Japanese style chisel questions

[Russ Kupiec]

I got a set of Japanese style hollow back chisels. I sharpened them at 30 degrees primary bevel and a small microbevel(1-2 degrees) and am impressed with edge life while chopping dovetails in hardwoods. I have found that the edge is more brittle(chipped a corner) than my American chisels. Since I got them I have read a couple of things that say the primary bevel should be greater than 30 degrees.
1.Looking for opinions on primary bevel and secondary bevel.
What works for you guys?
2. The rings keep coming loose, can anyone point me to an article or video that explains how to secure the rings so they do not come loose?
Thanks for your help

[Stanley Covington]

I got a set of Japanese style hollow back chisels. I sharpened them at 30 degrees primary bevel and a small microbevel(1-2 degrees) and am impressed with edge life while chopping dovetails in hardwoods. I have found that the edge is more brittle(chipped a corner) than my American chisels. Since I got them I have read a couple of things that say the primary bevel should be greater than 30 degrees.
1.Looking for opinions on primary bevel and secondary bevel.
What works for you guys?
2. The rings keep coming loose, can anyone point me to an article or video that explains how to secure the rings so they do not come loose?
Thanks for your help

Russ:

They are more brittle than Western chisels. The extra edge retention ability comes at price, but everyone becomes accustomed to using them in ways to prevent chipping.

1. 30 degrees is usually fine for butt and mortice chisels. Paring chisels are often sharpened to 25 to 28 degrees. Personal preference, really. A secondary bevel is not an improvement, although it is quicker to sharpen using one for a time. If you make the decision to sharpen without a secondary bevel, you will jump ahead on the learning curve.

2. Remove the hoop. Use a rat-tail file to bevel the inside edges top and bottom. Clean any ridges on the inside of the hoop with a file. Drive the hoop on, and then a little further, perhaps 1/8" past the handle's end. You can use a socket wrench or closed-end wrench, or even a crescent wrench with a hammer. Drive the chisel into some softwood, a 2x4 for instance, to hold the chisel up while you drive on the hoop. After the hoop is seated, hold the chisel in the air with one hand, and strike the corners of the handle's edge projecting past the hoop and round them over. This slight mushroom will hold the hoop in place. If the hoop is loose, roll some postcard or manila folder paper around the handle and drive the hoop on over it. Cut off the excess.

Don't soak the end in water to soften it in preparation for mushrooming. That way lies madness.

Good luck.

[Derek Cohen]

Hi Russ

Everything that Stanley says. He lives by his chisels.

The only little extra I will impart is for tapping down the hoops: you may get lucky and find, as I did, a brass pipe that will fit over the end of the handle, with enough thickness to connect the width of the top of the hoop. Hitting this will move the hoop in an even manner.

That is probably as clear as mud.

Regards from Perth

Derek

[Stanley Covington]

Derek's suggestion to use a brass pipe is a definite improvement.

Stan

[Jeff Bartley]

Russ,
I've just finished setting up a set of chisels and I'll echo what's already been said and add that I found a blog post by Chris hall (carpentryway blogspot) to be most helpful. Google search for the exact post, he gives a very clear explaination of setting the hoops.
The steps that haven't been mentioned yet are hammering the end of the handle while turning it (before setting the hoops) so as to compress the wood fibers just enough to allow the hoop onto the handle. After the hoops are set, soak the ends in a solvent/oil mix, then, as Stanley outlined, hold the chisel and hit it with glancing blows to round it over.
What kind of chisels did you get? The ones I found are labeled 'Yoshihiro' and I still don't know much about them except that they're readily available in Japan.

[Derek Cohen]

Here is the brass pipe I use for setting hoops. It comes off a garden hose fitting.





Place over the end of the chisel, and on top of the hoop. Strike with a heavy steel hammer. Once the hoop is lowered, peen the handle wood over it. On the right is a hoop that I set.



Regards from Perth

Derek

[Stanley Covington]

Nice tool Derek!

I don't believe kigoroshi is appropriate for chisel handles. I don't think oil or solvent is ideal either. Just my opinion based on a lot of years and a lot of chisels.

There is quite a bit involved in preparing the ferrule of the chisel, critical operations that get little attention, but add greatly to a chisel handle's life expectancy. There are some sources on the web in Japanese. I am preparing a blog and will post the procedures with photos.

Stan

[Jeff Bartley]

Stan,
What is kigoroshi? I'll look forward to a blog post, be sure to post a link!

[Andrew Hughes]

I too would like to see a blog on setting hoops on handles.I have one chisel that pretty screwed up from me trying to mushroom the end.Very embarrassing.

[Brian Holcombe]

I do as Stanley does and just peen them over while dry, they hold up best that way, in my experience.

[Russ Kupiec]

Thank you all for your help. Nice to borrow some clarity and confidence when I'm short of my own.
I'm envious of Derek's hoop setting tool. Is that the metric or imperial version?
In answer to Jeff's question, I bought a set of no-name chisels from Grizzly based on a Fine Wood Working review of European and Japanese style chisels. FWW rate these as best value. As I recall the Matsumura chisels got top honors. The Grizzly chisels sharpened very well and really hold an edge. The whole set ended up about $15 per chisel.

[Stanley Covington]

Stan,
What is kigoroshi? I'll look forward to a blog post, be sure to post a link!

Kigoroshi (directly translated as "wood killing") as it is applied to chisels is the act of crushing the wood cells/fibres of the chisel's handle's end with a hammer to make it small enough for the hoop to fit on. This technique is most commonly used for fitting intentionally oversized tenons into their mortises. The hammer crushes the wood's fibres/cells, but with time and a bit of humidity (or applied water) they swell back to close their original dimensions, locking the tenon etc in place. Sometimes it's used just to speed up assembly in timber frames when a tenon is a tad too big. The off-side face of a genno hammer is rounded for this purpose specifically. It is not elegant work, but it has its place.

Kigoroshi works best in the case of softwoods because they have cells that require less force to compress, and tend to spring back more completely with less permanent "set." The cells of harder woods like oak are not as forgiving, and have more "set" (a materials engineering term) after they spring back.

The problem with kigoroshi in the case of an oak chisel handle is that, although the wood fibres spring back to near their original dimensions, the cell walls are weakened locally. Don't let anyone without a structural or mechanical engineering degree and lots of experience measuring wood strength tell you otherwise. Is this a fatal flaw? Not in an assembled mortise and tenon joint, and perhaps not in a chisel either, but a weakened chisel handle is not a better chisel handle. There are more logical ways to get the job done that provide better long-term service.

A better approach is to bevel or radius the inside corners and smooth the inside surfaces of the hoop, as I described in my earlier post. If the handle is oversized, so much the better because, this will allow you to drive the the hoop onto the handle with great force (although the OP's problem was loose hoops). Using a large hammer and socket wrench socket, or better yet, Derek's widget, you can apply a tremendous amount of force. If this force causes the hoop to compress the wood, effectively creating a band of kigoroshi wood under the hoop extending to the butt end of the chisel, so much the better because it will keep the hoop on tightly and prevent the wood fibres below the hoop from spreading out. But the strength and durability of the handle's wood from the hoop to the ferrule will be undiminished.

After the hoop is set, and as you use the chisel, these beveled or radiused inside corners of the hoop allow the hoop to be gradually forced down the handle over time and thousands of hammer strikes without gouging the handle and/or splitting out pieces of it. This is very important.

At the butt end of the handle, the bevel or radius allows the mushroomed wood a more gradual and supported change in direction so the fibres will not break off so easily. Also, this bevel or radius encourages the butt of the chisel to automatically mushroom over the right amount. This is important because you don't want your hammer to cut off the mushroomed wood that extends out over the top of the hoop (this will cause the handle to become shorter quicker), nor do you want your hammer to hit the end of the hoop, damaging its face and deforming the hoop, which is exactly what will eventually happen if the butt of the chisel doesn't mushroom over on its own. This too is very important.

These are all techniques developed by and recorded over several hundred years by a guild in Tokyo of professional "Ana Daiku," a type of carpenter that specialised in cutting mortises. All these guys did all day was cut mortises in timbers back when every building had a hand-cut timber frame joined by mortise and tenon joints. The only tools they used were hammers and chisels. They did not do layout. They did not cut tenons. They just made precise holes in wood as quickly as they could like beavers on meth. All piecework, so speed and efficiency were critical.

BTW, it was these same Anadaiku that lead the charge in developing the Japanese chisel, especially the tataki nomi, to its current state of development. Korehide Chiyozuru, one of Japan's most famous blacksmiths, is recorded as saying that he did not like working for anadaiku because they were too picky and wanted too many special details included in their chisels, creating more work for him than a reasonable price could cover.

I was taught these techniques by old carpenters in Tokyo, have read the original instruction manuals created by the guild, and have used them for many years. But before I learned these advanced methods, I used the conventional methods most everyone else learns, and have experienced their shortcomings.

But every man must learn for himself.

I hope to have the blog up and running in a couple of months. I will let you know.

Stan

[Jeff Bartley]

I love hearing the background of work/tools and how it things developed dependent on one another. Thanks Stanley!

And that is a great hoop setting tool Derek!

[Mike Holbrook]

I ordered Ouchi chisels from Tools From Japan. When I got them I found a metal devise for setting the hoops enclosed. Similar to Derek's hose widget the devise I got was a heavy metal cap that simply fit over the end of the chisel with the hoop on.