FF-N-836 Nuts — Square, Hexagon, Cap, Castle & More
The standard for FF-N-836 nuts covers a broad family of general-purpose fastening hardware — including square, hexagon, cap, slotted, castle, knurled, welding, and single ball seat configurations. Designed for standard assembly with bolts and screws at normal atmospheric temperatures, this specification remains fully active, with Revision F published on January 12, 2023.
At a Glance
FF-N-836 Nuts Overview
FF-N-836 is a general-purpose federal specification covering a massive catalog of nut configurations. Unlike many older federal fastener specs that have been cancelled or superseded by commercial standards, the standard governing FF-N-836 nuts has continued to be actively maintained by the government to support ongoing infrastructure and military logistics.
Typical parts sourced to this specification are identified by a type and style designation (commonly recorded as "2 type and 11 style" combinations across the family). They are produced in materials including high-strength carbon steel and corrosion-resistant steel (CRES), with finish options such as black oxide, cadmium plate, or passivation depending on the end-use environment.
- Castle (castellated) nuts feature slots across the top that align with a hole drilled through the mating bolt, allowing a cotter pin to lock the assembly against rotation.
- Cap nuts fully enclose the exposed bolt thread end for a finished appearance and to protect against snagging or heavy corrosion.
- Welding nuts include a projection or pilot designed for resistance welding directly to a sheet metal panel.
Thread Fit and Tolerances
A critical component of manufacturing compliant hardware under this specification is ensuring proper thread engagement. The guidelines mandate Unified Inch screw threads, typically requiring a Class 2B fit for general assembly or a Class 3B fit for tighter, precision-critical applications. The thread class directly impacts the torque-tension relationship during installation, ensuring the nut will not vibrate loose under normal atmospheric conditions. For official document tracking and verification, engineers can utilize resources like the Defense Logistics Agency (DLA) ASSIST portal.
Nut Configuration Reference
The specification covers several distinct nut styles under one umbrella document.
Revision History
| Revision | Date |
|---|---|
| FF-N-836 (original) | 1965 |
| Rev. D | 24 Apr 1972 |
| Rev. E | 14 Feb 1994 |
| Rev. F (current) | 12 Jan 2023 |
Frequently Asked Questions
Is this specification still active?
Yes — unlike several other older Federal Specifications, it continues to be actively maintained by the General Services Administration, with Revision F published on January 12, 2023.
What's the difference between a castle nut and a slotted nut?
Both use a cotter pin through a cross-drilled bolt for anti-rotation locking. A castle nut has a fully castellated, crown-like top profile, while a slotted nut has simpler slots cut across a standard hex or square top.
What materials are used for manufacturing?
They are commonly manufactured using carbon steel or corrosion-resistant steel (per QQ-S-763), with finish options including black oxide, cadmium plate, or passivation depending on the environment and specific application requirements.
Need FF-N-836 Nuts to Print?
Ananka Fasteners manufactures compliant hardware in all configurations with full material traceability and Mill Test Certification.
Prefer email? sales@anankafasteners.com
