Coarse stone workhorse suggestion

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Wabisabi-Ken

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Hey guys, very new to sharpening and have had my first try at restoring an old worn out 200mm yanagiba that had a chip in it.

The process seemed to take forever, I was using a cheap naniwa BASE 220 coarse stone. I spent what seemed like an hour and have worn a fair bit of the stone away and didn't really remove much metal at all.

I plan to do many more of these restorations so I was hoping for suggestions on a coarse stone that would work reasonably quickly and last a fair while!

PS I have looked at the shapton glass 220 but it seems they aren't really available here in Japan for some reason!

Before
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After
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First I used an aggressive angle to get the chip out which worked quickly, then sharpened the kireha (sorry if my terminology isn't correct) at the same angle as it was before, looking at the before and after it looks like the shinogi line has barely moved up! Is this normal? Is my stone just not removing material like it should? Is my technique terrible? The new shinogi line seems to be reasonably well defined and consistent.

Any suggestions and advice welcome!
 

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I would suggest using a diamond plate for that. It will get the job done in no time. Atoma 140 and 400 plates could work very well. When I do a chip repair, I use an aggressive angle and very low pressure in the Atoma to make sure I don't chip the hard steels on a coarse diamond. After that I thin down the bevel with either 140 or 400 depending on how much steel I had to take off. Make sure you use low pressure not to create deep scratches that will be hard to remove. After all the profiling is done, I usually go down the grit on synthetics. I like the SG320 before continuing further to 600 or 1k and move further up the grit depending on the knife and the cutting needs.


Alternatively, you may prefer to use diamonds 140, 400 and 1K before going to synthetic and ultimately the jnats.

All depends on how much time you have and what kind of feedback you like while doing the knife work.

I personally prefer to use less diamonds and more stones if I have time to work with.

Good luck
 
I’ll echo the above, diamonds plates are the best solution short of a belt sander or xl water wheel for this kind of work. Infinite flatness and good speed. I go Atoma 140 / 400 for my heavier restorations and then follow up with a shapton glass 500, 1k, 2k and then naturals. I think I’ll probably eventually get a few vitrified diamond stones or a 600 grit plate. The feel isn’t awesome, but you get used to it pretty quick and the speed and precision are worth it in my opinion
 
Thanks for the replies guys, I will definitely have a look into diamond plates, if you were to choose between the 140 or 400 which would you go for? I am trying to keep stones to a minimum for now due to having a somewhat nomadic lifestyle at the moment! I dont mind spending a bit more time, but longevity of the plate or stone would be important since I plan on doing this kind of thing frequently. I would assume the coarser it is the less time you need to spend working the blade so that could translate to less wear?
 
I would assume the coarser it is the less time you need to spend working the blade so that could translate to less wear?
That's the right idea - 140 will leave deeper scratches which equates to faster material removal from the blade. It's the same as a coarse stone using larger abrasives. Be aware that an Atoma 140 will is not inexpensive and burns out quickly when used for thinning.
 
I agree that diamonds can wear out quickly Vs a synthetic stone. Also, 140 will get the job done quicker, but you will have to spend a lot more time on a finer grit stone to remove the deeper scratches from 140 and thus wear out your finer grits more. Having said this, if you go for the 400 grit, you will end up spending more time on it and will eventually wear it off quicker.

The question you need to ask yourself is how many chipped knives and thinning bevels you will have to do? If it's just a few, perhaps 400 would be a good all rounder. If you have a lot to go through, you should look for 140 or perhaps just use something like a fine concrete block or a brick. It will be so much cheaper than using a diamond plate.
 
If you can only choose 1, the 400 atoma would be my choice. For what’s it’s worth, so long as you don’t use a ton of pressure on soft cladding and tear the diamonds out, I can’t see a hobbyist wearing out an atoma… I’ve used mine for a dozen projects and it still cuts like a chainsaw and easily flattens stones. It’s one of those things I hear a lot but doesn’t mirror my liver experience. If you want the opinion of someone who’s been doing it longer than I, I think @nutmeg also thinks that wearing out a diamond plate isn’t something anyone who’s not grinding for a living should worry about.

I think the atoma is well worth the investment given its use for thinning and stone flattening
 
Most stones will take a long, long time. Some people have suggested sandpaper in the past, economical until you go through 20 packs of it (but never have to flatten anything!). Actual thinning on the atoma will most definitely cause some wear.

Shapton pro 120 moves steel quick. I’ve heard coarse crystolon and manticore as well… sigma 240 was another one mentioned. Of all the options I’m going to try sigma next. My real battle of ultra coarse stones is flattening them.

I’m surprised shapton glass isn’t available there… i would be happy to ship you some in exchange for a stone from morihei!
 
Thanks for the feedback guys! I Have some thinking to do and will need to have a look around to see what coarse stones I have available to me.

I am starting to wonder if there is something up with the knife also, because I just cant seem to get a burr on it! As far as I can tell my technique is fine, I was able to sharpen an old deba to hair shaving sharpness in no time. Along with a couple of other knives. It just feels like my stones arent really removing material away from the edge, could they be too soft or something like that? I just ordered a 40x magnifying glass to have a look at the edge to see whats going on, but regardless it seems like the issue is that I just cant get a burr happening...
 
Thanks for the feedback guys! I Have some thinking to do and will need to have a look around to see what coarse stones I have available to me.

I am starting to wonder if there is something up with the knife also, because I just cant seem to get a burr on it! As far as I can tell my technique is fine, I was able to sharpen an old deba to hair shaving sharpness in no time. Along with a couple of other knives. It just feels like my stones arent really removing material away from the edge, could they be too soft or something like that? I just ordered a 40x magnifying glass to have a look at the edge to see whats going on, but regardless it seems like the issue is that I just cant get a burr happening...


Are you certain the apex is meeting between the main bevel and the uraoshi? That'd be my only thought...
 
Are you certain the apex is meeting between the main bevel and the uraoshi? That'd be my only thought...
Hmm I don't think it is really, I can see ever so slightly that the apex hasn't come to a sharp point, by hand it feels close but I can see a faint sliver as if it has a micro bevel. But that must just be somewhat rounded off. I'd just thought surely by now the main bevel and uraoshi would have come together by now, I've spent maybe another half hour working on the main bevel and uraoshi haha. It just seems bizarre that it's taking so much to remove material.
 
Hmm I don't think it is really, I can see ever so slightly that the apex hasn't come to a sharp point, by hand it feels close but I can see a faint sliver as if it has a micro bevel. But that must just be somewhat rounded off. I'd just thought surely by now the main bevel and uraoshi would have come together by now, I've spent maybe another half hour working on the main bevel and uraoshi haha. It just seems bizarre that it's taking so much to remove material.


Yeah this is one of the things about Yanagi restos - to do them well takes considerable time, and often a lot of material removal, because you can't play with angles in the same way you can with other knives. The really annoying thing is if they've previously been sharpened like a double bevel knife at any point. Sometimes this can be almost imperceptible to the eye, but you have to completely flatten the ura if you want to get anywhere. Dunno if that might be what's happened on yours...?

Whichever way - what I'd recommend is sorting the ura first, before doing the main bevel side. This will minimize your material removal on the ura and then you can make the main bevel fit to that. Rather than sorting the main bevel first, and then making the ura accordingly. If that makes sense...?


(I don't know if the above is recommended practice for this kind of thing btw. But it works for me, and the reasoning seems sound.)
 
wearing out a diamond plate isn’t something anyone who’s not grinding for a living should worry about.


*Hollow laughter*

(Admittedly the stuff I do with my 140/400 perhaps isn't 'normal', but I get about 2 months tops out of replacement sheets 😬 ).
 
*Hollow laughter*

(Admittedly the stuff I do with my 140/400 perhaps isn't 'normal', but I get about 2 months tops out of replacement sheets 😬 ).
Interesting. I don't doubt that you're lived experience there is right, but it doesn't mirror my experience. I removed 12g off my Takagi honyaki (super abrasion resistant Aogami) with mine, flattened a dozen or so naturals, and done maybe a half dozen clad knife projects and don't have any problems with my original sheet... I guess its possible I forgot what they cut like new and am used to a sub-par experience now.

Do you use a lot of pressure and maybe are suffering diamond tear-out or are you just wearing them down? Or is it all that novaculite you play with causing this?
 
Haha... I was being a bit flip/silly, and you have indeed spotted exactly the reason for my short Atoma lifespan:

Or is it all that novaculite you play with causing this?


TBH I don't use mine on metal ever really, though I can imagine they last a good long time. It's lots of flattening of very hard naturals, particularly novaculites, that does for me. They're just so fast for it, and I lack the patience to be faffing around with SiC powder for hours on end!
 
Do Norton Crystalon stones have the same problem with loading as theirs India line has?
 
Not as badly. FYI, the spray WD-40 with the little straw attachment, works wonders for cleaning the swarf out of the stone.
Thanks, I will give WD40 a try.
 
Thanks for the replies guys, lots of help and food for thought.

I decided to get a king 300 stone and hope it did better than cheapo home line naniwa 220. It definitely does perform a lot better (no visible dishing) but after another 30 odd minutes of attacking the main bevel I still wasn't getting a bur on the uraoshi side. So just to check my sanity I went for a slightly higher angle on the main bevel just to get at that apex, after a short time I could feel a bur and worked my way up a couple of grits to get the knife to a respectable sharpness!

IMG_20220607_001621.jpg


So I'm glad I got there in the end but not so stoked on cheating and using a more aggressive angle basically because I feel like I just can't make fast enough progress with my stones, so I think I will bite the bullet and buy an atoma, the question is..... 140 or 400? Would the 400 still be a lot faster than say the king 300? Or should I just go for the 140 so I can really chew through material if needed... My next project is a massive 330mm masamoto yanagiba that has very small chipping along the whole length of the blade, I'm excited to see how that turns out
IMG_20220607_004154.jpg
 
Thanks for the replies guys, lots of help and food for thought.

I decided to get a king 300 stone and hope it did better than cheapo home line naniwa 220. It definitely does perform a lot better (no visible dishing) but after another 30 odd minutes of attacking the main bevel I still wasn't getting a bur on the uraoshi side. So just to check my sanity I went for a slightly higher angle on the main bevel just to get at that apex, after a short time I could feel a bur and worked my way up a couple of grits to get the knife to a respectable sharpness!

View attachment 182985

So I'm glad I got there in the end but not so stoked on cheating and using a more aggressive angle basically because I feel like I just can't make fast enough progress with my stones, so I think I will bite the bullet and buy an atoma, the question is..... 140 or 400? Would the 400 still be a lot faster than say the king 300? Or should I just go for the 140 so I can really chew through material if needed... My next project is a massive 330mm masamoto yanagiba that has very small chipping along the whole length of the blade, I'm excited to see how that turns outView attachment 182989


I really like my King 300, it is a great cheap low wear rougher water stone. I find I need to give it a quick SiC 80/120 lapping every few knives to keep it cutting well, otherwise it can get pretty fine, almost same as a 1k stone. I use crystolon and india stones if I need something rougher than the king 300. I just dislike the feeling of dragging metal on diamond plates and avoid them. Certainly go for the 140 diamond if you want a really fast steel chewer however.

I havent often worked hard on thinning bevels of knives, I have done it a few times and just didnt feel like it was worth the effort all at once. I also don't think I would feel like I cheated if I got the knife sharp regardless of the angle. You can work a little more off the main bevel each time you sharpen to get things more balanced going forward. I guess it wont be as pretty looking however on that type of knife if thats the final goal. How much difference in angle is there? You might not have far left to go.
 
I guess it wont be as pretty looking however on that type of knife if thats the final goal. How much difference in angle is there? You might not have far left to go.
Yeah I hear ya, Im not too fussed about it but I guess getting the knife looking good is also a goal and Im guessing a good flat bevel would help a lot for getting a half decent kasumi finish (I am really keen on getting into kasumi finishes). Also this is my first single bevel knife so I was eager to sharpen it "right" just for the sake of it.

I had the bevel flat then lifted the spine maybe 2mm or so. To be honest I felt like I had not long to go the whole time haha, I could see that the bevel was reasonably flat with the consistent scratch pattern the stones were making along the while bevel apart from the very apex, thats what made me decide to just increase the angle at the apex and get it done with.
 
That little extra bit of lift to hit the apex is not necessarily a bad thing. Maybe not the traditional way to do single bevel sharpening. But it means you have a little micro convexity at the end. This will make your apex stronger and will improve food release properties without significantly diminishing sharpness. Basically a micro bevel with the shoulders rounded off.
 
That little extra bit of lift to hit the apex is not necessarily a bad thing. Maybe not the traditional way to do single bevel sharpening. But it means you have a little micro convexity at the end. This will make your apex stronger and will improve food release properties without significantly diminishing sharpness. Basically a micro bevel with the shoulders rounded off.
Yeah after looking more into single bevel techniques it seems what I have done is one of the normal methods actually, so I will take that as a win. Next goal is to get a nice Kasumi finish.. I can see that becoming a deep rabbit hole too haha. Lets goooooo!
 
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