PDA

View Full Version : normal dulling?



slowtyper
07-07-2011, 01:30 AM
Lately I have been using my yoshihiro carbon usuba a lot. I sharpen it until it can push cut regular paper and feels very sharp. I put on a microbevel with just a few strokes and I can see that bevel glint in the light.

Now I am doing katsuramuki and after a few cucumber the knife is noticeably duller. Same with shaving green onions, after a single bunch of onions I can feel it is duller. Need to strop and all is right. Wire edge? I thought the microbevel should take care of that. I mean it isn't dull, still sharp but not as razor sharp as when I start. This can't be normal can it? Could my microbevel be too small to be effective? Would another stone help? Currently use bester1200 and arashiyama6000

JBroida
07-07-2011, 02:09 AM
roughly what angle are you doing the microbevel at? how does the ura look? Are you using a flat grind on the bevel or is it more hamagurbia? Do you do anything to clean up the edge for burrs/ wire edge after putting on the microbevel? Is there a chance you are rounding the edge on your strops? What stropping compounds are you using?

tk59
07-07-2011, 02:19 AM
You can still get a wire edge after you put a micro but I usually don't get this sort of problem on carbon. How much pressure are you applying when you put the micro? It should be pretty light. If you deform the edge too much while applying the microbevel, you may form another wire edge.

Also, exactly what do you mean by "noticeably duller?" Does it still push-cut paper? Does it still shave easily with both sides of the edge?

EdipisReks
07-07-2011, 06:43 PM
that sounds like it would likely be a wire edge. i only experience noticeable dulling after prolonged board contact. it's not the best way to remove a wire edge, but try lightly pulling the edge on the corner of your cutting board a couple times before you start processing food, and see if your edge lasts longer.

Lefty
07-07-2011, 07:48 PM
I don't see a problem with that. It's an effective way to remove burrs...

slowtyper
07-12-2011, 06:21 AM
roughly what angle are you doing the microbevel at? how does the ura look? Are you using a flat grind on the bevel or is it more hamagurbia? Do you do anything to clean up the edge for burrs/ wire edge after putting on the microbevel? Is there a chance you are rounding the edge on your strops? What stropping compounds are you using?
Whoa lots of questions!

Microbevel seems like roughly a 20-25 degree angle? I don't really know how to answer how the ura looks....not really sure what I'm looking for. I mean it definitely goes all the way to the edge and its fairly even all the way around.

At first I followed your videos for the hamaguriba however I realized after I was lifting the blade too high when I did the edge. I wasn't getting the edge completely. Also I have to admit that when i am supposed to see two distinct bevels I see nothing...after I "round" the two bevels, I can feel it on the stone but again...I see nothing. Am I blind? Maybe I dont know what to look for.

Anyways, now when I sharpen I do the edge first, then pretty much lay the big bevel flat and try to flatten it. I don't really go to town to flatten it, just do it a little bit each time I sharpen.

Also, I took the microbevel off and actually am seeing some improvement so at least I can narrow it down to knowing that I need to fix my microbevel.

i also thinK I was going too hard on the strops. I use leather (not sure what kind...some scrap leather from a store) on handamerican chro..ox...I have been using a much lighter touch (pretty much just the weight of the knife)..and much slower...and also seeing better results. Hard to say what exactly did it since I am too impatient to try changing one thing at a time.

One more question...what angle do you strop at? I read slightly higher than the edge angle...but what about when I have a microbevel? I was a bit confused about that.

mikemac
07-12-2011, 11:44 AM
If it feels that dull that quickly, it has to be a wire edge, and stropping will mostly 're-align' the wire edge at this point.

Stropping on most leather with preassure will round the edges so thats usually a 'weight of the knife' thing.

With or without a microbevel, when stropping (trailing edge), lift the spine and gently & slowly push forward...keep lifting the spine until the edge just bites into the leather...thats your angle

Dubsy
07-13-2011, 09:30 PM
personnaly, i dont see how stropping angle matters. leather isnt solid like a stone, so as long as your in the ballpark and arent putting pressure on the knife you should be fine. the leather will bend slightly and cover the rest of the edge.

EdipisReks
07-13-2011, 09:38 PM
personnaly, i dont see how stropping angle matters. leather isnt solid like a stone, so as long as your in the ballpark and arent putting pressure on the knife you should be fine. the leather will bend slightly and cover the rest of the edge.

i think angle matters at least as much with stropping as it does with a stone, as it's easy to actually blunt the edge on a strop when you let the knife dig in too much. leather gives a lot, even when you don't think you're putting much pressure on it. it's less of a problem with balsa.

Dubsy
07-13-2011, 11:11 PM
wait, you can strop with balsa wood?

slowtyper
07-13-2011, 11:39 PM
hm another problem....I was sharpening the usuba today (just with the 6K). Got it pretty sharp and was inspecting it. I notice that if I put my fingernail and press it on one side of the edge, I can see the steel "popping" or "bending" a on the other side. It's not just a tiny bit moving either, when I press it, it seems like a 1mm diameter circle of steel "moving" on the other side of the edge.

Is this normal for fragile edges like this usuba or does this mean I am sharpening wrong?

Dubsy
07-13-2011, 11:45 PM
back in high school there were a group of japanese exchange students that came, and gave the culinary arts program one of their school knife sets. they were better than the stamped mercers we have, but the edges were so fragile. same issue you had. i took one to a stone and put a flatter grind on it, around 30 degrees instead of the 20. no more issue. you're grinding the angle too steep.

slowtyper
07-13-2011, 11:56 PM
I don't understand...it is a single bevel knife...

Dubsy
07-14-2011, 12:09 AM
there are some japanese knives that have a second grind with the big one that reaches up the blade. think of it like those cheap greban knves that are so prevalent in food service, where they have a second grind that comes up about a 1/2 inch past the blade. just adjust your grind angle on that side, and you're problem should go away.

spaceconvoy
07-14-2011, 12:17 AM
Many people think single bevels are easier to sharpen because they have a 'built in angle guide,' but they're wrong. Single bevels are just as challenging to get right, but in different ways from double bevels, if not more so.

The main issue with single bevels is (typically) the difference in hardness between the hagane and jigane. Because the jigane is (again, typically) much softer than the hagane, if you don't make any adjustments while sharpening, you'll eventually lower the angle of the bevel (because the jigane wears away faster than the hagane).

Basically, yes, you are sharpening incorrectly. You shouldn't be able to flex the edge as much as you're reporting to us. Raise the angle to adjust for the difference in steel softness.

JBroida
07-14-2011, 12:38 AM
hm another problem....I was sharpening the usuba today (just with the 6K). Got it pretty sharp and was inspecting it. I notice that if I put my fingernail and press it on one side of the edge, I can see the steel "popping" or "bending" a on the other side. It's not just a tiny bit moving either, when I press it, it seems like a 1mm diameter circle of steel "moving" on the other side of the edge.

Is this normal for fragile edges like this usuba or does this mean I am sharpening wrong?

in your hamaguri, make the second bevel (the one from the lamination line to the edge) a little less acute... then you may want to micro the edge

slowtyper
07-14-2011, 01:42 AM
Right now for the edge, I lay the blade flat and raise it just a little bit. Since my hands are not so steady and I am a new sharpener, I always felt I was raising it higher than most would do it. So if I understand, I should be raising it even higher. Is there a rough rule of how high to raise it? I will give it a shot the next time I sharpen.

Thanks guys.

JBroida
07-14-2011, 01:45 AM
Right now for the edge, I lay the blade flat and raise it just a little bit. Since my hands are not so steady and I am a new sharpener, I always felt I was raising it higher than most would do it. So if I understand, I should be raising it even higher. Is there a rough rule of how high to raise it? I will give it a shot the next time I sharpen.

Thanks guys.

without seeing how you are sharpening it, its really tough for me to tell... i'm just giving my best guess. You have skype? Maybe i can help you out over a video chat or something?