Amongst my collection are a pair of tongue & groove planes (with the pairing collectively referred to as match planes). These planes were made by Charles Heathcott in Sheffield, England sometime between 1829 and 1849.
A tongue and groove is used to join boards edge to edge – typically flooring. A groove is cut near the middle of the edge on one board, and the mating edge of the other board is cut to form a tongue to fit into the groove. This joint is common in woodworking when an airtight, watertight or simple and strong joint is required. The common reference to boards joined this way is ‘matched boards’ and the planes that cut the joint as match planes.
Wooden match planes usually come as pairs (like my Charles Heathcott planes) which are tuned to each other for a tight fit between the tongue and groove. Typically the groove would be 0.005# wider than the tongue to allow the boards to go together easily but without any slop.
The tongue plane is a standard side escapement plane and employs an iron with a slot in it the width of the finished tongue. The fixed fence governs the position of the tongue relative to the surface of the board.
The groove plane however is actually a type of fixed plow plane with a metal keel. Because of the narrow profile this is necessary for strength, as wood simply would not have enough strength or ability to hold up under normal use. The iron is located on the leading edge of the rear skate by means of a V groove cut into the back of the iron, and fits into the corresponding inverted V on the skate. It is adjusted the same as any side escapement plane except for the fact the iron is not pressed against the blind side of the mortise, but rather located by the groove. The fixed fence ensures that the groove matches the position from the edge of the board of the tongue.
Each plane also has its own depth stop, so when you no longer get a stream of shavings exiting the plane, you have gone far enough.