FF-N-836 — Nut: Square, Hexagon, Cap, Castle & More
FF-N-836 covers a broad family of general-purpose nuts — square, hexagon, cap, slotted, castle, knurled, welding, and single ball seat configurations — for assembly with bolts and screws at normal atmospheric temperatures. The specification remains active, with Revision F published January 12, 2023.
At a Glance
Overview
FF-N-836 is a general-purpose federal specification covering a wide range of nut configurations — square nuts, hexagon nuts, cap nuts, slotted nuts, castle (castellated) nuts, knurled nuts, welding nuts, and single ball seat nuts — all designed for assembly with bolts and screws at normal atmospheric temperatures. Unlike many older federal fastener specs, FF-N-836 has continued to be actively maintained, with Revision F published as recently as January 2023.
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), and are produced in materials including carbon steel and corrosion resistant steel, with finish options such as black oxide, cadmium plate, or passivate depending on the application.
- 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 corrosion.
- Welding nuts include a projection or pilot designed for resistance welding directly to a sheet metal panel.
Nut Configuration Reference
FF-N-836 covers several distinct nut styles under one umbrella specification.
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 |
FF-N-836 — Frequently Asked Questions
Is FF-N-836 still an active specification?
Yes — unlike several other older Federal Specifications, FF-N-836 continues to be actively maintained by the General Services Administration, with Revision F published 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 FF-N-836 nuts made from?
Commonly carbon steel or corrosion resistant steel (per QQ-S-763), with finish options including black oxide, cadmium plate, or passivate depending on the environment and application.
Need FF-N-836 Nuts to Print?
Ananka Fasteners manufactures FF-N-836 nuts in all configurations with full material traceability and Mill Test Certification.
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