Plane Tuning

Most traditional Japanese planes and chisels will require some knowledge and tuning to use them to their full ability.

In Japanese craft tradition, a blacksmith manufactures only the blade of plane or a chisel. In some cases they may manufacture a chipbreaker to match a plane blade, but most of the time a separate craftsman will be asked to manufacture a chipbreaker. In either case, most Japanese planes and chisels are finished by craftsmen who are not the blacksmith, whose job it is to cut the wooden dai for a plane, or fit a wooden handle to a chisel. 

The belief that permeates and underpins this system is one of specialisation – traditionally, Japanese craftsmen will only learn one trade in order to master that skill and material totally. Blacksmiths do not work with wood, toolmakers do not forge their own blades. What this means is that when a woodworker purchases a traditionally made tool, he holds the sum total of several artisans’ work in his hands. It is left to the new owner of the tool to tune and refine it, allowing all of its parts to work together in harmony.

A Japanese chisel will require 1-2 hours of preparation before it can be used. This includes flattening the back of the blade, sharpening the bevel and then fitting the iron hoop to the handle. 

A Japanese plane will also require about 1-2 hours of work to tune it for use.  This includes flattening the back of the blade, sharpening the bevel of the blade and flattening the chipbreaker to ensure a precise fitment against the blade and in the plane body. The blade will also need to be tuned to the plane body. This is a more time-consuming task, as the blade acts as a wedge in two ways – against the sides of the plane body, and against the supporting timber beneath it.

Plane makers in Japan, whether mass-producing or doing small runs of bespoke tools, universally size their plane bodies to be too tight to fit the blacksmith’s blade. This is because if a plane with a tightly fitted blade were to move to a drier environment (which is especially a concern if a plane is being shipped to Australia), it would become too loose to use.

For a woodworker, there are many wonderful benefits that come from tuning your own tools. The first and foremost is learning about the relationship between timber and steel and how they relate to each other. Ultimately the process of woodworking revolves around using steel to shape timber, so holding a well-founded understanding about how a blade can be held in place with only pressure from a simple wedge, or how a chisel can withstand a lifetime of striking thanks to well-fitted hoop, deepens a craftsperson’s connection with his work and his appreciation for the tradition that he is continuing.

The journey of woodworking is a long and rewarding one, not only thanks to the beautiful forms that are created along the way, but also because of how they come to be created. Learning about these tools and understanding how to get the best out of them makes for better craftspeople. For those who prefer to pick up a tool and get straight to work, western style planes and chisels are available from many fine makers and are often ready to go straight off the shelf. We own western planes and also some hand-made Australian planes and enjoy using them all.

One more important point on tuning Japanese planes, is that there are many ways a plane can be set up to achieve different tasks. The traditional planes we sell are setup as a smoothing plane, however they can be alternatively be set up as a jointer or as a roughing-out plane to remove larger amounts of material. Traditional Japanese furniture is finished off the plane and not sanded - a smoothing plane can leave a piece looking and feeling perfectly flat. A chisel can also be setup for paring or, by placing a micro-bevel on its edge, the same chisel can be used to strike through Australian hard woods. With a detailed knowledge of how these tools work and what can be done to change their attributes, they open up a world of possibilities in the craft of woodworking.

Tuning a Japanese plane before first use

The aim of tuning any Japanese plane is simple - to seat the blade squarely inside the plane body, and so that it will be held firmly in position with the appropriate amount of the cutting edge available to the wood.

Tools required

The tools required are few but can be specialised. They are; 
  • A small hammer or mallet for gently tapping the blade or the plane body while adjusting the blade. A crowned striking face will remove the likelihood of damage to the wooden body, along with gentle, repeated taps.
  • A method of flattening the back of the blade. We recommend our glass plate with adhesive sandpaper, used in conjunction with water stones. 
  • A method of sharpening the bevel. We use our range of Cerax waterstones.
  • A fine tool for paring the sides of the plane that  may constrict the blade. A small 3mm chisel or fine file are ideal.
  • A lead pencil
  • A way of paring away timber in small increments from below the back of the blade. A sharp chisel of about 12-18mm works well.
  • Finally, a metal file for tuning the rear corners of the chipbreaker to seat it close to the blade's edge. 

Flattening the back of the blade

A flat back of the blade is fundamental to forming a sharp bevel across the length of the cutting edge, and also a prerequisite to seating the chipbreaker tightly to the blade.

We use a flat glass plate covered with adhesive sandpaper to flatten our water stones when they are dry. After rubbing the back of the blade on a flat stone, the high spots that have been abraded will be visiblly dulled on a coarse stone, while the low spots that have not been touched by the stone will retain their factory finish. A 1000 stone is usually sufficient for this first step, though if a blade is severely out of flat, it will be significantly quicker to use a harsher stone, or begin by flattening the back on the stone itself, and then moving on to the water stones.

We flatten less than the front 10mm of the blade - that is, the cutting edge, and only enough material behind it to keep it flat and balanced on the stone.

Once the back of the cutting edge is uniformly flat, move on to the next grit available. This applies regardless of the brand of waterstone or oil or diamond stone you use, as long as the surface is flat. Diamond stones are designed to retain their flatness and so are especially god at this job while requiring little maintenance.

Sharpening the bevel of the blade

The skill of maintaining sharp tools is fundamental to working wood, and is one that can be acquired, honed and practised over a life time. There are many different tools and many different techniques that people employ in pursuit of "sharpness", but we would consider this a "quick-start" guide for those looking to get good results from Japanese water stones.

All our tools ship with a ground bevel, but are far from as sharp as they can be made to be. Depending on the manufacture of the tools, these bevels may be nice and flat, or they may have a "hollow grind", but either form will allow them to be balanced on a flat sharpening stone with hand pressure.

Used blades may suffer from heavy gouging or rust pitting, which would require regrinding the bevel, but a new blade should be free from nicks or dents, and often would be ready to be presented to a 1000 grit stone. Place the blade bevel down on the stone, holding it in such a manner as to support the angle of the tool.

Applying gentle pressure, move the tool back and forth while keeping the angle of the tool on the stone uniform. This is, in one sentence, the simplest and most difficult aspect of sharpening a tool on a waterstone. Be patient, experiment with what works for you. Work the stone evenly, moving your strokes around the stone to spread out the dishing that will occur as the stone is worn away by the sharpening process. 

Depending on the function of the tool, you may wish to tune the form of bevel. Chisels benefit from a flat, square bevel. Plane blades that will be used for smoothing benefit from a very slightly curved bevel that presents the middle of the blade to the work surface but does not allow the edges of the blade to protrude past the plane body.

If you begin to sharpen the bevel of the blade and find only the centre of the bevel is contacting the stone, the blade has been intentionally shaped at the factory to suit it to smoothing. If you want to keep this profile, work on different segments of the blade at the time, placing pressure alternately at the centre and at the edges. Once the whole length of the bevel has been worked, the process can be repeated on higher grit stones. 

If you would like to tune your plane for heavy material removal, increasing the curve of the blade will allow you to take bigger 'bites'. Work the edge more than the centre.

If you would like to tune your plane to leave very flat surfaces, work the centre of the blade harder in order to bring it back to the same plane as the edges. A rougher stone or diamond plate will be a great help in this.  Adjusting the sole of your plane will also be necessary to use it as a jointing tool.

Moving beyond the 1000 grit stone gives you a higher polish on the bevel and a finer edge. If you do not have any higher-grit stones available, the slurry that has been worked up on the 1000 stone can be transferred to piece of softwood to turn it into a sort of strop. By working the slurry on wood the 1000-grit particles are broken down to smaller and smaller sizes, transforming them into 2000 or 3000-grit abrasives and lending a polish to your blade. 

If you do own finer grit stones, such as as those provided by in our 1000/3000 and 1000/6000 combination stones, repeat the process above for each grit until you have a uniform finish on the bevel. Once finished on a 3000 grit stone, a plane or chisel blade should certainly be able to shave hair - though testing their sharpness on a piece of wood instead may save you some explaining later.

For those interested in highly polished tools, final honing can be done with a leather strop.

Inserting the blade - sides

When inserting the blade into the plane, the first concern is to ensure that it is not being constrained by the sides of the plane body. Tap the blade in (leave the chipbreaker aside for the moment).

Wen the blade is in position and almost out of the sole, hold the plane up to the light to see if the plane blade is touching either side of the plane body. It needs a half-millimetre gap between the sides of the blade and the plane itself to squarely seat the blade to the sole. If there is no gap on one of the sides, this can be fixed. Removing the blade and use a 3mm chisel or a thin file to shave off some material from the interior of the plane body where it is contacting the side of the blade. 
Ideally, you would like the blade to be parallel or square to the sole with 0.5mm space on each side of the blade. Once the blade is bedded and the cutting edge is exactly where you want it, re-check these dimensions, especially if your blade is not settling square.

Inserting the blade - depth

Chances are that your plane blade will now be sitting in the plane body about 3-5mm from the actual mouth, a long way from actually working wood of any sort. The timber of the plane body that sits directly under the blade will need to be carefully pared away in order allow the blade to drop far enough to protrude from the mouth, taking care to maintain its tight fit to allow fine adjustments.
Rub the face of the blade that sits face-down in the plane (the side with the bevel) with the lead pencil, covering it with a layer of graphite. Then insert it into the plane and gently tap the blade as far as it is willing to go. Remove the blade by tapping the back of the plane, keeping a steadying finger over the blade. The pencil that was left on the blade should have rubbed off onto the timber of the plane below it - but only onto the highest spots. These high spots, easily visible thanks to the layer of pencil covering them, are ready to be pared down gently with a sharp chisel.
Slice away the pencil marks left on the plane body and insert the blade once more. It should slide in slightly further, but still may not protrude. Remove the blade again, check to see where the high areas are and pare them off once more.
Repeat this process until the blade draws level with the mouth of the plane, testing it as you go. Feeling (carefully) or testing on timber is much more reliable than using sight. It's important not to pare away too much timber from the plane body - if this occurs, the blade will be too loose, present too much of the cutting edge and be impossible too use. We have heard of people gluing a piece of paper into the plane to rectify this, but have not tried it ourselves. 
By now, if the blade is gently protruding from the plane and well-honed, you are holding a tuned tool that is ready to be used on some timbers. With the preparation of the chip breaker, its capabilities are greatly expanded. 

The Chip Breaker

The sits between the metal cross-pin of the plane and the blade. For the breaker to work effectively, it needs to have a flat front edge that sits just behind the cutting edge of the blade - 0.2 to 0.5mm behind it. As it ships, however, the chip breaker may not be close to the edge. 
Insert the chip-breaker into the plane and tap it lightly into position. If its front edge does not seat close to the blade's edge, it's rear corners will need to be adjusted with a metal file. Gently remove material from the rear corners, reinsert it into the plane and observe if it now sits close to the desired position. The chip breaker should not be required to wedge the blade in place - that is done by the plane body itself. If the chip breaker is still tight, take it out and gently file the rear corners once more. 
For the chip breaker to function properly, it is useful to flatten its back face in the same way as the back of the plane blade. If you are concerned about it being warped, place it on a known flat surface such as a glass plate. Hold the front flat on the surface and tap each of the rear corners - if you hear a noise, it means that corner has had more material removed than the other.