Fig. 1403.
For small lathe work of odd size as when it is required to turn work to fit holes reamed by a worn reamer that is below the standard size, a gauge such as in [Fig. 1403], is sometimes used, the mouth a serving as a caliper and the hole b as a collar gauge for the same diameter of work. It is obvious that such a gauge may be applied to the work while it is running in the lathe, and that when the size at a wears too large the jaw may be closed to correct it; a plan that is also pursued to rectify the caliper gauge shown in [Fig. 1402].
Fig. 1404.
Fig. 1405.
On large work, as, say, of six inches in diameter, a gauge, such as in [Fig. 1404], is used, being short so that it may be light enough to be conveniently handled; or sometimes a piece such as in [Fig. 1405] is used as a gauge, the ends being fitted to the curvature of the bore to be tested. Gauges of these two kinds, however, are generally used more in the sense of being templates rather than measuring tools, since they determine whether a bore is of the required size rather than determine what that size is.