Metallics JDS184SS 10 x 1-1/2 in. 5/16 Indented Hex Head Slotted Sharp Point Tapping Screws - 18-8 Stainless - Each

Either works. The JDS184SS has an indented hex head measuring 0.305 to 0.312 inch across the flats, so a 5/16 nut driver or socket seats on it, and the head is also slotted (drive type is listed as Hex/Slotted) with a slot 0.05 to 0.06 inch wide and 0.057 to 0.072 inch deep for a flat blade. Across the corners the head runs 0.34 inch. Head height is 0.105 to 0.12 inch, and the integral washer face is 0.384 to 0.414 inch OD, 0.019 to 0.031 inch thick, which gives it a bearing surface against sheet metal.

The JDS184SS is a Type A tapping screw with a gimlet (sharp) point, which is made to start in thin sheet metal or a punched hole without a pilot in light gauge material. It forms its own thread as it drives, at 12 threads per inch. In heavier stock, drill a clearance hole in the top sheet and a pilot in the bottom sheet; the gimlet point is a starting aid, not a drill point, so it will not cut through thick steel the way a self-drilling screw does.

They can. Fastening 18-8 stainless parts to aluminum or steel sets up a galvanic couple in some environments, which corrodes the less noble metal (the aluminum or the steel, not the screw). On exterior or damp jobs into aluminum, isolate the joint or use a fastener matched to the base metal. Where the assembly stays dry, the 18-8 stainless material is the reason to pick this screw in the first place.

No. The JDS184SS is not Buy American compliant and is not ARRA compliant, and country of origin is listed as multiple. If your project carries domestic-sourcing language, this screw will not satisfy it.

Head dimensions follow ASME B18.6.3-2010 and the thread form follows ASME B18.6.4, the tapping screw standard. One caveat from the manufacturer: dimensions for the #9 diameter are independent of ASME B18.6.4. That does not affect the #10 size, which is dimensioned to the standards above.

Hardness is Rockwell C28-38, which is the case range a Type A tapping screw needs to roll a thread in sheet metal without the point rolling over. Paired with the gimlet point and 12 TPI thread, it taps light gauge steel and aluminum as it drives.

Yes. Metallics offers other sizes and quantities in the JDS series by request; the JDS184SS covers the #10 diameter at 1-1/2 inch length. If you are standardizing a building or a service truck on one head style, you can stay on the indented hex slotted head and change the shank size.