7/8"-9 UNC-3A x 3-1/2" Flat Head Socket Countersunk Screw
Alloy steel, ASTM F835, zinc and clear plated. Machined to the customer's drawing in our Houston shop.
7/8"-9 UNC-3A x 3-1/2" flat head socket countersunk screw to ASTM F835 in alloy steel. Zinc and clear plated, with a flush-fit head.
Special socket products are machined from bar where the specification allows, with the socket broached and the threads rolled, or cut where the specification or order allows, then heat treated and plated as the specification requires. Shoulder, low-head, flat-head and set-screw patterns follow ASME B18.3 unless the drawing says otherwise.
About the material: The low-head socket screws: button and flat countersunk heads in alloy steel at 144 ksi (½ in. and smaller) and 136 ksi above, 37 to 44 HRC — rated below A574 because the shallow head, not the shank, limits the load. Read the F835 data page →
