FF-S-85 — Screw, Cap, Slotted and Hexagon Head
FF-S-85 covers slotted and hexagon head cap screws — the general-purpose externally threaded fasteners used to join components directly into a tapped hole without a separate nut. The specification superseded the earlier FF-S-91 and has continued through multiple revisions to the present Revision F.
At a Glance
Overview
FF-S-85 covers cap screws with slotted or hexagon heads — externally threaded fasteners intended to be driven directly into a tapped hole in one of the parts being joined, rather than paired with a separate nut. Because a cap screw's head bears directly against the top part while its threads engage the bottom part, thread engagement length and head-bearing strength are both critical dimensional requirements the specification controls.
FF-S-85 superseded the earlier FF-S-91 specification and has been maintained through subsequent revisions to Revision F. It sits alongside two closely related federal specifications: FF-S-86 (socket-head cap screws) and FF-S-92 (slotted, cross-recessed, or hexagon head machine screws) — together these three documents cover the bulk of general-purpose cap and machine screw hardware sourced under a Federal Specification callout.
Related Cap & Machine Screw Specifications
| Specification | Head / Drive Style |
|---|---|
| FF-S-85 | Slotted and Hexagon Head Cap Screws |
| FF-S-86 | Socket-Head Cap Screws (hex or spline socket) |
| FF-S-92 | Slotted, Cross-Recessed, or Hexagon Head Machine Screws |
Choosing between FF-S-85, FF-S-86, and FF-S-92 mainly comes down to head/drive style and torque requirements — hex and slotted head cap screws (FF-S-85) suit general assembly, socket-head cap screws (FF-S-86) suit high-torque or recessed applications, and machine screws (FF-S-92) suit lighter-duty threaded assembly with a mating nut.
FF-S-85 — Frequently Asked Questions
What's the difference between a cap screw and a machine screw?
A cap screw is designed to be driven directly into a tapped hole and typically has a larger, more precisely controlled head bearing surface for higher clamping loads. A machine screw is generally lighter-duty and often paired with a separate nut.
What head styles does FF-S-85 cover?
Slotted head and hexagon head cap screws — for socket-head (hex or spline recess) cap screws, see the related specification FF-S-86 instead.
Need FF-S-85 Cap Screws to Print?
Ananka Fasteners manufactures FF-S-85 slotted and hex head cap screws with full material traceability and Mill Test Certification.
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