Sticky edges - sharpness

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KC8QVO

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Apr 7, 2011
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I have noticed between 1095 and 3V that the 1095 seems like it is a lot easier to get "sharp". Since I know that means different things to different people, my explanation is that the edge #1 will cut paper VERY easily and #2 the edge feels "sticky", as I run my fingers perpendicular to the edge with very light pressure it "grabs" if that makes sense. 3V doesn't seem to get to that point.

In another thread over on Knifemakerforums Jerry Hossom describes his entrance in to the 3V use for blades and noted it would not polish under regular methods. According to the thread, and some subsequent correspondence between Jerry and a chemist, the reasoning as to why is that the vanadium carbide atoms are a lot tougher than the others and don't strip off under normal methods. Thus, the vanadium carbide atoms do not sit flush against the rest. This higher material (I equate the reasoning to grit on sand paper, but much finer) would cause light to scatter = no mirror finish.

Would I be on target in using the same reasoning why the steel won't polish as to why I have not been able to get the 3V steel as, seemingly, sharp as I can 1095?
 
I only have a VECP in 3V but I find that it takes a really fine edge. It's about as hard as S30V to grind(I reprofiled it) and polished the bevels. 1095 is a much less wear resistant steel and I;d say that's why you have an easier time getting it "sticky" sharp. I do find that 3V takes a good polish but you do need elbow grease.

VECP3-1.jpg


After a lot of use at the construction site and maintained with a 14u diamond paste loaded strop.

VECP4.jpg
 
1095 has absolutely no vanadium or chromium, nor any other elements to form those very hard carbides. That's why it sharpens up & polishes so much easier. Not just 'sticky' sharp, but it'll get wicked sharp at virtually any type of edge finish, from very coarse to a mirror shine. It's essentially as basic as true steel can be; just iron and carbon, and a minimum of anything else.

3V, on the other hand, has a quite-high amount of vanadium (2.75%), which accounts for most of the wear-resistance (hard carbides) in it.
 
According to Larrin (metallurgist dude) - 3V Vanadium Carbide is around 3-5microns in size. Whereas 1095 Carbon carbide diameter is less than 0.2um in size. In this case, once sharpening reaches hone (sub 5microns) stage, you need to use diamond/cbn/bn to abrade VC along with steel matrix. Otherwise, softer abrasives mostly abrade steel matrix surrounding VCs, which rarely result in sub-micron edge (aah blind squirrel lucky sharp).

Worth a try for 3V (or any hard steels) - use edge leading stroke only stages: dmt F -> EF -> EEF, then a few quick strops on bareleather or newsprint. Looking for: after F - bity, EF - bity & some ticky, EEF - sticky, strops - sticky and maybe tingle.
 
It sounds like diamond spray and a strop is the only way I am going to get the 3V any more sharp. Are there any recommendations on sprays/where to buy? I have a buddy at work that is getting me some leather scraps (used show leashes from beef cattle, its about 1/4" or more thick).

I spent some time with my 3V blade just now. I went to 600 grit on my Edge Pro at 24deg and worked up a burr on both sides, evenly across the blade. On the last pass I left the burr. Then I took the burr off with my slotted paper wheel/white rouge and buffed the snot out of the edge (more than I ever have, full speed on the wheel, slow passes with the blade putting pressure on it). I got the exact same results as what I have been getting all along. The paper wheel buffed the edge to a much more polished finish than the 600 grit wet stone left, but it still wasn't close to a mirror like singularity35's picture shows.
 
Just for the heck of it I decided to run all the way up the grits on my Edge Pro. Before I went to 600 grit and then the paper wheel, this time I continued on to 1000 grit wet stone and then 2000, 3000, and 6000 grit polish tapes.

The results are slightly better than the paper wheel finish in "sticky'ness", but the paper cutting ability is still not what I would consider "great". For as sharp as I think the knife should be at this point the amount of resistance through paper seems way too much.
 
KC8QVO said:
Just for the heck of it I decided to run all the way up the grits on my Edge Pro. Before I went to 600 grit and then the paper wheel, this time I continued on to 1000 grit wet stone and then 2000, 3000, and 6000 grit polish tapes.

The results are slightly better than the paper wheel finish in "sticky'ness", but the paper cutting ability is still not what I would consider "great". For as sharp as I think the knife should be at this point the amount of resistance through paper seems way too much.
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A few years back, I had similar experienced s30v on EP - the sharpness never there but if I worked really hard strop with Cr2O3 then sometime I get the edge sticky sharp but it seems to loose that stickiness just simply by breathing on it. Well, that BM 940 was collecting dust until 2011 when diamond stones+strops brought the 940 out of retirement.

To get high alloy steels (mostly high in VC and WC) sticky sharp via EP - Check out ChefKnivesToGo.com Ken's Corner.EP Diamond Sharpening Plates 1"x6", get 9,3,1.0,0.1 microns plates. If you want to spend the least, get a 3 micron plate/strop. For big budget - get 125,45,20,9,3,1,0.5,0.1 plates. btw - I prefer freehand way now, it's more flexible & rewarding as well.

edit: 3V has 2.75%V while s30v has 4%V (vandium), so s30v is tougher to sharpen
 
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Thanks for the great post bluntcut. That gives me some more information to go off of.

With the stones I have on the edge pro I can grind the steel OK - I can get a burr fine. I will say that it takes significantly more work than any other knife I've sharpened on it (some stainless kitchen knives, 1095, etc), but I can grind it.

That having been said, if I get down to the 1000 grit stone what would be the next logical step in diamonds? According to Komitadji's chart the 1000 grit EP stone = 7 microns (if I read the latest chart correctly).

If the EP stone is 7 microns and I go to a diamond stone of the same 7 micron value would I gain a sharper edge just by the switch to diamonds right there? Could I make a bigger jump from 7 to, say, 1 micron diamonds?

I will be getting some leather for strops. Would it be worth my time/effort to do the sprays?
 
KC8QVO said:
..That having been said, if I get down to the 1000 grit stone what would be the next logical step in diamonds?
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Yes, 3micron diamond. However I like to use diamond 9micron (dmt ef) then jump to finish at 0.5 or 0.1 micron strops, a toothy edge for kitchen and garden duties.

If the EP stone is 7 microns and I go to a diamond stone of the same 7 micron value would I gain a sharper edge just by the switch to diamonds right there?
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Jump to 3micron diamond next. I think this way because VC around 2-5micron in size, so need diamond to abrade steel & carbides. Imagine a micrograph(see Clip's post in spyderco forum), it probably shows carbides are partially protruding/raise above bevel & lumpy along the edge. Therefore use diamond & cbn once grit go below 10micron.

Could I make a bigger jump from 7 to, say, 1 micron diamonds?
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Sure, but won't be easy to remove scratches from 7 micron by using 1micron (even if diamond is more agressive), unless mirror finish is a non-goal.

I will be getting some leather for strops. Would it be worth my time/effort to do the sprays?
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Sure. Cow & horse leather are ok for 1 & 0.5micron spray, kangaroo leather will take 0.25micron spray. Horse butt & roo can handle a thick layer of 0.1micron mono/poly diamond suspension.

Keep in mind that, EP 0.1micron strop is simply a diamond film on aluminum backing - less flex/curve-up, which lessen the chance of rounding the edge. Use super light pressure when using charged leather with diamond/cbn to avoid rounding the edge. On other hand, charged leather is great for convexing + polishing the bevel, just use lower angle than the actual bevel angle.
 
Does the spray hang on for a while or is it something that needs re-applied routinely like rouge on a paper wheel?
 
KC8QVO said:
Does the spray hang on for a while or is it something that needs re-applied routinely like rouge on a paper wheel?
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A long while, usually keep on cutting until the strop is totally black <= at 1 & sub micron, which mean at least after a few hundred knives. Three times now, I recharged my buff paper wheel after ~50knives or so. But the buff/slotted wheel hone + polish in one, so it does more work than a strop loaded with sub-micron compound. Oh well, I'm a paper wheel newb.
 
Some small progress has been made over the past dozen years since I started working with 3V. Most notably Norax belts have made it possible to grind 3V down to 5 microns and finer, so a one micron polish isn't far away. I don't polish 3V blades, but the edges sparkle pretty nicely. At the time I spoke with that chemist I was happy to seize on any excuse besides my own incompetence. Honestly, I would have bet S30V was impossible to polish, but I've seen it done. I'm sure with diamond compounds you can polish anything.

For sharpening, I take the edge down to a 5 micron belt, and polish off what little is left of the wire edge with a leather belt that last saw white compound maybe six months ago and not much of it then.
 
Jerry Hossom said:
Some small progress has been made over the past dozen years since I started working with 3V. Most notably Norax belts have made it possible to grind 3V down to 5 microns and finer, so a one micron polish isn't far away. I don't polish 3V blades, but the edges sparkle pretty nicely. At the time I spoke with that chemist I was happy to seize on any excuse besides my own incompetence. Honestly, I would have bet S30V was impossible to polish, but I've seen it done. I'm sure with diamond compounds you can polish anything.

For sharpening, I take the edge down to a 5 micron belt, and polish off what little is left of the wire edge with a leather belt that last saw white compound maybe six months ago and not much of it then.
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More likely that your 3v edge is less than 1micron thick using the 5micron belt. Physics of moving abrasives is quite different than static abrasives.
 
Jerry,
Thanks for the comments. I should have dated the post I referenced - 3/3/2009 http://www.knifemakerforums.com/showthread.php?t=672

On the topic of stropping with spray - I would imagine the smooth side of the leather would be what I would want to use as the rough side would seem more abrasive in and of itself, correct?

It would also probably be preferable to mount the leather on wood or metal so it doesn't flex much, if any, and to the same point thinner leather won't compress like thicker leather.
 
I'm sure that's correct, Bluntcut. The edge is essentially polished after the 5 micron belt. All I'm really doing with the leather belt is stripping off the wire edge, which hangs on with some tenacity I might add. I use the smooth side of the leather, running on a 1 x 30" Harbor Freight belt sander. The belt is thin and running over the platen where I'm stropping. I should note I have a total of five 2 x 72" leather belts that I've bought over the years to use on my variable speed Bader, and all wobble so badly I can't use them. The little 1 x 30 does the job very well, even on large blades. Also worth knowing, some top grain leather is abrasive all by itself, because of fine particles of dirt embedded in the leather.

On the 3V vs S30V comparison, it's been my experience that performance of S30V is greatly dependent on the quality of the edge. It is not very tolerant of a coarse edge, which can be viewed as an edge with a whole lot of little stress risers in it. A polished edge is more durable in terms of both wear resistance and resistance to micro-chipping. S35VN was introduced to help deal with the latter. Actually that's true of most high alloy steels, but stainless in particular. I'm convinced that most of the early negative reviews of S30V experiencing chipping problems was due to the edge most factories put on their knives. Many (I'm tempted to say most) sharpen at 220 grit and strip off the wire by a bunch of different techniques, ranging from buffing on a felt wheel, to a paper wheel, to a cloth or cork belt with or without compound, to simply running it over a surface like a piece of hardwood.

3V carbides are in the range of 1 micron. That's from the person who was Crucible's chief metallurgist. It's very different from most high alloy steels and is one of the few that's actually patented. It's why you don't see it or anything quite like it from other sources.
 
I am tossed up here.

The two options I see right now are diamond spray and a strop or a diamond plate. I see there are some plates available at chefknivestogo.com for the Edge Pro Apex. There are 3 significantly more expensive ones, the highest grit being 1200. I am assuming that these are real "plates". All the other ones don't look like real plates, almost like the tape sets I have that are stuck on aluminum blanks.

By using the Edge Pro I have I can keep consistent angles. However, the plates don't look like they get up to the low micron numbers, just the 1200 grit.

Will a strop be as abrasive, or should I rephrase that as "move as much metal as easily", as a diamond plate?

I suppose if I could see my edge up close I could tell better whats going on too. I don't have a microscope here but my dad has one. I'll see if I can get it one of these days.
 
For EP plates & strops that go from 165 micron down to 0.1micron diamond, see chefknivestogo.com ->Supplier ->Ken's Corner -> Diamond sharpening plates -> 1"x6".

Will a strop be as abrasive, or should I rephrase that as "move as much metal as easily", as a diamond plate?
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Yes. Diamond film strop (as above) or embeded diamonds in somesort of binder are actually plate except they are delicate so recommended to use only trailing strokes (aka stropping).

Loose diamond(or other abrasive) on backing such as balsa or leather will cut less agressive since abrasives move about (push, roll, etc) so stropping now include lapping interaction.
 
Ia there anything that is less delicate than the films? Or is that really the only option for the Edge Pro?
 
I've read somewhere that leather glued on tape blanks and loaded with diamond paste work well too. Edge trailing though, or you'd slice the heck outa them.
 
In general, it should be delicate at 1 & sub-micron level, a good property for delicately abrade metal around the edge. Singularity35 is right, you can glue a flatten leather charged with compound to an EP blank (or cut your own piece of aluminum or stainless steel blank).

A more creative way - take 1x6x1/16 hard balsa paste the mixture of diamond powder & resin, press flat with glass plate, when dry glue to an EP blank. Use the end part of spyderco ceramic stone to flatten your new EP strop.
 
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