Hand Tools #6 - Japanese Woodworking Tools - Part 2: Hand Planes

Having dealt with Japanese Marking Gauges, Marking Knives and Hammers previously, in Part 2 we look at Japanese Hand Planes.

Photo: Courtesy of the Takenaka Japanese Carpentry Museum.

In conversation with an enthusiastic novice hand tool woodworker last week, I was asked which is more expensive to start with: Japanese or Western Tools. This is not an easy question to answer, as both styles of tools come in a wide range of qualities and prices.

With regard to Hand Planes, you will definitely get excellent value for your money with Japanese models. The simplicity of the planes is unique and therefore a good basic Japanese Plane will set you back less than half the price of a good basic Western version. 

All Japanese Hand Planes are made up of only four parts: 

• The Body - usually made of Japanese White Oak
• A Steel Cross Pin
• A Chip Breaker
• A Blade

Let's go Japanese...

Japanese Plane Shaving Competition

Japanese woodworking tools differ in shape and use from Western tools, predominantly because of the use of soft wood as opposed to hard wood.

Smoothing Planes (hira-ganna 平鉋)

Anatomy of a Japanese Hand Plane

Hand Planes are the workhorses of Japanese woodworking. Although at first glance, they seem to be a very simple assembly of parts and quite uncomplicated, they are actually a very complex integration of angles, grooves and wedges.

Apart from some modern planes that use high speed steel blades, traditionally Japanese plane blades are made by laminating a thin piece of hard steel called the hagane 鋼, which forms the cutting edge, to a thicker backing of softer metal called the jigane 地金 supporting the hagane 鋼.

The reason behind this practise is very logical. White or Blue steel (high carbon content) produces an excellent edge, but due to the carbon content, it quite brittle. By forging a softer iron to the high carbon steel, immense strength is created within the blade.

You will notice that Japanese blades are in general thicker than their Western counterparts, due to this process. This blade thickness also contributes to a smoother cut with no blade chatter (vibration). Blades are hand-forged, so there will always be subtle differences between individual blades. The hollowed area on the rear of the blade is due to the forging process, however adds value to the blade as the rear is much easier to flatten that a Western blade. 

The dai (plane body) is therefore made to fit the blade, and a quality combination of the two requires great skill by the blacksmith and the dai maker.

Japanese Hand Planes are all based on the width of the blade itself. Although historically the measurements were done on the sun and ban system, today they are given in millimetres. 

Hira Kanna, the traditional or normal plane, has a blade that is set 40°-45° and is usually about 54mm  wide. Most other planes – scraping, rebate and moulding planes – are variations of this style. 

While Western manufacturers engineer the parts of the plane to assist in easing the work, the Japanese craftsmen concentrated on planing techniques, such as the pulling motion and use of the lower body position and leg muscles to ease effort and allow him to work for extended periods of time. 

An interesting characteristic of Japanese hand planes is that compared to their Western cousins, the blade position is much further back, towards the heel of the body of the plane.

The traditional Japanese craftsman rarely uses sandpaper to finish. The plane is the final tool used to prepare the surface of the wood. In Japanese woodworking, using the best quality plane, tuned for optimal cutting, is imperative for a smooth finish. 

Hira kanna means "normal plane" – the equivalent to the western world's bench plane, for reducing, truing and smoothing wood. There are several different hira kanna planes, although the three primary planes are:

• Ara-shiko – Roughly equivalent to the Jack Plane, used for reducing and the initial truing (levelling and  squaring) of your workpiece.
• Chu-shiko – Rather similar to a Jointer Plane, theses planes are used  for levelling wood to perfection, sufficient for edges to be joined together with no gaps.
• Jo-shiko – These are the Japanese equivalent of the Smoothing Plane, which puts a silky-smooth finish on wood, far better than can be achieved with sandpaper, which tends to scratch and blur the grain.

Within the wide range of Japanese Planes, there are also Chamfer planes, Single Sided Rebate Planes, Double Sided Rebate Planes, Skew Planes and many specific profile planes.

A Japanese Tachi Kanna (Scraping Plane)

A first time user of a Japanese hand plane should be aware that they do not arrive ready for use from the manufacturer, much the same as quality Western hand planes.

The best quality Japanese hand plane bodies (Dai) are made from specially selected, air-dried Japanese Red Oak (Akagashi) or Japanese White Oak (Shirogashi). When your hand plane arrives in South Africa having been made in the Japanese climate, a certain amount of shrinkage will occur. Shrinkage would also have occurred in Japan during the manufacturing process (remember this is after all a wooden bodied plane), and even Japanese woodworkers expect to adjust or "condition" their hand  planes for optimum performance.

Japanese White Oak Tree

Your first step is to flatten the sole of your newly acquired Japanese Hand Plane. There are several ways to do this.

The simplest way for the first time user to achieve this is to use sandpaper on a flat surface, such as your table saw bed. With the plane iron and chip breaker inserted firmly into the wooden body, (but not with the blade protruding!), rub the sole a few times across #220 grit sandpaper placed on a flat surface. Inspect the sole and observe the sanding marks. Take a sharp chisel or another plane iron and scrape the areas showing sanding marks. Again, rub on the sandpaper and repeat the scraping until the sole is flat. Flatness will be obvious because there will be even sanding/scraping marks over the length and width of the sole. It is very important to go very slowly through this process, very little at a time.

Flatness can then be tested with an accurate Straight Edge.

The next step is to remove the blade and chip breaker by firmly striking the heel of the plane body (Dai) with a wooden mallet.

Place the plane iron with it's hollow side down, on a properly flattened #1000 waterstone and hone with even pressure directly above the bevel until the area immediately behind the edge is absolutely flat from one side to the other.

Go through the same process on both #3000 and #6000 grit waterstones until the back of the blade is finely polished. Next, hone the bevel side on a #1000 grit waterstone until you obtain a "wire edge". Then, alternately hone the hollow and bevel sides on your #6000 or #8000 grit waterstones until mirror polished. A good rule of thumb is to make about five strokes on the bevel for every stroke that you make on the back of the blade. 

When refitting your chipbreaker, place it in it's position on the iron, checking very carefully for any rocking or wobbling where it meets the blade.

Should your chipbreaker rock on the blade, adjustments to the chipbreaker are made by tapping down one tab (found at the top of the chip breaker) or the otother tab until the chip breaker sits perfectly even on the blade. When the chipbreaker and blade mate perfectly, you then hone the chip breaker (hollow side down) on a #1000 grit waterstone, until a flat area is established directly behind the edge. The next step is to polish this area on a #3000 grit and then #6000 grit waterstone to a mirror finish as well.

Once the above has been properly accomplished, turn the chip breaker over and sharpen it at an angle of 20° on a #1000 grit waterstone until the edge is sharp, then polish the bevel and hollow side on a #6000 and then an #8000 grit waterstone. Finally, hone the chip breaker at an 85° angle on your finest grit waterstone for between 10 and 20 strokes. This will add a secondary or "micro bevel" on the chip breaker. The ideal chip breaker breaks the shaving without offering any further resistance.

Now that you have properly prepared your chipbreaker and blade, it is time to return to your dai (plane body).

Because of the shrinkage of the plane body, initially it is unlikely that the plane blade will protrude through the sole.

Firstly,  push the blade into the body as far as possible by hand only. Do not force the blade! There should be some sideways (lateral) movement of the blade.

If not, remove the blade, and with a narrow chisel, pare a slight amount from each side of the opening for the blade. This will allow lateral movement for the plane iron and will eliminate the chance of cracking the wooden body of the plane as the blade is driven in.

Replace the iron and once again push it by hand into the body as far as possible.

Inspect the opening at the sole . If the blade is within 1.6mm of the mouth opening, it should be possible to tap the top of the iron with a small plane hammer until the edge of the blade protrudes through the sole. If the edge is greater than 1.6mm from the mouth opening, remove the blade and rub a soft lead (2B, 4B) pencil on the sides and back of the iron. Push the blade again by hand, as far as possible into the body.

Remove and carefully pare, scrape or file the area of the Dai (Plane Body) marked with the pencil lead until you have removed the traces of the pencil lead.

Replace the iron, and check if it is within 1.6mm of the mouth opening. If not, repeat the above procedure. Normally , repeating this process two or three times will be sufficient. Check the sole from time to time to ensure it has remained flat.

When the iron is finally fitted and in place, inspect the width of the edge of the iron at the opening. The edge should NOT be wider than the width of the throat. It will generally be necessary to grind or hone away additional material from the corners of the iron's edges. Inspection of the iron will show that the corners have been partially removed by the maker. The user must make final adjustments. If the corners are not fitted, it is possible for a chip to lodge between in the iron and the slot in the Dai. If this happens, the cutting effect will be lost until the chip is removed.

At this time, check the chip breaker to ensure that it can slide easily into the Dai. If the Dai is too narrow, pare off a bit of the sides so the chip breaker can be easily inserted into place.

This completes adjustment for Japanese smoothing planes.

It is a good idea at this time to seal your Dai. This is easily accomplished by covering the throat opening with masking tape and filling the throat area with a good quality Tung oil finish.

Set your Dai aside until the oil begins to seep from the ends of the Dai. Allow it to dry over night and repeat the process.

In Part #3 of our series on Japanese Tools, we shall talk about Japanese Saws: Types, Applications, Techniques and Care.

Until next time, let's make shavings, not dust!