5/16-18 x 3 1/4 is built for legacy machinery and industrial assemblies that still specify a square head set screw instead of a headless socket screw.

Typical applications include large adjustment stops, travel-limit hardware, and machine fixtures. The product record carries the size; the requested point is selected from the Half Dog, Full Dog, Cone, Oval, and Flat menu. Point selection should reflect the shaft feature, acceptable marking, and expected service adjustment.

Availability-row diameters and unusually long lengths are handled as quote-driven square-head requirements by Cold Headers. Review the selected point, wrench clearance, and mating feature before substitution. The square head equals the nominal diameter across flats, giving the wrench size a direct relationship to the screw size.

Technical Highlights

• Head: Square, wrench-driven
• Material: Low Carbon Steel, Case Hardened
• Point Styles: Half Dog, Full Dog, Cone, Oval, Flat (specify at order)
• Thread Size: 5/16-18 (UNC)
• Thread Fit: 2A (per ASME B18.6.2)
• Length: 3 1/4 in.
• Width Across Flats (F): 0.312 / 0.302 in. (max/min)
• Across Corners (G): 0.442 / 0.415 in. (max/min)
• Head Height (H): 0.245 / 0.224 in. (max/min)
• Dimensional Standard: ASME B18.6.2

Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.