Question

It is required to measure the effective diameter of a screw using the two-wire method. The distance across 10 threads measured using a scale is 12.5 mm. The size of the best wire for metric threads is __________mm.

• A. 0.64
• B. 0.72
• C. 0.52
• D. 0.25

Answer 1

The correct option is B 0.72

$\text{P}=\frac{12.5}{10}=1.25\text{mm}$

$\text{d}=\frac{\text{P}}{2}\sec \left(\frac{\theta }{2}\right)=\frac{\text{P}}{2}\sec \frac{60}{2}=0.72\text{mm}$