Fig. 153.
It is sufficiently accurate, therefore, for all practical purposes to set the pencil on the centre-line at the point A in Figure 152 and mark the curve 14, and to then set the compasses by trial to mark the other two curves of the chamfer, so that they shall be an equal distance with arc 14 from line 9, and join lines 10 and 13 at the same distance from line 9 that 14 joins lines 3 and 4, so that as in Figure 153 all three of the arcs would touch a line as C, and another line as D.
Fig. 154.
The United States standard sizes for forged or unfinished bolts and nuts are given in the following table, Figure 154 showing the dimensions referred to in the table.
UNITED STATES STANDARD DIMENSIONS OF BOLTS AND NUTS.
| Bolt. | Bolt Head and Nut. | ||||||
| Diameter. | Standard Number of threads per inch | Long diameter, I, or diameter across corners | Short diameter of hexagon and square, or width across J | Depth of Nut, H | Depth of bolt head, K | ||
| Nominal. D. | Effective. * | Hexagon | Square | ||||
| 1/4 | .185 | 20 | 9/16 | 23/32 | 1/2 | 1/4 | 1/4 |
| 5/16 | .240 | 18 | 11/16 | 27/32 | 19/32 | 5/16 | 19/64 |
| 3/8 | .294 | 16 | 25/32 | 31/32 | 11/16 | 3/8 | 11/32 |
| 7/16 | .345 | 14 | 29/32 | 1-3/32 | 25/32 | 7/16 | 25/64 |
| 1/2 | .400 | 13 | 1 | 1-1/4 | 7/8 | 1/2 | 7/16 |
| 9/16 | .454 | 12 | 1-1/8 | 1-3/8 | 31/32 | 9/16 | 31/64 |
| 5/8 | .507 | 11 | 1-7/32 | 1-1/2 | 1-1/16 | 5/8 | 17/32 |
| 3/4 | .620 | 10 | 1-7/16 | 1-3/4 | 1-1/4 | 3/4 | 5/8 |
| 7/8 | .731 | 9 | 1-21/32 | 2-1/32 | 1-7/16 | 7/8 | 23/32 |
| 1 | .837 | 8 | 1-7/8 | 2-5/16 | 1-5/8 | 1 | 13/16 |
| 1-1/8 | .940 | 7 | 2-3/32 | 2-9/16 | 1-13/16 | 1-1/8 | 29/32 |
| 1-1/4 | 1.065 | 7 | 2-5/16 | 2-27/32 | 2 | 1-1/4 | 1 |
| 1-3/8 | 1.160 | 6 | 2-17/32 | 3-3/32 | 2-3/16& | 1-3/8 | 1-3/32 |
| 1-1/2 | 1.284 | 6 | 2-3/4 | 3-11/32 | 2-3/8 | 1-1/2 | 1-3/16 |
| 1-5/8 | 1.389 | 5-1/2 | 2-31/32 | 3-5/8 | 2-9/16 | 1-5/8 | 1-9/32 |
| 1-3/4 | 1.491 | 5 | 3-3/16 | 3-7/8 | 2-3/4 | 1-3/4 | 1-3/8 |
| 1-7/8 | 1.616 | 5 | 3-13/32 | 4-5/32 | 2-15/16 | 1-7/8 | 1-15/32 |
| 2 | 1.712 | 4-1/2 | 3-19/32 | 4-13/32 | 3-1/8 | 2 | 1-9/16 |
| 2-1/4 | 1.962 | 4-1/2 | 4-1/32 | 4-15/16 | 3-1/2 | 2-1/4 | 1-3/4 |
| 2-1/2 | 2.176 | 4 | 4-15/32 | 5-15/32 | 3-7/8 | 2-1/2 | 1-15/16 |
| 2-3/4 | 2.426 | 4 | 4-29/32 | 6 | 4-1/4 | 2-3/4 | 2-1/8 |
| 3 | 2.629 | 3-1/2 | 5-11/32 | 6-17/32 | 4-5/8 | 3 | 2-5/16 |
| 3-1/4 | 2.879 | 3-1/2 | 5-25/32 | 7-1/16 | 5 | 3-1/4 | 2-1/2 |
| 3-1/2 | 3.100 | 3-1/4 | 6-7/32 | 7-19/32 | 5-3/8 | 3-1/2 | 2-11/16 |
| 3-3/4 | 3.317 | 3 | 6-5/8 | 8-1/8 | 5-3/4& | 3-3/4 | 2-7/8 |
| ... | 3.567 | 3 | 7-1/16 | 8-21/32 | 6-1/8 | 3-1/16 | |
| 4-1/4 | 3.798 | 2-7/8 | 7-1/2 | 9-3/16 | 6-1/2 | 4-1/4 | 3-1/4 |
| 4-1/2 | 4.028 | 2-3/4 | 7-15/16 | 9-23/32 | 6-7/8 | 4-1/2 | 3-7/16 |
| 4-3/4 | 4.256 | 2-5/8 | 8-3/8 | 10-1/4 | 7-1/4 | 4-3/4 | 3-5/8 |
| 5 | 4.480 | 2-1/2 | 8-13/16 | 10-25/32 | 7-5/8 | 5 | 3-13/16 |
| 5-1/4 | 4.730 | 2-1/2 | 9-1/4 | 11-5/16 | 8 | 5-1/4 | 4 |
| 5-1/2 | 4.953 | 2-3/8 | 9-11/16 | 11-27/32 | 8-3/8 | 5-1/2 | 4-3/16 |
| 5-3/4 | 5.203 | 2-3/8 | 10-3/32 | 12-3/8 | 8-3/4 | 5-3/4 | 4-3/8 |
| 6 | 5.423 | 2-1/4 | 10-17/32 | 12-29/32 | 9-1/8 | 6 | 4-9/16 |
* Diameter at the root of the thread.