Which will last longer, CBN vs Diamond

[Sharpco]

Hello everyone.

I wonder which will last longer on the Tormek, CBN or Diamond.

Tormek said Diamond is better.
https://www.tormek.com/international/en/knowledge-inspiration/diamond-wheel-sharpening/

But Vadim(Knife Grinders) claimed CBN is better.
http://knifegrinders.com.au/11CBN.htm

How do you think about that?

[Ken S]

This is not a simple A or B is better question for several reasons.

There is an acute lack of generally available information and testing. The most complete source I am aware of is on the Knifegrinders website. Although Vadim is a CBN vendor, I respect his integrity and testing methods. I have faith that he is fair minded and objective.

I have not seen similar published testing from other sources. I have full faith that Tormek would not market an inferior product, however, I have not seen supporting evidence testing to support that faith. I do not mean to imply that Tormek is hiding anything. I hope we will see more in depth testing and analysis of both wheels.

Ken

[Sharpco]

Thanks Ken.

I respect Vadim, but I thought there was reasons why Tormek chose diamond.

[jeffs55]

It seems to me that Tormek would say diamonds are better since that is what they sell. In this case Vadim does not have an axe to grind......................... or does he. He has no fiduciary incentive to prefer one over the other. Take that for what its worth. I have no experience with either one but the internet says diamonds are harder so that must be true, right?

[Ken S]

Jeff,

I would expect any vendor to prefer the products he happens to sell. In this case, both Tormek and Vadim seem polite and professional. I do not believe either has an axe to grind with the other. Tormek is experiencing rapid growth due in part to heightened interest in knife sharpening due to Vadim's research. Tormeks are the workhorses in Vadim's sharpening business. This seems like a win-win situation to me.

Out of respect for Tormek, Vadim stopped posting about CBN wheels when he began selling his own CBN wheels. This avoidance of a possible conflict of interest is honorable.

The hardness difference between diamond and CBN is a well documented fact.


Youngbin,

You ask a very valid question. When I first reviewed CBN wheels for the forum, the Tormek diamond wheels were not yet in existance. The only one I was aware of who used them on a Tormek was Vadim. At the time, I had already been looking for a coarse grinding wheel for my Tormek. I had already found the Norton 3X 46 and 80 grit wheels. They both cut quickly and can be used wet with the Tormek with water. I should say that they can be adapted to work with the Tormek. The largest diameter available is eight inches (200mm). This is perfect for the T4 but constraining for the T8. They have a one inch bore, requiring an adaptor to for the 12mm Tormek shaft. (This is not a big project.) They have both the pros and cons of conventional grinding wheels like the SG series: They diminish in diameter with use. They need occasional retruing. They can be retrued and dressed, so this is both a curse and a blessing. Like the SG, they can be used with heavy grinding pressure. If they were ever made to Tormek specifications, they would be my first choice for heavy grinding.

When Tormek introduced the 250mm diamond wheels, there were no CBN wheels ideally suited for wet Tormek sharpening. The CBN wheels at the time were ideally suited for high speed, eight inch dry grinders.
Granted, CBN wheels grind cooler than conventional wheels, however, they still have dust problems when used dry. So do the earlier Tormek 200mm diamond wheels. In fairness, Tormek has only marketed these for the T2, which is only used dry. There are rumors of a new series of 200mm diamond wheels from Tormek which can be used wet or dry, like the 250mm series. The new CBN wheels, pioneered by Knife Grinders have accurately machined 12 mm bores and binding which is designed for wet grinding. Both diamond and CBN wheels require careful use to reach full longevity.

I believe the tried and true SG wheels will remain the practical choice for most Tormek users. However, the present generation of both diamond and CBN wheels have become much better suited for the Tormek environment. I have used both. Both get the job done.

Ken

[cbwx34]

Hello everyone.

I wonder which will last longer on the Tormek, CBN or Diamond.

Tormek said Diamond is better.
https://www.tormek.com/international/en/knowledge-inspiration/diamond-wheel-sharpening/

But Vadim(Knife Grinders) claimed CBN is better.
http://knifegrinders.com.au/11CBN.htm

How do you think about that?

I doubt you'll find any independent research anytime soon... that would make a legitimate comparison.  The time, money, incentive, etc. just isn't there.  And some of the seller claims on either side, for example, X lasts longer than Y, don't seem to have any research to support them.

For now, all there really is, is user feedback, and so far, I haven't seen any that demonstrates one is better or worse than the other.

[Sharpco]

Perhaps the difference is insignificant. Both are good abrasive, but I wonder if there are any researches.

[John_B]

In practical use I think another factor in either wheels longevity will be how light or heavy a touch users have. From my reading a delicate touch is required.

[Ken S]

I agree, John. Touch is far more important than most users realize.
Ken

[BeSharp]

Here's Vadim's article on where diamond is better than CBN, and also where CBN is better than diamond:

http://knifegrinders.com.au/Manuals/CBN_AKMarticle.pdf

[Ken S]

Well written article.
Ken

[Even]

Hello.

I have been using both CBN and Diamond wheels on my tormek for almost 2 years.
Both options have held up well and can see no fault in them.

I use regular tap water on both diamond and CBN.
This is because I think there was too much clutter when I used ACC fluid, as this changes the consistency of the water.
I have not yet had problems with rust on any of the wheels, this despite daily use in clean tap water.

The wheel that has most wears in 2 years of use is probably my CBN # 80. But this is what has been used most in total as well (this cut more like an 140-160grit now).

I do not think u make a mistakes no matter what you choose.

The biggest advantage of CBN is that you can choose grits from 80 to 1000, and then you can also get rounded corners on the stone that are well suited for sharpening knives.
And then you have a guarantee even if you use tap water.

The advantage of Tormek's Diamond Wheels is that you can buy them from dealers around the world, and then it's easier to advertise if there should be a problem.

Even

[Ken S]

Even,

I appreciate unbiased, factual, balanced posts.

Well done.

Ken

[Sharpco]

Thank you all