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Fixing Overgrinds?

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stevenStefano

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Pretty sure my knife isn't overground, but the problem is the same as if it was. My Masamoto has a small part just before the heel that does not hit the cutting board flat. I think it was me using a ceramic rod and not starting from the heel. I tried to fix this for quite a while on a 220 grit stone but I think I made it worse then I sort of made it a little better. Basically I spent about an hour to get back to where I started. Any tips for this? Should I just grind the whole back 3rd of the blade for ages and eventually it will flatten itself? Something else I noticed is the impact the burr has. Should I deburr occasionally when doing this? Any tips are appreciated
 

Seb

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Is it a KS or a western-handled Masamoto?
 

stevenStefano

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It is a 240 KS. The part I am talking about isn't massively noticeable but I think it would still affect cutting
 

TamanegiKin

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Hey Steven,
I had the same problem with my KS awhile back.
My issue was that I wasn't sharpening equally at the heel, I was letting up at the very end.
I went back to my lowest stone (king 800) and did the last third of the blade paying extra attention at the heel.
I could see where I had been lacking even pressure and adjusted.
It took maybe fifteen minutes, I kept stopping making sure I wasn't altering the profile of the knife.
Not sure if I went about it the correct way but I fixed it.
Here's a link to my thread, its got a couple pics linked in it. Hope this helps, good luck.

http://www.kitchenknifeforums.com/showthread.php?2097-Grind-issue-Say-it-ain-t-so!&highlight=
 

stevenStefano

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Thanks TamanegiKin. The knife was perfect when I got it, definitely my fault. I tried adjusting pressure but I definitely made it worse and went back to normal sharpening to lessen it a little, it was almost like i moved the problem area further along the blade. Maybe I started too coarse? I also have a King 800. Something I noticed is that it almost seemed like the burr on the problem area picked up slurry and it built up on it, making it worse
 

Marko Tsourkan

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Pretty sure my knife isn't overground, but the problem is the same as if it was. My Masamoto has a small part just before the heel that does not hit the cutting board flat. I think it was me using a ceramic rod and not starting from the heel. I tried to fix this for quite a while on a 220 grit stone but I think I made it worse then I sort of made it a little better. Basically I spent about an hour to get back to where I started. Any tips for this? Should I just grind the whole back 3rd of the blade for ages and eventually it will flatten itself? Something else I noticed is the impact the burr has. Should I deburr occasionally when doing this? Any tips are appreciated
The way to fix a "hole" in the edge, is to remove metal along the whole edge. I find Atoma 140 be a perfect tool for that but DMTXXC will do just fine. It will however, kill your edge (and make it thicker), and you will need to thin the area above the edge before putting a new edge on, something that many people might not be keen on doing. Grinding down just the 1/3 at the heel will introduce a minor, I repeat, minor distortion to the profile, but that might be an easier route.

M
 

mateo

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Not to highjack... what about legit manufacturer overgrinds? I have a set of Shun steak knives that are overground (see pic below)... is the only way to fix this to grind down the side of the blade until it's flat?

Blade looking from the top:


As you can see, it's a good 1" section on a 5" steak knife... I'm just glad I got these for free!
 

Marko Tsourkan

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Not to highjack... what about legit manufacturer overgrinds? I have a set of Shun steak knives that are overground (see pic below)... is the only way to fix this to grind down the side of the blade until it's flat?

Blade looking from the top:
Now that doesn't look good at all. From the pic it looks to be slightly shy of 1/32, which is not insignificant. If you want a proper profile, than removing metal to along the edge is the way to go, but that introduces complications that I described in the post above.
 

stevenStefano

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Thanks Marko, that sounds about right. Been using a Naniwa 220 stone for coarse stuff because I've been stingy about buying an Atoma but I guess now is the time to get one
 

Eamon Burke

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Protip: On double-bevels, small overgrinds will often work themselves out over time with proper sharpening technique. My first gyuto, a Tojiro had 2. Now none.
 

tk59

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Marko is absolutely correct. You should cut on a POS stone you don't care about or a diamond plate until the "hole" is gone. Then, thin and sharpen as evenly as possible. IF the overgrind extends up the side of the blade and is deep, the blade is toast unless you want to completely regrind it from the overgrind out to the tip. Eamon is also correct but unless you sharpenoften and try NOT to get a burr on the overground part, the "hole" will be perpetuated and it's basically a crappy situation all around, IMO. That's a "protip" from a cook's perspective. Markos is a "protip" from a sharpener's or knifemaker's perspective. If this were an out of the box issue, I'd return it, no question.
 

stevenStefano

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Thanks for the tips everyone. I think on a diamond stone it shouldn't take that long to fix, I'll just grind the last 3rd of the blade as Marko suggested. It doesn't extend up the face of the blade at all, it is just the edge. I am pretty sure it happened because I was using a ceramic steel and not starting at the very end, the knife was ground perfectly when I got it. Just want to make that clear in case people are looking at buying a Masamoto and get the wrong idea
 
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