Metallics JSPM18SS 10-24 x 1 in. Pan Head Slotted Machine Screws - 18-8 Stainless - Each

18-8 stainless is the usual pick for wet, damp, and exterior work because it will not rust-bleed the way plated steel does once the coating is scratched during install. These screws are 18-8 stainless through and through, not plated, so a cut-off end or a driver-marred slot does not become a corrosion point. For heavy chloride exposure such as coastal or pool rooms, 316 stainless is the step up.

The pan head measures 0.357 to 0.373 in. across with a head height of 0.099 to 0.11 in., so it stands about a tenth of an inch above the surface. A pan head is not a flush-seating head, so it is right for a flat surface or a through-hole with a washer, not for a countersunk hole where a cover has to sit tight. If you need the head buried, use a flat head instead.

Both the Buy American and ARRA compliance flags are marked compliant on the JSPM18SS, which is what a public-works or federally funded spec package asks for on fasteners. Country of origin is listed as multiple, so if your submittal requires a single named origin per lot, that is worth confirming against the lot you receive.

They ship in a jar of 100, which is the order minimum (100 count). There is no loose or per-piece break, so plan on the full jar. For a service van that is usually welcome, since 10-24 x 1 in. is a screw you burn through on device and cover work.

They are built to ASME B18.6.3-2010, the standard that governs inch-series machine screw head and thread geometry, with material to SAE. That is the reference to put on a submittal when the spec calls out a standard machine screw rather than a proprietary fastener, and it is why the head and slot dimensions are held to a stated range.

Slotted drive cams out more readily than Phillips or square drive, so these are better suited to hand driving or a low-speed driver with light pressure. The slot runs 0.05 to 0.06 in. wide and 0.053 to 0.068 in. deep, so match a flat-tip bit to that width rather than grabbing whatever cabinet screwdriver is closest. For high-volume powered driving, a combination or Phillips head screw is the easier call.

Tensile is listed at 80,000 psi minimum with hardness Rockwell BBS-B9S. Treat that as an approximation: there is no single performance standard governing stainless machine screws, so the figure is not a guaranteed structural rating. For load-bearing attachment, work from a graded carbon steel fastener with a published strength class instead.

The JSPM18SS is the 10-24 x 1 in. configuration in the Metallics SPM machine screw series, and other sizes and quantities in the series are available by request. If you are standardizing a facility on one thread so every box and ring takes the same screw, specify the 10-24 thread and vary only the length.

The jar weighs 0.83 lbs and measures 3 in. long by 3 in. wide by 2.15 in. high, so it drops into a standard van bin or parts drawer without repacking.