Intro: How to Build a Japanese Hand Plane
A Japanese hand plane is also known as a Kanna. The major difference from western planes is the Japanese plane is pulled, not pushed. The plane is made of either Japanese red or white oak, while the blade is a lamination of hard iron to softer iron. I will be making a smoothing plane which is similar to a Stanley no. 4 in its function. The Japanese planes are readily available to buy, although I just want to see if I can make one out of scraps of wood and metal laying around with minimal tools and effort. In fact, the only material I bought was the epoxy. In pic #1, I got the one on the right(similar to jack plane) off eBay. The one on the left(a jointer) I bought only the blade and made a sub-blade and a body from quarter sawn red oak. While the one in the middle is the plane I make in this instructable. I recommend reading material over the kanna to fully understand the tool before building one.
Step 1: Laminating the Blade
The body of the plane is made only after the blade is in hand. Therefore, the first step is to make the planes blade. The blade is comprised of a very thin layer of hard, high carbon steel forge welded to a large section of soft iron or soft, low carbon steel. As visible in the above picture with my materials, I have an old Wards Master blade laying around which will be the hard cutting edge, any good steel will work. The flat bar is a cheap, soft metal which will make the wedge of the blade while the saw blade will add thickness between the soft and hard metal. The measurements are available in pic #2. The blade is around 4 inches long and 2 inches wide. The thick end is 5/16" and the thin end is 3/16". I shaped the wedge before laminating with an angle grinder. Remember to not burn the hard metal. After shaping, I used J.B. Weld to hold the three layers of metal together. After a day to let the epoxy dry, I ground the blade to a 25 degree angle and honed it to a razors edge.
Step 2: The Planes Body
For the body, any hard, durable wood will work. I had some plain sawn white oak left over from some stairs I will be using. The wood is only 3/4 inch thick so two pieces will be glued together for a thickness of 1.5 inches. The final dimensions of the body will be 9.5 inches long and 1 3/8 inches thick. The width of the body is the blades width plus a 1/4 inch on each side(Pic #4 above). Before glue up I rough sketched the outline onto the white oak. For the glue I used Titebond and clamped it to dry for 24 hours.
Step 3: Shaping the Beds
The are many ways the cut out the blade's bed. The standard method is to mortise out the bed with chisel. Instead I sawed the body blank in half with a hand saw and sketched a final dimensions(pic #2). I am making a high angle plane at 65 degrees, although the normal blade angle is around 45 degrees. The blade is a wedge that tightens the further the blade is set. Therefore, the blade groove is the shape of the blade(pic #5). So draw the angle for the blade's bed and then trace the blades wedge shape over it with the blade about 1/8 inch away from the mouth(pic #4). The cut should be the width of the blade. Next is draw the cut for the bed where the shavings exit. I want a tight mouth opening so I measure close to the blade. The angle of this cut is around 55 degrees and is not as deep as the blade groove. This cut is 1/4 inch shorter of blade width on each side. After the cuts are made, chisel out the waste and glue the two halves together(pic #6).
Step 4: Fitting the Blade
If the halves do not align or the blade doesn't fit, chisel out the waste. As visible in pic #3, my blade sits to low, but no problem. Just glue a piece of thick paper to the blades bed. This should add thickness to the bed and the blade will tighten against the cheeks. The right position for the blade to sit(pic #4) is about 1/8 inch from the mouth opening.
Step 5: Shaping the Body
Now is time the square the body by planing the sides, top and bottom. Add a bevel the tops edges for comfort, but do not touch the bottom edges, they are to remain square. The bottom should be perfectly flat at this stage like picture #4. The Japanese plane is unique because the bottom is not flat. For a smoothing plane the bottom only touches the wood at the front of the plane and right before the blade(pic #5 and #6). There are special planes used for shaping the bottom of the plane, although I just use the planes blade at a 90 degree angle in a scraping motion.
Step 6: Chipbreaker
The chip breaker or sub-blade is not necessary for the plane, but I will add one for demonstration. The chip breaker is the width between the cheeks of the body(pic #1). My chip breaker is half the length of the blade and is made of soft metal. The breaker is sharpened like the blade and is held in place by a rod, I used a nail.(pic #2). The corners of the breaker hammered over to create a tight fit between the blade and rod. I used a vise to hold the blade and bent corners with a hammer. I used soft metal because of its ease to bend without breaking.
Step 7: Finish
Finally, the plane is finished. I added a couple of coats of linseed oil to seal the wood. I then tested the high angle plane on purpleheart, a very hard, tricky wood, and sweetgum, an interlocking grain wood that tears out, and the plane took off fine shavings leaving a nice glossy finish. Overall, I spent about 4 hours making the plane, although had to wait several days for drying glue. If you have any suggestions or questions just comment.