Salguod wrote:


The first part of your question would be better answered by someone like Tom from Jende Industries...he sells the Chosera stones and is a really knowledgeable guy about all things to do with sharpening...see his video on shaving with a knife he sharpened. It is complicated and each steel is different so there are a variety of approaches. I love 1095 and A2 tool steels...they are respond well to the diamond paddles
and the ceramics followed by the strops with diamond pastes. Usually that is as far as I go unless I am experimenting and Darlene is out of the house, then I bring out the wet stones Choseras, soak them so they develop a slurry as you go and keep the spritzed with water. The results are extraordinarily
good and I use these for my finest knives like my PXL from Fallkniven with 3G laminated powder steel or my STS-5 combat/survival knife with CPM154 SS. Send a PM to Tom at Jende Industries and he will be happy to add to you knowledge in this area.

Thanks for the good wishes. I have kidney stones in both kidneys and have had 6 surgeries over 38 years...the dang things keep on growing back in. You can be sure I will have some Lagavulin and/or Laphroig sitting next to me when I return home after each surgery. That won't be for awhile though so meanwhile I think I will have a tipple of Laga now before bed when I dream of bent vises...the Lagavulin will help me have a dreamless sleep I hope! ROTFLMAO!

Best to you chum
Leo

Salguod wrote:


Thanks for the intro, Leo!

Basically, you can make it as easy or as complicated as you like!

The grit comparison is by microns, which is the most mathematically correct way to present them without too much confusion. The size of the particle equals the size of the scratch.

Well, yes, and no. You need to take into account the friability (rate of break down) of the abrasive and binder, the action of the paste/swarf/slurry, if any, and the biggest variable - technique.

Technique first - heavier pressure is good for stock removal since it pushes the abrasives deeper into the steel, but light pressure is best for obtaining the best finishes that won't cut through the ever thinning edge of the edge. What is heavy and what is light has some defining parameters, but is ultimately different for everyone.

Action of the paste/swarf/slurry - Diamond plates are subjected more to wear-down meaning that diamonds start off with sharp jagged and pointy edges that cut aggressively. For simplicity, imagine the diamond is in the shape of a pyramid, the tip of the pyramid is sharp and pointy, but as the diamond wears, the pointed area becomes wider, with a larger surface area as time passes that doesn't cut as deeply. This is advantageous on finer grits. The dust from sharpening will also clog the surface on the plates, making less of the abrasive stick out, therefore slowing down the action as well while making it perform at a finer grit. The WEPS ceramic stones follow this same premise, only without diamonds.

Diamond paste is a different beast - it has the freedom to roll around and scrub the surface more than to scratch at depth, like the fixed diamonds on the plates. In other words, the pastes are "less" aggressive, and are better suited for polishing surfaces rather than stock removal. That's a basic answer to why the higher grit diamonds are in paste form. On leather, the softness allows for a cushion that will round the edge of the edge over, but on something a little more solid, like balsa, the pastes are more aggressive.

Choseras work on several levels - They start off using the actual grit to scratch, but as this happens, abrasive and binding agent gets released and mixes with the abraded steel particles and breaks down, forming a paste. This paste, when worked correctly can actually produce a finer grit edge than the number on the stone. Also there are burnishing effects from the metal in the paste scratching the knife's edge, creating a shinier surface. The binder is also a softer abrasive, which tends to "polish the grooves", and adds to the smoothness of an edge.

Shaptons are somewhere between the Diamonds and Choseras - they have a hard binder which scratches deeper, but they don't load up as readily (in fact, using them clean is the best). The abrasive does not get released, and there is no interaction with the binder, which leaves perfect little scratches all lined up in a row, but without polish to make it "smoother".

SO....

Diamond plates tend to make edges that are rather toothy and somewhat serrated. They pass hair cutting tests because the grooves cut into the edge are clean due to no breakdown. These edges are more aggressive.

Diamond pastes will still give your edge of the edge little serrations, which make it more "toothy".

However when you switch over to Choseras, you still get some serrations due to the large grit size breaking off the bits of the thinning edge, but the overall surface is much more consistent. These edges are smoother.

Shaptons abrade things without polishing, so you get a very cleanly defined edge with grip.

The WEPS ceramics are similar to the Shaptons, but because of the loading up, will tend to polish the grooves more, leaving a clean, but not necessarily perfect edge.

Here's a progression I did using the stock WEPS and the Choseras. You can see the differences between the diamond scratches (which are still good, mind you!) and the Chosera.

Here's one using the WEPS 600 and the Shaptons. You can see the differences between the Choseras and Shaptons here (lighting is different, though.)


I hope this helps!

See what I told you Doug! The guy is a veritable encyclopedia on sharpening!
Good stuff Tom! Many thanks my friend!

Leo

Well, I forgot to answer the ZDP question

ZDP-189 - As far as I know, it is an extremely hard steel, RC 64 and abrasion resistant, so I'd go with diamonds all the way.

This is where things get even more fun. I'm not a dedicated steel junkie, so please bear with me if I mess up some of the finer details.

You have hard steel, and then you have abrasion resistant steel.

Hard steel is a result of heat treatment of a given steel, which varies greatly from knife maker to knife maker. Rockwell 60 and below is considered softer steel, and Rockwell 60 and up is considered hard steel. You can loosely apply 1/10 of the RC hardness to the Mohs scale directly, as most conventional steel is between 5 and 6 on the Mohs.

The factors that influence which sharpening medium to use here are based upon the corresponding hardness of the abrasive. Diamonds are 10 on the Mohs scale, and abrade all knife hardnesses (so far!). Silicon Carbide and Aluminum Oxide (which Shaptons and Choseras use) are in the 9's and can abrade steel every bit as well, so there is really no surface issue with these types of abrasives cutting into RC 64 steel. Sandpaper is usually feldspar, quartz or emery, which averages in the 6's on the Mohs, so there is definitely some more "evenness" between the fight of steel vs. abrasive scratching action, which can be positive in certain applications, mainly surface polishing.

The binding agents play a larger role here in determining which brand of abrasive medium to use. The general rule of thumb is a harder steel needs a softer stone, and a softer steel needs a harder stone. The softer stone allows for more abrasive to be released, thus cutting more effectively into the harder steel. On softer steel, you can easily cut through the steel with the abrasive relatively intact, so there is no real need to release abrasive at a high rate.

Diamonds negate this theory, since they still cut through everything, but then practicality enters the equation - do you really need diamonds to cut a RC55 steel? Not really, it's a little overkill, but at the same time, there is no need to ponder if it will sharpen a certain steel type.

Abrasion Resistant steels pose different problems. These use more exotic materials, usually powdered steels, which when treated, form certain carbides in the steel. Most Carbides are generally in the 9 range on the Mohs, so we have a serious competition happening for scratch ability now. Ironically abrasion resistant does not equal "Hard" as in RC 90. Because of the powdered steel, the hard carbides are essentially embedded in a matrix of "softer" steel, which can be as low as RC 55-60. On most conventional sharpening stones, you can abrade the matrix enough to produce "carbide popout" which essentially gives you a serrated edge where the carbides literally fall out, not abraded through. You can still polish the bevels, although going is very slow to get through the carbides.

Diamonds cut through everything, and on abrasion resistant steels, they are king for doing any profiling or serious repairs. Keep in mind that the fight is still there....

Bringing these abrasion resistant steel to higher refinement is also tricky - it is subject to carbide popout as you make the edge of the edge too thin for the steel to hold the carbides.

Anyway, I'm starting to ramble...

Tom, thanks for the excellent and informative answer!

It sounds like ZDP-189 and other abrasion resistant steels might best be tackled with the WEPS by using the diamonds down to 1000 grit (7 micron) and then the 5 and 3.5 micron strops. Perhaps adding the 1 and .5 strops for a really fine mirror.

Would going "diamond all the way" like this reduce the chance of carbide popout? Because the diamonds would have a lesser chance of abrading the different hardness’s unequally? And perhaps the strops (as opposed to stones) would lessen the chance of carbide popout?

Or do I have it all wrong?

Carbide popout is a finicky thing... even with all diamonds.

You run into several issues as you add more refinement to abrasion resistant steels. The first is that There is a point of diminishing returns with the more abrasion resistant steel - the higher you go in grit, the slower it abrades. Of course diamonds still cut, but they will progressively slow down at each grit level.

More importantly, the diamonds abrade through the carbides once the abrasive becomes smaller than the size of the actual carbides - I don't know for sure what that size is, but I am guessing somewhere between the 4K and 8K range (2-4 microns) based on my observations (which is by no means extensive in the super steel area) - In theory, this can cause carbide fracturing, where the comb-like gaps in the carbide itself become too unsupported and snap off like a pencil point, leaving you with a "whole" thickness of carbide again that is still secured to the steel. This theory seemed to be proven with my recent attempt to sharpen an s90v Spyderco military knife to shave ready. I'd get it to a certain point, where it was screaming sharp, and then the edge would disappear on me.

With the surrounding steel being rather "soft", I found that while it was difficult to abrade through the carbides, the steel itself was still rather flexible, and I could feel the edge had rolled somewhat after stropping (since I was going for a shave, I used lower angles and the edge of the edge became very thin).

The solution was to add angles to the steel as I went higher in refinement. This accounted for all the issues presented here. The higher angle allowed the carbides to be abraded through with finer grits, but left enough structural stability in the serrated carbide to not fracture. It also solved the issue of rolling the edge that was too thin for stropping. I ended up at about 35 degrees per side for my shave on the s90v.

ZDP-189 may react differently, but I think they will follow the same route.

leomitch wrote:


He definitely is!

jendeindustries wrote:


It surely does! Thanks a lot, Tom. Just out of curiosity: which magnification factor do you use you microscope on to produce the photographs?

mark76 wrote:


Ah, 400x I just read. Thanks, Tom.

Anytime!

The actual size is 1mm wide by .75mm high in those pictures.

I currently own the diamonds stones up to 1000 and I am looking for an upgrade. Without saying I am looking for the best finish possible.

Just wondering if there are any thoughts on this progression:

Use the WEPS with the diamonds stones up to the 1000 then jump up to the 2000,3000 Chosera stone and then up to the 5000 10000 chosera stones.

How much of a benefit would there be with the 5000 10000 grit, Considering they are almost 200 bones. Also if it doesn't seem like a good progression I would appreciate a suggestion


My favorite knifes have ZDP189, S30v, and M390 steels (no particular order).

Thanks for the thoughts!