FF-S-210 Setscrews — Square Head & Slotted Headless

FF-S-210 covers two related but distinct setscrew configurations. First, it dictates the requirements for square head setscrews (inch series only), which feature a protruding square head that can be securely driven with a wrench. Second, it covers slotted headless setscrews (available in both inch and metric setscrews series), which are driven with a standard flat-blade screwdriver rather than a specialized socket.

Square head setscrews are typically deployed where the fastener is not fully recessed and external wrenching access is available or preferred — commonly seen in older machinery or in environments where a socket-drive tool isn't practical. Conversely, slotted headless setscrews serve the exact same locating functions as FF-S-200's socket-drive versions but utilize a basic slot. This can be advantageous in field conditions where a standard screwdriver is more readily accessible than a specialized hex key.

• FF-S-210 and FF-S-200 jointly replaced the earlier consolidated setscrew specification, FF-S-103, when that older document was cancelled.
• The most recent regulatory notice, Notice 1 (15 December 2000), officially confirms the document remains entirely valid for use, even though it is not being actively revised for new configurations.

To meet the rigorous demands of industrial assembly, FF-S-210 Federal Specification fasteners must be manufactured from high-grade carbon steel, alloy steel, or corrosion-resistant materials to prevent stripping under load. The choice between square head setscrews and slotted headless setscrews largely dictates the required installation tool and the maximum torque capacity of the joint. Always consult the Defense Logistics Agency (DLA) database for the most current military part numbers and material certifications before procurement.