| The pitch × 6, + 4 times the rivet diameter | = the diagonal pitch pd. |
| divided by 10 |
In this example the pitch has been found to be 3 inches, hence we have
| .875 | = diameter of rivet. | |
| 4 | = constant. | |
| 3.500 | ||
| 3 | = pitch of the rivets. | |
| 6 | = constant. | |
| 18 | ||
| 3 | .5 | = rivet diameter multiplied by 4. |
| 10 ) 21 | .5 | ( 2.15 = the diagonal pitch. |
| 20 | ||
| 1 | 5 | |
| 1 | 0 | |
| 50 | ||
The diagonal pitch, that is, the distance pd, [Fig. 3257], is therefore found to be 2.15, or 21⁄8 inch full.
The amount of metal left between the rivets, measured on the diagonal pitch, is twice the dimension h multiplied by the thickness of the plate, and as this (with the diagonal pitch determined as above) always exceeds the pitch a or a, therefore if the plate fails, it will be along the line a, and not through the diagonal pitch.
We may now consider the total amount that the plates overlap in a double riveted lap joint zigzag riveted, this amount being twice the distance e, added to the distance v between the rows of rivets.
The distance e, [Fig. 3257], is usually made one and a half times the diameter of the rivet, this being found to give sufficient strength to prevent the edge of the plate from tearing out and to prevent the rivet from shearing the plate out to the edge, rupture not being found to occur in either of these directions.
The rule for finding the distance v, when the diagonal pitch has been determined by the rules already explained, is as follows:
Rule.—To the pitch multiplied by 11, add 4 times the rivet diameter, then multiply by the pitch, plus 4 times the rivet diameter. Then extract the square root and divide by 10.
Placed in formula, the rule appears as follows, d representing the rivet diameter, and p the pitch.