Sharpening Japanese chisels - the irritating part

Re: Paring chisels for best edge

Pam Niedermayer - Austin, TX

>Yes, he's also writing guides and attaching sharpening videos to his ebay items. Very informative. I'll probably include a chunagura on the next order, he's selling them for cheap.

Interesting about bevels losing contact with very hard stones. I bought one pretty hard stone, but haven't tried it yet, will be sure to do so with chirping in mind. Thanks.

And yes, that 's what I meant. Ought things made from similar materials in similar geometries sharpen the same? Sounds like that's been your experience. Very interesting that you mention different bevel angles as a qualifier that could change the process.

Pam

Crest or Toms...

Scott Burr in Ben Lomond, CA

>A mighty good stropping compound in a pinch. My personal fav... A green crayon. Then you cant freshen-up with a chunk of forrest green.

Hmmm... seems things around here.

Scott Burr in Ben Lomond, CA

>Always get a little heated around election time.

What, precisely, was heated, Scott?

Pam Niedermayer - Austin, TX

>

ZOOM!

Bob Hackett

>Right over the head.Didn`t even try to put the glove up.

Ball,what ball?

MB

Re: Matte vs. Mirror Finish

Dave Burnard

>we're "birds of a feather" then. I finished mine, a hard way, shortly after I had switched careers and during the rapid process of forgetting more than I ever knew. Lucky for me, I was walking down a street in North Berkeley, puzzling over x-ray radiative transfer through highly magnetized superheaded plasma, when I walked past one of the 2 japanese tools stores there. ;)

The characterization of manmade stones having "uniform grit size" and manmade stone having "random grit sizes" may be part of the problem. In order for a stone to effectively sharpen at all, the distribution of particle sizes has to be pretty narrow. It only takes a few outliers from the previous stones grit range and you'll never remove all of the coarser scratches (since you'll constantly generate new ones).

I think it may have to do with the relative hardness/softness of the abrasive particles themselves. A paste of diamonds doesn't break down, but a paste of something softer will so that such a stone (manmade or natural) can change grits with the paste.

If I had one stone of perfectly hard 8000 grit abrasive and a second stone of softer 8000 grit abrasive that broke down to form a paste of smaller particles - which one could produce a better edge? Which bevel would be shinier? I know I don't know enough about that's actually going on at the microscopic level to say.

Re: Paring chisels for best edge

Dave Burnard

>I was thinking that sharpening a tool for a 40 degree bevel is a different experience than sharpening one for 15-20 degrees, and that a stone that works great for mortice chisels might not be the best for sharpening a razor or a very acute paring chisel or single bevel knife because of the different edge geometry.

Seems to me that this time of the years...

Scott Burr in Ben Lomond, CA

>Brings out the worst in people. I remember the last election and things got a "bit" ulgy. Just hoping it's not drifting that way...

Re: Sharpening Japanese chisels - lifespan?

Norman (Ottawa, Ont.)

>I have a question about Japanese chisels...

The Japanese chisels have hollowed back(s) running lengthwise.

I like the idea as it speeds up lapping of the back and provides a form of grip when gripping the chisel blade.

When the blades are ground back to very close to or

at the hollow(s), does the chisel then become useless ?

With the increased Rc hardness of the cutting layer,

it will probably not be necessary to grind back the primary bevel very often unless the blade edge gets chipped, a corollary to the increased hardness of the cutting edge layer of steel.

Norman

Re: Sharpening Japanese chisels - lifespan?

Denis Ch�nard, Orl�ans, Ont.

>In practise, both the bevel and the back are sharpened. That way it avoids running the edge to the hollow. That's different from a western chisel, where we do all the work on the bevel and then just break the burr on the back.

Traditionally, secondary bevels aren't used on Japanese chisels. I did put one on my DT chisels, next time I sharpen them I'll remove it to see if that makes much of a difference.

DC

There's a reason...

Bill Houghton, retired fun in Sebastopol, CA

>that religion and politics are off-limits discussions in a lot of settings. Particularly, I suspect, in the United States, where the dominant political structure is two-party, conversations tend to get polarized quickly, with resulting emotion getting pretty heavy.

Although I think this is an important election, best to keep conversations about it off-forum.

Re: Sharpening Japanese chisels - lifespan?

Norman (Ottawa, Ont.)

>I thought you would want to minimally lap the back.

Two reasons:

1 - the laminated high RC steel edge is much thinner than the overall thickness of the chisel blade, less laping of the back, more high-RC steel available..

2 - you would also want to lap to a minimum so as not to affect the forged or ground hollows in the back which in my opinion would be

very difficult to recreate.

Norman ( Japanese tool neophyte) :)

I'm in complete agreement Bill

Scott Burr in Ben Lomond, CA

>

Re: Sharpening Japanese chisels - lifespan?

Pam Niedermayer - Austin, TX

>You tap out Japanese blades when the edge gets too close to the hollow, which moves edge steel to the back.

Pam

Re: There's a reason...

Pam Niedermayer - Austin, TX

>Me, too, Bill; but I don't consider global warming a political issue. And I was attempting to draw an analogy to the manmade vs natural sharpening stones.

Do you seriously think it's political?

Pam

Re: Sharpening Japanese chisels - lifespan?

Dave Burnard

>You should probably "preferentially" lap the back during use - apply pressure only near the bevel when the chisel is on it's back. That way you won't be removing the hollow on the whole length of the chisel. Be careful not to do too much at any one time, since you may alter the geometry of the chisel

The other technique, which I use on chisels larger than 1/2" or so, is to treat them like a japanese plane blade and do what's called "tapping out" the blade. It involves using a small hammer to hit (all over) the iron part of the bevel which creates a slight deformation of the steel on the back side which when re-lapped reestablishes the "land" between the cutting edge and the hollow without excessively removing material on the entire back - or changing the geometry of the chisel. There have been various tutorials on how to do this online or in magazines.

You do this for plane blades every so often, and the point is that if you lap the back of a plane blade very much, you'll change it's thickness and/or geometry enough that it will no longer fit the blade groove in the wooden dai. So it's not optional for plane blades.

Among tool users I might be considered a little wacky for tapping out chisels, but it works for me and it's good practice for working with more expensive plane blades. I started because it's particularly suited to correcting distortions that can come about during use, say after chopping into particularly springy wood, or hitting a knot or other hard patch at the wrong angle. Something like that would take a lot of lapping, or vebel grinding to correct. If you use timber slicks - they're as big as a plane blade already.

Funny thing, now that I'm studying the making of japanese tools I've realized how much of this process takes place for every type of tool both pre and post hardening before the tool is finished.

Re: Sharpening Japanese chisels - lifespan?

Wiley Horne

>Norman,

Denis is correct. And so are you--one does minimally lap the back. When you sharpen your Japanese chisel, just work the back each time in the usual manner of sharpening, on the middle and final stone. Probably, just the final stone is enough. Just this little bit of metal removal is sufficient to keep the hollow receding away from the edge.

Bottom line: you tap out plane blades, but you don't tap out chisels, except in unusual situations where there is a big chip that has to be ground all the way back into the hollow.

Wiley

Re: Sharpening Japanese chisels - lifespan?

Frank D. in Montreal

>Just thought I'd throw in a pic for Norman to show how much hard steel there is in the blade: it's laminated to softer steel but still quite thick:

Is that those cheap chisels...

Denis Ch�nard, Orl�ans, Ont.

>...you were telling me about? :-D

DC

Ducking and running

Question, Dave

Denis Ch�nard, Orl�ans, Ont.

>Could we, instead of tapping, use a burnisher? There are carbides ones out there that would do the job. The rolling of the edge would be more controlled, I would think (but I could be wrong).

Thnx,

DC

Re: Sharpening Japanese chisels - lifespan?

Norman (Ottawa, Ont.)

>Thx Wiley and Frank for the clarification and photo..

Now I know I have just enough new found knowledge to be dangerous :)

Norman

Unfortunately, it's been made so

Bill Houghton, retired fun in Sebastopol, CA

>and perhaps we ought to resist that, and insist that it be kept in the realm of scientific discussion. Science as a culture, of course, is internally political (separate, that is, from electoral politics), but most scientists I know are willing to step away from that, or aren't involved in it in the first place, and consider a subject on its provable merit.

It's a tough problem in modern American life, figuring out how to keep scientific discussions from getting pulled into politics.

Wha...Huh?

John in New Mexico

>"Here we have a perfectly good rock making it's way toward entropy without our help for billions of years all of a sudden, after our help, change direction and head toward chaos."

Ummmm...I just don't get it. So the stone is naturally degrading, weathering, eroding and being re-deposited as sediment to form another, finer grained stone a few million years from now. Our help is accelerating the process, how is it changing direction. Entropy is basically a numerical value in a thermodynamic equation that represents the degree of disorder in a material. Popular culture as far as I know has loosely equated it with chaos, so again, where is the change in direction?

Are you saying that natural stones are superior due to a lesser environmental impact? Not trying to politicize, just curious what the actual point is. I guess I could make some assumptions based on the context of the rest of the thread, so maybe I'm picking nits a bit, maybe even attempting a nudge in the direction of linguistic precision.

John

Re: Wha...Huh?

Pam Niedermayer - Austin, TX

>I meant the rock to designate the earth, 3rd rock from the sun and all that. My understanding (and this might be all screwed up, I have just enough science to be dangerous) is that entropy is an undifferentiated space toward which all matter is moving.

As far as natural stones vs manmade ones is concerned, I meant to draw an analogy between our manmade environment and manmade stones. I think as manipulators of the environment we know just enough to be dangerous.

Pam

Re: Unfortunately, it's been made so

Pam Niedermayer - Austin, TX

>Yes, I think it's important to refuse to succumb to politicizing such vital issues. Now, granted that talk of solutions, because of their expense, is almost necessarily political to some extent; but the fact of global climate change is in no way, shape, or form political. It's a fact.

Pam