78 dating - Cccamporn
The rod is slipped through the round opening for it, atop the arched portion of the main casting, so that the smaller diameter is downward.
The rod is left free to move up/down through the arched portion of the main casting - do not tighten the screw to lock it in place.
The plane underwent many modifications during its production by Stanley. Then, probably during the mid-1890's, a mechanism to close the throat's opening was added so that the plane could work narrow surfaces, like grooving the edge of a board, to add lateral stability to the tool.
The first of which was arching the portion of the sole, forward of the cutter, into an open throat configuration. This mechanism, or 'shoe' as Stanley called it, attaches to the round depth gauge rod that slips through the arched area of the main casting and 'closes' the throat to give more of a bearing surface, or sole, on the tool.
This procedure is repeated over and over until the desired depth is reached.
In 1909, countersunk (from above) screw holes, through the sole, were added to allow wood bottoms or fences to be attached.
This rod controls the tool's depth of cut as the cutter is adjusted deeper.
It permits consistency from cut to cut, which would be difficult to achieve were the rod not provided. The use of the stop might not be intuitive to most, but it's very easy to use and rather clever in its simple operation.
This allows the tools to work recesses that are larger than the tool is wide.
In other words, the tool can be made physically 'larger' by attaching a wooden sole to it.
The shoe's use is very limited for most work, but functions best as a depth stop, which is explained next.
At the same time the shoe was added, a round depth gauge rod was made part of the shoe clamping assembly.
And here you thought routers are the stuff of the modern workshop. They've been around much longer than the ab NORMal kind has, but these kind ain't the 'lectrical kind.