knife snapped while straightening, explanation needed

i dont try and fix bent knives i replace them with good knives adn give the rejects to my fam. they are happy to have a good knife even if it has a slight bow in the blade
 
Understood Rick. This has actually been a very useful thread. Look, I'm not a knife maker. I have a rudimentary "enthusiast" understanding of metallurgy and heat treating. I'm a sharpener, and since I started sharpening for other people, I've gotten a lot of bent knives. I've been correcting them, carefully and successfully, up until yesterday when a knife broke on me.

If I've understood correctly, it might be because the grain growth was large, indicating a bad heat treat and over-hardening. It could be stresses from abuse, scratches, edge damage, etc. over the course of the life of the knife (I told the owner last night, and he said he'd been using the knife hard for about 15 years). It could be both.

In the future, I'll tell people that there are several factors that can influence the lateral strength of the blade and since I don't know anything about the knife when it gets into my hands or what it has been through or how it was heat treated, I can't guarantee that the knife will take a straightening and there is a risk it could break. If the customer is okay with that and insists that I try, then I'll try.
 
your best bet when asked to fix a bend on a production knife is to tell the person to send it to the factory and wash your hands of it
 
butcher_block said:
your best bet when asked to fix a bend on a production knife is to tell the person to send it to the factory and wash your hands of it
Click to expand...

I'll just be clear with customers from now on that several factors can cause the knife to break while straightening, and it's a risk I have to take if they want me to straighten the knife.
 
thats a good plan i was jsut pointing to more the point that a production house often even accounts for a % of returns so they ca get a free knife replacment

as ong as they know that and still want you to work the blade over then no worries at al
 
Rick Marchand said:
I made a prototype kitchen knife that I am using at home. I want to experiment a little more with the geometry before offering them to the public.

IMG_0047-4.jpg
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Oh, and I forgot to add that this is absolutely beautiful.
 
Magnanimous - I can offer nothing as to why the knife broke.
But, I'm left wondering how that knife would get bent in the first place....especially to the degree where it needed straightening. I spent nearly 30 years in pro kitchens and I've had that knife in my hand many, many times. Its a fine knife that can be a dependable work horse. I've never seen one bent.
I can be brutal on my kitchen knives at times. They're hard to bend.

I'm just curious if you know how it got bent. Impressive.

-Peter
 
butcher_block said:
thats a good plan i was jsut pointing to more the point that a production house often even accounts for a % of returns so they ca get a free knife replacment

as ong as they know that and still want you to work the blade over then no worries at al
Click to expand...

He brings up a good point, you might be able to send that broken knife back and get a new one out of Henckels.
OTOH, I use some Henckels, and judging from its condition, it appears that the owner(s) of that one got their money's worth out of it.

Rick, that Gyuto looks fantastic, the only suggestion I have is PLEASE make it "tall" enough that chef's with large hands can rock
it on the board without hitting their knuckles. It is a pet peeve of mine to have to adjust my grip to the knife in order to get the jobe done.

IMG_0047-4.jpg
 
why are sso many of you so quick to judge. You have no idea if he is a good knife sharpner or not. judge not lest you be judged.
Leroyk
 
Bigblue17 said:
Magnanimous - I can offer nothing as to why the knife broke.
But, I'm left wondering how that knife would get bent in the first place....especially to the degree where it needed straightening. I spent nearly 30 years in pro kitchens and I've had that knife in my hand many, many times. Its a fine knife that can be a dependable work horse. I've never seen one bent.
I can be brutal on my kitchen knives at times. They're hard to bend.

I'm just curious if you know how it got bent. Impressive.

-Peter
Click to expand...

I asked him, and he doesn't know. I've sharpened about 7 or 8 Henckels for him so far, and maybe 4 of them had bends near the tip, so he must be doing something with them. They are all Twins Four Stars, most of them Solingen, a few of them Brazil-made. The bend starts a few inches down from the tip. It's not severe, but noticeable and enough to affect cutting and especially sharpening. I can't stand sharpening a bent knife like that, so I straightened them. The first three were no problem. A little careful straightening over a period of time, and they straightened up beautifully. He isn't a professional chef, just a guy who likes to cook.
 
Seems to me that if the guy regularly bends his knives, then it's possible that this one just became brittle over time due to work hardening and eventually just broke. The best heat treat and quality control during manufacturing in the world can't prevent that. Time to give him Rick's phone number so he can get a new knife, and some basic instructions on how to keep them from breaking.
 
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