CarboNext - first sharpening advice.

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

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.

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

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.

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.

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...

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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.

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? :

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

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

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

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? :

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Yes.

tk59 said:

Yes.

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:goodpost:

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

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 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.

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..

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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.

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 :- ) )

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

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

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.)

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.

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

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.

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

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.)

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

Dave Martell said:

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

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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

rdpx said:

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

cclin said:

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

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

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.

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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....

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...

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...

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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.

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.