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The Cutting Edge


Janel

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Ford and I have just started talking about tool sharpening, actually over a couple different places in TCP, so here is a place for topical comments about our techniques and theories.

 

I'll repost Ford's response to my initial inquiry about using a strop...

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Hi Janel,

 

I think sharpening chisels and the like is made a bit over complicated at times. Before you begin, the potential of the tool is established by the actual angles of the cutting faces. This, of course, is dictated by the material to be cut and I would suggest, to a certain extent by the shape of the tool. For instance, a scraping tool will judder ( tech` term ) if the tool is too thin, not a great example perhaps but you probably get the idea.

 

Actual sharpening is simply the process of creating an accurate, and smooth interface of 2 or more planes. While shaping these planes, steel molecules are effectively rubbed up and over the edge, thus creating the burr, once all the planes have been honed through that point the burr ought to be removed as it can interfere with the cutting action. Also, to create a slightly more resiliant cutting edge it is in effect actually minutely blunted by the stropping action.

 

I may be wrong but I get the impression that you periodically strop your chisels while working, perhaps this will dull the edge over the course of the day. From my experience stropping is something that you do after you`ve actually sharpened the tool on a stone. As I mentioned earlier ( on another thread ), in the jewellery trade I was taught to simply stab the side of the bench ( only if wood ) to remove the burr, after sharpening a graver. I rarely, if ever feel the need to strop but will touch the edge to the stone whenever I feel it is not biting as I expect.

 

I don`t know if any of this is of any help but perhaps it might stimulate an exploration of the process for everyone on the forum. I`m pretty certain there are all sorts of variations on the theme.

 

as always,

 

Ford

p.s. looks as though I`ve made it as clear as mud, 2 minutes to demonstrate and half an hour to write about it."

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Thanks Ford!

 

I've had advice from another field of wood carving (larger, less art related), that encourages touching up with honing compound on cardboard between whet stone sharpening. The whet stone (from what ever degree of coarse to fine stones) sets or corrects the plane and angle of the cutting edge/surface, followed by the strop, or in the case of tools of the size I use, the cardboard/honing compound strop. Between the more aggressive metal removal of the stones the cardboard strop was recommended to keep the edge sharpened until the next whet stone episode is needed. The strop, in this scenario, produces a "miro-bevel", which must be the same blunting that you refer to above.

 

About the judder, I understand what you mean. My tools range from thin angle to wide angles, and I reach for the one that feels right for the job. If it judders, I reach for a different one, or take time to sharpen the edge if that is what is needed. Some tools are left or right oriented to accommodate the direction of the grain in the wood, so another bit of experience adds to the flow of activity when the judder is felt.

 

To wring a little more out of the judder, Komada Ryushi demonstrated a technique which depends upon a judder occurring deliberately, to give texture to the surface of the ivory being carved. (Used also in clay surface texturing, but I won't go further...)

 

Today I will try your approach and use one of my fine stones. You said: "...will touch the edge to the stone whenever I feel it is not biting as I expect." Does that mean you touch the angle at which the angles meet, the cutting edge, to the stone... or ... does one touch the plane(s) of the tool to the stone to create a new edge? ( Watching is better than words, but we only have words here.)

 

Thank you, Ford, and everyone else ... jump in with your knowledge or experiences.

 

I like to learn.

 

Janel

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Guest ford hallam

Hi Janel,

 

i don`t put micro-bevels on any of my chisels, i simply try and keep the cutting face as flat as possible. Too many angles and I get confused :D

 

Interesting to hear that you can utilise the judder to good effect, devilishly clever, those Japanese, are`nt they? B)

 

regards, Ford

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I think the "judder" or chatter when going contra-grain is also used in bowl turning/lathe work to produce surface texturing. Never occured to me to use this "problem" as an asset in woodcarving.

 

I don't have much to say about small chisel sharpening...I'm still learning by doing and trying to get it better each time. For ages I was using an oil stone, but lately I've switched to a combo grit man-made water stone. 1000 and 4000 grit, I think. It wears down a lot faster, especially with 3mm chisels and gouges and scrapers, so needs replaning often if you want to use the stone for anything larger such as a kitchen knife.

 

I am including below a tip from the website www.woodblock.com, created by a Canadian-born, 25+ year resident of Japan, David Bull. He is very skilled and creates beautiful copies of historic Japanese print images. I mentioned this tip on the forum ages ago, but since there's a topic for it now, I thought I'd copy it in entirety.

 

 

 

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Lesson #10: Sharpening narrow chisels ...

 

(a 'tip' from carver Mr. Susumu Ito, passed on here by David Bull)

 

 

 

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Carving a traditional Japanese print involves quite a lot of 'picky' delicate work, and many of the tools used are very small indeed. Store-bought 'aisuki' blades go down to about 0.5mm in width, but every carver also has a supply of smaller chisels that he has made himself. Sharpening these tiny chisels can be difficult ...

 

Each of the chisels and knives has two 'faces' that must be sharpened - the bevelled face, which may be curved (as in the 'aisuki' chisels) or flat (as in the carving knife itself), and then the back side, which must always be absolutely flat. In the case of large, wide chisels, keeping this back surface flat is not difficult, as the fingers can press the chisel down flat while rubbing the tool on the sharpening stone, but there is no room for the fingers to do this in the case of tiny and narrow chisels. It is all too easy to end up with a rounded surface, and a chisel sharpened that way will be difficult to use.

 

Experienced carver Mr. Susumu Ito was having a look at my chisels one day, and seeing that I must have been having trouble with this, showed me a little 'trick' for keeping the back flat. It involves using a small strip of wood (usually cut from the block currently being carved). Use a 'maru-nomi' (a shallow 'U' shaped chisel) and scoop out a piece about 3 cm long and 1 cm wide - cutting along the grain, not across it. Place this strip crossways on the top surface of the narrow chisel blade (the side with the bevel), and hold it there with a finger.

 

post-10-1133200544.jpg

Now place the flat surface of the blade against the sharpening stone. The strip of wood will extend out to either side of the blade, acting like a pair of canoe 'outriggers' to stop the blade from rocking as you rub the tool over the stone. The back surface of the chisel should thus come out completely flat.

 

This little trick works very well indeed, and I am grateful to Ito-san for passing it on to me. I'm sure he knows a million more

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Guest ford hallam

Greetings Doug,

 

thanks for that link, I`ve just been marvelling at the mans wonderful, delicate work. i expect I`ll be back frequently to learn more.

 

regards, Ford

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My experience seems to echo Ford's. I use a diamond Eze-Lap stone. It stays flat, cuts like nothing else, and is used dry. So I don't have oil interfering with my vision of the cutting edge, and getting everything oily (yuck). I used to use an india stone dry, and it worked well also. You just have to clean the stone occaisionally. I jam the cutting edge into a block of hardwood to break the burr off. I don't do any micro bevels (at least not intentionally :D). They seem to interfere with my cutting. I don't polish my cutting edge either unless I'm trying to make a brightcut.

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Guest ford hallam

Hi Robert,

 

You mentioned you use a diamond impregnated sharpening "stone", is that right? I`ve wondered about using one for some time. For my carving chisels I use hand forged blanks of HSS which are already hardened, I initially use a grinder to rough shape and then a diamond impregnated file to refine the form. After that it`s on to the rougher Arkansas stone. I also rarely polish the cutting face, I find it`s easier to feel whats happening at the "business end" like that.

 

I will have a quick search for one of those Eze-lap stones, they sound pretty efficient. Thanks for the heads up.

btw;

I really enjoyed the way you handled the treatment of your carved knife, patterned steel does look very impressive when rendered in this way, congratulations! :D

 

regards, Ford

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Robert and Ford,

 

Are you sharpening tools to be used for the cutting of metals or wood? Could there be any differences in the final steps to render a tool better for the cutting of wood vs. metal?

 

I've seen mentioned more than once not polishing the cutting face "to feel whats happening at the "business end". I've learned about the polishing of the cutting face and have done so with carving wood up to now.

 

Now I wonder about these things and will try more concepts tomorrow. I've used a translucent Arkansas stone today, along with various stropping methods with the tools that were in use today at my bench. This is all very interesting. I have made no conclusions yet, except that the wood in use currently responds best to the sharpest tools.

 

Janel

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Guest ford hallam

Hi Janel,

 

You may have point, ( pardon the pun :lol: ), perhaps taking wood cutting chisels to a finer finish or even polish will reduce drag and thus make for a slightly easier cut. The general principles still apply though, as I mentioned initially, the tools intended application is what determines the basic angles. final finish and things like micro bevels I suppose are a matter of personal preference.

 

Here is a link to the web-site of one of Englands better known woodcarvers, http://www.chrispye-woodcarving.com/ , he is offering an e-book which promises to deal with this topic in great detail. I`ve met the man and got the impression that he is indeed what his site would suggest. A genuine and honest, highly skilled and sensitive artist/craftsman.

 

regards, Ford

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guys and gals,

 

Not sure how helpful this all will be seeing as y'all are more experienced in the dark arts of carving and sharpening, but generally daiku (japanese carpenters) sharpen their chisels and other such 'blades' by creating two flat surfaces at an angle (which depends on the use), without any microbevels. This is achieved with 'coarse' waterstones. The resulting burr is generally removed by honing on a very smooth stone (high grit). Fairly standard stuff really. For myself these grits are 2000 and 8000 respectively. You'd think that a 2000 grit stone is nowhere near 'coarse' but for surfaces that don't require a lot of material removal it's very good (at least this particular brand).

 

I was somewhat surprised to hear that the burr is 'broken off' by stabbing the chisel point on a wooden surface (which sounds like a great ending to the sharpening of a chisel :lol:). Surprised not because I know this to be bad, but because all the things I have read/heard about sharpening Japanese chisels states that breaking the burr leaves the edge rugged... Hmm... I think next time i sharpen a chisel I'll try both methods and judge for meself.

 

Also, I was wondering whether anyone actually downloaded Chris's books.

The links want to download an .exe and have always been wary of getting those from the net... Anyone have any experience with these books?

 

-tassos

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Guest ford hallam

Hi, again, Tassos,

 

stabbing the chisel into wood to remove the burr, is a "trick" that I`ve only ever used on hand held gravers or burin. This would appear to only apply to metal cutting gravers. As Robert got his start under a German master as did I, my guess is that it is common practice in the European trade.

 

As you describe, the sharpening of Japanese chisels is both simpler but at the same time more refined, Certainly the result is just so satisfying.

 

regards, Ford

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Ford,

 

you're right in pointing out the difference in the material.

With wood (at least in my limited experience), the smoother the surfaces (and I suppose the edge), the more controlled and pleasant the cut...

Most of my frustrations with carving come from dull or badly sharpened tools...

Back to sharpening at that stage.

Or to a glass of sake. :lol:

 

-t

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Guest ford hallam

Hey Tassos,

 

I`ve got a uni-cycle that might help with the old balance issue, and if you find the sake interferes, you could always send it to me, :lol:

 

a toast, to slick tools :) and a replenished cup

 

kampai,

 

Ford

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About the .exe files, my Mac won't open them, so it is frustrating to me.  I think that they are aimed  at the other platform computers of the world.  I've sent Chris an email to ask about other options for the books/downloading.

 

 

Janel,

 

Let me know when you hear from him, 'cause I have been for some time interested in his books. Just wary of those exe's :lol:

 

-t

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Response from Chris Pye:

 

Janel - the exe files are completely virus free, but I understand some downloaders concerns - and they can always run their anti-virus software on them before opening. As a mac user, you'll be pleased to know I'll be making ebooks in pdf future...

 

Best wishes

Chris

Chris Pye: Woodcarver

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  • 2 months later...

I was looking through the Tandy Leather Factory catalog that came through my office door and they have a tool I thought might be useful for those on the forum who use jigs to aid chisel sharpening. http://www.tandyleather.com/prodinfo.asp?n...aitem=1&mitem=1

 

If that link doesn't work,go to the website and type in 88118 which is the stock number.

 

It's a handy looking honing jig which appears to be especially designed for small and narrow handled knives and chisels. The one I have can't be adapted well for my Dockyard brand tools, but this looks as though it will work.

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