Friday, April 20, 2012

Two on Test (Part 2)

In the first post I introduced a couple of bench chisels, or o-ire nomi, that I have been supplied by Iida Hardware in Ōsaka. The chisels have been supplied at no charge, in exchange for my review, and I have no commercial association to the store, though I have done a fair bit of business with Tomohito, the owner, over the years and have found him excellent to deal with. I do look forward to forging a closer relationship with suppliers I can trust and recommend to others.

New Japanese chisels out of the box can be used right away, in the same way a car that has been partially reassembled can be taken out on the highway for a quick high speed run. Not recommended. Japanese edge tools don't come ready to go unless they are at the really cheap end of the spectrum. They arrive more like a kit that needs some work before the tool can be used fully - and this is a kit supplied without instructions, which does frustrate some folks to no end. All you need are some pieces of balsa and styrene cement and the party is on! Oh wait, what am I saying?!

Chisels are flattened and sharpened at the manufacturing end (sometimes by someone other than the chisel manufacturer), then combined with a handle, or tsuka, which might be of several varieties of wood but is most typically red or white Japanese oak. Added to the ends of the handle is a lower ferrule, or kuchi-gane (口金) and an upper striking ring or kashira ()  - sometimes, though less commonly, also called a sagari-wa, meaning 'drop-down ring' (下がり輪). Usually the same maker produces all the metal parts, though on cheaper tools the upper and lower rings may be supplied by an outside manufacturer. The handle is almost invariably supplied by an outside manufacturer,sometime the same people who make plane dai.

The first task with a new Japanese chisel is to remove the kashira. That's right - no assembly required, only dis-assembly. The crown ring usually isn't fastened on terribly tightly, so it is fairly easy to tap off. Some people slide a flat-sided hammer along the handle and tap the ring off that way, however I prefer to wrap a spot of painter's tape around the upper part of the handle, place it in the open end of a suitably sized spanner clamped to a table, and use a drift to tap the handle down:

The tape is a precaution against marring the handle. Note that in the photo I have had to keep at least one hand on the camera - you would, however, want that hand to actually be holding the chisel so that when you tap the dear tool doesn't take a trip to the floor. A few gentle taps and you should have the ring off.

Next, inspect the ring to see how it looks on the inside. A decent quality ring will have a smooth inner surface. A mass-produced cheaper tool will sometimes - usually, I mean - have rough spots and metal shards on the inside of the ring. If the inside has any roughness, it needs to be dealt with otherwise fitting the ring properly could be problematic. A larger size chainsaw file is a very good tool for that tuning work. In this case, both rings were quite good inside and will need very little attention:

The rings are tapered internally at one end, the same end which fits first onto the handle. You want to be sure which way around the ring goes before fitting it to the handle.

With the ring off, I peel the manufacturer's sticker off the tsuka:

Here we have our two chisels, free of kashira and labels:

Nomi are shipped with a coating of lacquer on them, which protects against rust and damage from transport. You can leave it on there, but the partially worn lacquer looks a bit shabby after a while and the feel of the tool in one's hand is not quite as nice. It's a simple matter to remove the lacquer provided you have the right solvent. It's called 'lacquer thinner' and you will find it at your local hardware store:

What I do is place a clean cloth in a plastic tub and saturate the cloth with thinner. Using a wire helps direct the thinner from the spout into the container and not all over everything else:

Be sure to be using the thinner in well-ventilated conditions, and please, no smoking. If you're more sensitive to chemicals in general, you may wish to wear a respirator.

I then wrap the chisels in the thinner-soaked cotton and let them sit for 5~10 minutes. Then pull the chisels out, wipe/scrub them a few times with the soaked cloth, then wipe off the tool with a clean cloth. When done, the handle and shank, etc., will be squeaky clean, literally:

With the lacquer removed, we can get a better look at the forge weld on these two chisels. The Yamahiro first:

Notice that the line between hard steel (the shiny bit) and soft iron is quite even, and that the hard steel wraps around each side of the blade fairly evenly?  Those are good signs of skill in forge work.

The Kunitoshi brand tool has a slightly less cleanly done forge weld, however it is free of voids and decent:

The back of the Kunitoshi had a curious glob of metal stuck in place:

 I wasn't quite sure what it was, however it must be some sort of artifact from the grinding process on the back. I carefully gave it some lovin' with a needle file:

All better:

Next time,I'll sharpen the tools and fit the kashira back on. Stay tuned and thanks for visiting.

1 comment:

  1. Looking forward to the sharpening test and your conclusions on the edge quality. I have been using Yamahiro chisels for quite a while but don't know anyone else who does. I am curious for another knowledgeable opinion about their performance.


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