CBN Sharpening "stone"

Hi Yesh,

We learned that there was difference in diamonds cutting steel vs CBN. (it had to do with the effect on carbon) We made both in our triangles for the Sharpmaker so we and you could actually test the difference comparing apples to apples.

I personally felt that CBN might have the "edge" (pardon the pun) so I went ahead and made the 3 X 8 in discussion. As far as cost goes, we don't like to let cost guide us in performance and will generally go with the best performing material unless it's totally cost prohibitive.

As far as grits go, we're still in the testing and learning stage. So naturally we are interested in anyone's opinion that is actually using the stone.

sal

Is there any advantage when trying to use CBN on soft steels compared to diamond stones? I hear every now and then that diamonds get ripped out of the plate, when the steels used on them are too soft. (although I never experienced it on my Atoma plate or maybe I just didn't recognize it) Also the steel often more gets pushed around than actually cut.
Also I'm interested in why the grits are so close together. Wouldn't something for heavier reprofiling make sense on the lower side? Let's say 200/800?

P.S.: sal our names do look quiet the same.



Edited 3 time(s). Last edit at 11/15/2020 11:49AM by sai.

"I hear every now and then that diamonds get ripped out of the plate" never heard that. diamonds are susceptible to pulling out when you push too hard trying to force the cutting, and so overpower the bond strength to the substrate.

they are very much a case of light pressure, frequently, to let the diamond do the work.

there is no reason i can think of that CBN will hold any advantage unless they are bonded with a substrate that can take more force.

"Also the steel often more gets pushed around than actually cut."

not sure at what level we are talking here. smearing? cross sections of 0.0001? or visible to the eye?

this knife is non-heattreatable 316 steel. so soft that i can cut into it with a fully hardened knife or indent easily with a hammer
it was definately more work to sharpen, but because it couldnt take as narrow an angle on the apex and stay stable.
i've never noticed anything hand sharpening that i'd consider smearing. i've had gummy feeling before.. but its just a feeling, never a detriment




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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen

It sounds to me like sai might be noticing the burr being pushed around, considering the stone does not create slurry to minimize burr. Overgrinding is easy on these stones to form a burr, especially the 140 I have. I don't think it would be possible to push around steel from this stone unless it was either very high force in grinding (unlikely here) or a VERY soft steel along with higher forces.

I used the Spyderco CBN stone today when I thinned out and sharpened my 8" Victorinox Chef's Knife. I first marked the edge bevel with Dykem Red, and then right behind the edge bevel, I marked the area to be thinned with Dykem Blue. I then started thinned out the area right behind the edge marked with the Blue Dykem and make a relief bevel with a DMT 6x2" X-Coarse (Black) hone. The when the red area was small, like a micro-bevel, and the edge felt thinned out, I then started sharpening. I had cut off the bevel before thinning the blade, so it needed to be reformed. I went through a progression of the DMT X-Coarse, then the Spyderco CBN 400/800 until the edge bevel no longer reflected light, also would stick to my thumbnail, as well as start to push cut newsprint/phone book paper. I then used the Spyderco Sharpmaker with the Medium Rods, set at the 15°/30° slots to set the apex with 5-10 passes per side, crossing the scratch pattern. No burr formation, no stropping needed.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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What lubricant did you use with the DMT to do all that work?

SecondCrack,
I used the Blistersteel hard stone formula: 1 part mineral oil, 1 part dishsoap, 4 parts water.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Hadn't heard of that, interesting, thanks!

SecondCrack,
[www.youtube.com]




"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
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Thanx Jason,

I'll try that. I prefer to use some type of lubricant when using plated abrasives.

sal

I have not found DMT stones to be something I really like. They just seem to wear out too fast for me. I used them in my edgepro like contraption and the coarse blue wore out after a handful of knives. Is CBN any better? Am I doing something wrong? As finishing stones they give an aggression that is difficult to believe.

Chris.
Not sure. I use my diamond stones with a lubricant always, along with light pressure. I have found that makes them last the longest. DMT's recent production over the last few years seams to have issues with them wearing out. I had to have one of my DiaFolds that came with the DMT MagnaGuide DiaFold set replaced. I had never had a DMT plate wear out on me before. The Spuderco CBN stone is a better product, if you ask me from what I have seen so far.

"I am still discussing issues of steels and performance at this stage." -- Cliff Stamp, May his memory be a blessing
"Life is GOOD", -- Stefan_Wolf, May His Memory Be A Blessing
WordPress YouTube Facebook Patreon Locals Instagram Twitter

Quote
me2
I have not found DMT stones to be something I really like. They just seem to wear out too fast for me. I used them in my edgepro like contraption and the coarse blue wore out after a handful of knives. Is CBN any better? Am I doing something wrong? As finishing stones they give an aggression that is difficult to believe.

I wore out my blue DMT after a single reprofiling of an s35vn CRK folder.

i would suspect that it wore out because i was pushing very hard trying to speed things up. i dont think the binder is strong enough, or the diamond is embedded deep enough to not readily tear out on too much pressure. i dont think its specific to dMT

My problem is that i want to use a diamond file like i can a metal file, and bear down on it with a slow strong pull to gouge deeply, but i think this just makes them tear out.

Cliff sent me some of Sal's CBN rods to try (i think they are) and when they arrive i look forward to trying them out. they are with Bruce in USA currently.

This is actually a topic i do want to explore more.. How hard to people push when using stones etc.

we all say "hard, medium, feather lite" but i believe that this could be orders of magnitude different in meaning for different people.


it would be good to find some form of rig using a kitchen scale or something and sharpening stones to actually measure how much load we are applying on apexes or bevels when sharpening.

applying too much presure to an apex is going to weaken steel, too little pressure to the side is going to take forever to remove steel, and too forceful may tear out binder, too light not release enough grit in waterstone etc.

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It's not Cliff, its Dr Stamp
#kebabstickcut, it's a thing - make it happen