Japanese tools #24: Japanese kanna-mi (plane iron) restore - MaFe style Kanna jointer

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Blog entry by mafe posted 03-23-2014 03:04 PM 13998 reads 0 times favorited 9 comments Add to Favorites Watch
« Part 23: Bunmawashi - Japanese beam compass Part 24 of Japanese tools series Part 25: Japan meets Krenov II - MaFe style Kanna jointer (Handplane). »

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.

Like so.
I admit, I’m not a black smith – lol….

Then polish it a wee bit with a steel brush.

Better yes!

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.

Getting there.


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.

Best thoughts,

-- MAD F, the fanatical rhykenologist and vintage architect.

9 comments so far

View siavosh's profile


674 posts in 3114 days

#1 posted 03-23-2014 03:18 PM

Perfect timing! My first kanna is being delivered next week. Eagerly looking forward to your next post.

-- -- Discover the most interesting woodworking blogs from around the world

View stefang's profile


17040 posts in 4578 days

#2 posted 03-23-2014 03:23 PM

Keep up the good work Madssan!

-- Mike, an American living in Norway.

View Sodabowski's profile


2401 posts in 4076 days

#3 posted 03-23-2014 03:46 PM


-- Thomas - there are no problems, there are only solutions.

View mafe's profile


13344 posts in 4333 days

#4 posted 03-23-2014 04:32 PM

Here a video from Sumokun of the process:

-- MAD F, the fanatical rhykenologist and vintage architect.

View lew's profile (online now)


13427 posts in 4999 days

#5 posted 03-23-2014 06:00 PM

Super photo journey, Mads!

Looks like that glove is starting to show a little wear.

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View lanwater's profile


3113 posts in 4178 days

#6 posted 03-23-2014 10:04 PM

I was wondering what have happened to your hand to have so many bandages until I realize you tore the glove :)

Those small screens are good for nothing.

Great blog Mafe!

-- Abbas, Castro Valley, CA

View swirt's profile


6632 posts in 4215 days

#7 posted 03-24-2014 02:17 AM

Nice metalwork Mafe. As always, it was fun following along on your adventure.

-- Galootish log blog,

View CFrye's profile


11362 posts in 3083 days

#8 posted 03-24-2014 08:30 PM

Thanks for the pics and explanation of your journey Mads. Wonderful shavings from a beautiful tool! At first I thought the sound was off on the video, then reminded myself a Japanese plane cuts on the pull. LOL!

-- God bless, Candy

View mafe's profile


13344 posts in 4333 days

#9 posted 03-24-2014 09:57 PM

Hi there,
Lol Candy, yes I can imagine your confusion, Mads reversed… The pull is really good for my neck and shoulders.
Swirt, you know I love to learn new – and this was a new path to walk, so I was like a fish in water. ;-)
Ianwater, lol, yes I can see it looks like I’m wounded. Thanks.
Lew, I will buy a new… (It’s always happening to me when I sharpen).
Soda, ;-)
siavosh, sounds wonderful, then the blogs will have a purpose.
Thank you for taking time to comment, best of my thoughts,

-- MAD F, the fanatical rhykenologist and vintage architect.

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