weight is 7.1 lbs and the carton runs 7.25 x 4.5 x 4.5 inches, so it is an easy one to keep on the truck or stock on a shelf for repeat work.

Self-piercing screws are not dimensioned to the same standard as ordinary tapping screws, and there is no single industry standard for them. Metallics publishes the head, slot, and washer figures as a guide, and small deviations can occur lot to lot. If you are matching an existing driver bit or counterbore, work to the stated ranges: 0.244 to 0.25 in. head width and 0.096 to 0.11 in. head height.