Reccuring edge problem

E

EatingSarma

Joined
Jun 22, 2020
Messages
712
So, I have Recon1 Tanto in S35VN for a while now.

So I recently noticed a light reflecting spot, gave it a good sharpening and it was still kinda there.

It's as if that extremely tiny chip kept moving back along with the edge. Only when I gave up and went to finer stones - it stopped moving.

So, I sharpened it out. Finally. And day later - I see that same chip on that same place.

I repeat the process. And few days later - again, the same.


So I yet again sharpen it out, and without even closing a knife I cut a single piece of rope.
- and edge damage is back. At that same place.


Anyone ever encountered anything similar? How did you solve this?
 
Alberta Ed said:
Could it be an occlusion in the steel? Or could the edge be touching the liner or lockback spring when you close it?
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No. Edge is not touching anything. I checked the handle multiple times, and I did that rope cut test without closing the blade just because of that.

Rest of the edge is normal, just that one part loses it's edge instantly when I cut something...
 
I have ran into a similar situation. I had been sharpening kitchen knives for a customer when I noticed a couple "pits" in the bevel. They persisted as I removed more steel. I broke out the microscope and found there were indeed tiny pits or occlusion's that would show up as steel was removed.
In this case I believe it was rust. I'm not sure how it occurs, but as I removed the pits, more appeared. I have noticed this on customers knives twice. In both instances I talked to the users and they both admitted to occasionally leaving the knives in dishwater overnight. Don't know if that's what caused this but both customers left them sitting in water sometimes...
One of the knife brands was by a reputable knife maker in Ohio, the other was a popular cheap stainless brand sold in Target's and other home goods outlets.
Sounds like that's not the case with yours but similar, as in some kind of imperfection in the steel...
 
I had one knife in D2 steel that initially came to me with a chip in the edge. Under magnification, I could also see a crack propagating upward from the chip, deeper into the steel behind the edge. Chips can act like stress risers, creating cracks under stress which create more chips and sometimes even result in broken blades. I had to do some grinding of the steel near the edge until no sign of that crack remained, then resharpen it. It's held up fine since doing that.

I'm inclined to believe that problems like this are most likely the result of edges becoming overheated during factory grinding or sharpening. Sometimes you have to grind a good bit of heat-damaged steel away to get back into stable steel at the edge.
 
Obsessed with Edges said:
I had one knife in D2 steel that initially came to me with a chip in the edge. Under magnification, I could also see a crack propagating upward from the chip, deeper into the steel behind the edge. Chips can act like stress risers, creating cracks under stress which create more chips and sometimes even result in broken blades. I had to do some grinding of the steel near the edge until no sign of that crack remained, then resharpen it. It's held up fine since doing that.

I'm inclined to believe that problems like this are most likely the result of edges becoming overheated during factory grinding or sharpening. Sometimes you have to grind a good bit of heat-damaged steel away to get back into stable steel at the edge.
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I've used it for 2 years with no issues, so I have no idea why it surfaced now...

I'll try to really sharpen out deeper.
 
Gottagofishn said:
I have ran into a similar situation. I had been sharpening kitchen knives for a customer when I noticed a couple "pits" in the bevel. They persisted as I removed more steel. I broke out the microscope and found there were indeed tiny pits or occlusion's that would show up as steel was removed.
In this case I believe it was rust. I'm not sure how it occurs, but as I removed the pits, more appeared. I have noticed this on customers knives twice. In both instances I talked to the users and they both admitted to occasionally leaving the knives in dishwater overnight. Don't know if that's what caused this but both customers left them sitting in water sometimes...
One of the knife brands was by a reputable knife maker in Ohio, the other was a popular cheap stainless brand sold in Target's and other home goods outlets.
Sounds like that's not the case with yours but similar, as in some kind of imperfection in the steel...
Click to expand...
It's been in sweaty pocket a lot, so could be that? No visible rust tho.
 
My recon 1 was able to strike the inside of the knife, even though it didn't look like it at first glance.

When the knife is closed, try gently pushing the knife blade further into the handle, or push the lock back all the way in. See if the knife blade will go further into the handle and strike the inside of the metal lock back. Mine would.

When the knife was closed, the blade wouldn't be touching anything in the handle, but when I closed the knife with force or let it close under its own weight, it would swing back into the handle enough to strike the lock back mechanism before settling into position.

This is something I've seen can potentially happen in a few lockback designs, and not just from cold steel. For me, closing the knife gently solved the problem.
 
Surname said:
My recon 1 was able to strike the inside of the knife, even though it didn't look like it at first glance.

When the knife is closed, try gently pushing the knife blade further into the handle, or push the lock back all the way in. See if the knife blade will go further into the handle and strike the inside of the metal lock back. Mine would.

When the knife was closed, the blade wouldn't be touching anything in the handle, but when I closed the knife with force or let it close under its own weight, it would swing back into the handle enough to strike the lock back mechanism before settling into position.

This is something I've seen can potentially happen in a few lockback designs, and not just from cold steel. For me, closing the knife gently solved the problem.
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I would sharpen the knife and cut something with it without ever closing it.

Rest of the edge woud be not just with no damage - it'd even still be sharp, yet on that particular part of the blade, the apex of the edge would simply be gone.
 
Obsessed with Edges said:
Maybe that is indeed an occlusion or some other defect, like a pit or void as others have suggested, that was hidden behind the edge for a while and is now exposed through resharpening.
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Gottagofishn said:
I would be inclined to believe it is either an occlusion of some sort from the manufacturing process or possibly a crack as Obsessed mentioned. I can’t imagine normal use could cause any serious corrosion.
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SharpBits said:
Sounds like a bad spot in the steel. You could attempt a resolution via GSM support, but I doubt the gumbies on the help desk would understand the problem. They are generic multi-product customer support after GSM took over.
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So if there is a flaw in the steel, what is the best course of action?

To try to grind it out?
To keep using it until I eventually get past that?

Or to not use it at all if it could eventually cause a failure (breakage)?

I have some good memories with that knife, so I won't get rid of it. In case that this is making it unreliable for use, I will just put it away and carry either my other Recon 1 or most likely my Spyderco instead.
 
Striking the back spring. (Most likely option)

Or, you didn't sharpen far enough. Fine stone covered it up and it came back with a little use, because it was never really gone. (Second most likely)

A small spot of steel not having temper. (Highly unlikely)

Sending the knife back to the manufacturer will likely involve them sharpening it and sending it back.
 
I would attempt to sharpening it out using the Cliff Stamp method of flattening the edge on a stone and starting over with new edge. A better alternative might be to send it out for a pro sharpening, like Jason above offers.
 
EatingSarma said:
I would sharpen the knife and cut something with it without ever closing it.

Rest of the edge woud be not just with no damage - it'd even still be sharp, yet on that particular part of the blade, the apex of the edge would simply be gone.
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My knife would only ever strike the lockback on a very small point, leaving the rest of the blade razor sharp. It's possible that repeated strikes and sharpenings have cause that area of the blade to fatigue to where it is either damaged or will just no longer hold and edge.

I would still check just in case, even if you think it's unlikely. If this is the issue, it is both easy to check for and an issue that will be recurring with other solutions like sharpening. Might as well rule it out now as opposed to later.
 
Jason B. said:
Striking the back spring. (Most likely option)

Or, you didn't sharpen far enough. Fine stone covered it up and it came back with a little use, because it was never really gone. (Second most likely)

A small spot of steel not having temper. (Highly unlikely)

Sending the knife back to the manufacturer will likely involve them sharpening it and sending it back.
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I even took the knife apart and it's not touching anything. And there is also absolutely no traces of anything on either spring or backspacer or any other parts.
 
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