This gauge is used for checking concave and convex radius patterns, often as part of quality control after metal shaping. Other uses include inspecting machine rounded work pieces.
At one end of the gauge there are leaves suitable for measuring a concave radius.
At the other end of the gauge there are leaves suitable for measuring a convex radius. Both ends include the same range of measurements.
Any one of the leaves can be locked in place for individual use by adjusting the locking device. Clockwise to tighten, anti-clockwise to loosen.
What are the advantages?
The advantage is that it is simple to use as each end of the gauge has a specific function. It is favoured by pattern makers, and mechanics who use the tool to measure dies, check machined work pieces and check screw machine operations.
What are the disadvantages?
The disadvantage is that a leaf at either end is required to cover both concave or convex applications. Therefore, the extent of the measuring range is often limited to the number of blades which can fit onto the gauge.