Japanese kanna-mi (plane iron) restore
MaFe style Kanna jointer
I finally got back to the Naga-Dai-Kanna this week, some may remember I made the Japan meets Krenov jointer plane when I visited my friend Jamie in Scotland last summer. A beautiful plane, but then my shop had to be restored and were closed down for months.
So it never got going, this week I finally did, I will post two new parts, first here the kanna-mi and then the final setup and shavings.
Time to bring life to this beautiful old hand forged Japanese kanna-mi (plane iron) and osae-ba (chip breaker) I got of E-bay Japan some time back.
Japanese plane irons are laminated; it means that you have two layers of iron forged together, a crisp and hard thin layer on the cutting part, at the cutting side (up) and then a softer back and top of the blade.
First step was to remove the mushroomed iron away from the top of the iron, this is what happens when you beat with a steel hammer on soft steel (Japanese in general use metal hammer when adjusting).
Then tune the chip breaker. You can read about tuning chip breaker in my Japanese hand plane setup blog, here you will find all you need for general setup of a Japanese kanna.
Here the basic names from TAKENAKA CARPENTRY TOOLS MUSEUM interesting site btw.
In this blog we will focus on the kanna-mi (blade).
[Love that name kanna-mi, sounds like a name for a loved one].
First the ko (reverse side) of the blade gets a little flattening, this is to secure a firm grip and fit to the omote-najimi (bed of the plane).
The ko don’t need to be all flat here, the iron is so thick that there will be no shatter.
I use a 120 water stone, this is a rough bastard and will work fast in the soft metal, I leave the surface quite rough to make a good grip.
Then flip it and give it a workout on the stone.
(Now you can see the ko side got some shoulders to rest on).
A touch up on the edge.
Now we can see how the blade is.
The Japanese blades have a hollow center, this needs to be maintained otherwise it will like here, just have cutting edge on the sides.
(This blade is probably not a high quality blade, then the hollow would usually be deeper and the edges more crisp, but it can also be due to wrong sharpening – we will see how it performs later).
So I need to make a tool for restoring the cutting edge.
There are many versions, mine is an old shoemakers anvil, it will be easy to move around and I have it in the shop.
First I grind the edges of to make a better shape.
I admit, I’m not a black smith – lol….
Then polish it a wee bit with a steel brush.
This was what we came from.
A blade with no cutting edge.
Before we get started, I will write NEVER HIT ON THE CUTTING PART OF THE IRON’ only the soft laminated steel. ;-) Did you get it?
Of course I sit on the floor, when I work with Japanese tools – smiles.
Then what you do is to tap the iron with a hammer to bend the metal down towards the front.
Here I use a pointed hammer, like I have seen many Japanese doing.
But some use a bigger version like this one…
Then back to the stone, grinding off a little metal, to see where we are.
Now we are getting a cutting edge.
So now we have an edge and flat sides so we can fit it in the dai (body).
Then I cut of the ears.
This will prevent the shaves from getting stocked in the oshi-mizo (ditch).
Like this. ;-)
Not sure if I hit the right angle or if there are one…
But I’m sure it will work fine.
So back to the sharpening station.
First I put marker on the bade to see where I am going.
A few hits on the diamond and I am here…
It’s clear to see I should have flattened my 120 stone, we are a little off here.
This will mean i will go deeper into the hollow and this will mean more work when sharpening in the future.
And a happy MaFe-San.
All we need now is to do the sharpening, that you can read more about in the first kanna blog:
Hope this can inspire to buy and recycle, it was my first try and I have a blade with a wonderful edge now, have learned a little from mistakes and will be happy to try again.
-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.