Chipping on my knife edge

E

ewjax

Joined
Oct 31, 2005
Messages
16
Hi folks,

I picked up my Benchmade 556 mini griptilian today to drop into my pocket, and suddenly noticed something wrong with the edge. Looking closely revealed some rather ugly chipping on the blade edge.

Here are some pics:

Left side:
556_chipped1.jpg


Left side closeup:
556_chipped_small1.jpg


Right side:
556_chipped2.jpg


Right side closeup:
556_chipped_small2.jpg


So the question becomes, did I perhaps do something incorrect when I sharpened this (I use the Spyderco Sharpmaker)? Is there something I can do to prevent this from reoccuring? Or have I just put too fine an edge on 440C steel? I just noticed that the other 440C knife I own, a Mini Pika, is doing something similar.

Thanks,
Elliott
 
Cliff Stamp said:
What were you cutting and how?

-Cliff
Click to expand...

This particular knife has seen zero tough duty. I may have cut paper to test sharpness, trimmed some string, opened a few soft plastic wrap things, etc. Nothing hard at all, very light duty.
 
ewjax said:
I may have cut paper to test sharpness, trimmed some string, opened a few soft plastic wrap things, etc. Nothing hard at all, very light duty.
Click to expand...

Then no, there is nothing you could have done wrong, even if you removed the edge grind completely and blended it back into the primary grind it would still do that all day long without visible damage.

Is it possible that someone else used the knife, or you hit something while cutting? In any case the solution is to recut the edge, remove all the damage and see if it still chips in use.

-Cliff
 
Now that really sucks.

I can't see how a sharpmaker would do that to any steel, unless one was vigorously whacking one of the stones with the blade of their knife.

Is that a factory bevel? I say there's something wrong with the heat treat/steel. Brittleness or something.

I'd return it to Benchmade and see what they think of it. If it's a bad batch of blades, I bet they know of more like this.
 
Crock stick sharpeners can do that. Vassile had that sort of problem sharpening some higanokami (Japanese laminated pocket knives http://playground.sun.com/~vasya/Higonokami.html ) and had to switch to bench stones. The BM could have been over-hardened or the blade might have had a slight edge burn when they sharpened it.... just enough to make the edge brittle. Anyway, the point of contact between the blade and the edge of a crock-stick is usually very tiny.... the pressure you put on the knife is directly concentrated there trying to push sideways on the edge... an ounce could translate to a pressure of several tons per square inch and cause small chip-outs on really hard edges (which means that unless you're grinding soft steel, don't push hard trying to make it cut faster)

If the edge was burned in initial sharpening, you can just grind it back a bit and get to more sound steel beneath. If the whole blade is too hard (maybe missed annealing), then give it a go on the bench stones and see what happens.
 
yuzuha said:
Crock stick sharpeners can do that.
Click to expand...

They can damage edges for the exact reason you noted, but in this case I would be skeptical because of the size of the chips, they are deeper than the actual secondary edge bevel. If the edge was chipping at that level during the sharpening I can't imagine you would not feel it on the stones, and they would snag constantly on cutting paper or plastic. That is pretty heavy damage, you can get that for example if you take a ~10 degree edge on one of the high carbon stainless and very quickly and roughly cut open a food can making a circular cut. It takes a fair amount of force and you have to be rough twisting the blade.

-Cliff
 
Oh for heaven's sake.

Mystery solved.

My 14-year old son saw me working on the knives, trying to sharpen the gouges out, and looked at me funny, so I asked him if he knew something about it. He said yes, one of his buddies had picked them up from my desk, opened them (the Pika and the Grip), and "whisked" them together several times, like you see chefs do. He was really horrified when I showed him the damage.

That explains the damage on the Pika too. Here I was thinking somehow all 440C was bad, or at least the two 440C knives I had were somehow bad, when all along, it was just the moron down the street.

Good grief.
 
I was so mystified about this, I was just about to suggest the Teenager Explanation myself :) All kinds of odd happenings when they're around.
 
And reason# 98743 for, if you do, have a good heart to heart with them. Preston
 
You can also be proud that your son "owned up" to what happened. "I dunno" would have been a very convenient answer. Kind of the answer I gave to my Dad 50 years ago when I chipped the hell out of his bowling ball trying to bowl with it on the sidewalk.
 
ROFL, like that commercial where all the plastic melts! Ya done got a case of the dread 440c rot. ^0^ It does beg the question though... are those chef's damaging thier knives the same way, or are they so soft that it just steels them on each other?
 
ewjax said:
Oh for heaven's sake.

Mystery solved.

My 14-year old son saw me working on the knives, trying to sharpen the gouges out, and looked at me funny, so I asked him if he knew something about it. He said yes, one of his buddies had picked them up from my desk, opened them (the Pika and the Grip), and "whisked" them together several times, like you see chefs do. He was really horrified when I showed him the damage.

That explains the damage on the Pika too. Here I was thinking somehow all 440C was bad, or at least the two 440C knives I had were somehow bad, when all along, it was just the moron down the street.

Good grief.
Click to expand...

Yikes.

Where's that little tike.:mad:
 
tim8557 said:
You can also be proud that your son "owned up" to what happened. "I dunno" would have been a very convenient answer. Kind of the answer I gave to my Dad 50 years ago when I chipped the hell out of his bowling ball trying to bowl with it on the sidewalk.
Click to expand...

A damn great son .. and perhaps even better, a father son relationship where honesty and integrity are paramount. No blaming is necessary because each would own and be responsible:thumbup:
 
:D. I agree, he 'fessed up...no reason to be hard on him. While this would be horrific damage for a knife that has seen zero heavy duty, it shouldn't be to hard to fix on a coarse benchstone, now that the mystery is solved.
 
Took a while with the Sharpmaker, but I finally sharpened those gouges out:

556_resharpened.jpg


Closeup:
556_resharpened_closeup.jpg
 
Heh, always a simple explination....

if i had kids and had a situation like that, i'd use it as a teaching opportunity....

"Today, Son, you'll learn how to properly sharpen knives" (starting with the beater knives)
 
When I saw the damage to the edge of that BM the first thing that ran through my mind was an incident at an old job. My small diagional cutters (for copper wire only) were used by a co-worker to trim some stainless steel Guitar strings. The damage to those edges looked very similar. I was going to suggest that as a possible cause, but your upstanding son put an end to the speculation before I could post.
 
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