Nick in a Sebbie blade after simple cutting

[Rok]

Hi everyone.

I have a small classic micarta Sebbie that I EDCed for a couple of years. I live in a city so most knife chores are extremely light. I sharpened it with Edgepro Apex, giving it about 18 degree per side, then used Sharpmaker for touchups (20 degrees, for ease of use). A short while ago, while in the woods, I cut a small fresh twig (about 1/2" thick) and whittled it sharp. When cleaning the knife a couple of days later I noticed it would tear the paper, starting about one third of the blade length from the choil. Upon inspection, there was a (very) small nick on the edge (I'd guess less than 1/5 mm, but visible with naked eye) that took more than just touchup to remedy.

I'm somewhat disappointed, since that probably means the blade really is a bit to brittle. I've used my Spydie Millie S90V to cut tin cans and such, always without nicks. Ditto with CQD MkI (154CM). Even the SAK I had as a kid managed without nicks (and the edge was far narrower than what my Sebbie has).

While I do sometimes abuse my knives a bit, I've never done it with my Sebbie (ie, no cutting of metals or similar, and I never use knives for prying). I only really abused my FBMLE (with no ill efects and no blade chipping, mind you). But then again, compared to Sebbie, that's a sharpened railroad track and not a knife.

Any thoughts? No flames, please. I'm not complaining or seeking sympathy, merely stating my observations and seeking opinions. Thanks.

Cheers,
Rok

 

[Haze]

In my experience the open back on the Sebenzas and Umnumzaan is often to blame for those little nicks and dings rather than through use. I "dangle" my keys my front pocket and find that they can cause those little rolls and dings.

I have chipped my Umnumzaans edge when trimming a bit of ply wood but that stuff is really dirty so it was not a great surprise, natural green wood on the other hand should be of little troube to just about any steel.

 

[Greg]

I also think the factory edge can be a bit "overcooked"--very easy to do with S30V. I good 3 or 4 hand sharpens will often result in a much tougher edge.

Greg

 

[OldDude1]

I believe it was mentioned (I think by KnifeNut1013) that on some blades, depending upon edge angle and steel, the Sharpmaker rods can micro-chip an edge. If I recall correctly, the contention is that the narrow contact surface presented by the edges of the ceramic rods concentrate the applied force on such a small area that some steels can micro chip. I have experienced this on a S30v Small Sebanza. IMO these small micro-chips create an opportunity, that allows a relatively soft but fibrous material to grab the edges of the micro-chip and pull out a larger and visible chip. This may not be the only contributing factor to your problem but it is something to consider. I have not seen this on my Sebenzas when sharpened only on the EdgePro. Comparatively light rod to blade contact pressure seems to eliminate this condition. Polishing the Edge seems also helps greatly. (If this concept is not attributable to Knifenut1013, I hereby apologize to him for my error. OldDude1

 

[marthinus]

In my experience the open back on the Sebenzas and Umnumzaan is often to blame for those little nicks and dings rather than through use. I "dangle" my keys my front pocket and find that they can cause those little rolls and dings.

I have chipped my Umnumzaans edge when trimming a bit of ply wood but that stuff is really dirty so it was not a great surprise, natural green wood on the other hand should be of little troube to just about any steel.

I agree about keys and coins getting into the back, so I made a plan on my old seb.

Some Kiaat wood that is held in place by friction. Since the tolerance is so high in the knife the wood does not come out in any use I put it through.

 

[DBH]

I think I have had one S30V sebenza have some microchipping on the edge. I reprofiled that blade, and now only strop it to keep is sharp. No problems since.

 

[giant1]

When the knife was new, I also had a a chip in the blade after cutting a cable tie. Since I sharpened the nick out it has been fine.

I really think they need a good sharpen when you get them new, not sure why. The edge just seems brittle out of the box but great after some use and a good sharpen.

 

[Toyz]

I believe it was mentioned (I think by KnifeNut1013) that on some blades, depending upon edge angle and steel, the Sharpmaker rods can micro-chip an edge. If I recall correctly, the contention is that the narrow contact surface presented by the edges of the ceramic rods concentrate the applied force on such a small area that some steels can micro chip. I have experienced this on a S30v Small Sebanza. IMO these small micro-chips create an opportunity, that allows a relatively soft but fibrous material to grab the edges of the micro-chip and pull out a larger and visible chip. This may not be the only contributing factor to your problem but it is something to consider. I have not seen this on my Sebenzas when sharpened only on the EdgePro. Comparatively light rod to blade contact pressure seems to eliminate this condition. Polishing the Edge seems also helps greatly. (If this concept is not attributable to Knifenut1013, I hereby apologize to him for my error. OldDude1

+1 - but related to my Benchmade with D2 blade. I have to sharpen that one with a stone in order to keep the microchip monsters from coming back.

I've only touched up my large sebenza on a strop - no problems yet.

I'll have to give it a go on the ceramic rods and see what happens.

 

[mm3]

I agree about keys and coins getting into the back, so I made a plan on my old seb.

Some Kiaat wood that is held in place by friction. Since the tolerance is so high in the knife the wood does not come out in any use I put it through.

That's a great idea! The open back is the only thing I don't like about my Seb.

Does the blade hit the spacer when the knife is closed?

 

[marthinus]

That's a great idea! The open back is the only thing I don't like about my Seb.

Does the blade hit the spacer when the knife is closed?

Nope. I thinned it out enough so that the blade can close without hitting the wood. I would say that using softer wood at that thinness would not work so if you do it use a harder type wood that can handle it.

It is quite enjoyable when making this piece of wood. When it is finished and it fits so tightly you have to use a screwdriver to push it out makes you feel you really contributed to the knife without making it look sloppy.

 

[Rok]

I believe it was mentioned (I think by KnifeNut1013) that on some blades, depending upon edge angle and steel, the Sharpmaker rods can micro-chip an edge. If I recall correctly, the contention is that the narrow contact surface presented by the edges of the ceramic rods concentrate the applied force on such a small area that some steels can micro chip. I have experienced this on a S30v Small Sebanza. IMO these small micro-chips create an opportunity, that allows a relatively soft but fibrous material to grab the edges of the micro-chip and pull out a larger and visible chip. This may not be the only contributing factor to your problem but it is something to consider. I have not seen this on my Sebenzas when sharpened only on the EdgePro. Comparatively light rod to blade contact pressure seems to eliminate this condition. Polishing the Edge seems also helps greatly

Thanks. That may very well be the case and I will give it a try by only using EdgePo for a while. Kind of sad, since SM is so elegant and fast to use though.

Cheers,
Rok

 

[JoHnYKwSt]

Was a large burr created while you were reprofiling the edge? If so, the weaked metal at the edge is still there and that is probably why it chipped. The weakend metal will go away with sharpening on the sharpmaker assuming another large burr is not created.

 

[Rok]

Was a large burr created while you were reprofiling the edge? If so, the weaked metal at the edge is still there and that is probably why it chipped. The weakend metal will go away with sharpening on the sharpmaker assuming another large burr is not created.

Nope, no burr. I'm decently proficient in sharpening, the knife was almost hair-whittling sharp prior to it (polished edge and all).

Cheers,
Rok

 

[JoHnYKwSt]

Did you create a large burr while you were sharpening though? Your end result may not have a burr but the weakened metal would remain.

 

[Rok]

Did you create a large burr while you were sharpening though? Your end result may not have a burr but the weakened metal would remain.

Nope. I'm one of those people who believe getting a burr means you've overdone it. Thanks for input though.

Cheers,
R

 

[Mr. Clean]

Nope. I'm one of those people who believe getting a burr means you've overdone it. Thanks for input though.

Cheers,
R

Then what happened was that you probably chipped a wire edge. You can't sneak up on a sharp edge and expect top notch performance, creating a burr is the only way to go for the best edge.
This is information I've learned from my foray into Japanese chefs knives and a few working pros that sharpen them. Create a burr moving through the stones, strop at the end. I've applied the same technique to my other knives and it's been quite a difference.
Heck even in the Edge Pro demo video the owner/creator states the need to raise a burr. It's just how things are. Again, you can get sharp without a burr, but the resulting edge is weaker.

 

[kamagong]

In my experience the open back on the Sebenzas and Umnumzaan is often to blame for those little nicks and dings rather than through use. I "dangle" my keys my front pocket and find that they can cause those little rolls and dings.

That's been my experience as well and IMO is one of the few shortcomings the Sebenza has.

 

[Rok]

Then what happened was that you probably chipped a wire edge. You can't sneak up on a sharp edge and expect top notch performance, creating a burr is the only way to go for the best edge.
This is information I've learned from my foray into Japanese chefs knives and a few working pros that sharpen them. Create a burr moving through the stones, strop at the end. I've applied the same technique to my other knives and it's been quite a difference.
Heck even in the Edge Pro demo video the owner/creator states the need to raise a burr. It's just how things are. Again, you can get sharp without a burr, but the resulting edge is weaker.

Not that I doubt your experience, but there was most definitely no wire edge. My sharpening technique is not the culprit here. The knife has a nice 18 degree edge with a 20 degree microbevel edge. What may be is the already stated stress created by SM ceramic rods.

Cheers,
R

 

[Thalestin]

Id keep using the knife and if it happens again id contact CRK. My guess though is that you nicked something and didnt relize it. It doesnt take much in many cases.

 

[molly's survival]

marthinus that looks great, what a neat idea. as far as the chip in the blade I've never had that happen but anything can