Question

For measuring the effective diameter of a metric external screw thread of 2.0 mm pitch, a 30.500 mm diameter cylindrical standard and 1.155 mm diameter wires were used. The micrometer readings over the standard and wires were 13.3768 and 12.2428 mm, respectively. If the pitch error in the bolt threads was 0.05 mm, what was the virtual effective diameter of the bolt?

• A. 27.605 mm
• B. 27.676 mm
• C. 27.634 mm
• D. 29.366 mm

Answer 1

The correct option is B 27.676 mm

$D_{eff}=M-(d+\frac{P}{2}\tan \frac{\theta }{2})$

$M=30.5+(12.2428-13.3768)=29.366mm$

$D_{eff}=29.366-(1.155+\frac{2}{2}\tan {30}^{\circ })=27.6336$

$V.C=0.05\cos 30=0.043$

$VED=D_{eff}+VC=27.676$