Three Wire Thread Measuring
Machinery's Handbook Formulas
| Maximum wire size | Ideal wire size | Minimum wire size | Measurement formula |
| .900/N or .900 x Pitch |
.57735/N or .57735 x Pitch |
.560/N or .560 x Pitch |
M = E - .86603P + 3W |
Example: To calculate wire sizes and measurement for a 7/16 - 14 thread.
| Maximum wire size | Ideal wire size | Minimum wire size |
| .900/14 = .0643
|
.57735/14 = .0412 | .560/14 = .040 |
| Measurement formula |
| M = E - .86603P + 3W M = .3862 - .86603(.0714) +3(.045) M = .3862 - .0618 + .135 M = .4594 |
M = Measurement over the wires
E = Pitch diameter found in Machinery's Handbook
P = Pitch of thread ( 1 / threads per inch)
W = Selected wire size
A set of wires for this method consists of the following wire sizes.
.018, .024, .029, .032, .040, .045, .055, .063, .072, .081, .092, .108, .120, .127, .143, .185
Be aware that even though your formulas might give you another number you can only use a wire size FOR WHICH YOU HAVE A WIRE!!