Three Wire Thread Measuring
Textbook Formula
| Maximum wire size | Ideal wire size | Minimum wire size | Measurement formula |
| .900/N | .57735/N | .560/N | D + 3W -
(1.5155/N)
|
Example: To calculate wire sizes and measurement for a 7/16 - 14 thread.
| Maximum wire size | Ideal wire size | Minimum wire size |
| .900/14 = .064 | .57735.14 = .041
|
.560/14 = .040 |
| Measurement formula |
| M = D + 3W -
(1.5155/N) M = .4375 + 3(.045) - (1.5155/14) M = .4375 + .135 - .1085 M = .464 |
M = Measurement over the wires
D = Major (outside) diameter of thread
W = Selected wire size
N = Number of threads per inch
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!!
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