DIMENSIONS
The diameter specifies the shank and threaded outside size i.e. 1/4" BSF bolt is 1/4" dia.
The length of the bolt is always measured from beneath the head. |
 |
| Thread lengths vary over the size ranges but are generally 3/4" to 1".
UNF bolts are often referred to by their spanner size rather than diameter i.e.
1/2" AF (across flats) - 5/16" dia. |
Spanner Sizes and Threads
| DIAMETER |
BSF
THREADS
PER INCH |
BSF
SPANNER
SIZE |
UNF
THREADS
PER INCH |
UNF
SPANNER
SIZE |
| 1/4'' |
26 |
7/16'''' |
28 |
7/16'' |
| 5/16'' |
22 |
17/32'' |
24 |
1/2'' |
| 3/8'' |
20 |
19/32'' |
24 |
9/16'' |
| 7/16'' |
18 |
45/64'' |
20* |
5/8'' |
| 1/2'' |
16 |
13/16'' |
20 |
3/4'' |
| 9/16'' |
16 |
59/64'' |
18 |
7/8'' |
| 5/8'' |
14 |
1'' |
18 |
15/16'' |
| 3/4'' |
12 |
1 3/16'' |
16 |
1 1/8'' |
| 1'' |
10 |
1 15/32'' |
12 |
1 1/2'' |
*Nuts are 1/6"larger across the flats
Metric
| SIZE |
THREAD
PITCH |
SPANNER
SIZE |
| M6 (6mm) |
1.00mm |
10mm |
| M8 (8mm) |
1.25mm |
13mm |
| M10 (10mm) |
1.50mm |
17mm |
| M12 (12mm) |
1.75mm |
19mm |
Tensile Strength
| Grade 'R' |
45-50 Tons/Inch² |
| Grade 'S' |
50-55 Tons/Inch² |
| Grade '8.8' |
50-55 Tons/Inch² |
| 
I-SIGHT DESIGN
