Tuning a Japanese hand-plane
I posted this item about how I tune my Japanese smoothing plane on my website yesterday, and I thought it might be of some interest here.
The weather has been a bit all over the place over the past few days, and while I was waiting for the finish on a couple of frames to dry, I checked my finishing plane for movement. The changing weather had affected it, and it needed to be tuned. It wasn’t too bad, and normally just a couple of minutes with the dai-naoshi kanna would have fixed it, but thought I would completely tune it from scratch, and put the photos here to show how I do it.
This is my finishing plane for rails, stiles and narrower pieces, so I have three touch points, shown in the next photo: what we would perhaps naturally call the front of the plane but is actually the back (daijiri) - 1; the area forward of the mouth - 2; and the front (daigashira) - 3. The surface between these three points is slightly concave so it doesn’t touch the wood being planed. The plane therefore “glides” along the planed surface on these three points. Because this is my finishing plane, these concave areas between the touch points are relieved only very slightly.
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This is what I use for tuning.
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Yes, it is sandpaper, and it works well: 220 grit sandpaper stuck on to 16 mm MDF, the plane being tuned, my dai-naoshi kanna (a scraper plane), and a small gennou for removing the blade. I also use a chisel.
First, I retract the blade slightly so it’s protected from the sandpaper, but down far enough so that it still applies the normal tension to the dai. Then I completely flatten the sole (dai shitaba) on the sandpaper using a normal planing motion.
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If you’re concerned about grit from the sandpaper attaching to the plane (it didn’t seem to worry any of the master craftsmen instructors at the College in Japan where I studied), you can wipe the sole with turpentine or the like after using the sandpaper.
Once the sole is perfectly flat, I then start on the concave areas between the touch points.
First, the parts to the left and right of the mouth. I simply use a chisel to carefully pare away a small amount of wood shown by the red arrows.
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I now work on the concave area between touch points 1 and 2. To start, I simply turn the plane around so it’s perpendicular to the sandpaper, and carefully sand the required area. Care must be taken not to sand too far either to the left or to the mouth.
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I then use the dai-naoshi kanna to cleanup and refine this concave area. As an aside, I always sharpen the dai-naoshi kanna blade before I use it. The sharper the blade, the better, cleaner and faster it removes fine scrapings of wood.
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Next, I work on the concave area between the mouth and touch-point 3 (daigashira) with the dai-naoshi kanna.
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I also use a sharp chisel to scrape away wood from near the mouth. This gives more control close to the mouth, and prevents the possibility of accidentally scraping away parts of touch-point 2.
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Once I’ve finished this, I check the sole lengthwise, across and diagonally for alignment of the touch-points and clearance in the concave areas. The area in front of the mouth is especially important.
After I’ve finished the dai, I check the blade. I sharpen often during use, so I have to tap out (ura-dashi) quite regularly.
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Here, the flat (ito-ura) is becoming quite narrow, so I’ll need to tap-out at the next sharpening session.
This is my finishing plane, so I progress through the grits up to 12,000. I use Shapton stones - 1,000; 2,000; 5,000; 8,000; and 12,000. For my non-finishing planes, I stop at the 8,000 stone. After sharpening I put the blade back in the plane and give it a try to make sure the tuning was successful.
And…
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the proof of the pudding is in the eating.
This process took about 20 minutes, including sharpening the blade, and juggling around with a camera in one hand.
This is how I do this process. It's quick and efficient, and it allows me to get back to the job with minimum delay.
Hope it's been of interest.
Des