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Rebuilding a Kiyohisa Oire Nomi

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Derek Cohen (Perth Oz)

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I sort of collect ... and use ... Kiyohisa chisels. I purchased a set of slicks about 12 years ago, which were a 3 year wait. I was lucky - soon after this there was a 6 year waiting list. Unfortunately, they are now no longer being made as Watanabe Kiyoei has been very ill for some time.

So Yamashita writes about Watanabe: Japan Tool - Chisels - Kiyohisa Oiire Nomi

There are better nomi than Kiyohisa, that is, blades which hold a longer edge, but using these always makes me smile.

I wanted some of the oire nomi - bench chisels - however they have become collector's tools and incredibly expensive. There are some silly prices on eBay. Not sure if they are actually sold at the asking money. I've been lucky, and managed to pick up a few - and new! - for very reasonable amounts.

A few weeks ago I purchased a 30mm oire nomi on eBay. It was going quite cheaply, mainly because it was 30 years old and used. It arrived yesterday, and I was disappointed. It had not been looked after. Yes, the blade was worn, but there is a lot of meat left, and it said to me that it was used well. It was smaller than expected, but not the issue on its own. It was the handle, now about 3/4" to 1" shorter than the original .. and this made it too small for my hand.

The advert in the auction did not represent the state of the chisel accurately. I could have sent it back, but the cost of doing so was prohibitive (what has happened to US shipping costs!!!). The Seller was really a good guy. We talked about it. In the end he refunded part of the purchase price (making it even cheaper), and I decided to renovate the chisel. Perhaps restore some of it past glory?

This is going to be one of those articles with LOTS of photos - all you wanted to know about dismantling and rebuilding an oire nomi :)

Here is the chisel when it arrived, alongside a 24mm Kiyohisa oire nomi (on the left), which is new ...




So ... we need to make a new handle. I have some US White Oak, which is the closest wood to the Japanese White Oak used by Watanabe among the others in my collection. That will have to do ... I can always make another handle if this does not work out.

First step is to remove the handle. These chisels are constructed with a tang and a socket. How do you get them apart? The answer is to rap the handle on a hard surface ...



Just keep tapping. It will come apart ... eventually.



Take note - the tag is square, as is the mortice ...





Next: remove the ferrule. It comes off the opposite way it went on! I had an idea to make a tool to do this from a short section of aluminium tube - hammered the end flat ....



... then popped the handle inside, and tapped the end down ...



... and off came the ferrule ...



Now we go over to the lathe. The White Oak has been turned into a cylinder, and the length of the handle marked from the 24mm Kiyohisa. I have orientated the wood until the grain runs as straight as possible ...



The other measurements that are needed are the diameter of the handle, and the start and end of the tenon ...



The tenon is turned from the latter measurements ...



Next, clean the inside of the ferrule. It is rusty.



It needs to slip on firmly, and sit flush with the end of the tenon ...



Drill out most of the mortice ...



... and then mark and chisel out an exact fit for the tang ...





The fit is as good as I could hope for - a little force drives it home ...



Back to the lathe to add a small chamfer to the tenon ...



Before the handle is cut to length, some finish is added. Initially, this was just Renaissance Wax. However, later when sharpening the blade I notice that this failed to stop the wood becoming black (as the tannin in oak is apt to do around iron filings). I returned later to re-finish the handle in Ubeaut Shellawax.



After 30 years, the ferrule has been hammered and has flat spots. These need to be removed otherwise it will not fit over the end of the handle. I used a knife to scrape the inside of the band ...



To re-fit the ferrule, the handle is marked off with about 2mm spare ...



At this stage the ferrule does not fit ...



... and the end of the handle needs to be pared ...



It can be hammered on until it lies flush ...



I do not own a tool for seating the ferrule. Over the years I have set the ferrules on Japanese chisels using a brass plumbing connector ...



Drive the ferrule down about 2mm below the end of the handle ...



Then peen the edges of the handle over the ferrule ...



The peened ends do not extend over the ferrule - it is the handle you hit, not the ferrule.

All put together ...



The blade is sharpened. Japanese blades are a composite of a hard steel layer, the “hagane”, and a softer iron body called “jigane”. In cheap or poorly made blades, the hagane is thin and uneven. The hagane in the Kiyohisa is thick and even ...



Three Kiyohisa oire nomi (6mm, 24mm and 30mm): US White Oak, Japanese White Oak, and Japanese Red Oak ...



I am happy with the new addition.

Regards from Perth

Derek
 

--Tom--

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Nicely done, hopefully the back had been well maintained?

I would expect the original handle was burnt onto the tang to make the mortice, something I’m yet to do but keep meaning to. Chiselling out is such a calmer more controlled process.
 

Derek Cohen (Perth Oz)

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The original tang was most definitely NOT burned into the handle. Burning is such a crude method. In a high quality chisel, such as this, the mortice was carved to fit the tang, and probably the same way I did this: drill out the waste, then shape the outline. The only change (probably for the better) from the way I did it, would be to mortice before turning the tenon (more support when chiseling).

Your concern about the back is a good observation. Japanese blades are hollowed to reduce effort in flattening, and over-enthusiastic flattening can remove this. In this case, the hollow is still quite pronounced. My only concern is that the bevel was ground at 25 degrees, and not 30 degrees. Changing it (back?) to 30 degrees would shorten the blade considerably, so I am leaving it as is, and we shall see how it goes. I may need to add a Unicorn Profile.

Regards from Perth

Derek
 

D_W

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I may need to add a Unicorn Profile.

Regards from Perth

Derek
Yay!! One of the things I noticed testing chisels is that the harder they are, the more sweetness they retain even with the unicorn party trick.

I chased the hardness thing with japanese chisels, and have three kiyotada chisels (interestingly, they're all from different eras and three different hardness ranges - it's very noticeable). The middle chisel is about right (and one of the later ones by shimamura). What I noticed over time is that a japanse chisel a step off of top hardness is far more pleasant to use.

And I've bought probably a couple of hundred chisels from japan now. To a T, the ones that come in near perfect shape but having shown a lot of use are a step off of highest hardness. The ones that are absurdly hard to the point that they'll chip (some on a loaded buffing wheel) are little used. I'd imagine the folks who bought them found them pretty sour.

The ones just slightly less hard just invite you to sharpen them - they retain enough toughness that the edge finishes wonderfully, but are still hard enough to have good edge strength.
 

Derek Cohen (Perth Oz)

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Clogs, the “hammer” is a Japanese “Gennou”. This is made by a master craftsman, who weld-forges-hammers together a hard and soft layer of steel. I have two made by Tenryuu and with the Tsuchime (hammer mark) finish.

I did make the handle, which has a deliberate curve. This one is West Australian Sheoak.

Regards from Perth

Derek
 

D_W

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May I ask what a "unicorn profile" is?
A lower primary and secondary and then a tiny steep bevel at the tip of a chisel. Can be done with stone or strop, but easier and more completely done with a buffer. Almost completely eliminates edge damage with chisels without increasing effort to use them.

Here are pictures of the back side of a chisel (japanese) with a couple of straw (not really straw, but pretend they're straw) final bevel angles after chopping maple sticking (not harsh chopping, just chopping). The yellow line is the highest remaining point on the edge, and the black air space is damage from chipping or folding (chipping in the case of a japanese chisel).



Note that the angles were chosen as chisels chip generally until they get to somewhere around 32-35 degrees, but a flat bevel of 32-35 degrees is blunt feeling and shoots stuff at you if you're chopping half blinds or some such thing.
 
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D_W

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The profile at the edge of the chisel looks like this:


In testing, the bottom right corner edge slipped through wood more easily and took less effort both at the start, but especially after some damage. This was only a minute or two of chopping, not some large amount.

(works great for softer trashy chisels, too - offers more improvement on them than it does on good ones).

There is a free article about this on wood central, but I have to caution, it's long, and the summary at the beginning covers the method fine. The rest is just to prove that it works.
 
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Rorschach

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I do the buffer trick on my chisels now, works fantastically and more importantly it is super quick and easy to sharpen.
 
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dannyr

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Yay!! One of the things I noticed testing chisels is that the harder they are, the more sweetness they retain even with the unicorn party trick.

I chased the hardness thing with japanese chisels, and have three kiyotada chisels (interestingly, they're all from different eras and three different hardness ranges - it's very noticeable). The middle chisel is about right (and one of the later ones by shimamura). What I noticed over time is that a japanse chisel a step off of top hardness is far more pleasant to use.

And I've bought probably a couple of hundred chisels from japan now. To a T, the ones that come in near perfect shape but having shown a lot of use are a step off of highest hardness. The ones that are absurdly hard to the point that they'll chip (some on a loaded buffing wheel) are little used. I'd imagine the folks who bought them found them pretty sour.

The ones just slightly less hard just invite you to sharpen them - they retain enough toughness that the edge finishes wonderfully, but are still hard enough to have good edge strength.
Never done it myself, but if some of the so-called top quality chisels are too hard (chasing high hardness boasting rights?) what about a gentle extra tempering? eg a few tens minutes at about 180C? - easy in a domestic cooking oven. (shouldn't be distorting?
(although they are bi-metals) and could almost do it with the handle on)
 

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