At what step in a process do diamond stones belong?

other memory

other memory

Joined
Jul 15, 2012
Messages
1,883
From what I can tell diamond stones are more of a stock removing tool rather than a, lets just call it, a fine edge making tool.

I've seen what a paper cutting edge looks like under a loupe. Its looks like a mirror finish, 0 undulations. After use, I've looked at the same edge. A lot of the mirror is still there, but surface abrasions begin to occur. I've also seen what the edge looks like after it is honed with a extra fine diamond stone (with excessively lite strokes). It becomes jagged. I believe this is what some refer to as "raising the burr"? Yes, no?

What exactly are people doing with diamond stones to attain an edge that can move onto stropping?
 
It's all about feel and a uber light touch.

Diamonds perform best with highly wear resistant steels, typically steels over 3-4% vanadium will show the greatest results.
 
Diamond hones, and finer polishing abrasives made of diamond, can be used literally to the exclusion of everything else, to obtain any level of sharpness or edge finish. The real differences come in how certain steels respond to them. An EF or EEF diamond hone may leave deeper scratches on less wear-resistant steels, and shallower scratches on more wear-resistant steels. The depth and width of those scratches will determine how the finish 'looks', whether it be a mirror or something a little hazier. The appearance of the edge finish has no significant bearing on how well the edge itself will cut, so long as the apex is clean and free of burrs, and not rounded/blunted in the process.

An edge can be 'ready' for stropping off of any hone, so long as the edge is fully apexed. The presence of a burr is the most reliable indicator of that; it's formed when the two bevels meet cleanly at the apex and, if done correctly, should ordinarily happen in the first (coarsest) stage of sharpening, no matter what type of abrasive is used (diamond, silicon carbide, aluminum oxide, natural stones, etc.). The subsequent stages of sharpening (medium, fine, ef, eef, etc.) serve to clean up the burr and further refine the apex.


David
 
BTW, if you click on 'The first sharpening' link in knifenut1013's sig line (post #2), you'll get a very good (excellent) example of what can be done with diamond hones and diamond pastes on strops. :)


David
 
I paper cutting edge doesn't need to be polished. You could go coarser, but I can go off a 80 grit belt on the belt sander and slice paper like nothing. I can even shave hair with it once I strop it a few dozen times. That jagged property your talking about is "toothiness". If you've ever polished an edge so much that it's harder to start cutting an orange peel, it's very polished. Most people prefer a toothy edge because it's like using a saw versus a knife. The saw is going to grab more when cutting and the knife will just glide over. Imagine that but on a very small level on the knife edge.

All you need to make a knife usably sharp is to apex the two bevels, anything past that is just refining that apex smaller and smaller so when the same amount of pressure is exerted when cutting the area of the apex is less leading to a higher PSI.
 
I recently read that diamond stones are only for ceramic blades, something about the steel knocking off the diamonds and wearing out the stone quickly.
 
whateatsrabbits said:
I recently read that diamond stones are only for ceramic blades, something about the steel knocking off the diamonds and wearing out the stone quickly.
Click to expand...

This only happens when grinding too heavily on the hones. Diamond hones work excellently with LIGHT pressure, and this also works to the benefit of the hone itself. Too much pressure is what does the damage, regardless of whether it's steel, ceramic or anything else. If used properly, diamond hones can last for years, even decades.


David
 
Last edited:
I rough with diamond hones, Then move on to finer stones. Natural, synthetic, chosera. Then I strop with different strops using lower and lower micron diamond compounds, micro fine honing compound or boron nitride sprays.

And yes, light pressure should only be used. With all hones and stones, but especially with diamond hones. They will all smooth out or break in after time.

James
 
alfred mcdougal said:
From what I can tell diamond stones are more of a stock removing tool rather than a, lets just call it, a fine edge making tool.
Click to expand...

Wow, there are a lot of misconceptions in your post. First: diamonds can be used at any point in the process. They are excellent at setting a bevel, reprofiling, and correcting problems at the coarser grits because they cut so fast. But they are also great for refining and even finishing at the higher grits. Some of the more experienced sharpeners here can tell you more about which steels benefit from which type of stones, but diamonds can be used for all of them from reprofiling to refining to finishing.


I've seen what a paper cutting edge looks like under a loupe. Its looks like a mirror finish, 0 undulations.
Click to expand...

That is false. A paper cutting edge is a fully apexed edge with the burr removed. It doesn't matter if it's mirror polished or not and doesn't matter how refined the final edge is. You can push cut paper with nary so much as a whisper coming off of a very coarse stone if it is sharpened properly.


What exactly are people doing with diamond stones to attain an edge that can move onto stropping?
Click to expand...

They are simply sharpening. At any grit. Any fully apexed edge with the burr removed benefits from stropping, regardless of how coarse or fine. Again, there are more experienced sharpeners here who can go into the details of which type of finish benefits most from which type of stropping, but all finished edges will benefit from a little stropping, regardless of coarseness or fineness of the final edge.
 
Right now, the edge looks similar to this at 20X magnification. The edge is ruff after VERY LIGHT strokes against a DMT extra fine stone. How do I apex this edge?

Rigotti+1000+grit+Chosera+800x.jpg
 
Your edge is apexed if it looks like that. The Apex is the point where the bevel slopes come together and meet air, and on a extremely small scale all apex points are round. Yes, that's even when the knife is uber sharp.

The DMT EF stone is a 9 Micron 1200 mesh stone, once broke-in it will produce a very high level of sharpness with lots bite to the cut. Diamonds are a sharp abrasive so the path they cut in the steel is very defined and this results in a very "toothy" edge, this is a trait of all diamond abrasives even up to the DMT 8000 mesh hone.

The pressure you exert during sharpening is critical when using diamond hones, diamonds need to only make contact to do their job and any pressure applied is too much. If your touch is light and the burr brought down as small as you can get it then I would speculate you simply have questions and not so much a issue.

Having a unclear understanding of a process leads to confusion, read some of the links in my Sig line and the sticky's at the top of the Maintenance forum. It will help you to better understand sharpening.
 
You must log in or register to reply here.
Back
Top