CBN or PCD sprays

[Johpe]

Hi there

Just wanted to get opinions if anyone notices any real difference between a CBN (Cubic Boron Nitride) spray and a PCD (Polycrystalline Diamond) spray of the same brand and particle size?

I’m guessing there should be some difference (except for cost and particle material)?

//Johannes

[Mark]

I don’t know if this is typical, but for me the CBN seems to work better. I was using 1,.5 and .25 PCD and while they work great the .75 CBN just gives me a better feeling edge. I don’t know how to describe it, It just feels “crisper”?

[Ken Buzbee]

I don’t know if this is typical, but for me the CBN seems to work better. I was using 1,.5 and .25 PCD and while they work great the .75 CBN just gives me a better feeling edge. I don’t know how to describe it, It just feels “crisper”?

Haven’t tried it, but several people I trust have said the exact same thing about CBN.

Ken

[Phil Pasteur]

Not sure why that would be. The idea of Poly diamonds…from what I have read is that they stay “sharp” longer due to the way they break down. CBN is not as hard, but only a few tenths or so less on the MOHS scale. I mentioned this to Ken Schwartz one time… he replied that it was not enough that you would ever notice it.. except maybe on an industrial scale..

http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

If anything, analytically, the CBN should be a bit slower to abrade, and break down faster…

Maybe that is the key, the particles round off and slow down faster. In theory… with additional time, you may get more of a polish at a finer level then when using the poly diamonds..
All of that being said… my experience has been with CBN and Mono crystalline diamond sprays.
I use a progression that is indicated by strictly rated grit. I simply don’t have any test sensitive enough to tell the difference between 0.125 CBN and 0.1 mono diamond. The only poly diamond spray that I have is at 0.025 microns. At that level, I wonder if results are as much wishful thinking as anything.
In any case, I have no CBN at that level to compare.

I would always be leery of those saying that they “think” or “feel” rather than that they have measurable repeatable results.

Maybe I am not enough of a purist or of a spray snob… or just out of touch with my ZEN …
But it think the reality is, the vast majority of people sharpening would never notice any difference between like rated CBN and Mono or Poly diamonds (of the same reliably measured concentration).

[Mark]

I’m sorry Philip, I thought Johannes was asking for personal opinions. I also don’t have any test sensitive enough to tell the diffrence so I have to go by how it “feels”

[Mark76]

I happened to have to the same question. So I had a Skype call with Ken Schwartz a few days ago. What I recall from it (my interpretation, not his literal words) is that CBN and poly diamond are about as effective. The advantage of CBN is that it is cheaper, but it isn’t available in very fine sizes.

Ken preferred poly diamond over mono diamond, since poly diamond had less of a tendency to clutter. That said, I’ve mainly used mono diamond until now and I’m very happy with it. (I did order some CBN and poly diamond, though :cheer: )

Molecule Polishing: my blog about sharpening with the Wicked Edge

[Johpe]

.75 CBN just gives me a better feeling edge. I don’t know how to describe it, It just feels “crisper”?

I would always be leery of those saying that they “think” or “feel” rather than that they have measurable repeatable results.

I’m sorry Philip, I thought Johannes was asking for personal opinions.

Yes, I was actually asking for opinions since my idea from the start was that very few people would have the necessary equipment in their basement or garage or were ever they keep their WEPS to actually be able to accurately measure any quantifiable difference between sprays of these particle sizes. But with that said, if someone actually have the hard facts or the proof of one material over the other, please do share! That would make it much easier to decide if it is worth the extra bucks for PCD spray. 🙂

But it think the reality is, the vast majority of people sharpening would never notice any difference between like rated CBN and Mono or Poly diamonds (of the same reliably measured concentration).

I also don’t have any test sensitive enough to tell the diffrence so I have to go by how it “feels”

Haven’t tried it, but several people I trust have said the exact same thing about CBN.

So basically it seems we have to agree to actually feel to have an opinion on this topic. 😉

I found Mr. Schwartz blog a few days ago with some interesting posts on PCD sprays (and CBN) from different vendors, but the really interesting parts was the SEM images of the sprays!
Precise Sharpening[/url]

[Phil Pasteur]

I’m sorry Philip, I thought Johannes was asking for personal opinions. I also don’t have any test sensitive enough to tell the diffrence so I have to go by how it “feels”

I was really not singling you out for any level of criticism. I simply have tried too many times to duplicate others findings… or feelings, to no avail. But then, we all perceive things somewhat differently. That doesn’t mean one is correct and another incorrect. But it does mean that discussions about feelings are not easy to have. Of course, if someone asks for an opinion, then that is what they get. I just try to caution people to temper their expectations when subjective answers are what they get in response to a question. Leery may have conveyed more than I intended in this case, maybe cautious would have been a better term to use.

No offence intended, hopefully none taken.

Phil

(BTW, I “think” that I “feel” a difference in my results between using 0.5 micron Mono diamond, 0.5 CrOx, and 0.5 micron CBN on bench strops. I am not sure that I can say any one is better than the other, just different.):unsure:

[Ken Schwartz]

In many instances the difference is unimportant between poly and CBN, so cost favors CBN.

For straight razor use, the verdict is pretty clear. At say 1/4 micron the CBN delivers a more comfortable shave. At tenth micron it’s a close call. Beyond that CBN isn’t available so there’s no contest. But the good news is that at a particle size 10x finer (0.025 micron vs 0.25 micron) the issue of comfort doesn’t remain a problem – the 10x finer scratch pattern isn’t a comfort problem, but it is – as expected – incredibly sharp.

For knife use, the balance goes more towards poly diamond, giving a more ‘toothy’ aggressive style of edge. Some of my customers swear by it and only want the poly, which I have available directly in grits from 4 2 1 0.5 0.25 .1 .050 and 0.025 microns. But quite often the vote goes to CBN for cost and because at the lower cost it still delivers a spectacular edge. Also I have a wider range of sizes of CBN going from as fine as 0.1 micron on up to 80 microns – 0.1 0.125 0.25 0.5 0.75 1.0 1.5 2 4 9 15 30 45 and 80 microns. Personally I use CBN most of the time. BTW for mono fans, I also carry mono in 0.025 0.050 0.1 microns too. I am also including an emulsion based formulation for both CBN and poly and mono in an ever expanding lineup. This is yet another topic. Early release of some of these in sample sized volumes is anticipated shortly. PM me if this is of interest.

—
Ken

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