Ships within 8 hours (on average).
Ships within 8 hours (on average).
Free Shipping RM48 (2-3 days if ordered before 2pm) Upgrades available at checkout (e.g. tracked service and courier for time sensitive deliveries)
Call: 01242 522244 Email: sam@fixaball.co.uk Website: www.fixaball.co.uk for technical and sales queries
Fixaball sells all lengths of UNC 4/40, self colour, allen/ hex, socket cap screw/ bolts.
What is a socket cap screw/ bolt?
The, ‘Socket Cap Screw/ Allen Bolt,’ term is used to describe a enerthat is either fully or partially threaded. A screw is fully threaded and a bolt is partialy threaded. Some engineers may call them screws if the person uses the shorter length range of sizes. The thread stays the same length as the ener gets longer and the maximum length of thread is equal to 2.5 times the diameter (or thereabouts). ‘Socket,’ refers to the hexagon shaped indentation found on the top of the eners’ head. Here, you can use a hexagon key (Allen Key) to tighten and loosen the ener. 'Cap' refers to the cylindrical shaped head.
Orders placed before 2pm are dispatchedsame day (Mon-Fri).
Standard, is Royal Mail, 2nd Class (2-5 days, most likely 2 days). For a er delivery time, select 1st class or courier at checkout.
Please make your'No. of Items in Pack', 'Length'and'Quantity'of packs, selection from the drop down menus.
UNC 4/40, Cap Head, Socket Screw/ Allen Bolt Length Available
FT - Fully Threaded
PT - Partially Threaded
#4-40x3/8",(FT) SOCKET HEAD CAP SCREWS UNC SELF COLOUR (1960) |
#4-40x1/2",(FT) SOCKET HEAD CAP SCREWS UNC SELF COLOUR (1960) |
#4-40x5/8",(FT) SOCKET HEAD CAP SCREWS UNC SELF COLOUR (1960) |
#4-40x3/4",(FT) SOCKET HEAD CAP SCREWS UNC SELF COLOUR (1960) |
#4-40x1",(PT) SOCKET HEAD CAP SCREWS UNC SELF COLOUR (1960) |
High Tensile – 12.9 Grade.
Available Material: Plain/ Self Colour/ Black
Material/ Finish |
Appearance |
Level of Corrosion Resistance |
Typical Application |
High Tensile Steel (12.9 Grade) |
Self-Colour (black with no surface treatment) |
Low, without further surface treatment |
- No exposure to moisture - Often Greased/ Oiled |
UNC - UNF Socket Cap Screw/ Bolt Dimensions
Fixaball – Specialist Fixings and eners UNC/UNF Hexagon Socket Cap Screws Conforming to ASME/ ANSI B18.3 1960 Series |
||||||
Pitch TPI |
a |
ds |
h |
j |
||
Diameter |
UNC |
UNF |
Max |
Max |
Max |
Nom |
No. 4 |
40 |
48 |
0.18 |
0.11 |
0.11 |
5/16 |
UNIFIED THREAD STANDARDS
The basic American standards for ening screw threads as agreed upon by standard bodies of Canada, the United Kingdom, and the United States. They are a complete and integrated system of threads for ening purposes. Their outstanding characteristic is general interchangeability of threads achieved through the standardization of thread form, diameter-pitch combinations, and limits of size
Unified National (UN) thread form with a rounded root contour, applies only to external threads. (The UN thread form has a flat, or optionally, a rounded root contour.) The majority of eners with a Unified thread form (UNC UNF) have a rounded root contour i.e. are UNR threads.
Unified National Coarse (UNC) is a thread form with a 60 degree flank angle rounded roots and flat crests. For a given diameter it has a larger thread pitch than an equivalent diameter UNF thread. The unified thread is based on inch sizes and was first standardised in 1948 unifying the Whitworth and American standard thread forms.
Image is for illustrative purposes only.
| Updated: 19th June 2025
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