# CarboNext - first sharpening advice.



## rdpx (Feb 11, 2013)

After a few days using the new Gyuto, I think it is nearly time to give it a proper edge. 

Before I do so, I am posting a drawing of what I think I am supposed to be doing with it.

The knife is advertised as being 60/40 and it looks like it is something like that, but the angles of the bevels are probably 20-25*deg, though this is a rough guess.

What I am planning on doing is as shown in the drawing - regrinding the bevel at about 12-15*deg, and then putting a microbevel on that is similar to the angles that are there already [the red line].

What I would appreciate would be if you could tell me:

1. Does this look like I have correctly understood what needs to be done?
2. Is what I am planning on doing to the main bevel the same as "thinning" the blade?
3. Approx how many millimetres should I expect to be grinding back up the blade (ie. the distance between current beginning of edge, and what it will be when I am done)







Thank you!

R


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## ThEoRy (Feb 11, 2013)

That's roughly correct though I may suggest the magic marker trick. Simply paint the edge with a permanent marker and while sharpening be sure that you are abrading from the top of the bevel first then down to the cutting edge. This will take the guesswork/measuring angles out of the equation. Also, keep it simple for a while. Just work on setting clean bevels, refining it a bit and stropping off any burr/wire edges. Don't worry about compound bevels or micro bevels yet. I feel with that knife you may not even need that anyway.


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## stevenStefano (Feb 11, 2013)

Yes I think you understand it about right. I wouldn't worry about a microbevel though. I wouldn't say you are thinning, no, you're just setting a bevel. In terms of how much bigger the bevels will be, it's pretty hard to say. Everyone basically has "their" angle and I doubt many people even know what theirs is. To be honest I'd forget about putting a number on things, pick an angle and see how the knife performs and then next time you sharpen, make it more or less acute depending on how you liked it


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## Benuser (Feb 11, 2013)

The right bevel should be convexed, not straight. I wouldn't change the left one. A lower left angle doesn't really enhance performance but weakens the edge considerably.


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## tk59 (Feb 11, 2013)

I think you're fine. It's gonna be convex already if you grind it manually. I wouldn't bother with the micro initially. If you decide your edge is too fragile, I would put a micro on only one side and if that was still too fragile for your tastes, then maybe both sides.


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## wenus2 (Feb 11, 2013)

tk59 said:


> I think you're fine. It's gonna be convex already if you grind it manually. I wouldn't bother with the micro initially. If you decide your edge is too fragile, I would put a micro on only one side...


Yes.

I would really suggest not over thinking it. Just put an edge on it. This is one of the easier knives to get good results from.


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## rdpx (Feb 11, 2013)

Thanks all - I am trying not to overthink it, it's just that my understandings of all the explanations on here have not been clear. I just want to get the nod on what is in my mind before starting in on my new knife. 

So is this drawing more like what I should be aiming for? :


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## TB_London (Feb 11, 2013)

If the edge has stood up well and you want to sacrifice some strength for performance it looks fine to me. Magic marker is your friend when learning to sharpen


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## rdpx (Feb 11, 2013)

TB_London said:


> If the edge has stood up well and you want to sacrifice some strength for performance it looks fine to me. Magic marker is your friend when learning to sharpen



NB: Edge as is is OOTB which I am told is way below what the knife can do.


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## tk59 (Feb 11, 2013)

rdpx said:


> Thanks all - I am trying not to overthink it, it's just that my understandings of all the explanations on here have not been clear. I just want to get the nod on what is in my mind before starting in on my new knife.
> 
> So is this drawing more like what I should be aiming for? :



Yes.


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## rdpx (Feb 11, 2013)

tk59 said:


> Yes.



:goodpost:

That is what I needed to hear....Thanks!!


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## gic (Feb 11, 2013)

Interesting, I too am about to sharpen my new CarboNext but am going a completely different route: I decided to put a symmetric 10 degree back with a 15 degree microbevel. I just don't like the PITA value of asymmetric grinds - ) ) 

but I love microbevels since I got my edge pro. I was converted by among others Chad Ward's arguments in favor: it seems to me an uber thin back bevel (which I define as slightly more than the knive could take as a stand alone V edge) than adding a 3-5 degree higher microbevel always gives the best combination of good retention with good performance.

Of course on a carbonext I suspect the limits might even be something like 8 degrees with a 12 degree microbevel on a carbonext but at roughly 60HRC that seems pushing it while 10/15 is a piece of cake and I love the performence of other knives that I have done 10/15 with..


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## tk59 (Feb 11, 2013)

It's good you found your happy spot. Personally, I like my edges without microbevels for the most part. I love the feel of a super keen, thin edge. Since I'm not a pro, I can go a long time with it and it's great. In many cases, microbevels are like putting long-wearing tires on your car. It just isn't going to take the corners as well but if you're logging lots of miles on the freeway, maybe it's worth it.


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## ThEoRy (Feb 12, 2013)

gic said:


> Interesting, I too am about to sharpen my new CarboNext but am going a completely different route: I decided to put a symmetric 10 degree back with a 15 degree microbevel. I just don't like the PITA value of asymmetric grinds - ) )
> 
> but I love microbevels since I got my edge pro. I was converted by among others Chad Ward's arguments in favor: it seems to me an uber thin back bevel (which I define as slightly more than the knive could take as a stand alone V edge) than adding a 3-5 degree higher microbevel always gives the best combination of good retention with good performance.
> 
> Of course on a carbonext I suspect the limits might even be something like 8 degrees with a 12 degree microbevel on a carbonext but at roughly 60HRC that seems pushing it while 10/15 is a piece of cake and I love the performence of other knives that I have done 10/15 with..



It's only a pain in the ass because you are using an edge pro. Freehand it's simple. TBQH Most Japanese knives aren't made to be sharpened perfectly symmetrical and in my experience perform better with at least a slight asymmetry.


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## gic (Feb 12, 2013)

Now you have piqued my curiosity. Why do you say "Most Japanese knives aren't made to be sharpened perfectly symmetrically" ?

I grant you that they are not ground symmetrically out of the box (although many of my Japanese knives came with pretty crappy edges OOB and often seem to be almost randomly ground, they are described as 70/30 say and I just can't see that when I actually start sharpening it.

But of course the CarboNext OOB edge is just about the worst of the 10 or so Gyutos I have bought:- ) ).

But "made" is a strong word. My assumption has always been the knife starts out perfectly symmetrical out of the forge. Then someone puts it to a wheel and/or stones and grinds it either symmetrically or asymmetrically. But the knife could take either when it started out as a piece of steel from the maker or it could even be given a left handed asymmetry instead of the more common right handed one..

(I tried freehand before I got the edge pro, unfortunately I discovered I just don't have a good enough muscle memory or motor control at my age to make it fun or even really effective. Becoming a good enough free hander to out perform what I can do with the edge pro is just not in the cards for me any more. Now if I had started say 30 years ago, the story would be different :- ) )


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## Benuser (Feb 12, 2013)

It's not so much about the edge, it's about the entire geometry. With almost all J-knives the axis is offcentered. For best results have the edge in the extension of the axis. 

http://www.kitchenknifeforums.com/showthread.php/5656-Asymmetry--The-REAL-DEAL


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## Notaskinnychef (Feb 12, 2013)

Seeing all this makes me paranoid for when I sharpen my carbonext. I'm still practicing on crap house knives and i haven't had the balls to take my CN to the stones yet lol


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## gic (Feb 12, 2013)

So now this is getting very interesting and I too am glad I haven't started on my Carbonext. I wonder how to tell id a knife is simply ground asymmetrically (in which case one could theoretically do what what wants) and convert it to a symmetric grind or is actually forged/stamped asymmetrically in which case one should obviously never even try to adjust the symmetry.

Any ideas on how to tell if it is the former or the later?? (Of course if it is the later that would explain why left handed knifes are so expensive, they have to be forged/stamped differently in presumably smaller batches.)


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## Benuser (Feb 12, 2013)

Ignoring the edge, you may see that often the left face is flat, and the right one is more or less convex. The edge is as near as possible to the food to be cut in order to allow thin slices, and the convexity allows to push it away once cut and avoid sticking.
With very thin blades the difference isn't always very obvious.


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## Jmadams13 (Feb 12, 2013)

Really it would be best to read Dave's thread on asymmetry, as your already over thinking it. It would answer all your questions. He even goes into it concerning usin an edge pro


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## mpukas (Feb 12, 2013)

IMO, all this business with asymmetrical bevels on a symmetrical gyuto is unnecessarily complicated. Knives are ground by hand and theres bound to be slight differences from one face to the other. Unless its obvious, its probably not intentional to have asymmetrical faces

Unless a knife is ground with one face flat and one face convex, there's no point in doing anything other than either a 50/50 or 99/1 bevel. And a 99/1 bevel only if youre going for a particular cutting characteristic/style/method, like KC did (RIP). 

I initially sharpened my Yusuke 300 suji w/ a 99/1 bevel, and it steered through tall things like pineapple and melon. Changed to a 50/50 and problem solved with no loss of performance/sharpness. If I was using it as a dedicated slicer for say cooked meat, maybe a 99/1 edge would perform slightly better, but I doubt it. 

60/40, 70/30, 12 on side  20 the other side, etc on a knife with symmetrical faces isn't going to make a noticeable difference, and only makes sharpening more complicated than it needs to be. Theres already enough going on to not have to bothered by such nonsense.


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## Dave Martell (Feb 12, 2013)

I like the first drawing if the micro bevel is removed. Thinning and working both sides evenly.


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## Dave Martell (Feb 12, 2013)

gic said:


> So now this is getting very interesting and I too am glad I haven't started on my Carbonext. I wonder how to tell id a knife is simply ground asymmetrically (in which case one could theoretically do what what wants) and convert it to a symmetric grind or is actually forged/stamped asymmetrically in which case one should obviously never even try to adjust the symmetry.
> 
> Any ideas on how to tell if it is the former or the later?? (Of course if it is the later that would explain why left handed knifes are so expensive, they have to be forged/stamped differently in presumably smaller batches.)




*ALL* Japanese knives are asymmetric (the entire blade as well as the edge)


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## rdpx (Feb 12, 2013)

Dave Martell said:


> I like the first drawing if the micro bevel is removed. Thinning and working both sides evenly.




Now you tell me!

CN sharpened as per drawing 2, though not so straight.

Am pretty happy with it. I did a bit of slow #240, then some #1000 then polished it with the 6K. 

It looks pretty good and seems fairly sharp.

Will attack drawing 1 when I am next minded. Thanks everyone.
RDPX


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## cclin (Feb 12, 2013)

rdpx said:


> Now you tell me!
> 
> CN sharpened as per drawing 2, though not so straight.
> 
> ...



how about some "before & after" pictures??:hungry:


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## rdpx (Feb 12, 2013)

cclin said:


> how about some "before & after" pictures??:hungry:



I will have a go in next day or two.... wont be as pretty as factory edge though !


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## rdpx (Feb 12, 2013)

mpukas said:


> IMO, all this business with asymmetrical bevels on a symmetrical gyuto is unnecessarily complicated. Knives are ground by hand and theres bound to be slight differences from one face to the other. Unless its obvious, its probably not intentional to have asymmetrical faces
> 
> Unless a knife is ground with one face flat and one face convex, there's no point in doing anything other than either a 50/50 or 99/1 bevel.



Funnily enough, far from being complicated, I actually found today (first real sharpen) that doing it asymmetrically actually seemed easier to achieve. I just had to grind the R side a lot, then follow up with a bit on the left. It seems fairly even I think, though god knows if it is 60/40 or 70/30 or 80/20 or whatever, but it is definitely R side biased. If I was trying to make it 50/50 that would have seemed to be a lot more difficult to get correct.

I found using my 8x loupe to check the edge helped a lot. The "mirror" finish on the edge is lovely, though there are scratches on the blade face which I tried really hard to avoid, to no avail. Might have to polish them out at some point....


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## gic (Feb 12, 2013)

OK now I am really confused: most of the gyuto's I bought were said to be 50/50 ground in the manufacturers descriptions like my Mac's or my Tojiro's which are the usual knives I use??? 

Sorry to be such a newbie...


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## Dave Martell (Feb 13, 2013)

gic said:


> OK now I am really confused: most of the gyuto's I bought were said to be 50/50 ground in the manufacturers descriptions like my Mac's or my Tojiro's which are the usual knives I use???
> 
> Sorry to be such a newbie...




Years ago when none of us knew anything about this subject the retailers and manufacturers had it made but then we started figuring this stuff out and began asking questions which drove (some of) them to address our questions in their product descriptions. 

The issue that a retailer (or manufacturer) faces is how do they answer the question of how to sharpen asymmetrically? They answer is they can't....or won't. They will say to sharpen 50/50 because they want you to think that the knife they're selling isn't asymmetrical - they want you to feel good - go ahead and make that purchase without fear of how to maintain your new knife. The problem with that is the reality is somewhat different than what the salesman wants you to believe. 

See *Asymmetry - The REAL DEAL* for the true scoop on this subject.


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## mpukas (Feb 13, 2013)

KCMA was an advocate of just sharpening the right side and deburring on the back. Mainly because it took him half the time since he only had to sharpen one side, and also because he knew how he wanted his knives to perform and used them in that manner.


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## franzb69 (Feb 13, 2013)

i wanna see the after pix =D


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## Benuser (Feb 13, 2013)

By the way: most Tojiro are 60/40, amongst those the DP series.


http://tojiro.net/en/guide/part_edge.html


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## gic (Feb 13, 2013)

wow live and learn, I thought they were 50/50 like my Mac's for some reason. Luckily I haven't had to sharpen them, just used a ceramic hone, yet so I didn't ruin that :- )


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## franzb69 (Feb 13, 2013)

me too, thought they were 50/50 as well


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## Benuser (Feb 14, 2013)

Dave Martell said:


> I like the first drawing if the micro bevel is removed. Thinning and working both sides evenly.


Why would you thin the left side, it's already flat? Or do you mean to ease the shoulder?


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## Dave Martell (Feb 14, 2013)

Dave Martell said:


> I like the first drawing if the micro bevel is removed. Thinning and working both sides evenly.





Benuser said:


> Why would you thin the left side, it's already flat? Or do you mean to ease the shoulder?




I try to do the same amount of work on both sides equally. The reason I do this is because I've seen what the fix is for steering. Since back when I first started sharpening Japanese knives I've always had customers send in gyutos that steered or twisted and ask for me to fix this problem. In almost all cases I see that a lot of sharpening/thinning was done to the right side and almost nothing done to the left. So I simply equal the balance out by removing material on the left side. By all accounts this fixes the steering/twisting problem. That's why I tell folks to work both sides evenly. yes you'll still have one side (the right) with a taller bevel (because of the blade's asymmetry) but that doesn't mean that you haven't worked an equal amount. Now should someone desire a more single sided knife that has some desire to steer then by all means go for thinning and working on the right side only.


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## Benuser (Feb 14, 2013)

Thanks, Dave.


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## Benuser (Feb 14, 2013)

Interesting point. Misono convexes its left edges as well. With a Hiromoto AS, sooner or later you have to remove cladding to free more core steel, and so the end of the left face will get slightly convexed. I must admit that reduces steering.


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## rdpx (Feb 15, 2013)

Ok, by popular demand, here are some photos of my sharpened CarboNext..... please feel free to say if anything looks like I might have done it wrong, but I am pretty pleased with it. I think the advice about #240 being too harsh was correct, but you can only really tell on the macro shots. This took me a while...but it now cuts very very nicely indeed. Need to get some polishing grade paper for the blade sometime....


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## rdpx (Feb 15, 2013)

OOTB choil:


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## wenus2 (Feb 15, 2013)

That choil comparison is really cool, you sure can take some pictures.

It looks good. If you're happy with how it cuts, then I'm happy for you.
Let us know how that acute angle holds up for you.


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## stevenStefano (Feb 15, 2013)

You photography is really nice, I like it. Any chance you could post a few farther out shots though?


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## rdpx (Feb 15, 2013)

stevenStefano said:


> You photography is really nice, I like it. Any chance you could post a few farther out shots though?



Hi Steven, thanks!
When you say further out do you mean of the whole knife? Tell me what you want to see and I am happy to post one in next day or so.

Point here was to show the edges. At the size these reproduce on the page, a "full-length" shot would pretty much just look like a.n.other CarboNext (ie see it here!) . Actually, looking at that again, what I have done ain't going to compare well to the shiny OOTB CN. Apart from the edge, of course, which is a lot better.


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## rdpx (Feb 15, 2013)

I was just having a look at that choil shot in photoshop, and I make it that the edge angle is about 17*degrees. Assuming it is consistentish all along the blade, that seems awfully low like 8/9*deg on each side. Is that going to hold or is it too extreme?


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## Dave Martell (Feb 15, 2013)

I hope that you never get your hands on something that I've worked on. Damn pictures show too much!


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## rdpx (Feb 15, 2013)

Dave Martell said:


> I hope that you never get your hands on something that I've worked on. Damn pictures show too much!



I could blackmail you for free knives for life, or post macro shots of the blades....

:viking:

Whole thing does need a bit of a polish though. It seems even if I am extremely careful I put scratches in it. I had odd looping scratches on the blade about 1cm from the edge, then realised it was my fingers moving up and down the surface, rubbing in wet grit from the stones.... how do you avoid that? Or do you just have to accept it, and polish it out after the fact?

So what do you reckon to my first sharpening attempt, Dave?


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## Benuser (Feb 15, 2013)

rdpx said:


> I was just having a look at that choil shot in photoshop, and I make it that the edge angle is about 17*degrees. Assuming it is consistentish all along the blade, that seems awfully low like 8/9*deg on each side. Is that going to hold or is it too extreme?


I don't know what you where able to see on your screen, but I guess you haven't actually seen the very edge.


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## don (Feb 15, 2013)

Really impressive photos, and your first sharpening job looks better than mine. I'm far from an expert on technique, so I'll let others provide more constructive feedback.


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## rdpx (Feb 15, 2013)

Thanks Don.



Benuser said:


> I don't know what you where able to see on your screen, but I guess you haven't actually seen the very edge.



This is as big as it gets on my screen, Bernard...


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## Benuser (Feb 15, 2013)

Very nice pic, great geometry, still hard to say though. At 5mm from the edge, thickness is some 0.5mm. The thickness of the very edge is in the same order as aluminium foil -- 10 micron. So, I remain a little sceptic about viewing the very edge. 
What angles have you sharpened at?
If you would find your edge to be too fragile, you may add a microbevel on the right side, see Jon Broida's video.

P.S. With free hand sharpening every bevel will end slightly convexed.


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## Benuser (Feb 15, 2013)

A trick to verify the angle: slide your flat blade on a board or a piece of leather, and lift the spine till the edge bites. Your sharpening angle is a few degree lower. Try with both sides.


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## cclin (Feb 15, 2013)

nice edge! any chip prone issue ?? It look like too fragile for a all-around gyuto......try to cut or chop some hard root veg.


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## eto (Feb 15, 2013)

Dave Martell said:


> I try to do the same amount of work on both sides equally. The reason I do this is because I've seen what the fix is for steering. Since back when I first started sharpening Japanese knives I've always had customers send in gyutos that steered or twisted and ask for me to fix this problem. In almost all cases I see that a lot of sharpening/thinning was done to the right side and almost nothing done to the left. So I simply equal the balance out by removing material on the left side. By all accounts this fixes the steering/twisting problem. That's why I tell folks to work both sides evenly. yes you'll still have one side (the right) with a taller bevel (because of the blade's asymmetry) but that doesn't mean that you haven't worked an equal amount. Now should someone desire a more single sided knife that has some desire to steer then by all means go for thinning and working on the right side only.



This style of sharpening works for me as well. It just makes sense.


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## franzb69 (Feb 15, 2013)

looks only very slightly asymmetric. 60/40 alright.


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## Benuser (Feb 16, 2013)

Are you sure you have seen the pic in post number 49??


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## Dave Martell (Feb 16, 2013)

rdpx said:


> So what do you reckon to my first sharpening attempt, Dave?




While your pictures show great detail I couldn't use them to tell how you did at sharpening the knife.


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## Lefty (Feb 16, 2013)

I'm either brilliant, stupid or somewhere in the middle, but all I do is sharpen until a burr is created, flip it back and forth, deburr, repeat at different levels, until desired sharpness is achieved. Don't over complicate things.


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## franzb69 (Feb 16, 2013)

what lefty said

=D

i've kinda believe what boar d laze (the resident know it all on another forum) says about 60/40 bevels, as the carbonext is 60/40....

http://www.japanesechefsknife.com/KAGAYAKICarboNextSeries.html

that it shouldn't really bother a lefty or a righty.

so you can pretty much sharpen it 50/50 for the meantime without much problems.


but when you do get to the point that you need to thin the knife, then problems will start showing. such as steering.

thinning it will solve that. thinning it properly that is. i can't tell you how as i haven't gotten to that point yet with japanese knives that i need to thin it down because i am getting into steering problems.

of course i have thinned a knife and i have done it a few times but not a lot with asymmetric knives. only with my aritsugu kyoto that was bought used and was already thinned by the previous owner then was neglected and then sold to me. i thinned it a little just to clean up the blade face coz it was pretty beat up and enough to thin up the already barely visible shoulder.


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## rdpx (Feb 16, 2013)

Dave Martell said:


> While your pictures show great detail I couldn't use them to tell how you did at sharpening the knife.



spoilsport


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## Keith Sinclair (Feb 16, 2013)

Lefty said:


> I'm either brilliant, stupid or somewhere in the middle, but all I do is sharpen until a burr is created, flip it back and forth, deburr, repeat at different levels, until desired sharpness is achieved. Don't over complicate things.


 
Sounds good lefty,these days I kick in a final bevel on a 4 or 5K.It's more durable edge & makes a blended convex bevel which I find works well for kitchen knives.


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## rdpx (Feb 16, 2013)

I think the edge I made is too acute. Seem to be getting a couple of micro nicks in it, if that makes sense. Will try a small bevel on R-side at some point, as suggested in the "microbevel on asym.." thread... [it still cuts beautifully, mind you]


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## Benuser (Feb 16, 2013)

Might be the edge is too acute. Then, you're right to put a microbevel on the right side. However, another explanation would be remainings of the original weak edge. Microchipping is very common with brand new knives. Has perhaps to do with buffing in factory. Once you've abraded enough steel the problem is over. As you seem to work very carefully there is no reason not to start with your coarse stone next time.


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## Benuser (Feb 16, 2013)

http://m.youtube.com/watch?client=mv-google&gl=NL&hl=en&v=xwnFrjiAA_8&p=EBF55079F53216AB


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## rdpx (Feb 17, 2013)

Benuser said:


> Might be the edge is too acute. Then, you're right to put a microbevel on the right side. However, another explanation would be remainings of the original weak edge. Microchipping is very common with brand new knives. Has perhaps to do with buffing in factory. Once you've abraded enough steel the problem is over. As you seem to work very carefully there is no reason not to start with your coarse stone next time.



Thanks Bernard, all very helpful, especially that video you linked to.

Job done. Remarkably easy and quick, almost disappointingly so! Will let you know if it hold it better now. Knife is cutting like a dream, could be used for microscope slide specimen prep!


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## Benuser (Feb 17, 2013)

Glad to hear! Meanwhile we've got used to your pix, you've set the bar very high.
Most important though is your knife performs well. Great job.


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