Question

A hole of 30 mm nominal diameter has to be inspected by GO-NOGO plug gauge. The hole tolerance is $\pm 0.030$. If gauge tolerance is 10% of the hole tolerance and there is no wear condition, the dimension (in mm) of the GO plug gauge as per the unilateral tolerance system is

• A. $29.976\begin{array}{c}+0.000\\ -0.006\end{array}$
• B. $29.976\begin{array}{c}+0.00\\ -0.003\end{array}$
• C. $29.97\begin{array}{c}+0.003\\ -0.003\end{array}$
• D. $29.976\begin{array}{c}+0.006\\ +0.00\end{array}$

Answer 1

The correct option is A $29.976\begin{array}{c}+0.000\\ -0.006\end{array}$

Work tolerance on hole = 0.06 mm
Gauge tolerance = 0.006 mm



${\text{(Upper limit)}}_{GOgauge}=30-0.03+0.006$

= 29.976 mm

${\text{(Lower limit)}}_{GOgauge}=30-0.03$

= 29.970 mm

$\therefore$ GO gauge dimensions

$=29.976\begin{array}{c}+0.000\\ -0.006\end{array}\text{or}29.970\begin{array}{c}+0.006\\ -0.000\end{array}$