Can't keep them sharp

S

Slow7

Joined
May 9, 2010
Messages
21
I sharpen my own knifes, if it isn't sharp it's just a shinny stick

I lost an old knife I had carried for years and bought a Kershaw skyline to replace it. In the process I caught the knife bug and ended up buying a few higher end expensive (to me) knifes. The skyline still works fine but two of the others I can't keep sharp. I have tried different angles, different stone/ strops and even sent one out to a noted utube pro to sharpen for me. I use all three about the same these are the
890 torrent Blade Steel 154cm
940-1 Blade Steel S90V
kershaw skyline Blade Steel Sandvik 14C28N
the only blade that stays sharp is the $35 skyline while I sharpen or strop the other two almost every time I use them. Any suggestions or ideas what I am doing wrong?
 
What kind of stones are you using I have heard of people using non-diamond stones and they couldn't get it sharp because the stell was so hard that they needed to have a stronger surface to remove material. I could be wrong but that is my understanding. You can't sharpen a knife if you don't remove material.
 
[QUOTE="You can't sharpen a knife if you don't remove material.[/QUOTE]
Just for that reason I bought top of the line diamond stones, and diamond drops for stropping. When done sharpening they will take hair off your arm, or do all the popular phone book paper tricks.
 
Slow7 said:
[QUOTE="You can't sharpen a knife if you don't remove material.
Click to expand...
Just for that reason I bought top of the line diamond stones, and diamond drops for stropping. When done sharpening they will take hair off your arm, or do all the popular phone book paper tricks.[/QUOTE]

Maybe this is more obvious but since it is a harder steel you may have to sharpen it more and for longer in order to remove any amount of material to make a difference. Other than that I have absolutely no clue why they wouldn't be sharpening correctly.
 
For starting out with sharpening I always recommend a sharpmaker with the extra diamond stones.

Pretty much fool proof set up for a beginner.

Use the diamond stones to get all the angles right. Then you can just maintain it with the stones.

Matt
 
Let's start fresh.
Any alloy used in knives will be cut by diamond, the only differences will be the rate at which it is cut, stubbornness of the wire edge, and said alloys performance with a toothy or polished edge.

Before we get too far ahead of ourselves, let's get the basics down.

How do you sharpen?
Free hand or with a controlled mechanism (WE, Lansky, DMT Magna, et al)?

When sharpening your knife, how do you know when you are ready to sharpen the other side?

Are you raising a burr on each side prior to moving up to the next grit?

What is your grit progression?

How coarse do you start on a regular sharpening session?

I haven't seen anything by the OP saying that one steel was harder (HRC) than another. Even if he does, it doesn't change the steps needed to sharpen his knives.
 
I'd recommend OP to read the stickies, especially what sharpening about.

A wild guess is that he hasn't apexed the other two.
 
That's what I was thinking, hence the Mini questionnaire.
 
If you can't get your knives sharp with diamond stones, that means your sharpening technique is lacking. Read forums, watch sharpening videos on youtube and practice.
 
Slow7 said:
Just for that reason I bought top of the line diamond stones, and diamond drops for stropping. When done sharpening they will take hair off your arm, or do all the popular phone book paper tricks.
Click to expand...

I think some missed the fact that you can get it sharp... it just won't stay sharp.

My .02, it may be a burr/wire edge issue. They're harder to remove on "better steel" knives (because it's better steel)... so they'll get sharp, but won't stay sharp. And a burr/wire edge will seem very sharp.... shaving hair, phone book paper splitting, etc.

So, how do you deburr your knife? I find alternating higher angle / edge leading passes on a fine stone works well on higher end steels. The diamond stropping should work too (what do you strop on?)... may just need to work on that a bit.
 
I'm going to go out on a limb and say it because Benchmade usually uses very broad angles from the factory. You might have to make the edge more acute to improve longevity.
 
Before we get too far ahead of ourselves, let's get the basics down.

How do you sharpen?
Free hand or with a controlled mechanism (WE, Lansky, DMT Magna, et al)?
I am using the KME system with diamond stones

When sharpening your knife, how do you know when you are ready to sharpen the other side?
Are you raising a burr on each side prior to moving up to the next grit?
Perhaps I need to work on that better, using fine stones it is often hard to detect the burr, so I keep an even count

What is your grit progression?
600 to 1500 then 3M paper 2500 then leather with .5 micron emulsion

How coarse do you start on a regular sharpening session?
Unless I am re-profiling I always start with 600 or higher

I haven't seen anything by the OP saying that one steel was harder (HRC) than another. Even if he does, it doesn't change the steps needed to sharpen his knives.
The steel hardness all feels about the same?

A noted sharpener sharpened my 940-1 and it didn't last a week before I was touching it up. I will pay more attention to my burr when sharpening.

Thanks to everybody for all the help!!
 
Slow7 said:
I sharpen my own knifes, if it isn't sharp it's just a shinny stick

I lost an old knife I had carried for years and bought a Kershaw skyline to replace it. In the process I caught the knife bug and ended up buying a few higher end expensive (to me) knifes. The skyline still works fine but two of the others I can't keep sharp. I have tried different angles, different stone/ strops and even sent one out to a noted utube pro to sharpen for me. I use all three about the same these are the
890 torrent Blade Steel 154cm
940-1 Blade Steel S90V
kershaw skyline Blade Steel Sandvik 14C28N
the only blade that stays sharp is the $35 skyline while I sharpen or strop the other two almost every time I use them. Any suggestions or ideas what I am doing wrong?
Click to expand...

If you're sharpening the 154cm and S90V the same as the 14C28N, that may be your problem. 14C28N is a fine grain steel and takes a killer Edge with little effort. I've found that S90V retains a working edge better leaving it course/toothy. Try a toothy edge on the 154cm as well.
Your stropping material/method may be killing your edge. I use a leather strop to remove the burr only. Too much stropping will dull your edge. There's a difference between stropping to remove a burr and refining an edge. As remember a sharpie is your friend. It will let you know if you have the correct angle and if you're truly reaching the apex of the blade.
 
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Ajack60 said:
If you're sharpening the 154cm and S90V the same as the 14C28N, that may be your problem. 14C28N is a fine grain steel and takes a killer Edge with little effort. I've found that S90V retains a working edge better leaving it course/toothy. Try a toothy edge on the 154cm as well.
Your stropping material/method may be killing your edge. I use a leather strop to remove the burr only. Too much stropping will dull your edge. There's a difference between stropping to remove a burr and refining an edge. As remember a sharpie is your friend. It will let you know if you have the correct angle and if you're truly reaching the apex of the blade.
Click to expand...

Thanks Ajack60
That actually explains a LOT I have been trying to keep a highly polished razor edge on both the 154 and the S90V. I will use your method and strop just to remove the burr and see how they hold up. Thanks
 
Many high carbide steels tend not to hold a polished edge for long, but then stay "working sharp" for a long time from that point onward. I'd actually try skipping the high polish like Ajack60 suggested above--try just getting a crisp edge on it at a coarser grit and see how it holds up. What are you routinely cutting here, and under what circumstances? That may be a factor. Highly polished edges will rapidly lose slicing aggression, while toothy edges will tend to deform more readily when used in push-cuts, so striking a balance between the two is usually called for.
 
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FortyTwoBlades said:
Many high carbide steels tend not to hold a polished edge for long, but then stay "working sharp" for a long time from that point onward. I'd actually try skipping the high polish like Ajack60 suggested above--try just getting a crisp edge on it at a coarser grit and see how it holds up. What are you routinely cutting here, and under what circumstances? That may be a factor. Highly polished edges will rapidly lose slicing aggression, while toothy edges will tend to deform more readily when used in push-cuts, so striking a balance between the two is usually called for.
Click to expand...

A good picture of where I went wrong is starting to come to mind. I just kept trying to get a more and more polished edge. Your right the knife stays sharp but doesn't bite into my cut, no tooth. Just cutting everyday stuff boxes, twigs, flowers, rope, etc. THANKS
 
You said the two blades that do not stay sharp are the ones you strop after every use. That could be the problem.
 
everyone has already mentioned what I would have said lol

more course say 600 give or take grit is perfect for those steel types.
also I wouldn't go from 600 to 1500 myself but don't think that would cause your problem. also before going to the next grit make sure all the scratches from the last grit have been removed and your apexed. when you reprofile don't use the 50 grit to apex. apex with the 140 grit. this is because the 50 grit just rips the edges off.

a mirror edge generally doesn't last nearly as long in catra tests and other cutting tests from what I remember.

stropping could be rounding the edge. lots of folks do this when first learning.

also, do you have a magnifier? a loup or digital will work. I find this necessary to look at the edge after every step.

was apostle p the guy you had sharpen them? I wouldn't blame him just askin
 
Stropping can easily ruin a good sharp edge, I went through that a long time ago and have gotten pretty good at it. My
definition for sharp is a brand new razor or scalpel. I don't strop after every use but do touch them up once or twice a week depending on use.

I just re sharped both knifes at 1500 and they are the one I am carrying is holding up very well.

Thanks for all the help, I really thought a mirror polish was the way to go. Seems these knifes prefer a more robust working edge.
 
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