Ceramic vs Diamond vs Synthetic vs Natural Sharpening stones

Jason B. said:
Although tungsten is hard it's not harder than most of the abrasives used in stones, it's actually much softer than even aluminum oxide. You should also be looking at the Knoop hardness scale, it's more accurate.
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I think I've heard of that other hardness scale you're speaking of>>It has been a long time ago when I was going to college taking their Machine Tool Technology courses. It seems to me that there is also another hardness testing device too >> other than the "Rockwell" hardness tester that most of us are familiar with. It seems like I also heard reference to a "Vicker's" hardness test device and also a Brinell hardness tester as well. All I've ever used up to this point has been the Rockwell Hardness tester that we had at the lab where I was going to school at.

I'm going to dig up some of my old text books and see if I can find this other hardness scale you're speaking of. Yeah you're right because even some of the more common abrasives are usually way harder than any of the blade steels we work with. Thanks for calling that to my attention because I'm definitely going to check it out for sure.

i don't know if any of these other hardness testers are available at the school I used to attend>> they let me use their Rockwell tester whenever I want to. I've also got an older book on abrasives that I found at a thrift store about a year ago. But again I'm anxious to check out this other Hardness scale because most of the time the "Moh's Scale is the one you hear of 90% of the time.
 
Yeah the tungsten carbide is always a sintered matrix, it's the only way to use it. And it is available in hardnesses approaching AlOx for sure, just depends what is mixed with it in the sinter. It probably would be more expensive to make a stone sized plate out of - last time I checked carbide scrap price it was $12 a pound IIRC. Best bet would be to find a surplus place with some usable sized pieces of anyone wanted to try it. I might try it myself, I definitely have some laying around.
 
Well I'm glad I asked some of you guys about materials like Tungsten Carbide>> and it's funny in a way with all those TC type sharpeners Ive seen on the market because it appears to me that about all they would be good for would be like a "steeling" action>> you know like using a "butcher's steel" which really doesn't sharpen anything per se but rather merely aligns the edge which is already well beveled and relatively sharp and only needs some "touch up" or fine tuning to get it cutting again.

A lot of the woodworking vendors have been touting those TC sharpening tools and the consumer not even being aware that simple aluminum oxide sandpaper is head and shoulders above it as an abrasive.

However I do believe there are going to be a lot of newer ceramic type abrasives coming down the product pipeline that will someday approach the hardness of diamond. I do see it coming eventually.

It is funny too as hard as most rock and minerals are that there are so few natural whetstones and when you take "novaculite" which was always known as an Arkansas Stone. Just a few years ago that was the one big stone everyone wanted>> but now they are truly out of date. Now I don't hear much of any natural stone being used for knife sharpening anymore.
 
Wouldn't quite call Arkansas stones 'out of date', at least not yet. ;)

Natural stones, i.e. 'Arkansas' stones, can still be quite nice on steels suited to them, like simple carbon (1095, CV) and low-alloy stainless steels (420HC, 440A, Victorinox & Opinel stainless, etc), none of which have significant quantity of hard carbides to get in the way. The novaculite is still hard enough as an abrasive to do a nice job on these steels, but goes about it more gently. Sometimes that's a very good thing, and a gentle approach can sometimes coax a real nice finish out of an edge. Appropriate tools for specific jobs, in other words. :)

I have a little medium Arkansas stone that's a nice shade of pink & white; used with some oil, it's becoming one of my favorite stones for maintaining edges on some of my Case CV knives, and does a nice job on Case's stainless as well (420HC).


David
 
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JD Spydo said:
Well I'm glad I asked some of you guys about materials like Tungsten Carbide>> and it's funny in a way with all those TC type sharpeners Ive seen on the market because it appears to me that about all they would be good for would be like a "steeling" action>> you know like using a "butcher's steel" which really doesn't sharpen anything per se but rather merely aligns the edge which is already well beveled and relatively sharp and only needs some "touch up" or fine tuning to get it cutting again.

A lot of the woodworking vendors have been touting those TC sharpening tools and the consumer not even being aware that simple aluminum oxide sandpaper is head and shoulders above it as an abrasive.

However I do believe there are going to be a lot of newer ceramic type abrasives coming down the product pipeline that will someday approach the hardness of diamond. I do see it coming eventually.

It is funny too as hard as most rock and minerals are that there are so few natural whetstones and when you take "novaculite" which was always known as an Arkansas Stone. Just a few years ago that was the one big stone everyone wanted>> but now they are truly out of date. Now I don't hear much of any natural stone being used for knife sharpening anymore.
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As long as carbon steels continue to offer performance advantages in certain applications, Arkansas stones will have a place at the table. Consider probably 90% of all knife sales are of low carbide stainless and carbon steel. These days I don't camp or backpack with anything but carbon steel and touch up my edges on a fine silt stone and ash from the fire. A small soft Arkansas would be right at home.

Also, those Tungsten carbide scrapers are doing a lot more than aligning the edge on all but the very most wear resistant steels. They function more like a file with only one tooth row. Butcher's steels likewise act like a file and are certainly removing steel. The smooth meatpacker's steels are doing the burnishing/aligning.
 
DeadboxHero said:
Martin, love your posts :)

Do Arkansas stones offer any advantages?
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If I had the luxury of setting up a large bench just for full-time sharpening, I'd have a small area for my Arkansas stones. They are still prized and sought after by the woodworking segment of the market, and this is where I'd use them most often (and still do occasionally).

They tend to be slow relative to waterstones, and with lower abrasive potential. On lower RC carbon or gummy stainless they can have issues cleanly removing the burr, also adding to working time. On higher RC carbon they rock. Being a hard stone they work a lot like a ceramic but make a brighter finish for their rated grit value. Good feedback as well. Is possible to turn out an edge way finer than one might expect from how these are graded.

My analogy above, a fine silicon carbide/soft Arkansas combination puck would be the bomb for carbon steel camping tools. A lot of it is the feel of using them and the allure of the natural stone. Some of mine come in cedar boxes, just opening them up is a positive experience. I've had my set for many years and learned on them quite a bit, but these days I don't think I'd seek them out without a specific need as my other stones do what I need and with less time and QC. Also are no guarantees you'll be getting a good stone one to the next. For most folk though, their common cutlery, kitchen knives, chisels etc will turn out extremely sharp off of a Washita/soft progression, as good as any manufactured stone. Get into steels with higher alloy/carbide content and the wheels start to fall off rather quickly.

About five years ago I went to an estate sale and picked up a huge soft Arkansas, had to be 10" x 2.5". Bonded to a wooden base it looked to be all of 100 years old and well used and cared for - barely any dishing, surface like velvet. I fumbled it on the basement floor within reach of my workbench and it shattered into a dozen pieces. What an ignoble end for such a grand old stone - that felt terrible.

Martin
 
Before the wider use of Tungsten Carbide tooling, Corundum (Aluminum Oxide) was the common sharpening abrasive. With the proliferation of WC (Wolfram Carbide) tooling, Carborundum (Silicon Carbide) was developed to hasten the process of sharpening the harder WC material (72 HRC). Vanadium Carbide, found in some steels, has a hardness of 82.
 
Been testing Grinderman Stones lately (Made In Russia), they are a Silicon Carbide with a ceramic binder, Waterstones for the Edge Pro and Profile Systems.

Very interesting, very hard and give very little slurry.

The ones I am testing are 120, 220, 400, 600 and 1000 grit.

Will be more on these once I am finished with the testing of the Techstudio Profile Sharpening system and post the full review.
 
Silicon carbide does NOT cut tungsten carbide tooling well. It's more or less usable for a "roughing-in" type process - sort of akin to using a hatchet to make joinery for furniture. They are too close in hardness to get clean edges that will last.
 
eKretz said:
Silicon carbide does NOT cut tungsten carbide tooling well. It's more or less usable for a "roughing-in" type process - sort of akin to using a hatchet to make joinery for furniture. They are too close in hardness to get clean edges that will last.
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Material hardness chart, bottom of page, Silicon Carbide is much harder than tungsten carbide, Vanadium Carbide is the hardest found in steel knives. https://www.tedpella.com/Material-Sciences_html/Abrasive_Grit_Grading_Systems.htm

[video=youtube;K_R1yxULRuQ]https://www.youtube.com/watch?v=K_R1yxULRuQ[/video]

[video=youtube;EytTUsg3J6s]https://www.youtube.com/watch?v=EytTUsg3J6s[/video]


S125V 400 grit SIC, mile of cardboard......Still slices Phone Book Paper

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CPM 10V Mile of Cardboard...400 grit SIC......Still slices Phone Book Paper

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Spyderco K2 Mile of Cardboard, 400 Grit SIC....Still slices Phone Book Paper

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RWL-34..... 3,000 FT of cardboard... 400 Grit Silicon Carbide... Still slices Phone Book Paper

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JD Spydo said:
Now when they rate abrasives on the "Moh's Hardness Scale" it starts at the top with "diamond" being right up at number 10>> because at this time diamond is the hardest known substance here on the earth. It's much harder than any steel alloy or even ceramic too for that matter.

I've often wondered why super hard materials like Tungsten Carbide or other super hard materials that you never hear of being used as abrasives. I'm also wondering what all of the nanotech sciences are going to produce in the area of abrasives as well. I also think we will soon be seeing ceramics just about as hard as diamond before too long. Just in the area of conventional sandpaper there has been huge improvements.
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There is plenty of research going into synthesizing new materials with hardness greater than that of natural diamond. Most of it is focused on starting with different allotropes of carbon - graphite, fullerenes or just plain old amorphous carbon - and results in substances akin to carbon nanotubes. They have succeeded in beating natural diamonds' hardness. There has also been some noise out of the boron nitride camp recently with hardnesses approaching natural diamond, depending on crystal structure and particle size. Unfortunately, I don't see how carbon nanostructures would be much use in sharpening no matter how hard they are due to their inherently small size: a buckyball has a molecular diameter of about 1 nm. That's without considering production cost of such materials.

I thought this article was pretty dope though. Lasers + magnetic diamonds = sharpest knives ever? We can always dream.
 
Lol, don't care what the chart says. I've tried to grind tools using those materials, it ain't happening. Theory doesn't always line up with real world usage. Try calling a few machine shops or tool grinding shops (real shops, not some guy working in his garage) and ask how many use SiC grinding wheels to grind their tungsten carbide tooling - if there are any, I'll eat my hat.
 
eKretz said:
Lol, don't care what the chart says. I've tried to grind tools using those materials, it ain't happening. Theory doesn't always line up with real world usage. Try calling a few machine shops or tool grinding shops (real shops, not some guy working in his garage) and ask how many use SiC grinding wheels to grind their tungsten carbide tooling - if there are any, I'll eat my hat.
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As long as the abrasives are larger than the carbide size, it will cut pretty well. When dealing with Tungsten carbide tools, the percent of Tungsten is far higher than what one will find in HSS.

I've also noticed Tungsten carbide comes in a variety of hardness, with the top end coming close to that of AlOx and SiC, close enough IMHO to cause issues at higher finish values.

Here is the link to a thread not long ago where you were good enough to do some micrograph progressions on M2. This opened my eyes a bit, and helped make sense of some of the issues I had seen previously.


http://www.bladeforums.com/forums/s...wear-resistant-steels-(S30V-S90V-CTS204P-etc)
 
eKretz said:
Lol, don't care what the chart says. I've tried to grind tools using those materials, it ain't happening. Theory doesn't always line up with real world usage. Try calling a few machine shops or tool grinding shops (real shops, not some guy working in his garage) and ask how many use SiC grinding wheels to grind their tungsten carbide tooling - if there are any, I'll eat my hat.
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What does that have to do with sharpening knife blades?

In manufacturing most use either CBN or Diamonds these days.
 
HeavyHanded said:
As long as the abrasives are larger than the carbide size, it will cut pretty well. When dealing with Tungsten carbide tools, the percent of Tungsten is far higher than what one will find in HSS.

I've also noticed Tungsten carbide comes in a variety of hardness, with the top end coming close to that of AlOx and SiC, close enough IMHO to cause issues at higher finish values.

Here is the link to a thread not long ago where you were good enough to do some micrograph progressions on M2. This opened my eyes a bit, and helped make sense of some of the issues I had seen previously.


http://www.bladeforums.com/forums/s...wear-resistant-steels-(S30V-S90V-CTS204P-etc)
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Never had any issues working with SIC, even on the higher carbide knife steels personally, could be the stones that I normally use and am used to. Very high quality and very hard SIC industrial stones, but then I don't sharpen over 400 grit (40 Micron or so) either these days.

Never had much use for diamonds, I have some diamond stones, but never need them so they sit and collect dust.
 
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Ankerson said:
What does that have to do with sharpening knife blades?

In manufacturing most use either CBN or Diamonds these days.
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Nothing, I was responding to the gentleman (tiguy7) who segued the conversation on the post a couple above mine - you know, the one where he mentioned SiC being used to cut WC tooling before the advent of common diamond and CBN abrasive usage?
 
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