Metallics QK10-5M 8 x 3/4 in. 1/4 Hex Head Slotted Sharp Point Self-Piercing & Tapping Screws - Steel Zinc - Each

No pilot hole needed. The QK10-5M is a sharp point self-piercing and tapping screw, so it pierces thin sheet material and forms its own thread as it drives. Twin lead threads cut the driving torque, and the undercut under the head gives you more thread engagement once it is seated.

Not necessarily. Metallics states that head dimensions on self-piercing screws differ from standard tapping screws, and that there is no single industry standard for self-piercing screw dimensions, so the published values are a guide and deviations occur. If you are matching an existing countersink or a tight bracket slot, check against the 0.244 to 0.25 in. head width and the 0.322 to 0.348 in. washer OD before you commit to 5,000 pieces.

The head is a 1/4 inch hex with a slotted drive, so you can run it with a 1/4 in. hex driver in a screwgun or back it out with 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 in. wide and 0.052 to 0.074 deep, so use a thin flat tip if you go that route.

It carries an integral washer with an outside diameter of 0.322 to 0.348 in. and a thickness of 0.019 to 0.031 in. That spreads the load over a wider footprint than the 1/4 in. hex head alone, which helps when you are fastening into thin sheet metal or through a slotted strut or bracket hole.

The QK10-5M is boxed in a 5,000 piece minimum, and the box runs 19.3 lbs. Metallics notes other sizes and quantities are available by request if 5,000 of the #8 x 3/4 in. is more than the job needs.

The QK10-5M is carbon steel with a zinc plating, which is a dry-interior finish. It holds up fine in conditioned indoor runs, panels, and ceiling work, but for exterior, wet, or corrosive locations you want a stainless or hot-dip galvanized fastener instead. Zinc plate will bloom and rust in standing moisture.

The QK10-5M is flagged compliant for both Buy American and ARRA, with country of origin listed as multiple. For a federally funded spec, cite the compliance flag and confirm the origin documentation on the specific lot you receive.

Case hardness is Rockwell C28-38, from AISI 1018 to 1022 low carbon steel. That is enough case to form threads in light gauge sheet without the point rolling over, while leaving the core ductile enough that the screw does not snap off in the hole when you torque it down.

15 threads per inch on a #8 diameter, 3/4 in. long body. It is a coarse twin lead thread, which is what lets it tap its own hole in sheet material and keeps driving torque down on a screwgun.