Metallics JTEKD27SS 10 x 3 in. 5/16 Indented Hex Head Self-Drilling & Tapping Screws with Washer - #3 Drill Point - 410 Stainless Steel - Each

Minimum torsional strength is 61 lb-in, with the screw hardened to Rockwell C38-46. That's the point at which the fastener twists off, so set your driver clutch below it. Metallics notes minimum torques are the same for stainless and steel self-drill screws, and drill time is about 2.5 seconds through a 1 mm plate. At 3 inches long there's a lot of shank to twist, so a controlled screw gun beats a high-torque impact here.

A 5/16 hex driver. The indented hex washer head measures 0.305 to 0.312 inches across the flats and 0.34 across the corners, so a standard 5/16 magnetic nut setter seats it cleanly. Head height runs 0.105 to 0.12 inches.

410 stainless is the hardenable grade, which is what lets a stainless screw drill its own hole. It gives better corrosion resistance than plain carbon steel for exterior strut, conduit standoffs, and damp mechanical rooms. It is not the equal of 300 series stainless in salt spray or chemical exposure, so for coastal or heavy washdown work spec a 300 series fastener into a pre-drilled hole instead.

The washer is integral to the head, not a loose part. It's a formed hex washer head with an outside diameter of 0.384 to 0.414 inches and a washer thickness of 0.019 to 0.031 inches. That spreads bearing load over sheet metal and strut, but it is a plain metal flange, not a bonded EPDM sealing washer. For weather-tight roof or panel penetrations you need a separate sealing washer or a bonded-washer screw.

The JTEKD27SS is flagged Buy American compliant and ARRA compliant in Metallics' data, with country of origin listed as multiple. On a federally funded project, pull the mill and compliance documentation for the specific lot with your submittal package.

That's the use case for a Type BSD screw at this length. The 3 inch shank lets you pass through strut, a backing member, or insulation before the point reaches steel, and the drill point handles a base panel of 0.110 to 0.175 inches. Where the hole is already drilled or you're fastening into wood or masonry, a self-driller is the wrong tool. Use a machine screw and nut, or an anchor, instead.

They ship in a jar with a minimum order of 100 count. Shipping weight on that jar is 1.78 lbs. If you need a different size or a different pack count, Metallics offers other sizes and quantities by request.

Head and body dimensions follow ASME B18.6.3-2010, and the thread and drill point follow SAE J78 - 2013. Note that SAE J78 does not cover #7 diameter drill screws, which is why the #10 diameter is the common spec'd size for this head style.