Toothing, Truing, Keying, Gluing or Veneering Plane
This unusual plane with its serrated blade set perpendicular to the grain of the wood. The blade is set at 90º to the sole of the plane. The blade called an iron was traditionally made of wrought iron, hence the name iron, with a thin steel of veneer forge welded to the face of the iron. When sharpened only the thin cutting edge is of steel with the rest of the sharpening done on soft iron. The steel back is then serrated with parallel grooves to produce a fine saw tooth pattern. When the bevel is sharpened the tip is serrated and cuts tightly grained wood such as curly maple or burls and not chip it out.
Toothing planes are commonly used to prepare surfaces prior to gluing such as for veneering. Keying is also used on pieces like ivory and brass to roughen the surface prior to gluing. Intentional roughing of the surface prior to gluing increases the holding ability of the glue by up to 30%. This increased the surface area, hence a better glue joint.
What I am writing about now is using this fine plane for a purpose for which I am sure it was used in the past, although I have not run on any documentation. This information was extrapolated from experimental archaeology. I have seen some Russian planes that were finished on the outside with a toothing plane, the bodies were curly wood, the surfaces obviously planed with a toothing plane then scraped. The lines ran parallel to the sole of the plane. This got me thinking about other uses for the keying plane.
Making a mitered door for a clock and after cutting the miter in the miter board, I shot the ends with a jack plane on a miter shooting board, but it was still a bit off, I had a belly in one piece. I laid the toothing plane on its side, worked over the miter and now it is keyed ready for gluing. I worked over all of the miters after shooting them with the keying plane on the miter shooting board. There must be other uses for this valuable hand tool.
Toothing Plane Iron made from a modern block plane replacement blade.
About 28 lines per inch serrations
Gnomon is 6″ long