A Deeper Investigation into Spyderco Diamond vs cBN: Which is better?! Why!?

[Deadboxhero]

For as long as I can remember, there has been two options available for the Spyderco sharpmaker.

Electroplated diamond or electroplated cBN.

I've always felt it was a mystery and what I liked about Spyderco is that they offered both options for end line users to determine the differences However, it's been many years and it's a mystery. I would like to understand more.

While we could regurgitate the standard literature about the industrial differences in grinding operations between diamond and CBN and the hardness difference in the literature.


Common literature we all see and read whenever we google search the differences between diamond and CBN which doesn't give us context for the actual differences we would see with hand sharpening on the sharpmaker. Source https://www.cdtusa.net/blog/diamond-or- ... %20degrade.

I feel none of that helps us choose which one we should purchase for the sharpmaker since we are not using it in high power grinding. So this makes this rather curious if there's any significant differences or if it's just redundant. I'm rather excited to see what happens when we look more closely with testing and seems Spyderco still generously offers both products for the consumer to choose.

The real question is what are the differences that we can observe when purchasing one or the other of these products and what are the results when sharpening with the sharpmaker?

Are there differences in cutting speed, cutting, finish durability and longevity to either one of these products?



This will be an ongoing thread and I will update this original post as the testing results come in.


For starters, let's look each under 300x magnification.

Starting with the diamond.


The diamond appears a translucent white color with silver nickel coated grains at the base. We have the same grit range ~60um average but to my eyes it appears we have slightly less abrasive volume and the angles of the cutting facets appear to be less aggressive. I'm curious if this translates into small differences in cutting power and surface finish.


The cubic boron nitride appears as a amber color with silver grains near the nickel base. To my eyes, it appears these amber grains may be more loosely adhered to the surface. I'm curious if there is a difference in longevity. It also seems to my observation the cutting facets are more aggressive so I would find that curious to see qualitatively if there's any differences. Grit size appears to be the same average of ~60um.



I think it would be interesting for us to look at

-cutting speed
- longevity
- surface finish
- Edge sharpness


While we won't have the extreme control like we what if we used a robotic arm (which is not a half bad idea) perhaps we will keep it more "real world" and see if there's significant differences an end user would see or who knows, maybe it's so close It's just scatter.

So, I think it'd be interesting if you have any ideas to share about the testing and we'll keep this an ongoing test.

-shawn

[Wartstein]

Like many I´ve always been interested in the "CBN vs diamonds" . thing...

In the end I personally decided for the CBN as my most abrasive sharpmaker rod, just cause sóme said it would have better longevity.

Perhaps I should get diamonds too, just to be able to compare and also contribute to this thread:
While I am not an experienced sharpener at all, I think this is one of those topics where both the experiences and inputs of experts and those of "average Joes" (if at all) can be interesting:

While experts can go into the matter on a deeper level, it should be at least equally of value if "normal end users" actually can experience a difference between the two kinds of rods and/or even make use of those (differences, if they can be perceived at all).

[yablanowitz]

I did purchase both. No scientific testing, just an old man who has freehanded for almost 60 years. The first project was taking a new K390 serrated Police4 from 20° down to 15°. I started with the CBN rods, then switched to the diamonds. I found the diamond rods cut a little faster and left a coarser scratch pattern than the CBN. YMMV.

[JoviAl]

I’m going to hold my hands up and say I can’t actually tell any measurable difference between the two I use them interchangeably and they both sharpen SE stuff just fine. I’d be BS-ing if I pretended I could tell the difference in a blind test.

[Doc Dan]

I bought the CBN with my Sharpmaker just because I didn't have experience with it. I have diamonds in other sharpeners. I cannot say which is better from Spyderco. I think my diamonds cut faster, but I have no idea what grit they are as they only say F and M. The CBN gives a smoother edge than any of my diamonds.

[kennethsime]

In the end I personally decided for the CBN as my most abrasive sharpmaker rod, just cause some said it would have better longevity.

Same. I'd certainly like something that cuts faster, though.

[WilliamMunny]

Shawn,

Hope all is well and the kiddo is doing great. Good topic, there is a ton of discussion on this topic with very little conclusive evidence if one is better than the other. I don’t think diamonds being harder has any impact as either will cut any steel. Below is a quote from Sal a few years back, the last two paragraphs being the most interesting.

On the flip side, Sal has asked you in 2019 on this forum if you had a preference, haha.


“Mon Mar 19, 2018 3:34 pm

Hi Tjkoko,

Welcome to our forum.

We've been making diamonds for our Sharpmaker since 1981. Even before we had the medium grit stones, we had diamond sleeves. When we could, we made diamond triangles. The problem with diamonds is that they are attached to a steel embryo using a plating process. The diamonds are very hard. Harder than the steel embryo or the plating material that adheres the diamond to the steel. People using the diamonds to sharpen will generally press too hard, which loosens the diamonds from the plated material so longevity is not as desired. Diamonds work best with a very light touch, as the diamonds are much harder than the blade, it doesn't take much pressure to be effective. Getting customers to do this has been very challenging. Most people think (or simply intuit) that "if I press harder, they will cut faster".

CBN has some advantages over diamonds in cutting steel and it is hard enough to sharpen any steel, I felt that if we made our triangles in CBN as well as diamonds, people could try both and in time we might see a difference or advantage to one or the other.

I use CBN and I also use diamonds, but I use a very light touch and take the time to do a careful job not to damage the diamond / CBN. I believe that the CBN might be competitive in that it cuts as well, and I believe adheres better to the plating. Hope that helps?

sal”

[weeping minora]

I have no experience with Spydercos diamond abrasives, though I have experienced their 8×3" CBN stone.

I have the tendency to agree with sal's statement in that electroplated CBN seems to adhere to the base and wear a bit slower, versus diamond seeming to wash out, in a touch faster amount of time. This would lead to CBN having a greater lifespan in sharpening a higher number of times/knives, before replacement, or re-plating, is necessary.

I'd like to see Spyderco start to branch out a bit and start experimenting with bonded CBN/diamond stones, since they are starting to offer extremely high wear resistant materials (15V, REX121, REX T-15, etc.).

[Guts]

Interesting topic as usual Shawn. Only CBN abrasive I own is the Spyderco benchstone, but admittedly haven't used it much. Seems to cut similarly to Spyderco's diamond Sharpmaker rods from what I remember though. Wish I had a fullsize Diamond benchstone from Spyderco too to compare. Maybe I'll try and sharpen one side of a knife with the CBN benchstone and another with the Diamond rod to see if I notice any difference.

I'll just throw it out there, but wouldn't say no to some resin bonded diamond/CBN from Spyderco with more grit offerings

[Steeltoez83]

I felt the spyderco cbn rods and stone broke in faster than other plated diamond stones of similar surface finish. I prefer the benchstone for more surface area for knives versus the rod format. I personally thought the diamond rods would have left the lineup years ago in favor of the 400 and eventually the 800 grit cbn rods. Id like to see magnification shots of both diamond and cbn rods after 1,000 passes to see which one has held up better. Maybe clean the rod side used with barkeepers friend every 100 passes and check under magnification. Id use a different side of the rods for a different experiment such as cutting speed or surface finish with bess testing. And I'd test a variety of different alloys because after all spyderco provides them for us. I've never tried the spyderco diamond rods but I have used their cbn benchstone quite a bit and I like it. Good luck with your testing Shawn.

[jwbnyc]

A Double Stuff 3 with with 400 and 800 grit CBN would be a useful thing to have.

[Bill1170]

I have reprofiled a bunch of SE Spyderco knives from 20 to 15 on my Sharpmaker CBN rods (Endela and Endura in VG-10, Caribbean in LC200N, Pacific Salt in H1, and most recently an Endura in K390. That last one took the longest.)

I’m amazed at how well the rod corners have lasted after~12 hours of continuous profiling work. I don’t have data on my diamond rods, but I feel they degraded faster with far less use. The CBN just keeps cutting. It feels more durable under extended use, but I lack sufficient data to prove anything.

I wonder if the CBN grains resist fracture better, or maybe they are better anchored in the nickel plating.

[crazywednesday]

For as long as I can remember, there has been two options available for the Spyderco sharpmaker.

Electroplated diamond or electroplated cBN.

I've always felt it was a mystery and what I liked about Spyderco is that they offered both options for end line users to determine the differences However, it's been many years and it's a mystery. I would like to understand more.

While we could regurgitate the standard literature about the industrial differences in grinding operations between diamond and CBN and the hardness difference in the literature.


Common literature we all see and read whenever we google search the differences between diamond and CBN which doesn't give us context for the actual differences we would see with hand sharpening on the sharpmaker. Source https://www.cdtusa.net/blog/diamond-or- ... %20degrade.

I feel none of that helps us choose which one we should purchase for the sharpmaker since we are not using it in high power grinding. So this makes this rather curious if there's any significant differences or if it's just redundant. I'm rather excited to see what happens when we look more closely with testing and seems Spyderco still generously offers both products for the consumer to choose.

The real question is what are the differences that we can observe when purchasing one or the other of these products and what are the results when sharpening with the sharpmaker?

Are there differences in cutting speed, cutting, finish durability and longevity to either one of these products?



This will be an ongoing thread and I will update this original post as the testing results come in.


For starters, let's look each under 300x magnification.

Starting with the diamond.


The diamond appears a translucent white color with silver nickel coated grains at the base. We have the same grit range ~60um average but to my eyes it appears we have slightly less abrasive volume and the angles of the cutting facets appear to be less aggressive. I'm curious if this translates into small differences in cutting power and surface finish.


The cubic boron nitride appears as a amber color with silver grains near the nickel base. To my eyes, it appears these amber grains may be more loosely adhered to the surface. I'm curious if there is a difference in longevity. It also seems to my observation the cutting facets are more aggressive so I would find that curious to see qualitatively if there's any differences. Grit size appears to be the same average of ~60um.



I think it would be interesting for us to look at

-cutting speed
- longevity
- surface finish
- Edge sharpness


While we won't have the extreme control like we what if we used a robotic arm (which is not a half bad idea) perhaps we will keep it more "real world" and see if there's significant differences an end user would see or who knows, maybe it's so close It's just scatter.

So, I think it'd be interesting if you have any ideas to share about the testing and we'll keep this an ongoing test.

-shawn

Great thread. Thanks for starting it.

[vivi]

I felt the spyderco cbn rods and stone broke in faster than other plated diamond stones of similar surface finish. I prefer the benchstone for more surface area for knives versus the rod format. I personally thought the diamond rods would have left the lineup years ago in favor of the 400 and eventually the 800 grit cbn rods. Id like to see magnification shots of both diamond and cbn rods after 1,000 passes to see which one has held up better. Maybe clean the rod side used with barkeepers friend every 100 passes and check under magnification. Id use a different side of the rods for a different experiment such as cutting speed or surface finish with bess testing. And I'd test a variety of different alloys because after all spyderco provides them for us. I've never tried the spyderco diamond rods but I have used their cbn benchstone quite a bit and I like it. Good luck with your testing Shawn.

I have diamond rods around a decade old if anyone with a high powered microscope wants to take a look.

[olywa]

A little more anecdotal evidence here. I used diamond rods on my Sharpmaker initially, but I was pretty heavy-handed with them due to inexperience. By the time I started using a lighter touch they were pretty well worn. I picked up CBN rods a couple of years ago and my touch is a lot lighter these days. They have held up extremely well and I have supplemented them with the benchstone and the webfoot because of that. But I'm tempted to pick up a fresh set of diamond rods to see how I like them when I don't mistreat them.