by Brian Holcombe
This is an extract from ISSUE II of “The Lost Scrolls of HANDWORK” magazine
I will detail the process of making a Japanese plane body, known as a dai, to compete in the annual NYC Kez, hosted by Mokuchi in Brooklyn, NY. Kez is short for Kezurou-Kai, which translates to ‘Let’s plane’, a competition in which participants compete to create the thinnest wood shaving.
In competition, the shaving must not only be thin but completely intact, it must also be the full width of the board (usually around 2″) and the full length of the competition board which is typically 8′. World record holders have pulled shavings as thin as 2 microns, which is almost impossibly thin, being far thinner than a human blood cell at 8 microns.
In Japan, it’s my understanding that competitors use Hinoki cypress, while in the US we will be competing by using yellow cedar, which is actually a cypress and very similar in quality to good Hinoki cypress. The yellow cedar we use is very old and tightly grained.
Competitors often cut their own dai, some choosing exotic materials or laminating their dai in hopes of creating a dai that will wear well, hold their tune for a good length of time and hold the blade with good support. I’ve chosen to use beech, which is not entirely ideal, especially by comparison to Japanese white oak, but shares some commonalities. Beech is the traditional western plane making wood, it can grip and release the blade repeatedly without losing its ability to do so. Beech is fairly stable and very much available. In my case I’ve chosen beech because of those positive traits and the fact that I can access it locally.
The cut-out process starts by prepping dai blanks, choosing material that is rift sawn and with grain running straight on all faces to reduce or eliminate runout. I resaw the blanks to the required thickness of 35mm and down to a width of 80mm and 85mm. I’ve cut multiple blanks, some I will set aside to age and two I will cut out. One will be used, the other discarded.
I’ve chosen a blade by Shoichiro Tanaka of VAR white 1, Tanaka is one of few makers using VAR white 1. This would be an ideal blade for competition with exception that it is 65mm and so less ideal than the typical 70mm, but it was made available and so I have chosen to put it to the test.
Next in prepping the dai block, I plane all four sides square, starting first with the sole which I adjust using winding sticks. The sole of a plane is the ‘bark side’ of the wood block, this is done so that any tendency for the board to cup results in two ‘skates’ on the outside edges of the sole, which are easy to flatten down without enlarging the plane’s mouth and so that blade is not clenched by that same cupping effect.
Once the block is squared I can begin my layout, starting first by marking the mouth line with a knife, then transferring that mark to the side of the dai where I can layout my blade, wear, escapement and bedding angles.
This dai is specifically made for a single blade, meaning it will be used without a cap iron, chip breaker, sub blade, or secondary blade (however you like to call it). When cutting shavings this thin and on such fine stock, a single blade is ideal. Few competitors will want to complicate matters by adding a chip breaker, if they do it will be simply so that their normal planes can be used to compete with.
If you inspect closely you’ll note that the wear angle, which refers to angle between the top blade and the mouth opening, is extremely tight. I’ve shown it being a single line in fact. The reason for this is that my goal in cutting the dai will be to set the wear angle so tightly that only a fine shaving can pass through.
The escapement angle is transferred back to the sole and used to set the width of the mouth opening. This is not to be confused with the distance between the blade and mouth which will be next to nothing.
The lines are next transferred to the top of the dai and knife marks are then applied.
I begin chopping out the dai, first cutting the mouth area, then flipping the dai onto its top side to begin cutting the bed and escapement.
The mortise is now formed in its rough shape, and it looks just that. I’ve remained inside the lines and have nearly come through the bottom of the plane to meet the work I’ve done at the mouth.
Finally, I break through, then close in on my final fit by chopping the bed until it is fairly thin. Next, I true up the escapement and the wear until a clean surface is achieved and finally I pare the sides cleanly.
Now I can cut the side grooves, this is a fairly critical bit of work. I use a flush cut saw to form the top of the groove, which is the critical cut, then again on the lower part of the groove.
After which I clear the grooves with an 3mm chisel.
Now I have something to work with, but still much effort remains. At this point I finish trimming the bed down to my knife lines, leaving the area nearest the mouth quite heavy.
Finally, I can bed the blade, I do so carefully to ensure that I can create a nice fit between the bed and blade nearest the mouth. If done correctly a ‘smile’ is formed.
At last I detail the dai, rounding over the back, chamfering all corners (except of the front and back of the sole) and finish planing the exterior faces. I’m ready to begin tuning.
I’ve carefully tuned the sole, as detailed in my previous posts on the subject. Happily, I was able to keep the mouth exceptionally tight, in this case from the sole it appears to be closed.
However, when we sight down the blade we can see that a shaving will be able to fit through.
The proof is in the pudding as they say, however this pudding would suggest I have a great deal of tuning ahead of me. The shaving is thin and full length, but not nearly thin enough, a real winner would be revealing a cheese cloth appearance, suggesting that it can barely hold itself together.