High vanadium/carbide tear-out questions

eKretz said:
The DMT EEF is rated 3,000 grit and would fill your gap nicely. Once the plate wears in it leaves a very fine finish but still cuts quick.

For us to know better what to recommend as far as your edge progression it would help to know what you are doing with the knives. Different tasks need different progressions if you want the longest lasting edges suited to the task at hand.
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Yeah I should have clarified this. I was referring to the refinement of scratch patterns pursuant to mirror polishing. Not everything I sharpen would require a mirror, in fact most wouldn’t. I’m thinking to the future if I should sharpen for side income. Mirror polishes seem to be incredibly popular (two factors: Instagram and people incorrectly thinking that polish positively correlates to sharpness).

Beyond that, I just want to have a range of options in terms the end of my progression, depending on the steel and the desired edge. I think there will be instances where I would like to go higher that 1500 grit and as it stands now, I can’t. At least with high vanadium steels.

Unfortunately, there EEF DMT stones for the KME don’t seem to exist. It looks like it stops at EF.
 
Obsessed with Edges said:
there seems to be a consensus that the relevant threshold for vanadium content is right around that 3% - 4%
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I still find 3% - 4% edges (Para2 S30V) benefits from use of diamond for the final stone; as far as edge durability is concerned. I can always get a sharp edge off ceramics on S30V but the edge cuts well longer if finished on diamond.
 
wootzblade said:
But even people who have read our study on sharpening high vanadium knives keep mixing diamond and ceramic plates in sharpening them, getting a less stable edge than they could using diamonds only.
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Ceramic stone and stroppers . . .
Listen to this ! ! !
There is a difference between "sharp" off the stone cutting little hairs and two days down the road of using the knife at work.

I don't look at the carbides but have such repeatable everyday cutting tasks on abrasive and edge torquing materials that I can tell in a day the difference between say, a blade of S110V sharpened on ceramics to finish it and a blade sharpened on diamond to finish it.
NO QUESTION
I was going to keep quiet and just read this thread since I can't actually see the carbides myself. I don't know if they are tearing out or taking a vacation or getting obscured by the burnished matrix metal or just not getting sharpened but diamonds make a dif ! ! ! . . . in any case. I couldn't stop from commenting.
 
I thought that Michael Christy's video, which I watched the other day, was a little light on detail regarding the issue of tear-out.

And one thing that sort of bugged me was that after talking about how tear-out might occur with alumina hones, (as opposed to diamond), he still goes to the Spyderco ultra-fine after sharpening S90V on diamond hones...(though he does usually end up stropping with diamond paste as a finisher).

Seems like he could skip the Spyderco ceramic hone with the high vanadium carbide blades.

Anyway, just something that was on my mind after viewing the video.
 
I don’t often chime in on these types of things, because sharpening is a thing I do, but I don’t consider myself qualified to speak with authority on the subject. I preface this reply in this way to highlight that I’m not trying to talk down to anyone or criticize with this reply. For the most part, my expectation is that a lot of people replying here are more at home in this lane than I am.

With that understanding in place...

Given that this is said to be a thing that’s relevant only at a sub 3 micron level...

How relevant is this to people?

I use S35VN a lot, which falls into the vanadium range where this is said to start being a Thing. However, I don’t see a reason for apexing beyond 3 microns for EDC use.

What am I missing?
 
I don't think you're missing anything. Most folks would fall into the same camp as you do. There are others here who like to push the envelope...if not for any practical purpose, then because they can.

I admire their talent and ability even if I am not driven to follow suit.
 
Banter 247 said:
I don’t often chime in on these types of things, because sharpening is a thing I do, but I don’t consider myself qualified to speak with authority on the subject. I preface this reply in this way to highlight that I’m not trying to talk down to anyone or criticize with this reply. For the most part, my expectation is that a lot of people replying here are more at home in this lane than I am.

With that understanding in place...

Given that this is said to be a thing that’s relevant only at a sub 3 micron level...

How relevant is this to people?

I use S35VN a lot, which falls into the vanadium range where this is said to start being a Thing. However, I don’t see a reason for apexing beyond 3 microns for EDC use.

What am I missing?
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Considering most people strop with green compound in the sub 3 micron range .. Could be a bigger deal than you think.
 
Mo2 said:
Considering most people strop with green compound in the sub 3 micron range .. Could be a bigger deal than you think.
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The green compound I use is the DLT green, at 6k grit (3 micron being roughly 8k, if memory serves?), and only a few passes. I welcome correction if I’m wrong, but a few passes of light pressure stropping with 6k compound leaves me well short of a 3 micron apex, does it not?

Again, not trying to talk down or act like I know anything. I’m out of my lane here. Putting out my current impression for the sake of getting better information, if my impressions are wrong.
 
Banter 247 said:
The green compound I use is the DLT green, at 6k grit (3 micron being roughly 8k, if memory serves?), and only a few passes. I welcome correction if I’m wrong, but a few passes of light pressure stropping with 6k compound leaves me well short of a 3 micron apex, does it not?

Again, not trying to talk down or act like I know anything. I’m out of my lane here. Putting out my current impression for the sake of getting better information, if my impressions are wrong.
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I used to use 1 micron green. It varies what you buy and your background. Do you know what everyone else uses? May vary wildly.

Alot of normal people do very basic sharpening and will never get the full use of the particular steel they are buying. So yea it does not really matter to everyone. Unless they want to learn and produce the best that they can achieve.

Who's to say this specifically happens only below 3 micron only? Who came up with that?
 
Mo2 said:
I used to use 1 micron green. It varies what you buy and your background. Do you know what everyone else uses? May vary wildly.

Alot of normal people do very basic sharpening and will never get the full use of the particular steel they are buying. So yea it does not really matter to everyone. Unless they want to learn and produce the best that they can achieve.

Who's to say this specifically happens only below 3 micron only? Who came up with that?
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3 micron finish would be required to prevent the carbides from hiding within the cuts, iirc.

Definitely recognize and appreciate that people will prefer varying levels of finish. Very cool with that. I generally use a 1k apex, but I’ll never begrudge anyone for their own preferences.
 
The carbides tear-off does exist, but not as much during sharpening as Todd S. has shown by SEM, as in the real cutting.
E.g. D2 has up to 20 micron carbides.
The razor edge I put on knives is 0.1 micron.
As you can imagine, with a low edge angle there is not enough steel matrix around those huge carbides to keep them in place. In the past I tried edge angle of 10 dps on D2, and after a day of workload clearly saw the very edge turning ragged due to the carbides tear-off. This never happens with the 20 dps edge.

To minimize the large carbides tear-off, firstly, we do not put too low an edge angle - the 15 dps is the lowest safe edge angle for them; and secondly, we minimize that by fine polishing the wear-resistant carbides with diamonds progression of 10 micron - 5 micron - 2.5 micron - 0.5 micron and avoid conventional abrasives not to abrade off the steel matrix around them.

There are studies showing how the Powder Metallurgy technology turns 10-15 micron vanadium carbides into near 1 micron during heat treatment e.g. CPM M4 https://ir.library.oregonstate.edu/downloads/8g84mp812
CPM steels are not the same as the traditional, they are not prone to the carbides tear-off thanks to the small wear-resistant carbides size, and we can sharpen them at a lower edge angle.
 
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wootzblade wootzblade I just read the report Edge Rolling in High Vanadium Knives Sharpened with Aluminium Oxide versus CBN/Diamond and I have a question. Did you do any testing of mixing abrasives types, i.e. shaping on aluminum oxide and finishing on 3 micron diamond, or shaping on cBN and finishing with the Tormek compound? If not would you consider doing this for Elmax where the effect was most dramatic?
 
I've had good luck with D2 at 26° and a 30° microbevel, held up very well.

In general I've had good luck sharpening high carbide steels with SiC up to about 800 grit ANSI and finishing with diamonds. Normally I sharpen all high carbide steels on diamonds from start to finish - its just easier to reach for a combination plate than to set up on an oil stone and switch.
 
HeavyHanded, sure thing your diamond-honed edge will hold.
The carbides tear-off takes place in wear-resistant steels honed with conventional abrasives, mainly in traditional with their huge carbides. I only wanted to draw attention to the role of the edge angle in this phenomenon.
 
Mr.Wizard said:
wootzblade wootzblade I just read the report Edge Rolling in High Vanadium Knives Sharpened with Aluminium Oxide versus CBN/Diamond and I have a question. Did you do any testing of mixing abrasives types, i.e. shaping on aluminum oxide and finishing on 3 micron diamond, or shaping on cBN and finishing with the Tormek compound? If not would you consider doing this for Elmax where the effect was most dramatic?
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We can tell without exhaustive testing that an edge apexed with conventional abrasives and honed with diamonds will have properties of all-diamond sharpened edge, while the edge apexed with diamonds/CBN but honed with conventional compounds like Totmek honing paste will have properties of all-Al2O3 sharpened.
This is because weakening of the steel matrix happens during fine honing, not bevelling.
 
wootzblade said:
HeavyHanded, sure thing your diamond-honed edge will hold.
The carbides tear-off takes place in wear-resistant steels honed with conventional abrasives, mainly in traditional with their huge carbides. I only wanted to draw attention to the role of the edge angle in this phenomenon.
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I'll add that the microbevel proved to be essential when working with D2, and is a good strategy for many of the high carbide steels if a more acute angle is desired. The trick is applying the micro without causing any carbide displacement, as these steels don't do well with lateral stress when worked thin. None do really, but where other steels might roll, these will crumble.
 
Mr.Wizard said:
A feather touch I presume? Edge leading or trailing? Medium of choice?
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Starting with the edge as burr free as possible off of a coarse DMT or equivalent I use a light leading pass on an EF or EEF at about 2° higher angle per side. Between 5 and 10 passes and maybe one or three passes on a hard paper strop with some diamond in the honing compound. I honestly believe on the high carbide steels you get a better outcome with use of a guide of some sort. Is not necessary, but does seem to improve the outcome a little.

On low carbide stainless or carbon steels I use the same strategy much of the time, but using a coarse stone to set-up, and microbevel on the Suehiro G8. On the waterstone I'll start with a few leading passes and finish with one or two trailing passes/side. A guide doesn't seem to help much if at all on these steels.
 
HeavyHanded said:
I'll add that the microbevel proved to be essential when working with D2, and is a good strategy for many of the high carbide steels if a more acute angle is desired. The trick is applying the micro without causing any carbide displacement, as these steels don't do well with lateral stress when worked thin. None do really, but where other steels might roll, these will crumble.
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Smart, as is your above post. Smart compromise between the cutting performance of a low-angle edge, and edge stability.
Many things you mention in passing, like side-notes, turn very important when I think about what you say.
 
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