Monday, May 2, 2011

More Toothing Plane Info

One of the first mention of a toothing plane is in the classic tool reference book, "Ancient Carpenter" by Henry Mercer. On page 127 and figure 120 he illustrates a "toothing plane" with the purpose of "scratching the surface of a slab of veneer to help the glue to stick."

The use of the Tooth Plane is very well desceribed ca.1815-1816 by James Smith in the "Panorama of Science and Art": "With this kind of plane, however hard the stuff may be, or however cross and twisted its grain, the surfacwe may be made everywhere alike, and will not be rougher than if it had been rubbed with a new fish-skin. This roughness may be effectively removed with the Scraper."

Joseph Moxon (who does not mention a toothed iron) tells us in "Mechanics Exercises" (ca. 1703): "But if it be very hard Wood you are to Plane upon on Box, Ebony, Lignum Vitae, &c. It is set (the iron) to 80 Degrees, and sometimes quite upright. So that these hard Woods, are, indeed more properly said to be Scraped, than Planed."

James H. Moncton, writing in "The National Carpenter and Joiner" (1873) states, page 6: "Veneering is a very simple operation and every carpenter ought to be able to do such work when needed; the surface of the material, upon which the veneer is to be laid, should be well scratched with at tooth plane..."

The conclusion is, in general, that the toothing plane is used both for leveling the wood surface, both on the carcase and the veneer, as well as providing an improved glue surface. I have used toothing planes for over 40 years and there is always one close at hand when I am at the bench.

I have posted some pictures of toothing irons. The oldest is by James Cam and was made in 1780. Note how much of the tooth is ground away. Normally the iron has grooves which are at least 1-2 inches on the end. The teeth grooves are made exactly like a rasp is made. The iron blank is annealed so that it is soft. Then, using a punch chisel, the maker punches the grooves along the end of the iron. The spacing between the grooves is determined by the use of the iron. Coarse, medium or fine grooves each has a purpose. Since the punch chisel is held at an angle, the grooves are slanted like teeth on a saw, producing teeth which are slanted when viewed from the end. Once the grooves are formed the iron is tempered and the bevel is ground using a wet stone. Never use a dry grinding stone since the temper of the teeth will immediately be destroyed.

To sharpen the iron, never put the grooved side on the stone. It is a simple matter to refresh the bevel side using wet stones (water or oil). The bevel angle is not important, but should not be too shallow, or the teeth will have a tendency to break off.

Toothing planes have a large range of angles, with the blades set often between 80 degrees and 105 degrees. I also use the iron by itself in my hand to reach difficult areas. I also have toothing irons which have been ground to a rounded end for concave surfaces.

When you select a plane, look for the length of grooves that are left. Longer is better. Also, look at the condition of the bevel. Many irons are improperly sharpened.

Good hunting!


Anonymous said...

Is there and optimum angle for the scraper plane?
or is it a trial and error depending on the material?

W. Patrick Edwards said...

As only the teeth drag over the wood the angle is very forgiving. I have many different toothing planes and they all have different angles, so I suspect it was not like the preferred angles for block planes, smoothing planes, molding planes, etc. Most are 80-85 degrees, some at 90 degrees and a few at 105 degrees.

A bigger consideration is the size of the teeth spacing. Softer woods need larger teeth, harder woods finer teeth. Veneers need very fine teeth, if at all. You do not tooth sliced veneers, and the saw marks left by the French saw (scie à bois montant) are so fine and regular that it is not necessary.

However, if you were to hand saw your own veneer, it would be necessary to use a toothing plane. Just like the guys in Roubo during the 18th century.

Anonymous said...

You are referring to the bedding angle but in reference to the clearance angle of the cutter, a lower angle would give less pronounced teeth and a higher angle would give more pronounced teeth. I am just starting to use a couple (18 & 25 TPI) bedded at 80 degrees and will use them for a variety of tasks. Of the planes that you have in your collection or in use what is the approximate clearance angle of them?

W. Patrick Edwards said...

I assume by your question you are referring to the throat clearance of the plane. The opening in the bottom of the plane just in front of the teeth.

Almost all the toothing planes I own have had years of hard use, and the bottoms of the planes are worn, which opens the throat. Unlike smoothing or bench planes, the throat clearance has little effect on toothing planes. Since the blade does not remove a shaving, there is no effect of a large throat or benefit of a small throat. The teeth just scrape the surface at a very steep angle.

In fact, if the angle of the blade is shallow, like a smooth plane, the teeth do not work. They dig in and pull up wood unevenly, and will break off. They need to be almost vertical to work and set very shallow. Just lightly scrape the surface.

I hope this answers your question. Unfortunately, the proper use of toothing planes is almost lost these days, except among luthiers.

Anonymous said...

What I am referring to is the grind angle of the iron which will affect the the depth of the toothing. In other words a plane bedded at 80 degrees and an iron sharpened at 30 degrees would have toothing deeper than the same plane but iron sharpened at 65 degrees. With the iron in the plane, the clearance angle I am referring to is the angle formed from between the sole and the bevel of the iron.

Your answer above answered another question I had but assumed that was what it would be.



W. Patrick Edwards said...

OK, I understand you want to look at the bevel angle the blade is ground with. I can say that all the toothing blades I own, and that is several dozen, have completely different bevels. There is absolutely no common agreement, and I suspect that these irons have passed through various woodworkers with more or less understanding of their function.

It is true that grinding will destroy the temper of a toothing blade immediately. They can only be sharpened on the bevel side using a water or oil stone.

I prefer a steeper bevel than a shallow bevel. I tend to reshape irons rarely, since the length of teeth is limited on each blade. However, I find a shallow angle makes weak teeth.

Since the tips of the teeth are the only part of the iron to contact the work, they need to be supported with a steep bevel, which strengthens the tip.

Remember, the bevel has no cutting function, unlike a regular plane iron. The only reason for the bevel is to reduce the thickness of the iron at the tip.

Therefore, use a steep angle, if you have a choice.

It is important to note that the teeth are on the front of the iron and the bevel is at the back. Never sharpen the tooth side of the iron. I have seen that ruins the blade forever.

Jack Ervin said...


Thanks first for the blog and thanks for the response to my questions about toothing planes. From information gleaned here and other blogs I decided to build my own planes. Using Lie-Nielsan 212 18 & 25 tooth blades. The bodies are European beech along the coffin style of Clark & Williams of small smother that Bill Clark built for me. As I stated above the planes are bedded at 80 degrees. The information I got from above about sharpen angles was very helpful in a starting point on my journey to using these tools. The initial sharpening angle was 45 degrees and I just honed only the tooth line to the root at 65 degrees. After setting up, I am using them and now have guidelines to further tweek them as using feedback gives. I check this blog regularly an look forward to new installments. Thanks again for your sharing all that you have as it will surely help to carry on this rich tradition.

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