Japanese Herashi Kanna (Scrub Plane)

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This was something that I hadn’t seen done before so I figured I’d give it a go. In Toshio Odate’s book there is a reference to a plane called a Herashi Kanna. Odate also calls it a “cutting down plane” since it’s used for thicknessing pieces down to size from the raw stock.

The concept is identical to a western scrub plane. A highly pronounced convex on the blade along with a wider mouth to allow thicker shavings to get through. On the Japanese planes you still have to tune the sole as you normally would.

For this one I decided to add some end grain Jatoba to the mouth to help it wear slower over time. Plus the previous patch was cross grain oak and it would’ve gotten torn to bits on rougher stock.

Alot of grinding on this one to make the blade the right shape. Luckily a little work from my die grinder and a few hours on the waterstones and it was good to go. I did have to tap out this blade as well to get the edge in good shape.

The end grain at the mouth definitely helps the sole to last a bit longer. Plus when planing it seems to help it be a little slicker, this might be psychological but it does look fairly cool.

Once of my friends said that this plane is more of a mulcher than an actual kanna. It’s very effective going across the grain or at a 45’ angle on the grain. I slightly convexed the sole of the dai to help make it easier to tune. This also helps the blade cut easier because there’s no wood on the corners to throw the cut off.

It’s really satisfying to plane it and watch the big chunks of wood come blasting off the timber. I’ve tried it with a little bit of water on the wood which helps it work better too. This was done for the Wood by Wright tool buildoff thingy so it will be given away. I have another cheapo kanna I’ll probably do this to for myself. It’s turned out to be extremely handy.

What I didn’t expect was the cut patterns it leaves on the wood. I could easily just do a large panel or piece like this and leave it as is. Sort of like the “adze texture” thing you see on some furniture.

Thanks for reading/watching

-- www.youtube.com/lemongrasspicker