Diamonds: An improvement over what I have now?

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bgentry

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Aug 3, 2009
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I'm considering buying a few DMT dia-sharp plates and what I read here seems very positive. I just wonder if it will work faster or better than what I'm using now.

What I want to do:

1. Normal sharpening of my knives and the knives of others. Mostly basic stainless steels. I sharpen almost everything to 15 degrees (per side) with a 20 degree microbevel.
2. Experimenting with reprofiling high quality steels to smaller edge angles. I want to practice on some mediocre to crappy knives that I have and then take my brand new Delica FFG ZDP-189 down to 10 or 12 degrees per side. :)

What I've already got:

1. Norton combo 8" stone with medium SiC on one side (about 180 grit) and fine AlO2 on the other side.
2. Spyderco Profile stones in medium and fine.
3. Spyderco sharpmaker with the basic stones.
4. A couple of leather strops loaded with cheap hardware store green compound.

I use the medium SiC for setting initial bevels and getting a burr on both sides. It works fairly quickly. Will diamond work faster or better? Reprofiling even from 15 degrees down to 12 or 10 seems like a lot of steel needs to come off. I generally use either the profiles or the sharpmaker for polishing the microbevel once it's set. I strop some knives but not others.

If I do get the diasharps, I don't want to get a full set. I've read a half dozen threads about the subject. Some have recommended just coarse and extra fine. I wonder, will coarse take metal off fast enough for the type of reprofiling project I have in mind? What if I only bought X-coarse and extra fine? Several people say the gap from C to XF is not a problem at all. What about from XC to XF?

This is maybe too much to ask all at once. Thanks for any consideration and wisdom you have to share.

Brian.
 
Here are some things to consider:

1. Diamond is much, much harder than SiC or AlOx (as with your Norton stone), so it'll always cut faster. That doesn't mean others won't work, it's just a matter of speed and how much time you're willing to give. The difference in speed will be most noticeable with the 'supersteels' like S30V. And 'softer', simpler steels can sometimes feel almost buttery on a diamond hone, because it cuts so aggressively. An emphasis is placed on using very light pressure with diamond hones, for this reason.
2. If you want highly polished edges, you'll need every grit available, at least at the med/fine/EF/EEF end. Skipping a grit (or range of grits), from XC to EEF won't do it, unless you put in a LOT of time & elbow grease with the EEF. You'll also likely need diamond compounds in 3/1 micron, for mirrored edges.
3. Certain steels will resist sharpening much more (S30V and other of the 'CPM' steels, especially). Diamond really helps with those.
4. If you don't want or need polished edges, you won't need nearly as many grit levels. For most knives, especially smaller folders/pocketknives, you could do most of your work with Coarse grit & higher. Any one of those grits, from Coarse onward, can give an excellent working edge by itself. It comes down to how coarse or fine an edge you prefer to use. If you're going to reprofile a large, thick blade, especially in abrasion resistant steel (S30V/S90V/D2, for example), starting as coarse as possible will save you a lot of time & effort.

Most of the above applies to heavy removal of steel. Light maintenance can be done much more simply, with what you already have (ceramics and stropping, especially).
 
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Forgot to mention one thing, that I really like about diamond hones. They're VERY EASY to clean up afterwards (dish soap & hot water, or perhaps some Comet/Ajax). They just don't load up as badly and stubbornly as other stones. Use water only for lube, maybe with some dish soap, or use them dry. No oil.
 
The jump from X-coarse to X-fine is too much. You'll need the other grits. My experience w/ diamond has been some different. They are only some harder than SiC or India ( 9.2 Mohs, 9.6 and diamond 10). Their cutting speed maybe somewhat increased and would be noticed more w/ steels high in vanadium. The coarse SiC cuts at about the same speed as the X-coarse diamond. These two are close. Their wearing and economy is-- still discussed and cleaning maybe some easier. To me their greatest benefit is the better edge they leave and remaining flat while sharpening. Your mileage may vary. DM
 
Moh's scale is misleading, in the sense that it doesn't indicate how much harder one material is than another. It only ranks materials in ordinal terms (no measurement unit). It doesn't quantify the differences in force needed, in comparing two materials, to indent/scratch another material in the ranking order. For example, Corundum (natural form of Aluminum Oxide, Al2O3) is listed at 9 on the scale, with diamond at 10. In terms of absolute hardness, diamond is approximately 4 times as hard as Corundum. Here's a reference:

http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

Edited to add:
By the Knoop hardness test, which is another way to quantify hardness in measurable units, diamond is ~3x the hardness of silicon carbide (9.1 - 9.5 on varying versions of Moh's scale).
 
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Whether diamonds are better than what you have already probably depends on what steels you're trying to abrade. In my experience, a properly formulated SiC stone is going to be faster than diamond even though diamond is harder. SiC gouges out and removes steel and diamond tends to tear right through it. Even if I start with diamond, I end up using SiC to remove the deep scratches the plates leave in the edge bevel. Diamond has it's place though. It's so hard that that the clean gashes it creates in steel makes for really sharp micro-serrations.
 
Hmmm.

Regarding polished edges: I like edges that can shave and cleanly slice paper, so I tend to polish the microbevel with at least the medium ceramic and sometimes both the fine and a strop. I think I'm getting good edges doing this, but I'm really still learning so...

On the primary bevel, I always leave it at my most coarse level. I've considered trying to polish it as well after seeing the AMAZING beautiful edges some here can produce. But I'm not sure it's worth my time just for looks. I'm also not sure if it will change the cutting behavior very much. Cutting behavior is what I'm most interested in.

David and changeofseasons seem to indicate that I'm not going to see much of a difference in cutting speed from say a medium SiC versus a coarse diamond. On "most steel". What about the one super steel I plan to reprofile: ZDP-189. Will diamond cut ZDP significantly faster than SiC? Or will SiC and ceramic combined give me some sort of edge problem? I thought I read one or two people complaining that ceramic with ZDP-189 either produced a burr that was really hard to remove or micro-chipped the edge. I can't remember the details. Anyone have good or bad experience with ZDP on ceramic, SiC, and/or diamond?

Thanks.

Brian.
 
Waterstones will be the better choice for a steel like ZDP, its "hard" to sharpen but its not like S110V its more of a super carbon/stainless steel. Steels with high amounts of vanadium that have great wear resistance are where diamonds really shine.

Diamonds are great but unless you use them as a set they will not work into the kit you have.

If you are looking for new stones than look to a proper set. Trying to add to what you have will never work in your favor.

As for cutting speed, its a lot more complex than one abrasive being harder than the next. Diamonds are fast but probably not a great difference considering the steels you have.
 
I kind of dismissed water stones quite some time ago due to the messy and maintenance aspects. They're actually really cool and seemingly super effective; I just don't think I'm willing to work with them as they are designed.

Your post (knifenut) brings a few questions to mind for me. First, what do you think would be a better setup for sharpening "normal" steel *and* ZDP-189:

1. What I have now: Medium SiC, medium and fine sharpmaker stones (plus profiles), green compound on leather.
2. Coarse and extra fine DMT dia-sharps. Green compound on leather.

From what I've read (a lot of research actually), the white (fine) sharpmaker stones should be very close to the DMT XF in scratch pattern and therefore "effective grit".

I guess the other question is: Is there something I should be adding to my existing kit rather than dia-sharps, or is it so mis-matched already that I need to get all of some other system? I have this weird thing where I think I'm fairly good at sharpening, but I don't have anyone else's work to compare to in real life, so I'm never sure if I'm getting good edges, really good edges, or edges that dull way too fast due to some mistake in my technique and/or equipment.

Finally I should add that, being a guy, I tend to focus on the equipment. I realize though, that it's really the technique that does a huge amount of the work with respect to the final results. To quote someone from another discipline: "It's the Indian, not the arrow."

I think my technique continues to improve, in no small part due to reading posts here. I can think of one specific thing that was a total head slapping moment for me when I read it from knifenut: The idea of "riding the edge". Giving more attention to those parts of the blade that are more dull, or mis-shapen. I've learned from you (knifenut) and others here. I thank you and them. :)

Brian.
 
So far I have only seen a few messy stones and those were either low grit or King stones. King waterstones are the stones that gave all other stones a bad rep, but to tell you the truth, muddy stones are the most fun and often produce the better edges.

My go-to stones for sharpening recently have been the 1k and 6k arashiyama stones and would be my recommendation to you. After your medium Sic you could follow with the 1k and 6k then be done. The benefit is you can gap large grit ranges with very few stones and yield amazing results.

Like I said before though look to a new set, you can only mix and match stones in a few ways.
 
Regarding 'effective grit' comparison between the white Sharpmaker hones and the XF DMT:

The XF DMT (9 micron) will leave a noticeably coarser finish (not yet polished). The white Sharpmaker rods will more closely approach a polished finish, more so if you precede them with at least the XXF DMT (3 micron) and the brown rods. I have all of these; just used them again today. I have noticed that the XXF DMT (3 micron) will begin to show a little polish after it's been broken in a bit. Still not quite as polished as the white rods.
 
I don't think in the stones mentioned there is a good coarse stone for reprofiling. One can do it using a x-coarse dmt. A Norton SiC coarse can be procured for half the money. Even as a work horse it will last a very long time and cut any steel. Then take it to the coarse dmt and remove most all the burr and you'll have a very sharp edge. DM
 
Regarding waterstones: What I meant about "messy" is that you have to use them wet and continue to wet them, which means a basin of some sort, or outdoors on a table that's water resistant or something. I don't think I'm willing to go to that trouble. I like sharpening on my desk or the kitchen counter and I'm not willing to use and store a big basin and do the soaking and the flattening and the cleanup. I understand they're awesome. I'm just not willing to do the work they require. It's one of the reasons I also don't have an Edge Pro: Too much work with the water stones.

But thank you the recommendation. As far as "a new set", do you mean a whole stepping through DMTs of XXC, XC, C, F, EF, EEF ? If so, I don't have the funds or the desire for so many grits. I'm really looking for 3 or maybe 4 grits total. If one of our late members can whittle hair with 4 grits, I'm hoping I can do a better job than I have been doing with 3 or 4 grits. Which is why I had asked about DMTs in C (or XC), EF, and then the strop. I hope I don't sound ungrateful for your advice. My decisions here are about my time and money and not about the merit of your suggestions.

Brian.
 
Obsessed with Edges said:
Regarding 'effective grit' comparison between the white Sharpmaker hones and the XF DMT:

The XF DMT (9 micron) will leave a noticeably coarser finish (not yet polished). The white Sharpmaker rods will more closely approach a polished finish, more so if you precede them with at least the XXF DMT (3 micron) and the brown rods. I have all of these; just used them again today. I have noticed that the XXF DMT (3 micron) will begin to show a little polish after it's been broken in a bit. Still not quite as polished as the white rods.
Click to expand...

Interesting observations. Sal has said several times that you can't really rate the grit of the Spyderco ceramics as "grit" or "micron size". A thread over on the Spyderco forums equated fine white to 7 to 9 micron, but your observations are different. I've never tried a true 7 or 9 micron abrasive so I can only read what others say.

Brian.
 
David Martin said:
I don't think in the stones mentioned there is a good coarse stone for reprofiling. One can do it using a x-coarse dmt. A Norton SiC coarse can be procured for half the money. Even as a work horse it will last a very long time and cut any steel. Then take it to the coarse dmt and remove most all the burr and you'll have a very sharp edge. DM
Click to expand...

According to the table coarse SiC is 100 grit, 141 micron, while medium SiC is 150 grit, 93 micron. I guess that's a noticeable difference. It's weird though because XC DMT is 220 "mesh", 60 micron, which is far finer than either of those stones. In your experience what cuts faster, XC DMT, or Coarse SiC ?

I think I'm starting to confuse myself by trying to use numbers to try to correlate what different people are saying about different setups. It's too bad there isn't a number or two numbers that really tell the performance of an abrasive in terms of cutting speed and finish left behind. Steve's chart attempts to show these relative properties, but it's not to scale. I asked him about it and it's just a general idea and doesn't tell you how *much* faster or sharper various stones get a blade. Just a general idea.

Brian.
 
Sal has said before they were 15, 6, and 3 microns and in my experience that's about as spot on as it gets. Regardless of other factors a 15, 6, and 3 micron finish is what can be expected from spyderco ceramics.

I do understand you point of not wanting a mess but I do think the level of mess you envision is a little on the extreme end. Most quality stones today are splash-n-go so its not much different than using a little water with a diamond hone.

From here its not really easy to suggest much different than you have, spyderco ceramics leave a finish and sharpness that's not easily beat by your average stones. A set of spyderco benchstones would be a upgrade to what you have now but its not going to be different. You would gain speed due to increased size of the grinding surface and possibly better bevel straightness for the same reason.
 
I'll disagree a little with knifenut. I think a DMT xxc would fit right in and work well with what you have now. And for reprofileing I can't think of a better bench hone to use. I'd agree the Spyderco bench hones would be a better choice than the Sharpmaker rods but really if your getting real good edges with what you have now then use it.
 
bgentry said:
Interesting observations. Sal has said several times that you can't really rate the grit of the Spyderco ceramics as "grit" or "micron size". A thread over on the Spyderco forums equated fine white to 7 to 9 micron, but your observations are different. I've never tried a true 7 or 9 micron abrasive so I can only read what others say.

Brian.
Click to expand...

The thing to keep in mind in comparing grits, especially when comparing to diamond, is that the diamond cuts so much more aggressively for the specified grit/mesh. This is why a relatively 'fine' diamond grit, like 9 or 3 micron, will leave a coarser finish than a 'fine' ceramic at a larger particle size. That smaller particle of diamond will really dig in to the steel. In relative terms, the diamond is about 4 times as hard as the ceramic ('alumina', aka aluminum oxide), meaning it'll leave a scratch of about the same size, at about 1/4 of the pressure used, when compared to aluminum oxide at the same particle size.

I don't put much stock in rated grit sizes, when comparing one abrasive type to a different abrasive. It's really only meaningful when comparing finish results within one abrasive family (all diamond, or all ceramic, or all SiC, etc.). With more use, you can sort of interweave different abrasives into your sharpening scheme, as you become more familiar with how each one performs. But until then, most would be better off sticking to one abrasive, in order to predict what the result will be.
 
Just to add a bit to the conversation - I've noticed some of the same issues being discussed here about switching from one media to another and how it affects the results. Honestly I'd have to recommend the Norton combination India stone followed by the Spyderco Fine and EF stones for price etc. For about 70 bucks total you'll have everything covered. If you're working with tougher steel the AlumOx will still cut it no problem, you just have to make sure the stone stays unglazed and unloaded. While diamonds are way above the rest in terms of absolute hardness, Mohs is all that matters for grinding purposes. Unless your stone is only marginally harder than your steel, they all cut about the same speed minus differences in abrasive shape - on soft metal a file cuts just as fast as SiC or AlumOx sandpaper or a diamond plate.

As far as a transition goes, I agree that crossing stone types doesn't work as well as using all one type. AlumOx stones work well with each other - I took an edge recently from the coarse to the fine side of a Norton India stone, from there to a well lapped Spyderco Fine (I believe it equates to an EF) at which point it would whittle hair following a bit of stropping. Under magnification the scratch pattern was extremely fine - some of the troughs appear to be a micron or even less. The Spyderco stone also works well following my King waterstones which I believe are also AlumOx. It takes a lot more work to finish an edge with the Spyderco stone coming off of other media, though once you get down to the polishing stage it becomes easier to cross media.

I love diamonds and the edge they leave, but they don't play nice with recurve profiles no matter how slight. With the solid stones I can radius one long side and sharpen any blade configuration I come across.
 
Gentry, I've already answered that by saying the two are close. The 220g diamond cuts like a 100g SiC but I'd save the diamond and use the crystolon as its more economical. The x-coarse diamond is bumpy you can feel it scarping over the diamond grains, even hanging on some. I'd bet the xx-coarse is even more so. Thats why I prefer the SiC for rebeveling and the diamond for sharpening. Don't think in terms of grit as they are configured differently. Gain some experience and you'll know which you like and why. DM
 
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