Metallics TEKD34M 14 x 2 in. 3/8 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - Steel Zinc - Each

A 3/8 inch hex socket. The TEKD34M has a 3/8 indented hex washer head, with head width measured at 0.367 to 0.375 inch and width across corners of 0.409 inch, so a standard 3/8 magnetic nut setter in an impact or screw gun drives it. There is no slotted or Phillips option; drive type is hex only.

The TEKD34M is carbon steel with a zinc finish, which is a dry indoor or protected-interior plating. Zinc gives handling and light humidity protection, not weather exposure. For roof decking, exterior cladding, or anywhere subject to standing water or coastal air, use a stainless or coated-for-exterior self-drill screw instead of this zinc plated steel one.

Three specs cover it. Head and body dimensions follow ASME B18.6.3-2010, threads follow SAE J78-2013, and the steel is AISI 1016-1024 case hardened to Rockwell C32-40. Note that SAE J78 does not include specifications for #7 diameter drill screws, which does not affect this #14 size. The item is also flagged ARRA compliant and Buy American compliant.

No pilot hole. The TEKD34M is a Type BSD self-drilling and tapping screw, so the drill point cuts its own hole and the threads tap it in one pass. Set the gun to a moderate speed and keep steady pressure until the point breaks through, then let the threads pull the washer head down.

Overall length is 2 inches in a #14 diameter. Part of that length is consumed by the drill point and the thread engagement in the base metal, so plan on fastening a stack-up noticeably thinner than 2 inches. It is a common size for strut, hangers, and bracket work where you are going through an accessory into steel.

It is an integral washer formed as part of the indented hex washer head, not a loose washer you assemble. Washer outside diameter runs 0.480 to 0.520 inch with a thickness of 0.030 to 0.050 inch, which spreads the clamp load over a slightly larger footprint than a plain hex head and helps when fastening through a punched or slotted accessory.

They ship in a box of 1,000 pieces, and 1,000 is the order minimum, so this is a bulk buy rather than a small handful. The full box weighs 24.4 lbs. That quantity suits crews doing repeat strut, hanger, or enclosure mounting work rather than a one-off repair.

The head stands proud. Head height is 0.172 to 0.190 inch plus the integral washer, so the hex and washer bear on top of the material rather than countersinking. If you need a flush surface, for example under a panel or a finished face, choose a flat or wafer head self-drill screw instead of this indented hex washer head.

No. Metallics states minimum torques are the same for stainless and steel self-drill screws, so swapping material does not change your driving torque target. The difference is corrosion performance, not installation torque. This TEKD34M is the steel zinc version.