The following are the sizes of finished bolts and nuts according to the present Whitworth Standard. The exact sizes are given in decimals, and the nearest approximate sizes in sixty-fourths of an inch:—
| Diameter of bolts. | Width of nuts across flats. | Height of bolt heads. | |||||||||
| 1⁄8 | .33 | 8 | 21⁄64 | f | .10 | 93 | 7⁄64 | ||||
| 3⁄16 | .44 | 8 | 29⁄64 | b | .16 | 40 | 5⁄32 | ||||
| 1⁄4 | .52 | 5 | 33⁄64 | f | .21 | 87 | 7⁄32 | ||||
| 5⁄16 | .60 | 14 | 19⁄32 | f | .27 | 34 | 17⁄64 | ||||
| 3⁄8 | .70 | 94 | 45⁄64 | f | .32 | 81 | 21⁄64 | ||||
| 7⁄16 | .82 | 04 | 53⁄64 | b | .38 | 28 | 3⁄8 | f | |||
| 1⁄2 | .91 | 91 | 29⁄32 | b | .43 | 75 | 7⁄16 | ||||
| 9⁄16 | 1.01 | 1 | 1 | 1⁄64 | b | .49 | 21 | 31⁄64 | f | ||
| 5⁄8 | 1.10 | 1 | 1 | 3⁄32 | f | .54 | 68 | 35⁄64 | |||
| 11⁄16 | 1.20 | 11 | 1 | 13⁄64 | b | .60 | 15 | 19⁄32 | f | ||
| 3⁄4 | 1.30 | 12 | 1 | 19⁄64 | f | .65 | 62 | 21⁄32 | |||
| 13⁄16 | 1.39 | 1 | 25⁄64 | b | .71 | 09 | 45⁄64 | f | |||
| 7⁄8 | 1.47 | 88 | 1 | 31⁄64 | b | .76 | 56 | 49⁄64 | |||
| 15⁄16 | 1.57 | 45 | 1 | 37⁄64 | b | .82 | 03 | 13⁄16 | f | ||
| 1 | 1.67 | 01 | 1 | 43⁄64 | b | .87 | 5 | 7⁄8 | |||
| 1 | 1⁄8 | 1.86 | 05 | 1 | 55⁄64 | f | .98 | 43 | 63⁄64 | ||
| 1 | 1⁄4 | 2.04 | 83 | 2 | 3⁄64 | f | 1.09 | 37 | 1 | 3⁄32 | |
| 1 | 3⁄8 | 2.21 | 46 | 2 | 7⁄32 | b | 1.20 | 31 | 1 | 13⁄64 | |
| 1 | 1⁄2 | 2.41 | 34 | 2 | 13⁄32 | f | 1.31 | 25 | 1 | 5⁄16 | |
| 1 | 5⁄8 | 2.57 | 63 | 2 | 37⁄64 | b | 1.41 | 28 | 1 | 27⁄64 | |
| 1 | 3⁄4 | 2.75 | 78 | 2 | 3⁄4 | f | 1.53 | 12 | 1 | 17⁄32 | |
| 1 | 7⁄8 | 3.01 | 83 | 3 | 1⁄16 | f | 1.64 | 06 | 1 | 41⁄64 | |
| 2 | 3.14 | 91 | 3 | 5⁄32 | b | 1.75 | 1 | 3⁄4 | |||
| 2 | 1⁄8 | 3.33 | 7 | 3 | 11⁄32 | b | 1.85 | 23 | 1 | 55⁄64 | |
| 2 | 1⁄4 | 3.54 | 6 | 3 | 35⁄64 | b | 1.96 | 87 | 1 | 31⁄32 | |
| 2 | 3⁄8 | 3.75 | 3 | 3⁄4 | 2.07 | 81 | 2 | 5⁄64 | |||
| 2 | 1⁄2 | 3.89 | 4 | 3 | 57⁄64 | f | 2.18 | 75 | 2 | 3⁄16 | |
| 2 | 5⁄8 | 4.04 | 9 | 4 | 3⁄64 | f | 2.29 | 68 | 2 | 19⁄64 | |
| 2 | 3⁄4 | 4.18 | 1 | 4 | 3⁄16 | b | 2.40 | 62 | 2 | 13⁄32 | |
| 2 | 7⁄8 | 4.34 | 56 | 4 | 11⁄32 | f | 2.51 | 56 | 2 | 33⁄64 | |
| 3 | 4.53 | 1 | 4 | 17⁄32 | b | 2.62 | 5 | 2 | 5⁄8 | ||
The thickness of the nuts is in every case the same as the diameter of the bolts: f = full, b = bare.
When bolts screw directly into the work instead of passing through it and receiving a nut, they come under the head of either tap bolts, set screws, cap screws, or machine screws. A tap bolt is one in which the full length of the stem or body is threaded, and differs from a set screw, which is similarly threaded, in the respect that in a set screw the head is square and its diameter is the same as the square bar of steel or iron (as the case may be) from which the screw was made, while in the tap bolt the head is larger in diameter than the bar it was made from. Furthermore a tap bolt may have a hexagon head, which is usually left unfinished unless ordered to be finished, as is also the case with set screws.
Fig. 386.
Cap screws are made with heads either hexagon, square, or round, and also with a square head and round collar, as in [Fig. 386], the square heads being of larger diameter than the iron from which they were made. When the heads of cap screws are finished they are designated as “milled heads.”
