Description
Overview
Imperial UNF and UNC fasteners are selected by thread form, diameter, length, material, finish and strength grade. UNF is a fine thread form and UNC is a coarse thread form; they must not be mixed with metric threads.
This selected size is specified with diameter 7/8 in, length 4 in, thread 7/8 in.
Sold in multiples of '10 pieces. 1 Box = '10 pieces.
Material, Grade & Strength
SAE Grade 5 is a medium to high tensile imperial fastener grade used where greater strength than low carbon steel is required. Use compatible imperial nuts and washers of suitable strength.
Finish & Corrosion Protection
Plain finish has no plated corrosion protection and is best used in protected, oiled, painted or indoor environments.
Typical Uses
Imperial UNF and UNC fasteners are used in equipment, vehicles and machinery designed around inch-series thread systems.
Technical Tips
- Do not mix metric and imperial threads.
- Confirm whether the thread is UNF or UNC before ordering.
- Use matching imperial nuts and washers.
- Select the correct spanner or socket size for the hex head.
Selection Advice
Select the product by matching the thread, size, material, finish and function to the assembly. Avoid choosing only by appearance or a partial part number.
Dimensions – ASME B18.2.1 7/8 UNC x 4 in
| Standard | ASME B18.2.1 |
|---|---|
| Product | Hexagon head cap screw / bolt, inch series |
| Thread | 7/8-9 UNC |
| Length (l) | 4 in (101.6 mm) |
| Across flats (s) | 1 5/16 in (33.3 mm) |
| Head height (k) | 35/64 in (13.9 mm) |
| Thread length (b) | 2 in (50.8 mm) (ref.) |
| Weight (calculated) | 386.45 kg per 1 000 pieces |
Material, Grade & Strength
| Material | SAE Grade 5 steel |
|---|---|
| Grade | SAE J429 Grade 5 (1/4-1 in) |
| Tensile strength (min) | 827 MPa |
| Proof load stress | 586 MPa |
| Hardness | 25-34 HRC |
Finish & Corrosion Protection
Plain / self colour: No applied coating. Stainless, brass and nylon parts are supplied plain; plain steel parts need oil, paint or protected environments.
Nominal dimensions per ASME B18.2.1. Weights are calculated from nominal dimensions and are a guide only (±10%). Values for fit and strength should be confirmed against the standard for critical applications.
Specifications
| Measurement Type | Inch |
|---|---|
| Thread Size | 7/8 in |
| Thread Per Inch | 9 |
| Thread Type | UNC |
| Thread Style | Partial Thread |
| Drive Size | 5/16 in |
| Drive Type | External Hex |
| Head Style | Hex |
| Diameter | 7/8 in |
| Length | 4 in |
| Material | Hi - Tensile Steel |
| Finish | Plain |
| Grade | Grade 5 |
| Standards Met | SAE |
| Package Quantity | 10 |
| Package Type | Box |