Once you go CBN...

[BluntCut MetalWorks]

There are many level and layers of sharpening goal among people. Sometime want doesn't backup with know-how different than don't care... so on.

I happen to care quite a lot on edge quality. Abrasive size tolerance + shape + density + friability coef all are important to me. But at the same time, I am frugal/cheap, only spend if I have to (ok sometime on a want not a need or experiment). From what I am reading/hearing, Ken offers high quality, good enough for you guys good enough for me. Now, DLT 0.5um CBN in question perhaps more like 1um median +- 2um, which is similar in size tolerance in most lapidary products. OK, could be worse, but not sure why one would mft/kitting using worse tolerance when normal lapidary grit tolerance avail on the cheap per kilogram. Perhaps DLT can recategorize their CBN products with size at 80 percentitle given upper mesh size has reasonable industry cut off. Misleading info on a product is unproductive for all involve.

Learning need objectiveness. A more versatile/skilled sharpener is well informed and adaptive.

Bluntcut I imagine most really don't care as long as the knife is sharp. Folks like myself that are in the business of sharpening depend on a consistent product that covers allot of bases. Ken's product has never failed or disappointed me. When you get into the finer items such as straight razors and finer knives this is when the quality of the product shines. Customer and personal satisfaction is my goal. I depend on Ken to provide me with the finest products available. It just doesn't get any better.

 

[ksskss]

"As for implying DLT CBN products contains a large percent of CBN (or unknown) particles with diameter greater than 3um. It's more of a marketing than scientific speak. If unknown particle are just combination of soft binder/emulsion and material softer than steel, virtually no impact on the result. Clumped/conglomerated CBN into a larger chunk is not the same as solid CBN particle because clumped chunk most likely to have very low friability coefficient. Perhaps, DLT or you or somebody need to provide some proof. As simple as strop a mirror surface with DLT 0.5um CBN, will there be scratch pattern caused by 3-20um particle."

One of the more frustrating things that a serious sharpener encounters is going on to a higher level of finish only to have a random scratch occur in the middle of his work, requiring him to go back to a coarser grit to remove the scratch.

Now if we compare CBN to a less precisely graded product and a product that doesn't work as well on steels which CBN is designed to also handle, we are comparing a product sold by the carat weight to a product sold by the ton (or retail by the pound) - a much less expensive product.

You pay more for a more highly refined product. More for a more highly researched carrier (emulsion in this case) for the particles to be optimized for the task of knife sharpening. This took me years of research to optimize. Many of my customers go beyond the 0.5 micron level to even finer grits. If they had random particle scratches in their finishes I would be getting complaints and returned product. You see the same thing when buying produce or any other 'select product'. A more precise PSD uses a better grade of abrasive.

So let me explain the data a bit further. In the micrograph presented earlier you can see the very large crystalline structures (more than one) present in the product as well as the clusters of agglomerated CBN particles present. If you look closely you can see the individual particles are also of various sizes. This is characterized in the PSD test in more detail.

Indeed, if the large crystal in the center of the micrograph were included in the PSD test we would show the presence of particles EVEN LARGER than 20 microns.

If you look at the first page of the PSD test results you can see that one of the test conditions is that ultrasonification is on. This reduces the clumping seen in the micrograph so that individual particles are evaluated as ultrasonification 'breaks up' clumping. So if ultrasonification was off, the results of the test would be significantly worse. So in this instance, far from a marketing ploy, this presents the results of the product in a more facorable way than what is actually present in the 'real world'. This is more than fair. If it was marketing, it would have been tested with ultrasonification off.

Hope this more fully explains the data. Thanks for the opportunity to explain this in more detail.

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Ken

 

[BluntCut MetalWorks]

Thanks Ken. Looking at the micrograph, I like some clarifications...

Are those particles with white center - agglomerated type? To me, look like beaded between binder and cbn.

I can see quite a few conglomerated(all black, amazingly in Weaire-Phelan shape) particles 3-8um. This type of clumping probably did survived the ultrasonic but still would break up right away when impact by steel (edge bevel). If you don't mind, please blue-circle/mark a handful of non-solid CBN particles with size 3+um.

If you don't mind, please red-circle/mark a handful of solid CBN particles with size 3+um.

There is no question, a tighter size tolerance (almost len polishing level) product will cost a whole lot more. Your products would easily to verify in such quality - I don't have to do that since others already done so :thumbup:. As for DLT CBN products, are they std industrial lapidary tolerance or complete garbage/contaminated with particles 40x larger than spec? When I buy cheap diamond/cbn labeled as 1um, I actually re-label them as 3um (hopefully it's 99.9 percentitle). Most of the time, I contaminated my strop with swarf & larger particle from prev grit hitch a ride on the edge.

 

[ksskss]

The particles with white centers are contaminants - not agglomerated particles. They are of unknown type - clearly crystalline, but what characteristics they have - Moh's hardness etc - I did not characterize them further as they simply should not be there.

The clumping or agglomeration present may have some of the characteristics of Weaire-Phelan structures but this is a different phenomena entirely. Rather than solving a space efficiency problem with polyhedra having tetrahedral vertices, what we are dealing with here are electrostatic forces which increase as the particle sizes get smaller, so that agglomeration effects increase with finer particle size. The properly designed emulsion or carrier seeks to minimize these electrostatic forces. There is great art to doing this correctly. Think of this more like the electrostatic forces presented in a large molecule by the hydrogen atoms which influence the tertiary geometry of the molecule for instance.

You can see the particles with clear centers scattered throughout the light micrograph. Some of them are present on end and a bit harder to see, but there are more than enough of them in various orientations and sizes.

Again the light micrograph is more difficult to see at this lower resolution variations in CBN particle sizes - an SEM would be more useful here - but are accurately characterized for size distribution with the PSD testing.

I also recommend keeping strops in their own ziploc bags to reduce airborne contamination. You would be amazed at the large particles floating around in the air, some abrasive and some not abrasive.

I considered characterization of the contaminants or an SEM of the sample an unnecessary expense given what the light micrographs demonstrated.

I don't carry cerium oxide which is used for lens polishing but do carry diamond abrasive as fine as 1.2 million grit, which is typically finer than the commercial cerium oxide in grit.

Here's an image taken using my CBN product at 500x magnification using 0.125 micron CBN. Note the absence of scratches. You could not achieve this without previous compounds having large contaminants or a wide range of particle sizes.

Since you mention lapidary applications, for gem polishing, some of my products have been used to produce finishes which produce a scratch pattern which cannot be detected using light microscopy. Here's an example showing a scratch free facet.

---
Ken

 

[BluntCut MetalWorks]

Thanks for excellent educating info, Ken! OK, now I am twice convinced (if there is such a thing that your CBN & polydiamond are super high quality.

I could be wrong here but electrostatic adhesion/bond is very weak, so friability term may not even applicable here. Not the realm of crystalline nor intermolecular bonding radar. I guess, it isn't fair to ask you to prove anything. Since your products as far as I concern - bonafide. To clear thing up and possible beneficial for DLT to provide a micrograph images of mirror surface after stropped with DLT 0.5um CBN product. After that, result also need to be replicate/validate by an indi-3rdparty.

 

[HeavyHanded]

Again, no arguments with any of the above, for scratches to be undetectable with light microscopy generally any scratches are about .3 micron or less - most apertures will not clearly resolve lower than .2 micron deviation.

I am dubious the larger structures are CBN in the DLT sample. By nature CBN is extremely resistant to glazing, those are very round edged - could be anything but likely not CBN. Some of the larger blobs could even be bubbles. No arguing with the laser analysis though, is a wide range for a product with a specific size spec'd on the label.

It would be better if fine particle control is unobtainable at a given price point to simply call the material "Fine", "Super Fine", "Medium" etc and avoid being called out.

 

[ksskss]

For coarse particles electrostatic charges are quite weak. But as you go to smaller particle sIzes where the surface area to volume ratio increases, electrostatic forces increase significantly to the point where particle agglomeration can clump particles together with forces greater than the mechanical forces exerted during hand sharpening.

My products are tested during development specifically to avoid this problem during development at each grit.

---
Ken

 

[ksskss]

I agree - those structures are definitely not CBN. Specifying as precisely or loosely graded might be less confusing than fineness which would usually be associated with particle size.


---
Ken

 

[ksskss]

Unfortunately I have more bad news to report. This knockoff product is now being carried by another vendor as a Bark River endorsed product. I already knew about this. What I did not realize is that they are STILL using both pictures of my product AND the description of MY product, but shipping this alternate product to customers! I had mentioned this issue of what was being published on the website once to them, thinking it was just an administrative issue of poor website maintenance which happens, but this shipping of an alternative product is a bit more than that. The customer who bought the alternate product returned it and then notified me of this practice. Very disappointing! I mention this as I believe 'sunlight is the best disinfectant'.

---
Ken

 

[ksskss]

This other vendor has made the correction to their website, so while they are not selling my product they are not using pics of my product or descriptions.

This is at least straightforward and appreciated showing it as an honest confused mistake.

DLT however is still using the description of my product that I wrote to sell their product


Sad.

---
Ken

 

[HeavyHanded]

This other vendor has made the correction to their website, so while they are not selling my product they are not using pics of my product or descriptions.

This is at least straightforward and appreciated showing it as an honest confused mistake.

DLT however is still using the description of my product that I wrote to sell their product


Sad.

---
Ken

I don't have an interest in this one way or the other, but DLT website seen by my browser appears to use a very generic description of the product. All the images in the OPs post and on DLTs site appear to have been scrubbed of your name. The OP never made any attempt to attach your name to the product, and even the DLT rep merely claimed a third party resource did QC re due diligence, at least to base level industry standards. I don't believe anyone is claiming your product is inferior in any way to any other. While I can certainly understand defending your efforts and product, I'm starting to feel JR88FAN summed this up on page 1.

Maybe Ken should purchase the proper membership to advertise his magic potion here.....

It's one thing to defend yourself, but that post is 1% defending and 99% selling.

At the very least, it might be time to start a new thread on this one.

 

[BluntCut MetalWorks]

Thanks for the updates, Ken.

Edit removed part about DLT... Since Martin actually did the scrutiny.

 

[pjwoolw]

The description on the DLT site is misleading for the product they are selling. The description is for a product they are not selling. I can understand folks getting a bit tired of all this hullabaloo but people shouldn't be misinformed.

There is verbiage written by Ken for his product that may not apply to the DLT product. Maybe DLT should take a look and revise their description and save themselves and their customers some grief.

 

[HeavyHanded]

The description on the DLT site is misleading for the product they are selling. The description is for a product they are not selling. I can understand folks getting a bit tired of all this hullabaloo but people shouldn't be misinformed.

There is verbiage written by Ken for his product that may not apply to the DLT product. Maybe DLT should take a look and revise their description and save themselves and their customers some grief.

I'd like to see this misleading text, I can't find it or am not recognizing it as such:

* micron (****** Grit) CBN Emulsion. Packaged with a convenient screw off lid with a dropper tip. * fluid ounce bottle.

Laser diffraction has its limits for accuracy, especially with sharp edged materials - I don't see where DLT is being deliberately misleading. I don't see why Ken wouldn't or shouldn't tout his product as being superior graded.

I am not sure this thread was ever the place for this discussion, no one ever came out saying Ken's product wasn't top quality, only that the DLT material worked well for them. For it to go on like this Ken should really upgrade his membership - its not a big deal.