Ranking of Steels in Categories based on Edge Retention cutting 5/8" rope

Steel130 said:
Same here. M390 still amazes me at how aggressively it cuts at that lower grit finish :D.
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High vanadium steels seem to really benefit from a courser edge finish. As well as other types of steel. I use 400 grit for kitchen use because when cutting tomatoes and meats it's nice to have some bite, much more affective. H1 for example, in my uses doesn't hold a polished edge very well. I think there would be a substantial difference in edge holding with a coarse edge. I'm sure Jim will test it one day:)
 
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The only blades I generally like a polished edge on are fixed, chopping type blades and blades used mainly for woodwork/bushcraft type usage as its mainly push type cutting.

Thanks Jim! Best thread on the Forums!
 
Jim,
The coarse edge vs. polished edge is an interesting conversation. What I want to know is if you start with a finer edge does it develop into a "coarse edge" after some use? That was always my assumption, but it seems as though that is wrong if a coarse edge can outlast a polished edge of the same steel. Can you explain that farther?
 
I too am curious as this makes me wonder how my strop brings an edge back?

Damn it Jim. I just figured out why water is wet and why women have secrets! I was so close to understanding the riddle of steel and the origins of the universe when this question comes up.
 
nccole said:
Jim,
The coarse edge vs. polished edge is an interesting conversation. What I want to know is if you start with a finer edge does it develop into a "coarse edge" after some use? That was always my assumption, but it seems as though that is wrong if a coarse edge can outlast a polished edge of the same steel. Can you explain that farther?
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No, not exactly. A polished edge will dull out and feel coarser, however it is nothing like an actual coarse edge one puts on at first. When an edge dulls, essentially what happens is: nicks, rolls, or rounding of the edge will dull the blade. This can all lead to a coarser feeling edge, but the edge is actually being "destroyed", and the apex is rounded.

The coarse edge is more favorable in Jim's testing because rope is fibrous and benefits from serrations (in this case microscopic serrations from a coarse edge) far more than a plain smooth polished edge which would round out very quickly, and not cut nearly as well.

Remember serrations last longer than a plain edge when cutting fibrous materials (rope for example). The same logic applies microscopically. A coarse edge will last longer than a plain edge.

RWT said:
I too am curious as this makes me wonder how my strop brings an edge back?

Damn it Jim. I just figured out why water is wet and why women have secrets! I was so close to understanding the riddle of steel and the origins of the universe when this question comes up.
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I haven't done a ton of testing on stropping (particularly the super low micron stropping), however what I know is that a strop shouldn't "bring" an edge back. It usually only hones an already sharp edge and is required constantly to maintain an edge. Wait too long as it won't do much.
Stropping helps to hone by evening the edge and or decreasing the toothiness of the edge by helping to almost "break" away the teeth which leaves you with a smooth edge which is excellent for push cutting.
 
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nccole said:
Jim,
The coarse edge vs. polished edge is an interesting conversation. What I want to know is if you start with a finer edge does it develop into a "coarse edge" after some use? That was always my assumption, but it seems as though that is wrong if a coarse edge can outlast a polished edge of the same steel. Can you explain that farther?
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It's because the edge is more aggressive and efficient at cutting so it takes far less effort (pressure) to make the cuts through the rope, and or most other things as well.

Think of a serrated blade, it will keep cutting for a very long time vs a non serrated blade.
 
I've always wondered how a blade would perform with one side polished and the other left at about 320. Been meaning to try it
 
Ankerson said:
It's because the edge is more aggressive and efficient at cutting so it takes far less effort (pressure) to make the cuts through the rope, and or most other things as well.

Think of a serrated blade, it will keep cutting for a very long time vs a non serrated blade.
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If you could, put "coarse" vs. "polished" in terms of capability to push cutting phone book paper, shaving arm hair, push cutting tp, and so on. I use a sharpmaker and can shave when I am done, but don't really know if that is "coarse" or "polished."
 
skwurll said:
I've always wondered how a blade would perform with one side polished and the other left at about 320. Been meaning to try it
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Most serrated knives are scalloped on only one side, essentially the same as this.

The lower grit or larger particles on the abrasive surface cut grooves into the metal - depth/width depends on size of particles, frequency depends on number of particles.

Cutting these grooves such that they intersect the line of the edge creates "teeth", serrations, with peaks and valleys along the edge-apex. If you cut these grooves along only one side of the blade, the apex will still have peaks and valleys. Cutting grooves into both sides will leave slightly less material (thinner) behind the edge and create a greater number of peaks and valleys at the apex due to the cut valleys on each side. Think of a saw with only a single row of teeth cut on one side, then cut those teeth in half along the other side so that you have the standard 2 rows of alternating teeth (well, not quit standard, but hopefully you get the idea)

Greater frequency and smaller particle size (i.e. higher grit abrasive) increases the number of peaks/valleys and reduces their size to a smoother finish, i.e. polish. Stropping compounds are designed to distribute a higher number of particles of very small size, so they function more for "polishing" than cutting. When you strop the very apex of a "coarse" edge, you effectively cut smaller ridges/valleys into the larger ridges left by cutting with the coarse abrasive. This "polishes" the apex without removing the ridges or "teeth" altogether. So if your teeth have been damaged/weakened from use, stropping them removes weakened metal and re-establishes an apex without removing the teeth. It can also work to clear material left behind in the valleys, like cleaning between saw-teeth.

When you strop without compound on a mildly abrasive surface, e.g. cardboard, you rely on that material's abrasive qualities to do this same work.
 
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nccole said:
If you could, put "coarse" vs. "polished" in terms of capability to push cutting phone book paper, shaving arm hair, push cutting tp, and so on. I use a sharpmaker and can shave when I am done, but don't really know if that is "coarse" or "polished."
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A sharp edge will do all of that, polished or coarse, except maybe push cutting TP.
 
Ankerson said:
A sharp edge will do all of that, polished or coarse, except maybe push cutting TP.
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Closest I've gotten to push cutting TP with a coarse edge was with quite a bit of stropping, and setting the blade about 15 degrees (vertical almost) from the hanging TP.
This was done with S30V@60.5 HRC.
Not exactly "push cutting" in my mind but about the closest I have gotten.
 
Luis G. said:
Closest I've gotten to push cutting TP with a coarse edge was with quite a bit of stropping, and setting the blade about 15 degrees (vertical almost) from the hanging TP.
This was done with S30V@60.5 HRC.
Not exactly "push cutting" in my mind but about the closest I have gotten.
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I always assumed that stropping a lot would take it from a coarse edge to a polished edge. I am beginning to think I have never really had a true polished edge. I have the regular fine stones on the Sharpmaker and not the UF's.

I feel like I am missing something. After seeing the results I decided I wanted a coarse edge and thought I would have to stop at the medium stones or something. Now it seems as though a coarse edge is all I have ever done. How do I tell?
 
Get yourself a decent 20-40 power magnification lupe and a whole new world will opened up to you. It really helps to be able to see your edge to make sure that you've gotten all of the "scratches" out from the previous grit stone and also to see your burr as you get to finer grits. This, alone, helped me get hair whittling edges with only a sharpmaker with the ultrafine stones. I picked up a 20x and a 40x for about $25 for both on Amazon IIRC. I have my doubts that they are really the magnification that they claim but I found that the 40x is perfect for seeing my edges and I don't even use the 20x.
 
I'm also planning to use my 40x lupe to go from the brown stones straight to the ultrafine stones to try to polish up the "micro serrations" a little. I'm curious if doing this will cause some of my CPM S30V blades to hold a good working edge longer that just using the brown Spyderco themselves or going all the way to the ultrafine stones. I won't be cutting rope so the "test" will be purely subjective on my part.
 
nccole said:
I always assumed that stropping a lot would take it from a coarse edge to a polished edge. I am beginning to think I have never really had a true polished edge. I have the regular fine stones on the Sharpmaker and not the UF's.

I feel like I am missing something. After seeing the results I decided I wanted a coarse edge and thought I would have to stop at the medium stones or something. Now it seems as though a coarse edge is all I have ever done. How do I tell?
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Not at all. A strop does not take a coarse edge to a polished one. It simply evens out the edge and gives a less rougher edge by "removing" some of the teeth off (teeth meaning microscopic "serrations" from the coarse edge). This gives you a good balance of slicing aggressiveness and push cutting (when you take a 400 grit edge then strop).

The ultra fine stones gives nice fine less aggressive edge and you can end up with a very nice and super sharp edge after stropping. A spyderco sharpmaker couples with some DMT stones for reprofiling can lead to push cutting toilet paper if your geometry is good.

The edge given by the sharp maker fine stones is similar to about a 1,000~ finish. It is not considered a coarse edge at all, the browns definitely are coarse. The white fine stones do not get a knife as sharp as a ultra fine stone and super light stropping can get it.

Here's a good way to measure your edge on the sharpmaker, this is without stropping at 20 degrees per side:
1. The sharpmaker brown stones' flat side should leave a hair popping edge. It should NOT feel terribly rough on the skin.
2. The sharpmaker white fine stones should leave a hair whittling sharp.
3. The sharpmaker ultra fine stones should leave a near shaving sharp edge. You should not feel any amount of discomfort at all, you may feel tugging but not much if at all (depends on your angle too). Once you strop it, you should not feel the slightest tug. Keep in mind some very high vanadium steels cannot obtain this type of edge (M390 for example).

At 15 degrees per side due to the increased pressure due to the finer edge:
1. Brown stones should shave hair off without feeling rough but not smooth.
2. White Fine stones should leave hair whittling, and nearly shaving sharp (should not feel much tugging).
3. Ultra fine stones should leave a smoooth edge that should not tug at all.

Also as a last advice:
Keep in mind finishing an edge with a even finer stone requires a more delicate and controlled touch on a strop than the previous stone used. This is why people with straight razors go to fraction of a micron stropping.
 
What is the benefit of a "hair whittling" sharp edge - beyond whittling hair, of course? Seems like it will not last longer in some applications.

It seems like "sharp" means different things, depending on what one is trying to cut.
 
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