what finish to put on edges?

[hardheart]

I'm trying to decide what to do with my folder edges. My folders have ATS34/154CM, D2, M2, AUS6, AUS8, 440C, S30V, 4 Victorinoxes and whatever carbon steel Opinel and Okapi use.

Trying to decide what grit to finish with for general use. I stop at 600 or 800 right now, but I was wondering if I should go further with some of them, like the M2. I also use a smooth steel, steatite rod, and Cro loaded strop.

 

[Cliff Stamp]

What are you cutting?

-Cliff

 

[redhawk44p]

Good thread. I am all ears.
I like a polished edge lightly stropped on diamonds after to give it some teeth.

 

[hardheart]

hmm, nothing too special. Just plain jane edc tasks, really. I don't use folders for woodwork; so mostly cardboard, packaging plastics like blister packs, nylon or manila rope 3/8ths or less, cable ties, very light vegetation, the rare automotive hose. I don't do food prep with my folders, nor dig in the ground.

Any 'work' I do with a knife tends to put the edge in danger, seems any job related cutting I do involves materials on or terribly near metal surfaces. The more common everyday stuff doesn't stress my edges much, but when they eventually dull past the point that a couple swipes on the ceramic rod or strop doesn't bring back a shaving edge, I'd just like to apply the best finish for the steel. Not really looking for spooky sharp edges, but just not to leave an edge too toothy. I have just a couple knives that I beat up on, so those edges I leave rougher, but I figure since I bothered to choose different knives partially based on steel used, I should focus more on edge finish for each steel.

 

[CMSpeedy]

My personal preference now is a finish with the Extra Fine Sharpmaker rods. They put a great general purpose edge on. IMO. I've gone to full polish with 3000 grit and it does not cut good for me. Not sure what grit equivalent this would be, but it is working GREAT for me. Puts on a wicked edge with tiny burrs. Not to mention it is VERY VERY easy.

 

[Dog of War]

Personally I like the finish you get with fine ceramic, like white Spyderco or CrockSticks, for general utility use. Also using a little ass-backwards logic, I think this has a lot to do with why Sharpmaker and similar sharpeners are so popular, they leave an edge that both push cuts and slices well.

Though Spyderco doesn't specify, and grits of different media are hard to compare, I've usually read that fine ceramic is about 1200 grit. Extra fine diamond, and hard black Arkansas stone are supposed to be about the same, at least to the extent you can roughly compare the three. I've never used x-fine diamond but some say the finish isn't as fine as fine ceramic; black Arkansas on the other hand seems to me to leave a more polished edge. Anyway a lot of people like each of these for a finished edge, leading me to think something in this general range is a good compromise for general EDC.

 

[Larrin]

Though Spyderco doesn't specify, and grits of different media are hard to compare, I've usually read that fine ceramic is about 1200 grit.

I think Cliff Stamp estimated it at about 6.5 micron, which is more like 2400 grit. That's pretty dang fine. So the question is, what grit are the ultra fine ceramic rods that are purchased separately?

 

[Cliff Stamp]

so mostly cardboard, packaging plastics like blister packs, nylon or manila rope 3/8ths or less, cable ties, very light vegetation, the rare automotive hose. I don't do food prep with my folders, nor dig in the ground.

X-coarse DMT at about ten degrees per side gives very high cutting ability and edge retention for those materials when cut on a slice, even on the soft steels with low wear resistance. The edges should be "spooky" sharp, you lose a lot of edge retention if they are not.

If you are cutting around metals a lot then increase the edge angle with a micro-bevel until the damage you are seeing is acceptable. Between 15-20 is likely depending on how hard you are cutting and the hardness of the particular steel.

-Cliff

 

[Django606]

For my S30V Sebenza I like to strop, and then lightly finish on the coarse Sharpmaker stones to give it a little more slicing ability. I barely notice any difference in push cutting ability, but notice the difference in slicing ability.

 

[hardheart]

That's something to try, I'm going to order a pair of double sided diasharps anyway, so I'll see how the X-coarse does for reprofiling. My rougher edges usually don't last long, but I sharpen my heavier used knives that way with a thick bevel, and those are usually AUS8, I prefer the edge to deform rather than chip. I have gone up to 4 digit grit on other knives, using Lanskys and Edgepro, and honestly I couldn't tell the difference in edge performance for the type of work I do.

So, the microbevel finish isn't important? I was going to see how fine I could go on a couple of blades, just to try it. I kinda wanted to see how differently M2 and D2 would act. One of my D2 knives is a Queen toothpick, so it badly needs reprofiling from the factory edge.

Spooky sharp is something around cutting hair away from the skin, isn't it? Seems like that would be some work getting that out of a coarse finish, though I did use to think that getting a knife to shave from the finish of a 'medium' Lansky stone (280) was fine.

 

[Dog of War]

I think Cliff Stamp estimated it at about 6.5 micron, which is more like 2400 grit. That's pretty dang fine. So the question is, what grit are the ultra fine ceramic rods that are purchased separately?

The info and charts I've seen are very inconsistent, but I've never seen the ultra- or extra-fine ceramic rated higher than 2000 grit.

According to this chart, 6.5 microns would be about 1200 grit:

http://users.ameritech.net/knives/grits.htm

Pretty much the same chart here:

http://www.woodcentral.com/bparticles/sharpening7142.pdf

I've seen Norton fine India rated from 240-400 grit, and for the life of me, the finish I get using diamond plates never seems to compare with any other abrasive rated at similar grit. Pretty much I just go with what gives me the edge I want.

 

[Django606]

Cliff, what kind of edge will cut a hanging hair? I am able to do this with the edge I have put on my Sebenza. Is this a trying test?

 

[Cliff Stamp]

The info and charts I've seen are very inconsistent ...

That is because they are often rated by the way weatherman judge cloud cover. The estimates I produced for the Sharpmaker rods were based on visual inspecton under magnification of multiple sharpened blades against known benchmarks (DMT stones) as well as verification using measured tests of sharpness at multiple finishes. It is trivial to use this method to judge the grit in a definate manner.

Cliff, what kind of edge will cut a hanging hair? I am able to do this with the edge I have put on my Sebenza. Is this a trying test?

Depends on the hair and exactly what you mean. If you are serious about sharpness you want to move to a definate test. The easiest one to use in a quantitative way is to push cut newsprint. There are several ways to do it. I pinch the sheet of newsprint between my fingers and the further away from that point you can push the blade into the paper, the sharper the knife. With a really sharp knife you can get out to 3+ inches.

So, the microbevel finish isn't important?

The micro-bevel finish determines the cutting ability, the relief grind finish has little influence.

Spooky sharp is something around cutting hair away from the skin, isn't it? Seems like that would be some work getting that out of a coarse finish, though I did use to think that getting a knife to shave from the finish of a 'medium' Lansky stone (280) was fine.

Coarse edges can be very sharp, Dozier's are very coarse for example. I have seen very coarse edges, 80/100 grit AO belts which would shave above the skin.

-Cliff

 

[hardheart]

Ahh, so for these folders, would you apply a different microbevel finish based on the steels, or does the regular range of use not call for it? I thought perhaps one finish would be more durable than another depending on the steel. I'll see what my Opinel can do at a coarser edge when I get the diamonds.

 

[Cliff Stamp]

Choice of steel effects grit finish indirectly. The harder and finer grained steels can take very thin profiles and thus most slicing starts to turn into push cuts. In such cases you start to revert back to high polishes even for cutting ropes and such. Note as well that the edge angle directly magnifies the micro-teeth size. The teeth produced at a 10 degree edge are twice as large as those on a 20 degree edge with the same stone, which is another reason you usually don't need to go very low to obtain extreme slicing aggression at low angles.

-Cliff

 

[omniphile]

This was NOT a direct recommendation from Cliff, but taking on board a few things that he mentioned in another thread about convex edges a few months ago, I honed a primary bevel on an old Gerber Folding Sportsman III with 440C steel at 10 degrees per side. Then over a period of time (and using some info from Cliff and frugalweaver on another thread about homemade woodbacked strops with various polishing compounds), I carefully created a convex edge.

This knife is used like yours for EDC stuff, but nothing too hard like cutting metal straps or anything, and the edge just scares the heck out of me. When no-one else is home (because I don't want to get a reputation of being a hone whore), I often just strop it a few times on a virgin leather belt and it maintains the sharpness.

I swear its much much better than the factory edge. If you have a bit of time to spare, you may like to try it. I might just be easily impressed, but it may be worth a test!

Cheers
Phillip

 

[Django606]

I'll try the newspaper tomorrow. Is this a straight up and down cut or a diagonal cut? (Diagonal seems easier)

 

[Cliff Stamp]

I'll try the newspaper tomorrow. Is this a straight up and down cut or a diagonal cut? (Diagonal seems easier)

No diagonal cuts, axes are sharper than that. Blade is at 90 degrees to the paper and there is *NO* draw. It is time to sharpen your knife when you can only slice the paper, and especially if you need a diagonal to do it. That is about 5% of optimal sharpness, not an exaggeration.

I swear its much much better than the factory edge.

Give it a few years and keep adjusting your bevels, you will sonn look at ten degree edges as your rough use work knifes and your serious cutting tools will run that as a micro-bevel. I am currently EDC'ing a knife ground at 4 degrees per side with a full height hollow bevel. You can set a caliper at 0.005" and it goes WAY up onto the edge bevel. You will also soon also start seeing the phrase "stainless steel knife" as as oxymoron.

-Cliff

 

[hardheart]

No diagonal cuts, axes are sharper than that. Blade is at 90 degrees to the paper and there is *NO* draw. It is time to sharpen your knife when you can only slice the paper, and especially if you need a diagonal to do it. That is about 5% of optimal sharpness, not an exaggeration.

hmm, my dendritic cobalt boye can't do this, but I figured I shouldn't even try because of the very soft metal used.

oops, not on newsprint, 20 lb paper. I have to be less than 1.5" away from the grip to push cut.

 

[Dog of War]

The info and charts I've seen are very inconsistent ..

That is because they are often rated by the way weatherman judge cloud cover. The estimates I produced for the Sharpmaker rods were based on visual inspecton under magnification of multiple sharpened blades against known benchmarks (DMT stones) as well as verification using measured tests of sharpness at multiple finishes. It is trivial to use this method to judge the grit in a definate manner.

Not to go too far OT with this thread, but available info comparing abrasives seems to be pretty lacking. I think I understand some of the reasons why manufacturers limit what they provide, but for an independent party to do what you did, Cliff, would be very useful and provide a better standard for practical comparison. Being limited to a simple microscope and micrometer myself, the best I've been able to do to measure stuff under magnification is to measure the thickness of a hair, and then use that as a crude gauge. I imagine physicists have better methods.

Another interesting thread would be discussion of crystal shape, structure and density of different abrasive media, which I think must be important factors. Also effects of an abrasive slurry vs. dry honing. Maybe I'm mistaken, but there seems to be a lot more involved than just the "grit" of the abrasive.