Ceramic vs Diamond vs Synthetic vs Natural Sharpening stones

eKretz said:
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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Why would anyone use SIC today in manufacturing with the other options?
 
JD Spydo said:
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.
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Have you found the textbook on abrasives? I would love to know about it
 
Ankerson said:
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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Is this still true?
 
As I look back, I see there was some misunderstanding going on in this thread. Fellows "never having problems cutting carbides" in knife steel are not what I was talking about. There are relatively few carbides in knife steel compared to the amount of carbides in tungsten carbide tooling used for machining. When using the SiC for knife steels you are mainly cutting the steel matrix, while still cutting the carbides sprinkled through that matrix or simply eroding the matrix around them and pulling them out (this mainly happens with the coarser grits). My comment was directed at the guy who mentioned that SiC was used to cut that machine shop tooling. While originally it was indeed utilized for that purpose, it worked so terribly that it was only used for rough shaping. Diamond cuts it much cleaner and faster. I still would advise the knife guys with the VC and similar steels to use diamond abrasives to get the cleanest edges. Silicon carbide does not produce as clean of an edge, and edge life suffers because of it.
 
Oh and there are a lot of different hardness tests. Rockwell, Vickers, Brinell, Knoop, Shore, Mohs... Probably others too. Some more useful than others.
 
T.S.S said:
Have you found the textbook on abrasives? I would love to know about it
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Jewelry Concepts & Technology
by Oppi Untracht
ASIN: B004G8P2S2

and

to a lesser extent another book by him:
Metal Techniques for Craftsmen: A Basic Manual for Craftsmen on the Methods of Forming and Decorating Metals

are interesting reading. I mean he is not only abrading very hard materials but is in the pursuit of perfect polishes as well.
You might want to just check them out from the library.

I own both but ^$.
Just the definition of the terms "Cut" and "Color" are worth pursuing. That was enlightening for me.

The stickies in this forum at the top of the page are excellent reading and worth book marking as well.
 
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Thank you Jim for this comment & information backed by lots of real world testing. DM
 
Consensus seems to be that silicon carbide works just fine for high-vanadium steels up until ~ANSI 400 grit, as does aluminum oxide (though not as effectively.) Vanadium carbides are tiny (about 3µ) and as the scale of the abrasive grains vs. the carbides changes it's sort of like going from shoveling fine sand (coarse grit) to shoveling gravel, and eventually full-blown riprap. I've found that apexing high-carbide steels on sintered ceramics with just a few light strokes per side is also effective, with no observable shortening of edge life, which I suspect may be partly for mechanical reasons; the grains being so firmly fused that under force they're able to still plow through material. Sintered materials have grains about the same size as the carbides, and I suspect they're acting similarly to a file would at that scale. This surely does wear on the grains faster than when used with low/no-vanadium steel, but hasn't seemed to hurt edge retention, either. Someone would have to do testing to verify this, though. There's still a noticeable increase in initial sharpness at the very least.
 
I would say beyond the fine diamond, 600 grit as it's doubtful 16u grit will impact a 3u carbide. (likely more like X fine) In real world testing
I have noticed 'a little' less edge retention when taking a high carbide steel to the x fine diamond. (s90v) . DM
added: Initial sharpness and how long the edge last are 2 very different items. Yes, I noticed a step sharper edge coming off the x fine diamond.
Also, cutting cardboard or sisal rope is not as abrasive on a knife's edge as
cutting up large 10 lb. chickens. Or a deer. Because your edge will encounter bone and the cutting board (wood or poly). Which work to curl and degrade the edge.
 
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Push cuts vs. slicing cuts and their affect on edge retention at different finish levels is a different variable set than the abrasive type used. Coarse grit edges are more likely to deform in pushing cuts and don't perform as nicely even when crisp, but hold an edge much longer in slicing cuts than highly polished edges, which quickly lose their slicing aggression and become slippery. Approximately equal finishes would need to be used if comparing the effects of the abrasive, specifically.
 
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