Poltova CBN or Venev?

[huntyukon]

Hey guys,

Got another question.
I’m planning on ordering some PDT Cbn stones.
This is what I’m looking to order:
- Metallic Cbn for 200/160um and 100/80um
- combined bond (metal & resin) for 50/40 and 40/28 (although I might leave the 40/28 out)
- resin bond for 20/14
From there I’d continue with my diamond matrix 10um 1700 and 5um 4K
I’m also thinking of maybe ordering their 35mm width variant. That should still fit well in the kadet pro stone holder, right?

I read somewhere on here (BF) that the venev resin bond Cbn are better and that only the Poltova metallic cbn are worth buying. Does anyone have any experience with the PDT combine bond and resin bond? The combined bond sounds really intriguing.

Has anyone used cbn stones (of any kind) on steels like aogami super and/or blue 1&2?
The main reason I’m thinking of going with cbn is cause I read they work well on those steels, but still work great with any of the “super steels” (Magnacut, Maxamet, s90v etc). Or does Diamond work just as well?

Thanks for donating some of your valuable time to help out a “newbie” like me again. That’s very much appreciated.

Cheers
Hauke

 

[Grasshopperglock]

I had to scribe the grit conversation on the back of two of my Poltava stones. The others had the grit listed.

I don't understand the 0/0 rating.

 

[huntyukon]

I actually prefer when stones are designated in Micron. From what I understand the higher number is the biggest size of diamond or cbn and the lowest number is the finest size in um.
For example, 200/160 means that the coarsest diamond/cbn is 200um and the finest diamond/cbn is 160um.
Someone please correct me if I’m wrong, though.

 

[Diemaker]

200/160 means a certain percentage doesn't go over 200 or under 160, there will be abrasives bigger and smaller than the stated numbers in your stone. The finer the abrasive the bigger the size variation is as a percentage of the rated size of the abrasive.

 

[huntyukon]

200/160 means a certain percentage doesn't go over 200 or under 160, there will be abrasives bigger and smaller than the stated numbers in your stone. The finer the abrasive the bigger the size variation is as a percentage of the rated size of the abrasive.

Thanks for clearing that up. On a side note, have you ever used your Matrix stones on steels like Aogami super and/or Blue 1&2, by any chance? If so, how did it cut those steels?

 

[Mr.Wizard]

I had to scribe the grit conversation on the back of two of my Poltava stones. The others had the grit listed.

I don't understand the 0/0 rating.

I don't see that rating in the Poltava catalog and it doesn't make sense. Are you sure it's not 1/0?

I actually prefer when stones are designated in Micron. From what I understand the higher number is the biggest size of diamond or cbn and the lowest number is the finest size in um.
For example, 200/160 means that the coarsest diamond/cbn is 200um and the finest diamond/cbn is 160um.
Someone please correct me if I’m wrong, though.

It depends on the standard, and the particular grade within that standard. Revision 14 of my GLGC has range and variance bars to help illustrate this. A line terminating in a dot means that the large majority of the particles are within that bound, while a crossbar means that the median particle size may be as far as that bound. Typically the fine particles are not as strongly bounded as the coarse ones.

Take GOST 9206 grade 14/10 for example. At least 95% of the particles by weight must be smaller than 14µm, and the median particle size may be as large as 10µm. Not illustrated for reasons of space and clarity, but that grade also has a bound that 95% of the particles by weight must be larger than 7µm and a hard limit of 20µm over which no particles may be found.

Compare GOST 9206 grade 3/2 and note that the bar terminates with a point rather than a crossbar at 2µm, This grade requires that 95% of the particles by weight must be larger than 2µm, and also that 95% be smaller than 3µm. A hard limit of 5µm is specified but again this is not illustrated.

 

[huntyukon]

I don't see that rating in the Poltava catalog and it doesn't make sense. Are you sure it's not 1/0?


It depends on the standard, and the particular grade within that standard. Revision 14 of my GLGC has range and variance bars to help illustrate this. A line terminating in a dot means that the large majority of the particles are within that bound, while a crossbar means that the median particle size may be as far as that bound. Typically the fine particles are not as strongly bounded as the coarse ones.

Take GOST 9206 grade 14/10 for example. At least 95% of the particles by weight must be smaller than 14µm, and the median particle size may be as large as 10µm. Not illustrated for reasons of space and clarity, but that grade also has a bound that 95% of the particles by weight must be larger than 7µm and a hard limit of 20µm over which no particles may be found.

Compare GOST 9206 grade 3/2 and note that the bar terminates with a point rather than a crossbar at 2µm, This grade requires that 95% of the particles by weight must be larger than 2µm, and also that 95% be smaller than 3µm. A hard limit of 5µm is specified but again this is not illustrated.

Mr. Wizard, you’re a fountain of knowledge! Like a magician , you always come up with the perfect and correct info on a certain topic.

 

[huntyukon]

I don't understand the 0/0 rating.

I see Poltova 1/0um and 0.5/0um on their website. That’s under their combined bond. Under their metal bond they show a 0.25/0 even.
As someone that’s still relatively new to the sharpening game, I had a bit of a tough time finding my way through their website.
So I ended up talking to Mykhaylo from PDT and he was very helpful in explaining certain things to me. Great guy and great service. At least that’s my experience.

 

[Grasshopperglock]

I see Poltova 1/0um and 0.5/0um on their website. That’s under their combined bond. Under their metal bond they show a 0.25/0 even.
As someone that’s still relatively new to the sharpening game, I had a bit of a tough time finding my way through their website.
So I ended up talking to Mykhaylo from PDT and he was very helpful in explaining certain things to me. Great guy and great service. At least that’s my experience.

Too late. I have the 240, 400, 600, 1000 and 2000.

The only stones that didn't list grit, but instead listed numbers in the, "0/0" configuration, were the 400 and 2000. So I scratched it into the back.

The only way I knew was to trust the paper label from Gritomatic.

 

[huntyukon]

Too late. I have the 240, 400, 600, 1000 and 2000.

The only stones that didn't list grit, but instead listed numbers in the, "0/0" configuration, were the 400 and 2000. So I scratched it into the back.

The only way I knew was to trust the paper label from Gritomatic.

Those are the metallic CBN? How do you like them so far?

 

[Grasshopperglock]

Those are the metallic CBN? How do you like them so far?

They make the plain diamond look archaic. No need to break in, that I've noticed. Not scratchy like diamond if that makes sense. Crazy nice edge finish.

They're smoother and better running. Seem easier to clean. With repeatable results regardless on how much I use them.

I won't go back to diamond. Unless I'm sharpening something abused. Big chips, rounded edge. Then I'll use a 150 diamond to hog off the metal. Then followed with 240 CBN.

 

[Grasshopperglock]

Oh...

They say you can run them dry and you most definitely can. They don't need a lube as recommended for diamond. They leave a super fine metal dust behind.

For dust control and ease of keeping things clean. I use a small spray bottle full of 50% rubbing alcohol. Misting the blade and sometimes the stone.

Can't use plain or soapy water or the stone will ride on top of the water film. It won't bite. Grits above 600. You can feel the stone float.

It doesn't do that with rubbing alcohol.


Plus, everything is easy to wipe off in between grits. The stones stay cleaner. CBN.

 

[huntyukon]

Oh...

They say you can run them dry and you most definitely can. They don't need a lube as recommended for diamond. They leave a super fine metal dust behind.

For dust control and ease of keeping things clean. I use a small spray bottle full of 50% rubbing alcohol. Misting the blade and sometimes the stone.

Can't use plain or soapy water or the stone will ride on top of the water film. It won't bite. Grits above 600. You can feel the stone float.

It doesn't do that with rubbing alcohol.


Plus, everything is easy to wipe off in between grits. The stones stay cleaner. CBN.

That’s perfect! Yeah, I’m getting myself some too. I’m just not sure if I’ll go metallic all the way. May be metallic up to 400 and from there the combine resin/metal bond. Also I’m debating to go 35mm (1.4”)wide instead of the usual 25mm (1”). I’m flying to Europe next month and I could get my hand on those directly from PDT. What do you think? The 1.4” should fit my Kadet pro stone holder just fine. Not sure though. Are yours the 100% concentration or 200%?

 

[huntyukon]

Oh, have you tried any cbn Paste yet? I used the cbn emulsion from Ken Schwartz and really liked it. Can’t get ‘em anymore though. Not sure who makes the emulsions for KME now

 

[chalby]

They make the plain diamond look archaic. No need to break in, that I've noticed. Not scratchy like diamond if that makes sense. Crazy nice edge finish.

They're smoother and better running. Seem easier to clean. With repeatable results regardless on how much I use them.

I won't go back to diamond. Unless I'm sharpening something abused. Big chips, rounded edge. Then I'll use a 150 diamond to hog off the metal. Then followed with 240 CBN.

Are you comparing plated diamond to metallic bonded CBN? If so, it's a bit apples and oranges. I don't think the abrasive in this comparison is really that important to performance with sharpening knives. Performance wise, metallic bonded diamond should be pretty similar to metallic bonded CBN all other things being equal.

 

[huntyukon]

Performance wise, metallic bonded diamond should be pretty similar to metallic bonded CBN all other things being equal.

Would you happen to if it’s true that cbn is better with steels like the Aogami blue steels? Better than Diamond, that is?

 

[chalby]

Would you happen to if it’s true that cbn is better with steels like the Aogami blue steels? Better than Diamond, that is?

Aogami steels are pretty basic in composition. You don't need anything special to sharpen them. CBN and diamond are recommended for steels that have a high carbide volume, particularly steels that have a high volume of harder carbides like vanadium or tungsten for example.

Aogami steels have some tungsten in them, but not at the volumes that would necessitate hard abrasives like CBN or diamond.

You would be perfectly fine using standard aluminum oxide stones for Aogami steels.

 

[huntyukon]

You would be perfectly fine using standard aluminum oxide stones for Aogami steels.

Are there any in particular you’d recommend?

 

[chalby]

Are there any in particular you’d recommend?

Depends. Any of the Japanese waterstones like Naniwa, Shapton, Suehiro, King etc. have their pro's and con's. One of the con's is that they will struggle with the "super steels" you mentioned. Likewise with the more traditional Norton India's and the like.

If you want one set of stones that can handle everything, you can look at more expensive options such as resin bonded diamond stones for slower cutting but better refinement(this is what I prefer for diamond/CBN class), metallic bonded stones as you have been discussing for better cutting speed but somewhat closer to the finish you will get from diamond plates. Diamond plates are the cheapest option but tend to leave a very coarse finish even in the finer grits and wear out much quicker. The most expensive option is vitrified which is perhaps the best allround option but obviously is hard to justify money wise. Basically you will be better off using diamond or CBN if you are sharpening steels like Maxamet or S90V. Magnacut you could probably get away with using regular stones.

If you just want a good set of stones for Aogami steels, then any of the Naniwa Pro/Chosera/Gouken Arata, Shapton Pro or Shapton Glass are very good splash and go stones. King make some splash and go like the King Neo and also soakers like King Deluxe for a cheaper option. Suehiro Cerax is another soaking stone that many people love. The list goes on and on.

 

[Grasshopperglock]

Are you comparing plated diamond to metallic bonded CBN? If so, it's a bit apples and oranges. I don't think the abrasive in this comparison is really that important to performance with sharpening knives. Performance wise, metallic bonded diamond should be pretty similar to metallic bonded CBN all other things being equal.

Try one. Compare the 400 grits. Plain diamond and CBN. So you don't have to think, "should". You'll know.

Try it on forged or powdered.

Ones a deposition of diamond dust on top of a plate. CBN is a diamond impregnated metal cookie.