This past summer I spent three months in Okayama working with Somakosha on prep work for a couple of overseas projects. During that time I also took a month to work on a furniture project for a client of my own using Somakosha’s shop (more on that in a future post). I ended up doing a lot of hand planing over that three month period. It was a really interesting mix of wood. I had the opportunity to plane plenty of soft wood like sugi (Japanese cedar) and hinoki, but also planed quite a bit of douglas fir, some Japanese red pine, and a type of Japanese hemlock called toga (栂). My own project was a furniture piece done in white oak. So all in all it was a good learning experience planing a range of wood species each with very different characteristics.
Despite the differences between all those wood species I essentially used the same sharpening method (micro-bevel) for everything that I planed, with a few minor variations here and there. Below are a few observations from that intensive period of planing.
Dealing with Chippy blades
My collection of planes has grown quite a bit since coming to Japan, and it’s been really fun to play around with a variety of blades. One thing I’ve noticed is that some blades are much more prone to micro-chipping during sharpening than others. In my usual sharpening routine I often sharpen the bevel on a course stone, and then jump up to an 8000 stone and start working on a micro-bevel. After the micro bevel I always hit the ura side of the blade to work back any burr that has formed. With certain blades I often end up with a bunch of micro-chips along the edge. It’s not necessarily something you can see with your naked eye, but under a pocket microscope it’s quite clear. My guess is that the burr is breaking off when I hit the blade on the ura side on the 8000 stone, resulting in an edge that looks jagged.
In those situations something that I have found helpful is to go minimal when sharpening on the coarse stone. Using a 1000 grit stone, I have been working the bevel just enough to almost remove the micro-bevel from the previous sharpening session. If you look at the edge in a good light or under a microscope you can still see a faint polished line at the edge; the remaining sliver of the previous micro-bevel. The result is you stop short of forming a burr. From there I proceed as usual to 8000 and 12,000 grit stones.
By holding back a bit and leaving a touch of the previous micro bevel, I’ve had much better luck getting really clean edges particularly on blades that are prone to micro chipping.
Another technique that has been working well for dealing with chippy edges, is to use a lot of pressure on the finish stone. On numerous occasions I have checked the edge after sharpening on the 8000 stone, only to find that the edge was still jagged, and full of little micro-chips. I found if I hit the micro-bevel one more time, using a decent amount of pressure, I could really easily and quickly remove the micro-chips and get a clean edge.
Planing White Oak
Below is a sharpening video taken while I was busy planing lots of white oak for a furniture project. I played around with a few different planes but ended up using a 60 mm Ishido kanna the most. There is a lot more resistance when pulling a plane on wood like oak. I found the narrow size was much easier to pull than a full size 70mm kanna. This particular Ishido kanna is also really easy to sharpen, and doesn’t seem too sensitive to micro-chipping. So I was able to start with a really course 700 grit Bester stone for quick re-sharpening sessions. I also found the wear on the edge of the blade was much heavier when planing the white oak and found the Bester could really quickly knock back any excessive wear. The Bester stone cuts really quick so it’s easy to form a burr, but the Ishido Swedish steel blade didn’t seem to be too negatively affected.
Using water when planing
Folks in Japan often wipe the surface of the wood with a wet rag just prior to planing. The water helps to push out dents and milling marks, but it also can improve planing performance as well. In particular it makes planing really difficult woods like sugi much more manageable. Recently I had one particular piece of sugi, that I couldn’t get a clean finish on. I could take one or two clean passes, but then the shavings always started to get fuzzy, leaving a rough surface. I resharpened a bunch of times, doing my best to get as sharp of an edge as I could, but I just couldn’t get a consistently smooth finish. One of my buddies came along and basically poured water on the surface, ran his plane over the board and was able to get a beautiful glossy surface.
The topic of using water during planing could become a blog post of it’s own. To be honest I’m not 100% sure about everything that is going on when you plane a wet surface. But talking to the folks I work with, there are a couple of running theories. One theory is that the water helps to keep the blade cool, allowing the sharp edge to last longer before being worn down by friction and heat. Another theory, that I think has the most impact, has more to do with how water affects the cellular structure of wood. With really soft woods like sugi or western red cedar, the summer grain fibers are floppy and weak when dry. By adding a little water, the weak summer grain will soak up the water filling the cells, giving the weak fibers some structural support, thus allowing you to cleanly plane the wood.
The downside of using water is that it can cause your dai (wooden plane body) to move. Some people try to counteract dai movement by either oiling or sealing the dai with some type of finish. Nonetheless sometimes dai movement is a problem, and sometimes it’s not. Another potential negative effect is that water can also cause the piece your planing to move, depending on it’s thickness.
For those reasons I have been hesitant and skeptical of using water, but I’ve also witnessed how much it can make planing really difficult soft woods much more manageable, and produce amazing results.
Sharpening and planing is a constant challenge. The more I play around the more I realize there is more to learn. I’m finding it more and more difficult to draw hard line rules. When people ask questions about sharpening most of the time I feel like the answer is “It depends.” Each person has their own unique method and style of sharpening and planing. And each blade, and each piece of wood has it’s own character which gets mixed into the equation. All together there are a ridiculous number of factors involved. I think what’s important is to find a system that is enjoyable, and from there just sharpen and plane like crazy. See what works and see what doesn’t. It can definitely be frustrating at times but when things go well, there is nothing quite like the experience of taking thin shavings and seeing the wood shine.
Have you ever planed green lumber? The thought came to me with the idea of using water to improve planing soft wood. Since green lumber has a lot of water, would that improve planing soft woods? thanks! I enjoy your posts.
-Jared, South Louisiana
Hi Jared,
Thanks for your comment. I recently had a conversation with a few other carpenters about water and it’s effect on planing performance. One topic that came up is that there is kind of a sweet spot in terms of how much moisture is beneficial for planing. If the wood is really wet, like green timber, it will be easy to plane, but tear out can be harder to stop. Also as the wood dries the softer summer grain tends to shrink more than the harder winter grain, so the surface can become uneven. I’m not sure what the actual number is for the idea moisture content for planing, but I’m interested in looking into it.
-Jon
Hello, and thanks for sharing your knowledge online! I was wondering, isn’t there a point where, if you make wood wet, you still have water trapped inside the fibres but the rest of the water has evaporated and and wood feels otherwise dry? wouldn’t that be the sweet spot?
I think you’re right that a good sweet spot is when the wood isn’t dripping wet but has some moisture remaining in the cells. Lately when I’ve had to plane some tricky material I have been wiping the wood with a rather wet rag, and then waiting for the water on the surface to evaporate a bit before planing. When I do that, the surface of the wood feels mostly dry but has a cool feel to it from the moisture that is still present. The wood becomes really easy to plane and the finished surface seems to be noticeably glossier and smoother than compared to using no water.
Hey thank you for sharing your knowledge, it’s definitely filling a knowledge gap on the internet when it comes to japanese carpentry techniques. I have a couple of questions, so I’m hoping you can help me out.
I have 3 kannas and have been getting to grips with them but I’m struggling to be able to flatten and square up stock with them and I’m wondering how is this achieved in japan?
My main problem is that there’s very little plane behind the blade, so as I’m finishing a cut and I reach the end of a board, I find it very difficult to keep the plane level and in line with the surface, there’s just hardly any plane to reference off. Also due to the relief in the sole as soon as the first cm of the plane has crossed the edge of the board, the plane tilts slightly since the board edge is now contacting the hollow of the relief.
The result is that the blade tends to dig in at the end of a cut and my boards end up messy and convex at the end.
I’m wondering how do japanese woodworkers overcome this?
Another thing I’ve noticed is that if I take a kanna with only 2 contact points to a flat board and plane for a while it will make the board hollow. I’m wondering this just me or is this known to happen, and of so why does it happen?
Hey Piers,
I have two theories regarding the difficulties you are facing. First the hollow relief behind the blade, and between the two points of contact, doesn’t need to be very much. Problems with the plane digging in at the ends, or getting concave or convex surfaces often happen when there is too much hollow between the points, and too much relief behind the blade. You really only need a very light amount of hollow, maybe a few thousandths of an inch, or .1-.2 mm for finish planing. For rough planing more hollow is beneficial as it will help ride on a roughsawn, uneven surface.
The second theory I have for you, is how much pressure you are putting on the plane when planing. Some people have a tendency to put a lot of downward pressure on the plane and that can exacerbate problems like you described. With a sharp blade softwoods should be able to plane with pretty light pressure. For hardwoods sometimes you do end up having to give a bit of pressure to hold the plane down, but it shouldn’t require a great deal of strain.
If you continue to have problems you can dial in the sole of your planes with more than the standard two points. 3 or 4 points can also be used. With 3 points of contact the third point is the very back of the plane, which greatly prevents the plane from diving in at the end of the board. A 4 point plane, has a 4th point of contact immediately behind the blade. Both of these styles are often used on longer planes for jointing boards, etc. The challenge of course is that with 3 or 4 points maintaining the condition of the sole becomes more of a challenge.
That said, when you are doing finish planing, a 2 point kanna is pretty standard, and with minimal hollow between the points and with a firm but light touch, the plane shouldn’t dig into the ends much, if at all. Particularly at the end of the cut, near the end of the board, try to go easy and kind of shoot the plane off the board. I’ve seen a lot of people who are starting out with kanna put a lot of downward pressure such that when they reach the end of the board the plane literally falls off as a result of them pushing down too much.
Hope that helps a bit, and let me know how it goes.
Best,
Jon
Hi Jon,
Thanks for your advice!
When I picked up my 2 contact point plane to check the extent of the hollow I discovered that it was actually contacting just behind the blade and at the end of the plane in front of the blade. I can’t be sure when that happened but seems like it could definitely account for the strange behaviour. So I flattened the sole again and I’ll let you know the result when I give it a proper test.
With regards to pressure I find I’m often putting quite a lot of force into my kanna, it seems like pretty tough work, not at all like the videos I see on YouTube where the plane appears to glide across the surface with almost no resistance taking wafer thin shavings. I’m wondering if this could be due to the mouth, which is pretty wide. The openings on my kannas are about 4mm and I haven’t got round to closing them up yet.
Also I knew I’d seen something about not totally grinding your micro bevel away somewhere else, it was this page which goes into quite a lot of detail – https://brentbeach.ca/Sharpen/jig%20faq%2002.html#thebest
Hey Piers,
Sounds like you made a good discovery regarding the contact points on the sole. Humidity changes can definitely change a planes condition, sometime really quickly. When doing finish planing I often check and recondition the sole of my plane before and multiple times during planing.
A 4mm wide throat is pretty big. That shouldn’t play a huge role in the ease of planing, but could definitely affect tear out issues and also can cause the plane to really dig in at the beginning and end of the cut.
Hardwoods definitely require more force than softwoods, but in either case the sharper the your blade is the easier the plane will be to pull.
Thanks for the blog link, I’m interested to check it out. Looks like a lot of good information. Some of my friends here in Japan, purposely leave a hair of the micro-bevel each time they resharpen so as not to form any kind of burr which may break away leaving a jagged edge. I haven’t been as fastidious about that myself but I do generally stop as soon as the micro-bevel disappears and try no to form too big a burr. It also depends on the blade itself. Some are more resilient at the edge and some are more chippy, in which case how you sharpen can start to vary a touch depending on the blade.
Hi Jon,
Thanks for sharing the technique. In the video, it seems that you have rabbets on the bottom of the kanna. I guess that could help to reduce the friction but I have never seen anyone has done this before. I wonder if you have rabbets on all your kannas and how helpful it is.
Thanks,
Jieyun