Need advice on what to do with "broken" santoku

kakefat · May 7, 2015

So while I was out shopping for groceries today my girl was cooking. When I came home it turned out she had used my Shun santoku to try and open a can of coconut milk. Needless to say this incredibly stupid action led to the edge breaking in a nice half moon shape. I am sad as fuck at the moment as I loved that knife as a family member. Sure as hell more important in my life than any family member. Cooks more meals for me too.

Anyway I now need to fix this as best I can. I have some benchstones and its time to grind. But I am unsure on what to do. Should I completely grind away the damaged part or should I simply sharpen over it and leave it as a unnecessary serration? I'm afraid grinding it off completely will ruin the tip cutting ability of the knife which is just excellent. But at the same time a deep seration right there is also in the way.

So I'm looking for advice. What would you do?

BluntCut MetalWorks · May 7, 2015

Just a little oopsy, quite easy to fix the knife. Tell your girl so...

Grind(more like scrape almost perpendicular against stone) & blend edge to green line. Minor thinning spray painted area (minor but important because you want the tip to be very thin for fineness cuts). Sharpen it up. Once you are happy with cutting ability, welcome to match the finishing for the entire blade.

kakefat · May 7, 2015

bluntcut said:
Just a little oopsy, quite easy to fix the knife. Tell your girl so...

View attachment 541453
Grind(more like scrape almost perpendicular against stone) & blend edge to green line. Minor thinning spray painted area (minor but important because you want the tip to be very thin for fineness cuts). Sharpen it up. Once you are happy with cutting ability, welcome to match the finishing for the entire blade.

Thanks for the opinion. This seems like a good way to do it. And I already told her it was easy to fix and that she shouldn't worry about it. Didn't want her to be sad because of it.

Benuser · May 7, 2015

Excellent advise, Good occasion to move the tip a bit upward. I would use the sides of a coarse stone, or coarse automotive sandpaper with a linen backing. Indeed, almost perpendicular. Thinning after that is most of the work.

Jason B. · May 7, 2015

Those blades are usually pretty thin, shouldn't be too difficult to grind it out.

What stones do you have?

Typically, you start by grinding the edge directly into the stone like your trying to cut the stone. You can also raise the angle to 45-50 degrees per side, this will remove steel quickly while allowing to maintan consistancy while grinding out the chip. After the damaged has been removed return to a normal sharpening angle and reset the edge.

Shun's are usually fairly thin so you might be able to start with a 1000 grit stone.

me2 · May 7, 2015

Funny, I had the opposite notion of everyone above. I'd shorten the blade to just behind the damage, then blend the new tip back into the rest of the blade. You'd end up with slghtly shorter blade with a little less belly, but basically the same outline as before.

Jason B. · May 7, 2015

Why would you want to shorten the blade?

Fred.Rowe · May 7, 2015

Raising the belly at the tip would go unnoticed. I would flatten the edge from the choil forward taking progressively more metal off as I moved towards the tip. In this manner the overall geometry of the blade would be unchanged. Any abrupt changes along the edge are usually quite noticeable.

Good luck with your project.

If you know some one with a belt machine it could be accomplished in short order.

mycough · May 7, 2015

bluntcut said:
Just a little oopsy, quite easy to fix the knife. Tell your girl so...

View attachment 541453
Grind(more like scrape almost perpendicular against stone) & blend edge to green line. Minor thinning spray painted area (minor but important because you want the tip to be very thin for fineness cuts). Sharpen it up. Once you are happy with cutting ability, welcome to match the finishing for the entire blade.

Good call Luong, don't want to discourage kids from cooking, I cook with my kids all the time. Russ

loonybin · May 7, 2015

kakefat said:
So while I was out shopping for groceries today my girl was cooking....

So I'm looking for advice. What would you do?

If by "my girl" you mean girlfriend, the answer is simple: get a new girlfriend!
If by "my girl" you mean daughter, gently explain what a knife is not to be used for, reassure her that it can be sharpened up just fine, and go to town on the stones.

Rey HRH · May 7, 2015

You ought to educate whoever used the knife that they should have used a can opener and the appropriateness of using a kitchen knife to open a can, much less a Shun knife.

I would send it to Shun for free warranty / repair if I were you.

kakefat · May 8, 2015

Jason B. said:
Those blades are usually pretty thin, shouldn't be too difficult to grind it out.

What stones do you have?

Typically, you start by grinding the edge directly into the stone like your trying to cut the stone. You can also raise the angle to 45-50 degrees per side, this will remove steel quickly while allowing to maintan consistancy while grinding out the chip. After the damaged has been removed return to a normal sharpening angle and reset the edge.

Shun's are usually fairly thin so you might be able to start with a 1000 grit stone.

I have a full set of spyderco benchstones as well as some waterstones I never use. I think the spyderco stones should do it well although I kinda wish I had a diamond one for the initial metal removal.

loonybin said:
If by "my girl" you mean girlfriend, the answer is simple: get a new girlfriend!
If by "my girl" you mean daughter, gently explain what a knife is not to be used for, reassure her that it can be sharpened up just fine, and go to town on the stones.

Its a girlfriend and not a daughter. But in my experience having a girlfriend can often be the same as having a daughter in cases like this.

Rey HRH said:
You ought to educate whoever used the knife that they should have used a can opener and the appropriateness of using a kitchen knife to open a can, much less a Shun knife.

I would send it to Shun for free warranty / repair if I were you.

I have considered sending it in for repair but I live in Norway so it would take quite some time and shipping is a bit expensive. I'm not quite sure yet but I'll see later today.

Thanks for all the replies, guys.

bodog · May 8, 2015

Since your girlfriend is an adult you should have her grind the chip out so she can 1) see how much effort it takes to fix something like that and 2) she'll learn how to do something she didn't know before. Use that knife to strengthen the bond between you and her. You can pull out a different knife and sharpen it while she's spending hours upon hours trying to remove the damage from a knife you like that she willfully and carelessly messed up. Or have her work enough overtime to buy you a new one. Two birds with one stone, you get a replacement knife for the one she messed up and two, you get some time to sharpen, or three, you now have an excuse to buy a belt grinder.

HurlockVanguard · May 8, 2015

I personally wouldn't change the geometry by removing metal just in the belly area; instead I would work the whole length. You might have to thin the knife behind the edge so that it's not too thick. I will link you some videos explaining everything. Shame you don't have diamonds.

kakefat · May 8, 2015

bodog said:
Since your girlfriend is an adult you should have her grind the chip out so she can 1) see how much effort it takes to fix something like that and 2) she'll learn how to do something she didn't know before. Use that knife to strengthen the bond between you and her. You can pull out a different knife and sharpen it while she's spending hours upon hours trying to remove the damage from a knife you like that she willfully and carelessly messed up. Or have her work enough overtime to buy you a new one. Two birds with one stone, you get a replacement knife for the one she messed up and two, you get some time to sharpen, or three, you now have an excuse to buy a belt grinder.

No she wont pay for it in any way. She understands that what she did is bad and she has learned from her mistake. She has repeatedly told me that she will replace it but I have said no. Adult or not she is still my girl, I cant make her do that. Thats just my way of looking at it though. Just the sort of relationship dynamic we have so I'm not saying your method is wrong either. I really want to get a belt grinder though.

HurlockVanguard said:
I personally wouldn't change the geometry by removing metal just in the belly area; instead I would work the whole length. You might have to thin the knife behind the edge so that it's not too thick. I will link you some videos explaining everything. Shame you don't have diamonds.

I think removing a lot of metal above the edge is a bit risky for me. I'm fairly good at sharpening by this point but I dont have experience with removing metal from other parts of the blade so using my favorite knife for experimentation doesnt seem wise. I would still love to see the links though. Always good to learn new things.

HurlockVanguard · May 8, 2015

kakefat said:
...
I think removing a lot of metal above the edge is a bit risky for me. I'm fairly good at sharpening by this point but I dont have experience with removing metal from other parts of the blade so using my favorite knife for experimentation doesnt seem wise. I would still love to see the links though. Always good to learn new things.

https://www.youtube.com/watch?v=IiYT3xPNkoE
https://www.youtube.com/watch?v=dU3ALY8OmZk - not a repair vid, but shows how easy it is to chip a knife.
https://www.youtube.com/watch?v=zEaSObShFX4
https://www.youtube.com/watch?v=teCsLt8BohY

I would recommend taking a look at Murray's dvd, the picture quality is much better than on his YT video.
Unless you also remove steel behind the edge i.e. thin it out, then you might experience reduced cutting performance. I've never handled a Shun, though that's what I think will happen.

Edit:
https://www.youtube.com/watch?v=twP_05UEHIM
https://www.youtube.com/watch?v=3jsTtnidY3w

loonybin · May 8, 2015

bodog said:
Since your girlfriend is an adult you should have her grind the chip out so she can 1) see how much effort it takes to fix something like that and 2) she'll learn how to do something she didn't know before.

This! And as an added bonus, you get to sit/stand behind her with your arms around her guiding her hands. What red-blooded male doesn't like pressing his body against his girlfriend?

napaknives · May 8, 2015

If you use a belt grinder, make sure that the blade doesn't heat up too much. Have a tall glass of water nearby. I speak from experience.

Pondoro2310 · May 8, 2015

Cheers to you for not getting too upset with your girlfriend. She obviously was not a "knife person." Treating her with respect is the right way to teach her not to abuse expensive tools.

Komitadjie · May 8, 2015

I'd approach it like Bluntcut suggested, with the exception that I'd be using my belt grinder instead of stones. I've fixed a LOT of knives for people that way, chips like that (or possibly missing tips) are perhaps the most common "major" damage I get to work on. Don't worry, once you've done it the first time, it'll be a "ho-hum" affair next time. Unfortunate, but a good learning experience and no real harm done.