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Hiromoto AS sharpening question

post #1 of 17
Thread Starter 

Hey this arrived in the mail the other day, reasonably sharp OOTB, however I decided to take it across a 1000 (JCK), 2000 and 5000 (korin, mizuyama) grit to really polish it up. The knife was stupidly sharp before stropping however after stropping gently on a leather belt it was quite dull.  I suspect I've folded the edge, which is surprising as I was under the impression super steel was pretty tough!   The only thing I can think of is re-sharpening at a more obtuse angle -- any suggestions?

post #2 of 17

If you don't mind a little scuff, you can probably take care of the whole thing by steeling the knife a couple of times to chase the burr, then deburring in a cork or piece of felt.  Otherwise, you might be able to raise a fresh burr on your 5K, chase it, then deburr.

 

Kitchen knives aren't straight razors.  In the future, don't strop your kitchen knives on a belt, it's too flexible and tends to roll long edges.  FWIW, AS (stands for Aogami Super) is not tough, it's strong ("tough" and "strong" are materials terms of art); but it's certainly not so strong you can't turn a wire into a burr on a belt.

 

Enjoy your new knife,

BDL

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post #3 of 17
Thread Starter 

hey thanks Stropping on my Misono's UX-10's never seemed to do this, but then again maybe I was never getting the knives as sharp.  Also, is it over kill going from the 1000, 2000 then 5000? The JCK 1000 I bought feels pretty rubbish (compared to the mizuyama), and in fact I'm thinking about just giving it away and getting a chocera or something nicer.
 

post #4 of 17
Thread Starter 

As for the scuff, the stainless on this thing scuffs when you show a dish scourer to it, I ended up rubbing the whole blade over a 5K stone and using a course brush with some toothpaste to give it a dull finish that wont show scuffs as bad.  I'm not quite sure what else could be done to keep it pretty...

post #5 of 17

the hiro AS cladding is super soft.  Rubbing the knife flat on a stone tends to do more harm than good.  Look into things like rust erasers or even wet/dry paper.  Just make sure to only rub in one direction when you do this.

 

As far as the edge.  1k-2k-5k is more unnecessary than overkill.  1k-5k works.  So does 2k-5k.  Using the leather belt is probably not best in this case.  Thin leather on a hard flat surface is better if thats the way you want to go.

 

Also, BDL is right.  Aogami Super is not tough.  It is geared towards having the best edge retention and corrosion resistance of the hitachi made carbon steels.  However, that also means its chip resistance (toughness) is pretty low (due in part to high hrc), its ease of sharpening is lower than other steels, and its ability to take a fine edge is lower as well (due to the large carbides formed by the chromium and tungsten).

post #6 of 17
Thread Starter 

So what knife will take the best edge, I'm looking at a Ryusen Blazen next, is that a step forward/backward? I also have some UX10's that I'm so so on, but they are still very nice in most respects, just not edge retention.

post #7 of 17

If you want a really sharp edge, your best bet is learning to sharpen better before purchasing a new knife. 

 

I meant to ask you why you used a 1K, 2K, 5K progression (Jon is right... too many stones), but forgot.  You want to stick with advice from people who actually know how to sharpen.  Are you taking Korin's advice?  Bless their little hearts, while their "resident sharpening expert" is an excellent sharpener, he does not do a good job of teaching sharpening.

 

Jon has pursued sharpening as much as anyone else, has great knowledge about the subject, likes to teach, is an excellent source for practical advice and has videos up.  There are few other people in the same class, but there are a few. 

 

Some people are very good sharpeners but not necessarily great teachers for typical sharpeners.  Murray Carter, for instance. 

 

Let me add something about Jon also sells wonderful knives and sharpening stones you can't get anywhere else.  He's one of three people I relate to most in the knife world, and one of very few from whom I'd consider purchasing.

 

At the risk of immodesty, I'm a good source for sharpening knowledge (but no videos).  My strength is relating practical skills to an intellectual understanding of WTF is going on with the edge.

 

The easiest way for most people to learn to sharpen well, is to learn to raise a burr, chase the burr, and deburr.  If you're interested in the physical process of why that works as well as the practical discipline of how to go about it, we can talk. 

 

I'm not a huge fan of the Hiromoto AS for all sorts of reasons, but will repeat my advice.  Hold off on a new knife until you get your sharpening kit and skills together. 

 

FYI, In terms of edge properties, the Ryusen Blazen doesn't do anything the Hiromoto doesn't also do.  Better handle though.

 

BDL

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post #8 of 17

I sharpen on wet&dry, going on 1000, 1200, 1500, 2000 grit. This is what they're supposed to be but I suspect theyre actually quite finer than that through usage. Is the basis of getting an edge sharper just going through the grits, holding a consistent angle, raising the burr, or am I missing something?


When 'sharpening' my knives, I usually start on the 1000, till burr is raised, proceeding through the grits, till I get to 2000, then stropping on a brown a4 envelope. I can get the edge so it can easily slice magazine paper, shave hair etc but I feel that I could somehow get the edge sharper than it is, but I'm not sure how to go about it. 

 

Does using a stone offer any huge advantages over W&D?

post #9 of 17

Getting a sharp edge and getting a good cutting edge are slightly different (though related).  Just making a sharp edge doesnt mean its going to cut well.  Cutting well is about a combination of edge geometry, getting a clean edge, and refining it appropriately.    The latter part is about keeping a consistent angle, raising a burr, going through the grits, and cleaning up your edge to get rid of the burr and/or wire edge.

 

Stones do offer a few huge advantages over sand paper.  First, they are faster overall (in almost all cases... and when its not, its because you're using a so-so stone).  Second, they have a bit more height to them for knuckle clearance.  Third, the binding agents do make a difference and can yield different results with regard to polish, cutting speed, and tooth of the edge.  Also, because stones can have some give and create mud, its easier to get more consistent and even finishes.  All that and they last a lot longer.

 

Oh... and you can do cool contrast things with them, blend bevels better, and a lot of other cool tricks.... and there are wider grit ranges available.

post #10 of 17
Quote:
Originally Posted by JBroida View Post

Getting a sharp edge and getting a good cutting edge are slightly different (though related). 

 

I think this may be the problem I'm having, but I don't know how to really resolve it. There is no doubt in my mind that the edge is very sharp, for performing tasks such as cutting paper and shaving arm hair, but it doesn't seem to actually perform incredibly in the kitchen, when it comes to cutting things. 

 

What would generally be the reasons for this, and how do I fix these problems?

post #11 of 17

it can be a wide number of things... do you have some pictures of your knife?  Mainly a picture of each side of the blade, a closeup of the edge, a closeup of the tip, and a choil shot

post #12 of 17

Posted by kingofkings View Post

I think this may be the problem I'm having, but I don't know how to really resolve it. There is no doubt in my mind that the edge is very sharp, for performing tasks such as cutting paper and shaving arm hair, but it doesn't seem to actually perform incredibly in the kitchen, when it comes to cutting things. 

 

What would generally be the reasons for this, and how do I fix these problems?

 

Use appropriate edge angles and symmetry for your knife.  If they're not appropriate now, you'll have to "re-profile."  Since you're knife isn't doing what you want, it's probably a good idea.

 

Sharpening kitchen knives on sandpaper -- "scary sharp" -- usually doesn't work well. 

 

If your knife is appropriately profiled you should be able to create a VERY sharp edge on a medium-coarse stone in the 1K - 2K range using the "burr method," of raising a burr, chasing the burr and deburring.  If the edge is reasonably refined, chasing and deburring should create a fine, fresh metal edge.  Moving up to a medium/fine sharpening/polishing grit in the 3K - 6K range and pulling a wire, chasing it, and deburring should give you a very fine, fresh metal edge; so fine that it maximizes actual sharpness.  Going higher up the grit scale doesn't make a knife any sharper, just more polished -- which may or may not be something you want.

 

As a short, "more often than not" answer, people who use sandpaper for sharpening, and/or "strop," often leave massive wires.  Quite likely, your sharp edges collapse as soon as they meet actual food. 

 

You use too many grits too close together.  It's pointless and tends to promote... wait for it... wire edges.  The more surfaces you use, the higher the probability of error.

 

Alternatively, you may be sharpening too acutely.  Bevels which are too steep will act a lot like wire edges, but the solution is different. 

 

What kind of knife do you have?  What angles are you sharpening?  What asymmetry?  How do you measure your angles and degree of asmmetry?

 

Do you use the Magic Marker Trick?  What does it tell you?  You can tell more from the Magic Marker Trick than almost anyone (with the exception of Jon) can learn from pictures of your knife.

 

Cutting arm hair is no big deal.  Cutting paper is more about a reasonable edge and knowing how to hold the kinfe and paper than a great edge. Try other sharpness tests, like cutting onions.  Even a few thumb drags will tell you more.

 

BDL

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post #13 of 17
Thread Starter 

So my initial woes with the AS with hitting scary sharp and then losing it on stropping, which apparently is not a wire edge (although I have a belt strapped to a draw which I pull tight on, does this change matters?) I've hopefully solved by drawing the blade through some cardboard a few times to debur. (no felt or corks handy).

 

On each grit 1000 (I got the 1000 from JCK but its an awful stone, so I'll probably ditch it) and 2000 I raise a bur chase it then polish on a 5000 with a few trailing strokes each side.

 

Last night I raised the angle up to 45 to create microbevel as shown in a JKI video, although I started on a 2000 stone, working back up to 5000, which may or may not have been ideal, as I thought the 5000 wouldn't have had enough bite to actually re-profile a small section of the cutting edge.

post #14 of 17

you would be totally fine using just the 5000 stone for the microbevel.  However, i would probably work on getting the kind of edge you want without the microbevel before using the microbevel.

post #15 of 17
Thread Starter 

I really feel sorry for this knife, it was a gift for my old lady, which I've proceeded to grind down to a petty knife.  Might have to get myself a cheapy to practice on.

post #16 of 17

Had your exact scenario with this repair.

 

700

 

 

 

Could pop hair but didn't cut well after reshaping and initial sharpening

 

700

 

The shoulders were too high so I went to stones to thin it out like Jon describes.I used 220 grit, 1000, 2000, 3000, and 6000 grits to thin and resharpen.

 

Now it cuts very well but I did scratch it pretty high in the middle. redface.gif

 

700

post #17 of 17
For best results, start with a relatively coarse stone with AS (J400). Don't convex, stay with that angle. The tungsten carbides have to be abraded.
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