Fine ceramic stones versus fine diamond: Which is better for general edge refining?

[maximus83]

I'm adding to my sharpening setup. Currently I have a DMT 10" 2-sided stone (extra-course/course) for heavy work. It's handy because the dense diamond coating makes it cut so fast. So for normal sharpening, I use the DMT coarse side for most repair work, resetting bevels, or for knives that are fairly dull. Then I finish on my Sharpmaker, using the ceramic fine and UF rods to refine the edge.

Now I would like to go to an "all bench stones" setup, so the Sharpmaker will be used mainly for touchups. So this leads to my question:

What would be the best general-purpose type of bench stones to supplement my DMT EC/C stone, where the purpose is refining the edges after doing heavy work on the DMT?

Currently I am looking at something either in a DMT diamond stone (like their fine/extra-fine 2-sided stones), or something in a ceramic (like Spyderco's fine and ultra-fine 2"x8" bench stones). I'm avoiding traditional options like water stones and the like, as I want to go with more man-made materials that are lower maintenance and stay flat over time. Right now, the ceramic seems like it may be a better choice. My thinking is, use the diamonds stones for what they are great at: fast cutting. And use the ceramics for what they are great at: super smooth edge refinement. I know the DMT fine/extra-fine stones probably do a great job, but I think after some initial cutting on the DMT coarse stone, the ceramics are able to do a really nice job of cleaning up the edge. I can already see this on my Sharpmaker, so moving to a bench stone, it seems logical to go with a ceramic bench stone in the same grit as the Sharpmaker. And if I find that I ever need an intermediate grit to take off a bit more metal after the DMT coarse stone and before the ceramic stone, I can throw in one of the Spyderco medium grit stones as well.

Thoughts on this?

 

[db]

I think you are on the right track. I personally haven't used the newer fine diamond hones and have read that they do have a break in time frame. You may be making just a little too big of a jump from coarse diamond to fine ceramic though. I think I'd add a fine diamond then the fine ceramic. I'm a big fan of the ceramic hones for finishing. I just really like the feedback I get from ceramic hones. Diamonds are my choice for coarse as well due to them staying flat and they will grind just about anything quickly. My own little personal rule has been anything over 1000 grit I go ceramic. Anything under 1000 grit I've gone with diamonds. I was tempted to try the higher grit diamonds at one time but my sharpening took a very different turn and now I use a belt sander for most all sharpening except touchups.I haven't used my water stones in a very long time. Truthfully they work great but I just got tired of the mess and flattening.I should probably sell them.

 

[Obsessed with Edges]

I'd also put something in between the coarse diamond and the ceramic. That's a big jump in grit, not just in terms of the abrasive size, but in the big difference in aggressiveness of the abrasive types. Among diamond hones, I've found a fine DMT (25 micron) to be the most versatile, and it's the one I use the most. For most blades, it's capable of doing some fairly major repairs to an edge, for dents/dings/chips/etc., and it's also a great touch-up & regular maintenance hone. If I were picking only one for that intermediate step, the fine DMT would be it.

Ceramics are great for cleaning up burrs & polishing, and I've never felt the need for a large bench ceramic to accomplish that. I have the medium & fine Spyderco bench hones, but haven't used them hardly at all. All of the polishing & burr/wire clean-ups I've done, have been accomplished using smaller ceramics (Spyderco DoubleStuff, and occasionally the Sharpmaker's rods). The refinement & polishing done with them is always best done with a feather-light touch. I prefer using a smaller hone for that, which lends itself very well to a light fingertip hold, for better control & finesse.

 

[maximus83]

Great tips as usual.

So, taking your approach Obsessed, since I already have the DMT C/EC duosharp, I could just add the DMT F/EF duosharp (F = 600 mesh 25 micron, EF = 1200 mesh 9 micron). And then use my Sharpmaker Fine and Ultrafine ceramic rods for refinement at the end. In this scenario, only thing I'd still need would be the DMT F/EF stone.

 

[Obsessed with Edges]

Great tips as usual.

So, taking your approach Obsessed, since I already have the DMT C/EC duosharp, I could just add the DMT F/EF duosharp (F = 600 mesh 25 micron, EF = 1200 mesh 9 micron). And then use my Sharpmaker Fine and Ultrafine ceramic rods for refinement at the end. In this scenario, only thing I'd still need would be the DMT F/EF stone.

That's what I'd do. I think you'll get a lot more use out of the F/EF DMT over the long run, compared to a ceramic bench hone. As I mentioned, an extremely light touch is best at the refinement stages, and for me (personally), that's more difficult to do on a bench hone, especially if sharpening a large, heavy blade. The reason I like the small handheld ceramics is, it's much easier to put the 'hone on blade', and still maintain a very, very light touch, as opposed to 'blade on hone on the bench', with much of my body weight leaning into it (and maybe the excessive weight of a large blade, too). I usually do it with the blade held edge-up in one hand (or supported in a clamp or vise or whatever), and the hone in the other, and just gently polish the bevel. It's also much easier to actually see the edge in flush contact, when done this way. For me, it's a much easier way to control everything. This is why I haven't used my bench-sized ceramic hones.

 

[maximus83]

Obsessed, you explained your refining technique (holdeing blade edge-up, running hone along the blade from heel to tip) in another post. I'm interested in that as well.

Do you find that this approach sort of "clashes" with the grind you've already put on your edge using ordinary bench stone techniques (where you grind more with the blade edge perpendicular to the stone)? I'm just wondering about this, if you grind one way on the bench stones, then go to the refinement process and slide your ceramic hone ALONG the blade from heel to tip, what does that do to your edge?

 

[Obsessed with Edges]

I'll throw in this one more thing. Don't know if it's still an issue with Spyderco's ceramic hones, but the ones I have (2 DoubleStuff hones, and the 2 large bench ceramics) all had some slight dishing from the factory. All of mine were purchased back in the early/mid '90s. I was always uncomfortable with the slightly raised edges of these hones, which could quickly undo a good edge refinement, if the edge were dragged across them. I flattened one of the DoubleStuff hones (using a DMT Duo-Sharp C/F, interestingly). Took a very long time, even for that small hone, and it altered the effective grit too (much finer now). After using it for some time, I've found it's been great; I use that one almost exclusively now. But the prospect of having to do that with the large bench ceramics was daunting, and won't be something I'll ever attempt.

 

[Obsessed with Edges]

Obsessed, you explained your refining technique (holdeing blade edge-up, running hone along the blade from heel to tip) in another post. I'm interested in that as well.

Do you find that this approach sort of "clashes" with the grind you've already put on your edge using ordinary bench stone techniques (where you grind more with the blade edge perpendicular to the stone)? I'm just wondering about this, if you grind one way on the bench stones, then go to the refinement process and slide your ceramic hone ALONG the blade from heel to tip, what does that do to your edge?

Actually, I'm seeing some additional benefits to doing that. I've found it's a lot easier to 'flip' a wire edge that way, and it's also easier to maintain steady angle. My edges have improved noticeably, as a result. If one is wanting to use & maintain a more 'toothy' edge on a blade, that may not be the best way. But all of my edges are maintained somewhere above EEF DMT (3 micron) or 800 - 2000 grit wet/dry sandpaper or more, with additional polishing by stropping with 1 micron dia-paste, or Simichrome. For these edges, it works great.

 

[maximus83]

Cool. After getting my large DMT f/ef bench stone, I may try a sequence like this for moderately dull blades:

* DMT coarse (if needed)
* DMT fine
* DMT extra-fine
* Spyderco ultra-fine ceramic SM rods. Might try your approach of clamping blade edge-up and running the corner of the triangle UF hone along the edge.
* Stropping

It'll be interesting to see what this sequence produces.

 

[Obsessed with Edges]

Cool. After getting my large DMT f/ef bench stone, I may try a sequence like this for moderately dull blades:

* DMT coarse (if needed)
* DMT fine
* DMT extra-fine
* Spyderco ultra-fine ceramic SM rods. Might try your approach of clamping blade edge-up and running the corner of the triangle UF hone along the edge.
* Stropping

It'll be interesting to see what this sequence produces.

Use the flats of the ceramic hones. It's way too easy to put too much pressure on the edge, when using just the corners of the hones. Using the flats will distribute pressure, which helps prevent rolling/chipping an edge, and I feel it also is easier to maintain flush bevel contact and steady angle that way. That's the only thing I'd change. Otherwise, I think that plan looks pretty good.

 

[Magnaminous_G]

take plenty of time with each step, too. Five extra minutes of quality sharpening with a coarser stone will save you 1/2 hour or more when you move up. Make sure that edge is ready for the next grit!

 

[maximus83]

Does it make any SIGNIFICANT difference if you add steps that are small increments of increasing the grit? For instance, rather than go straight from DMT EF (which is 9 micron 1200 mesh) to the Sharmpaker UF rods, maybe go from DMT EF to the SM Fine rods first, before going to SM UF rods. Wondering if that more incremental way to building up the edge with successively finer grits makes a big difference, or if it ultimately is not all that important. Seems like most experienced sharpeners that I have come across are able to get scary sharp blades with only 2 to 3 grits (or at most 4) required before going to stropping.

 

[Obsessed with Edges]

Does it make any SIGNIFICANT difference if you add steps that are small increments of increasing the grit? For instance, rather than go straight from DMT EF (which is 9 micron 1200 mesh) to the Sharmpaker UF rods, maybe go from DMT EF to the SM Fine rods first, before going to SM UF rods. Wondering if that more incremental way to building up the edge with successively finer grits makes a big difference, or if it ultimately is not all that important. Seems like most experienced sharpeners that I have come across are able to get scary sharp blades with only 2 to 3 grits (or at most 4) required before going to stropping.

It depends on how you want the finished edge to look, aside from sharpness. It is possible to make an edge extremely sharp, at either coarse or very fine finish. If you want the final edge to be somewhat less toothy and more polished, then more steps in grit, in tighter increments, will be necessary. The extreme would be a fully mirrored bevel, which virtually mandates multiple grit stages in tight succession. It's extremely difficult to remove all scratches from coarser grits, if skipping multiple steps and going immediately to finer grit. You could still do it, but it would take a very, very long time.

If you're mainly concerned about just making a good and very sharp working edge, I'm sure you have all you need. The key is to use the coarsest grit to fully and completely apex the edge (form the burr), then use the following grits to very gently refine it, without otherwise dulling or blunting that good starting edge. If you do the work properly with the first hone, then you won't need to take much time with each of the following steps.

 

[Magnaminous_G]

+1 to what Obsessed said. There are pictures on the internet (I'm too lazy to fish them up) of microscope photos of the edges of a knife after different grits. You can really see how the steel works on that microscopic level when you look at the pictures. Under that kind of magnification, the steel looks and acts more like peanut butter, and when you think about that, you start to understand why a burr forms, etc. So, with that analogy in mind, imagine you have a milk-jug sized lump of peanut butter that you want to make into a smooth cube with crisp edges. If all you had was a garden rake and a butter serving knife, you can see how you could hew the shape out with the rake, but then it would still be too rough to really move on to the much smaller butter knife. Now then.... you *could* do that--which gets to the heart of your question--but it would take a longer time. Better to go from the rake to a serving fork, then to a spatula, *then* finally to the butter knife. In the end, you are able to better contour the shape with much greater control by doing it in stages with increasing finesse, and it ends up being faster too.

So if you start with 100 grit (very rough) and make your edge, and then move immediately on to Spyderco ultrafine... you *can* do that, but you'd be spending a LOT of time on that ultrafine ceramic rod. You would cut the time spent sharpening drastically (and also make a better edge), if you go from 100 to 300 to 600 to 1200 to 2500, for example. For me, to reprofile a totally banged up, chipped edge (i.e., not one of my knives, i.e. doing someone else a favor), I use extra course/course/fine/extra fine, finish with the spyderco ultrafine bench stone and green strop. Besides the Spyderco, my benchstone are all DMT Duosharps, so it actually goes pretty fast. But I wouldn't want to go from extra course to extra fine. No way.

 

[Talley1013]

I'll throw in this one more thing. Don't know if it's still an issue with Spyderco's ceramic hones, but the ones I have (2 DoubleStuff hones, and the 2 large bench ceramics) all had some slight dishing from the factory. All of mine were purchased back in the early/mid '90s. I was always uncomfortable with the slightly raised edges of these hones, which could quickly undo a good edge refinement, if the edge were dragged across them. I flattened one of the DoubleStuff hones (using a DMT Duo-Sharp C/F, interestingly). Took a very long time, even for that small hone, and it altered the effective grit too (much finer now). After using it for some time, I've found it's been great; I use that one almost exclusively now. But the prospect of having to do that with the large bench ceramics was daunting, and won't be something I'll ever attempt.

Thats interesting. I had the same problem with my Spyderco bench stones. I noticed that the edges on mine were raised also. I didn't want to risk ruining my diamond stones so I have never tried to flatten the ceramics.

 

[maximus83]

I've seen other folks say that you can lap the ceramics by buying a relatively smaller, cheaper diamond stone, and using that for lapping (knowing that it's going to have a limited life span).

I'd be interested to hear if Obsessed or others think that's the way to go, and if so, what size stone and what grit would be recommended for the "diamond lapping stone."

 

[Obsessed with Edges]

Thats interesting. I had the same problem with my Spyderco bench stones. I noticed that the edges on mine were raised also. I didn't want to risk ruining my diamond stones so I have never tried to flatten the ceramics.

On occasion, you'll see many of the sharpening nuts around here warning against using too-heavy pressure on diamond hones, because it scrubs excess diamond off. So long as pressure is kept light, they hold up well. That fact was firmly cemented in my view, after using my Duo-Sharp to flatten that Spyderco ceramic. I had previously done something similar to a pair of Lansky ceramic hones, using a C/F Dia-Fold hone. That was my first-ever attempt at doing such a thing, and I did manage to scrub a lot of diamond off that hone. I went about it more carefully with the Spyderco & Duo-Sharp hone, using a lot of water to keep particles suspended, and keeping pressure very light. After finishing, there was virtually no perceptible new wear on the Duo-Sharp. It's in great shape.