Scary sharp after sharpening, then fades after use?

B

babtron

Joined
Jan 5, 2015
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Hey guys, I recently sharpened my Squeak (N690Co) and was able to get it "scary sharp". Easily cut thru phone book paper with no snags and easily cut my leg hair without really touching my skin. I put it to use today lightly. Cut some zip-lock like bags, some cardboard from a 12pk of beer and proceeded to test the edge on phone book paper again. It cuts decently, but not smooth as before. My newish Sage 1 with the factory edge easily cuts thru phone book paper after more use with no snags.

Is this a testament of me needing to raise my angle a little bit? It seems as if a really small burr is forming. It's a working edge and will still cut my leg hair. Just seems kind of premature compared to a Sage 1 with much more use.

Or is this more of a testament that S30V is far superior? I looked at the apex on my Squeak and there's no reflection of light anywhere also.

Thanks guys, I'm still fairly new to freehand.
 
I have no experience with that steel, but a scary sharp edge that suddenly fails is likely to be caused by a wire edge, an accumulation of debris on top of the apex. Very sharp and very fragile, it fail quickly and fold. That's the slight burr you noticed. Hard to remove without damaging the fresh edge once installed. Tell us a bit more about your sharpening procedure, especially about deburring.
 
If I'm reading your post right, the edge is not failing, but is just a little less sharp than before?

Here's something to think about; cardboard, by itself is one of the most destructible materials to very sharp knives and edges. It contains dirt, glue residue, and fibers that are tough to cut. If your knife is still cutting phone book paper after slicing cardboard, your doing okay. It's a knife, not a light saber. Any hair shaving edge is going to loose a tiny bit when cutting cardboard or any material.

I wouldn't worry about it. Theres variables when your talking about different steels and different knives.
 
Benuser said:
I have no experience with that steel, but a scary sharp edge that suddenly fails is likely to be caused by a wire edge, an accumulation of debris on top of the apex. Very sharp and very fragile, it fail quickly and fold. That's the slight burr you noticed. Hard to remove without damaging the fresh edge once installed. Tell us a bit more about your sharpening procedure, especially about deburring.
Click to expand...

Thanks for the reply! Deburring, I just hone and finish on my Suehiro Rika 5k really. I test it by cutting phone book paper and seeing if there are any snags. Don't really use strops. Is this something I should really do?

Might be off topic, if I strop, should I do the same motion as honing? Tip to heel.

jackknife-- Very true. Thanks for your reply! I'll see how the edge holds up as I use it more. It isn't really failing, it's still definitely sharp. No reflection of light on the apex, can cut the hair on my legs, some plastic candy packaging but phone book paper it snags.
 
babtron said:
jackknife-- Very true. Thanks for your reply! I'll see how the edge holds up as I use it more. It isn't really failing, it's still definitely sharp. No reflection of light on the apex, can cut the hair on my legs, some plastic candy packaging but phone book paper it snags.
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It'd be interesting to see how it resounds to a little stropping on leather. I'd be willing to bet that a some of the dirt in the cardboard made some microscopic bugs in the edge, and a light stropping will bring it right back to smooth cutting phone book paper.

Cardboard is nasty stuff.
 
You might also see a big difference if you baby it when cutting a little. Well, not babying so much as consider what you're doing as you cut. I have to deal with double and triple wall corrugated cardboard at work, even a sharp thin knife can choke if cutting straight down in. All that pressure is wearing the edge. Go through at a 45* so the cardboard can flow around the edge and it will not only cut easier, will cut far longer and dull the edge less. Many materials are like this.
 
I always try to use a utility knife for cutting cardboard any more than just a little piece. Got tired of having to polish my edge every night after work. Now I have my Leatherman on my belt, My folder in my pocket, and a utility knife in my back pocket with my wallet so it stays upright in the pocket. Hope I never get turned upside down. All my knives will be on the floor!
Card board is very destructive to a good knife edge, not to mention hidden steel staples. Get a U.K. to use.
 
jackknife said:
If I'm reading your post right, the edge is not failing, but is just a little less sharp than before?

Here's something to think about; cardboard, by itself is one of the most destructible materials to very sharp knives and edges. It contains dirt, glue residue, and fibers that are tough to cut. If your knife is still cutting phone book paper after slicing cardboard, your doing okay. It's a knife, not a light saber. Any hair shaving edge is going to loose a tiny bit when cutting cardboard or any material.

I wouldn't worry about it. Theres variables when your talking about different steels and different knives.
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^That sums it up nicely. Cardboard rarely leaves the edge unaffected, and a shaving or hair-popping edge is almost always a fragile and fleeting thing anyway. Sometimes you can get lucky with good steel, good edge geometry and edge finish, and you might notice a shaving edge lasts a little longer, even after cutting some cardboard or wood. But, I consider that to be the exception (a pretty rare one), instead of the rule.


David
 
Thanks guys!

Can anyone explain why the Sage 1's edge has still been able to cut phone book paper with ease? Is the edge just an example of a perfect, lucky edge where it lasts and lasts?

Also, I love having my knife sharp, but I'd like to have it last longer when breaking down boxes and stuff. Should I raise my angle a little bit?

Appreciate it guys!
 
babtron said:
Thanks guys!

Can anyone explain why the Sage 1's edge has still been able to cut phone book paper with ease? Is the edge just an example of a perfect, lucky edge where it lasts and lasts?

Also, I love having my knife sharp, but I'd like to have it last longer when breaking down boxes and stuff. Should I raise my angle a little bit?

Appreciate it guys!
Click to expand...

Cutting paper is affected by so many variables. For the most part, thinner edge geometry will make the most difference. Secondarily, a clean apex (burr-free) likely has the next-greater impact. Steel itself usually doesn't matter as much, as most any decent steel with decent hardening/tempering will handle it OK.

S30V (assuming this is your Sage's steel) does have the potential to hold up better after cutting cardboard and other abrasive materials, but it's not always guaranteed. The vanadium carbides in the steel are responsible for it's resistance to abrasive wear, which is what cardboard brings (as well as fiberglass, carpet, etc). Even so, poorly heat-treated S30V can be just as vulnerable to edge-rolling (separate from abrasion resistance), and even more so if it's at lower RC than even a low-wear steel at a higher hardness.


David
 
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HeavyHanded said:
You might also see a big difference if you baby it when cutting a little. Well, not babying so much as consider what you're doing as you cut. I have to deal with double and triple wall corrugated cardboard at work, even a sharp thin knife can choke if cutting straight down in. All that pressure is wearing the edge. Go through at a 45* so the cardboard can flow around the edge and it will not only cut easier, will cut far longer and dull the edge less. Many materials are like this.
Click to expand...

:thumbup::thumbup::thumbup::thumbup::thumbup:

That + a zillion!

Also try to actually slice as you go down through, from the blades kick all the way to the tip. That way you're really cutting with the blade instead of pushing it through all the material.
 
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