Sunday, December 21, 2014

Concave sawing

I'm often asked what to do when you break a bunch of teeth in one place but the rest of the saw is perfectly fine. Like the saw jams somewhere, you try to take it out, bend it a bit thinking it will be fine, and SNAP! 8 teeth cut in half somewhere in the saw.

This happened to one of those rusty saws I got from Gary last month. Perfect rip teeth, perfect cross cut, but a bunch of teeth off at the end of the saw.  (Look close to the mark on the envelop, there you see the missing teeth on the left saw.)

I sincerely don't want to file down that amount of steel, it's a waste. Of time, files and steel.

Was tun? (as Lenin said.) Concave sawing is the new revolutionary technique that will bring back to life all those forgotten saws laying around in Japanese flea markets.  Or maybe not.

The good thing of being the only westernerst in the interwebs sharpening japanese saws is that you can bluff. The bad, is that you don't learn as fast as you could.

After long consideration, I decided to file a slight curve on the saw, removing as little steel as possible so I get rid of the broken teeth but enough so the saw feels smooth when cutting.

At the moment, it looks like this on one side:

And on the other:

I still need to smooth a bit more the curve, there is still a small but noticeable jump on the left side of last picture.

Does it work? Yes. Is it historically correct? I have not the slightest idea. Did I save the other 95% of the teeth from becoming metal dust? Yep, in very deed. I'm behaving like Antigone going against the laws of the city? Who knows, I just hope not to end like her.

So, next time you feel in the mood for jointing, think it again and maybe give concave sawing a try. By the way, this doesn't feel faster at all, if anything it's slower because I was checking side by side and taking just a bit at the time. Perfect labour for a lazy sunday.

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