Edge damage question.

GeneK

KNIFE MAKER
#1
I had a fillet knife I made from 15N20 returned to me that has chips in the edge.



I have done the brass rod test with quite a bit of pressure and chopped into a piece of oak lumber and cannot get the knife to chip or deform the edges.



I've even push cut into the oak and twisted the knife with no edge damage. The blade is .010" thick behind the edge bevel, so I would think these tests would show a problem, but I'm not finding what it is.



I'm at a loss here as to where to go with this blade to try to fix it. At first, I thought I would remove the handles and re-temper the blade at a higher temperature. But, not being able to reproduce any chipping, I'm not sure if that's the right step.

I was told they were using it to cut up fish and noticed it wasn't cutting like it used to. I will be making a new one to replace this one, but would like to fix this one for him also. Any ideas?
 

J. Doyle

Dealer - Purveyor
#2
It's a tough question to ask but are you sure the person is being honest?

15n20 is pretty tough and from the tests you did, there appears to be no reason it wouldn't just fillet fish.

I have had only one knife returned to me. It had MASSIVE edge damage, worse than yours. HUGE long chunks were torn out of the blade.I was told "all I was doing was slicing backstrap and it just starting falling apart". This was from someone I knew VERY well and respected and trusted.

After conducting many tests that I would consider abuse on the undamaged parts of the edge, I couldn't even get a tiny chip or roll. I could draw no other conclusion than the knife had been grossly abused and I was lied to.

I replaced the knife but was very clear I wouldn't replace it again.

If that happened to me now, I'd probably not replace it even once. You can tell if a knife has been abused.

Your case isn't quite as severe, but pardon the pun.......something smells 'fishy'.
 

opaul

Well-Known Member
#3
I'm following this with interest. In looking at the photo it appears that the damage area are angular (almost squared at the end of each damaged area). I hope you can find out the cause. I'm in the same thought as J. Doyle, it seems 'just fileting' fish would not have caused this issue.
 
#4
I am of the opinion that there has been abuse and a lack of honesty on the part of the client. I replaced one that had the tip broken off and he was just cutting out an elk tooth like he had done 100's of times before. I believe he had been using the knife as a lever but without calling him a lier what can you do. Sometimes the good PR from a replacement is worth more than the bad pr from calling it for what it is. Add an clause to your of the knife card that states your knives are for cutting or slicing only and damage from other uses is not covered in your guarantee.
 

Rick Otts

Well-Known Member
#6
I agree with Von it's hard to get a good rep but all it takes is one mad person on the internet and you are in question.While I do believe the guy is not being honest age has taught me sometimes you got to give to get.
 
#7
That looks familiar, I made a test knife out of 1084 with a standard heat treat. Ground a zero bevel edge. The knife survived, the brass rod test, a couple hundred cuts on sisal rope, chopping wood and antler. If you have tried to chop antler it is very hard on knives. It failed when I clamp a machine screw in a vise, and tried to remove it. All the jagged edges are from the corners of the screw, trying to remove it several different times. The knife performed amazingly well until the screw. I'm not saying that's what happened but it looks really similar.
20190121_171147-772x1029.jpg
 

GeneK

KNIFE MAKER
#9
Thanks for all the responses. I'm in agreement with everyone that normal use wouldn't cause this.

After reading Ty's post, I grabbed an antler and did some chopping. I was able to produce one small chip. I reground the edge and sharpened it up and chopped more antler. This time I got some very small edge deforming, not chips, the edge was pushed in.




Even with this deformation, it would slice paper cleanly.



Could it be that the edge is too thin? I put the mocrometer on it and it's .008" behind the edge.

 

JeremyBartlett

Well-Known Member
#10
Gene,

I make a lot of kitchen and filet knives from 15n20. My heat treat regimen usually brings me to a hrc of 65-66 before tempering at 350 which brings me down to 61-62....I have never had one chip unless seriously abusing it. People always seem to overlook 15n20...it's a great steel. My guess, as with others here seem to think it was abused
 

Andre Grobler

Well-Known Member
#11
Evidence of a pull through sharpener especially those carbide ones with the rectangular v’s? 0.008” will need care and hard steel thin steel and pull throughs dint go together well...


I would just regrind the whole thing to 0.01” and return, that is not a flaw, it is an approbriate edge response to some torque... i am assuming it is not the day after delivery
 

DanF

Well-Known Member
#12
"all I was doing was slicing backstrap and it just starting falling apart".
LOL, well, everyone knows how tough that backstrap can be..., .

I will NEVER understand the mindset of people that buy a fine knife and then abuse it by using it for some other purpose than what it was intended for, and expect the maker to cover their folly.
 

opaul

Well-Known Member
#13
Evidence of a pull through sharpener especially those carbide ones with the rectangular v’s? 0.008” will need care and hard steel thin steel and pull throughs dint go together well...


I would just regrind the whole thing to 0.01” and return, that is not a flaw, it is an approbriate edge response to some torque... i am assuming it is not the day after delivery
You make a great point here
 

EdCaffreyMS

Forum Owner - Moderator
#14
are you sure the person is being honest?
I've gotta agree with John's statement. Time has taught me that although unfortunate, more times then not when there is a failure, the customer just isn't honest about. Usually that knife is actually just fine, but the customer has done something they simply should not be doing with it.

That aside, you still have to deal with the satisfaction of the customer..... lots of ways to approach that. My approach is to fix the blade, but before returning it, give them a speech of what I suspect happened/what occurred, and let them know that if it comes back with similar damage, they will be charged my shop repair rate. (That is, IF there are strong indicators of abuse)
There was a time when I would simply replace any blade, for pretty much any reason, but quickly discovered that not only are people greedy, but they are not honest either..... and they would often let a knife get rusty, and ikcy, then intentionally damage it so they could get a new one.
 
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C Craft

Well-Known Member
#15
There was a time when I would simply replace any blade, for pretty much any reason, but quickly discovered that not only are people greedy, but they are not honest either..... and they would often let a knife get rusty, and ikcy, then intentionally damage it so they could get a new one.
I hate to say it but there has never been truer words spoken!!
 

John Wilson

Well-Known Member
#16
Evidence of a pull through sharpener especially those carbide ones with the rectangular v’s? 0.008” will need care and hard steel thin steel and pull throughs dint go together well...


I would just regrind the whole thing to 0.01” and return, that is not a flaw, it is an approbriate edge response to some torque... i am assuming it is not the day after delivery
My thoughts exactly. This looks like a pull through sharpener to me.

I also expressly tell my customers not to use a Steel on the blade. A Steel is fine on a 58Rc european kitchen knife but has no place being used on a thin 61-62Rc blade.
 

GeneK

KNIFE MAKER
#17
This knife was sold about a year ago. He did question me on how to sharpen it as he couldn't get it as sharp as when it was received. He uses the Lansky sharpening system. I've never used one so not sure if that is an issue, I always use a diamond steel.

I don't have a problem replacing the knife. As several mentioned, it's not worth a bad rep at this point in my knife making career. I have used this same philosophy in cabinet making for over 20 years now, and it has served me well. I'm sure it will bite me at some point. I would just like to know what it was being used for to cause the damage it did.

I don't have a rockwell tester to check my knives. On 15N20, I normalize at 1600, thermal cycle at 1475 once and 1350 twice. I then heat to 1470, quench in Parks 50 and temper kitchen knives at 350. This fillet knife was tempered at 400, I now temper them at 375.

Thanks for all the thoughts and information.
 
#18
I would just like to know what it was being used for to cause the damage it did.
I remember many years ago I was with a friend who was returning a Craftsman screwdriver to Sears because it broke in half. The Sears man did not ask any questions he just replaced the screwdriver. Once the transaction was complete the man looked at my friend and said "I have already replaced the screwdriver and that will not change, but would you please tell me how you broke it"? My friend looked at the man and gave the honest answer "I was using it like a crowbar." The point is maybe just fix or replace the blade and once he receives it back contact him and tell him you would like to know how he broke it. Explain why it matters to you and that you will not take his new (fixed) knife away. I think if you are going to get an honest answer to the question this is the most likely way to get it.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
#19
Personally, I would repair or replace it without question. If it happened again, I'd refund it and not give the option to repair it or let them buy another one. Like it or not, clients have the option of buying a $30 knife anywhere that will cut just as well. Maybe it won't hold the edge as long but they will serve the need. They have different and higher expectations of a custom knife. Whether those expectations are realistic or not is something else. Knife failures easily seen as "Abuse" *is* covered by many makers and manufactures. It's a business and marketing decision. I find it hard to get behind that but it works for many. This is a chance to build your reputation on how graciously you handle it.

It appears it was torqued laterally, probably against bone cleaning out rib meat. If they were cleaning fish, some guys cut through rib bones and if the fish was big, I can see it stressing an edge. I wish I caught fish that big. Some edges fail. I'd grind the chips flush on the edge and resharpen it and send it back since you have tested the steel fairly well. It's a 5 minute repair. All you are out is postage.

Since you are seeking feedback on what might have happened, with out seeing it close up, I'd guess it was sharpened to a very thin edge and it couldn't take the lateral load when it hit bone.
 
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#20
Personally, I would repair or replace it without question. If it happened again, I'd refund it and not give the option to repair it or let them buy another one.
The Bark River junkies LOVE that unquestioned warranty. Mike Stewart has said he'd rather have a person destroy a knife trying to save their (or someone else's ) life than worry about the guarantee. This is a bit harder to do when not a production maker...but the less contention you can get into the better your reputation will fair....

where that balance is...I do not know....lol
 
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