We are moving to Hawaii, and with only a few short weeks remaining between now and the big event, I've been very busy. Building stuff using tools, as opposed to just playing with the tools themselves. And planing...... Lots of planing.
A few days ago, I was watching a YouTube video. I'm gonna warn you now. If you just love watching someone work (using Japanese tools), these videos are great.
It is a demonstration from a European woodworking event, and the sound is terrible. Not much is happening. It is long (1/5 is 45 minutes!).
If you want to watch, great! But this has been in my "watch later" list for nearly 2 years now, and prior to this, I only got to about 15 minutes before giving up. Well, a few days ago, I was in serious need of watching someone else work, and.....
Way in there, maybe around the 35 minute mark, there is one little tidbit of knowledge that I had been missing until now.
Do you ever feel like you are the last guy to arrive at the party? Surely all of you Japanese kanna enthusiasts already know this one, but in the off chance that you don't...... I've never seen this presented before.
When I am using a single blade kanna, I get long, thin shavings that actually leap from the throat of the plane. For someone used to western style planes, this is alarming the first time that it happens, and it's really fun!
When I use a double blade kanna, the shavings still make that amazing *Riiiiiiippp* sound, but the shavings are almost always curled forward, into little tightly rolled shapes. That is due to the "chip breaker" effect of the Osae-gane back blade, compressing the shaving as it comes off of the main blade.
Those Japanese carpenter's kanna don't do that, though. Even their 2 blade kanna send off those self-propelled shavings that I love, so what am I missing?
This is one of the old beater kanna that I fixed up a while back. There is something about the composition of the steel, the tempering, something. For whatever reason, the blade holds an acceptable edge for a very long time, and it is quick and easy to sharpen. It isn't suited for the finest work, but it is providing good service as a rough/jack plane, and I've been using it a lot.
The blade bed is uneven, so I fine tune things a bit, using Super-glue to tack down some thickish wood shavings.
It doesn't take much. The shaving is translucent, but is thick enough to give the main blade a little more lateral stability.
Because there is a big hump right in the center of the bedding surface, the main blade had a tendency to pivot, and the poor support translated into cut instability.
The little bit that I glued onto the right hand side helped greatly. It is the slightly cleaner strip on the side. Most of the bed is still scraped clean (although blackened and dirty looking).
What I am *really* working on is the fit of the back blade/secondary blade/chip breaker. The Osae-gane. This one was too tight, and with the main blade rocking and rolling, fine adjustment was difficult. It worked just fine, but I want it good...... REALLY good!
The Osae-gane needs to be set close to the cutting edge of the main blade. How close? As close as humanly possible!
0.1 mm is a good number, but how do you know? If I hold the kanna upside down and tilt it just right, I can get a glimpse into the throat.
Underneath the white horizontal line of the throat opening, you can see the sliver of main blade that is exposed. This is as close as I can get. Any closer and I can't see what is happening. I thought that this was good enough.
Not quite. This is probably close to 0.3mm.....I want 0.1 mm. So, back to what I learned from the video.
If the shaving curls forward.....
... tap the Osae-gane down, closer to the cutting edge. Small taps.
Bingo! Notice the soft sapwood on the left, the denser heartwood on the right. The shaving is perfectly even in thickness. Cool!
Hilarious! A kanna rooster-tail!
When properly adjusted, there is a very sophisticated interaction between the body and blade of the plane. The Osae-gane stabilizes the main blade, but it also conditions the wood shaving as it leaves the cutting edge. These shavings are only rigid for a few moments, before turning all limp and drifting away (or getting *in* the way). The shaving is NOT just getting thicker due to increased downward pressure on the cutting edge.
So.... Funny looking wood shavings are great and all, but the important thing is that tear-out is greatly reduced. 0.3mm was good enough for a flawless finish on an easy wood like pine, cherry, or walnut......but this Port Orford cedar can give me fits. Even stuff with perfect grain can blow out in the most unsuspected areas. Maddening!
This piece is flat grain, so diving/rising grain, combined with a handful of tight knots.
I can plane diagonally. I can zigzag back and forth, changing directions in the middle of the cut.
There is a little fuzz, but no big chunks are missing.
This is exactly the type of thing that would've been causing major problems before. The finish would be perfect, had I not gone too far in adjusting the Osae-gane. I overshot the edge a couple of times while trying to get some decent photos, messing up the main blade.
This was a big piece that was missing from my puzzle, I just didn't know it.