Help with Japanese Chisels

[Don Dorn]

I'm new to this type of chisel. A friend bought one for me that is 1/8" and I love it, therefore, I intend to add to the collection. It is my understanding that you don't hollow grind them but I'm also hearing that you must do something with the ring on the handle. Is this required for all Japanese chisels? I think they are going to make great dovetail chisels but the preperation seems extensive - any advise?

[Phillip Pattee]

Try this link for instructions on setting the hoops: http://www.toolsforworkingwood.com/Merchant/merchant.mvc?Screen=NEXT&StoreCode=toolstore&nextpage=/extra/setting_hoop_guide.html

As far as sharpening goes, I am not aware of any special requirements. All I've ever done is sharpen them like all my western style chisels.

[Eric Hartunian]

Hi, what you are referring to is setting the hops. That is where you compress the fibers of the handle, just near the end, then set the hoop on the handle, and set it in some oil (or water) for the fibers to expand, locking the hoop on. I have quite a few J. chisels, and all have arrived with the hoop set tight on the handle. If yours are tight, and not moving, then my advice is to leave it alone.
As for hollow grinding, most folks don't. You generally want to stay away from a power grinder with these, as you can quickly mess up the temper.
Let me add a comment that some might disagree with. You don't need to exercise any special zen with these tools. No need for expensive natural stones, etc. The biggest difference with these tools and their western peers is that you shouldn't use them to lever waste.
Sorry, didn't mean to be long winded.
Eric

[David DeCristoforo]

Good link for instructions on "setting" the hoop. And while it is generally considered "blasphemy" to hollow grind Japanese chisels many (including Krenov) do so. If there were a problem it would be with the "weakening" of support that the the soft steel "body" of the blade provides for the very hard laminated (and brittle) "edge layer".

YM

[Don Dorn]

I really appreciate these replies - The ring as it comes is slightly above the top of the handle, but it doesn't budge with any hand pressure and I'm worried it would defeat the purpose to force it off.

Eric, if using them as is won't be an issue, it would be my preference, but will do what is necessary to ensure a long life. I hollow grind most chisels, but think I will just keep the flat edge honed - they feel so good and balanced in the hand, I think I'm hooked.

BTW - I really appreciate the link.

[Steven Wilson]

I just learned to sharpen them on some Shapton stones by hand and am very satisfied with the results.

[Wilbur Pan]

I've attached a picture of the bevel of a Japanese chisel so we all can have something to look at. ;)

The shiny bit that is at the cutting edge is extremely hard steel that will keep an edge for a long time. This sounds great for a chisel, but the downside is that this steel is relatively weak and may chip. The darker metal is softer, but stronger than the hard shiny steel, so that by laminating the two together, it provides strength for the hard layer.

If you hollow grind the bevel, you'll remove a bit of the softer metal that's backing up the hard steel, and theoretically will make it weaker. That's why it's said that you shouldn't hollow grind a Japanese chisel.

In real life, it probably doesn't matter much. David Charlesworth uses Japanese chisels and he hollow grinds them regularly. I've taken used Japanese chisels where the bevel is actually convex, and put a hollow grind so that I could reestablish the bevel.

But it probably helps to remember why a chisel is hollow ground in the first place. It's basically an aid for sharpening in two ways. First, having a hollow allows you to more easily maintain the bevel angle. But Japanese chisels have relatively larger bevels compared to western chisels, so this is not so much of an issue. Second, a hollow reduces the amount of tough steel that you have to grind away on a waterstone, which is helpful if you have a Lie-Nielsen chisel made with A-2 steel. But since only the small area at the edge of a Japanese chisel is hard steel, that's not as much of an advantage, either.

I think that the real downside of hollow grinding a Japanese chisel is that the steel will lose its temper at a lower temperature than your average western chisel, so you have to be really careful.

What I would do is try to sharpen your Japanese chisel without hollow grinding them, and see how you do. I bet you'll find that it's easier than you think.

[Wiley Horne]

Don,

Congratulations on your new Japanese chisel!

In regard to the hoop, I agree with Eric, especially since it is not actually loose. After the first two or three strikes, that hoop will seat down into the handle wood and give no problems.

Also agree with Wilbur and Yoshikuni in regard to hollow grinding. It's doable. But especially on an 1/8" chisel, you're risking the temper. Because that small of a chisel affords virtually no heat sink. Unless you're quite experienced and careful at grinding, it's easy to blue a 1/8" chisel, simply because there isn't much metal there to soak up heat transients. And even short of bluing it, there is some risk of detempering from say, Rc64 to Rc58 (to pick a couple of numbers to illustrate the point), again because there isn't much metal there.

Wiley

[David DeCristoforo]

Just one more small point. The main reason for hollow grinding is to reduce the amount steel you need to remove to get a good edge. With a Japanese blade, because of it's laminated construction, most of the steel is much softer (and therefore much easier to remove) than a "typical western style" blade which is consistent throughout. On a Japanese blade only the very edge is really hard. So hollow grinding them would not offer as much advantage.

YM

[Don Dorn]

These replies are very helpful and I intend to leave the hoops. I may have left the impression that I prefer to hollow grind - and while I do it on all the others, I don't have any problem keeping a bevel on a stone by hand. I have water stones and an 1800 ceramic stone so I'm not in a hurry to hollow grind if it's not the thing to do (and it appears it's not). I look forward to adding to the collection and using them for dovetailing.

[Jim Koepke]

But it probably helps to remember why a chisel is hollow ground in the first place. It's basically an aid for sharpening in two ways. First, having a hollow allows you to more easily maintain the bevel angle. But Japanese chisels have relatively larger bevels compared to western chisels, so this is not so much of an issue. Second, a hollow reduces the amount of tough steel that you have to grind away on a waterstone, which is helpful if you have a Lie-Nielsen chisel made with A-2 steel. But since only the small area at the edge of a Japanese chisel is hard steel, that's not as much of an advantage, either.


My understanding is the reason tools are hollow ground is all the tool makers had large stone wheels to do the grinding so the bevel just naturally came out with a hollow grind.

There is not a grinding wheel in my shop, so everthing gets a flat bevel. Just recently some Hock blades were purchased and after using them for a while, they needed a little honing. It was interesting to me that it was easier to feel the blade register on the stone with the hollow grind than a flat grind. It also made for less work on the stones to get back to a razor edge.

It is not likely my methods will be changed just for this though.

jim

[Mark Singer]

IMHO You don't hollow grind a Japanese chisel. The main reason is the hollowed back does not work well with a hollow grind bevel. Pretty soon the curves intersect. You can flatten the back to reduce the hollow, its best to flat grind and hone and since it is a tradional tool I use traditional Japanese metods