Diamond stones

CKTG has a large amount of Edge Pro products so we've dedicated a forum to questions on Edge Pro sharpening systems, accessories and techniques.
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Drafter
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Diamond stones

Post by Drafter » Wed Jan 30, 2019 11:44 pm

When will CKTG get a 2000 grit diamond stone

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ChefKnivesToGo
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Re: Diamond stones

Post by ChefKnivesToGo » Sun Feb 03, 2019 2:35 pm

I’m going to ask about this on my next order. Not sure if they do them but if they do, I’ll get them.
Mark Richmond
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https://www.chefknivestogo.com

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Drewski
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Re: Diamond stones

Post by Drewski » Sun Feb 03, 2019 10:07 pm

What situations call for a higher grit diamond stone? I've got a 140 that I use to flatten stones or when I've got a big chip to remove. Seems like there's been more talk lately about diamond stones that are medium and higher grit, and I feel like I'm in the dark with my lack of knowledge.

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Otaku19
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Re: Diamond stones

Post by Otaku19 » Mon Feb 04, 2019 5:15 am

High carbide steels are more abrasion resistant and most of the waterstones on the market won't properly cut the carbides. I've even read about carbides being torn out by alumina based stones, though this seems to be controversial in the sharpening world. Silicone carbide and diamonds are the most effective way to cut the higher carbide steels. I've had great success in using the Spyderco ceramic stones which are still alumina based and I've never experienced any carbides being ripped from the edge.

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lsboogy
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Re: Diamond stones

Post by lsboogy » Mon Feb 04, 2019 9:33 pm

I'll take my J Nats to any steel - hardest steel I have seen was about 73HRC - machine tools for cutting exotic materials. The machinists sharpened the tools with whetstones.

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Organic
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Re: Diamond stones

Post by Organic » Wed Feb 13, 2019 2:16 pm

lsboogy wrote:
Mon Feb 04, 2019 9:33 pm
I'll take my J Nats to any steel - hardest steel I have seen was about 73HRC - machine tools for cutting exotic materials. The machinists sharpened the tools with whetstones.
Wow, that's some hard steel!

lenny
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Re: Diamond stones

Post by lenny » Sun Feb 24, 2019 10:06 pm

Otaku19 wrote:
Mon Feb 04, 2019 5:15 am
High carbide steels are more abrasion resistant and most of the waterstones on the market won't properly cut the carbides. I've even read about carbides being torn out by alumina based stones, though this seems to be controversial in the sharpening world. Silicone carbide and diamonds are the most effective way to cut the higher carbide steels. I've had great success in using the Spyderco ceramic stones which are still alumina based and I've never experienced any carbides being ripped from the edge.
I've heard about this so called tearing as well; Ben Dale mentioned something like this happening with carbides on modern, ridged honing steels in a recent interview. I'm inclined to believe it may be an issue too. However even if we assume this is something that we should worry about, after the 140 grit diamond stone sets the bevel and cleaves the carbides shouldn't we be fine?

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lsboogy
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Re: Diamond stones

Post by lsboogy » Mon Feb 25, 2019 9:27 pm

I'd guess the machinists in my plant would agree differently Lenny, they sharpen tools with better carbide structure and much harder steel than the knives we see here same as they have been doing for years. You can't machine flight control surfaces with dull tools - most nickel alloys work harden far beyond steel, so any plastic deformation of the material will result in scrap parts (big money for some - and the gear materials used in the geared turbo fan motors are very precise). But the bigger bits for some of the machining centers cost far more than our knives, and they do use stones and magnifiers to do the final edge work. Lotsa voodoo out there - well made steel has carbides that are bound far more tightly than you would believe, especially Martensitic steels. Austentite is face centered cubic, so if you get something that can apply a heck of a lot of pressure, you MIGHT get a chance at pulling a carbon out - Martensite is body centered tetragonal, so no chance you could pull out a carbide.

Wjhunt
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Re: Diamond stones

Post by Wjhunt » Tue Feb 26, 2019 5:06 am

Seems like there’s a description of rocks in jello that was used to describe steel with a high percentage of vanadium. The hrc of the steel has nothing to do with it. Abrasion resistance is the problem. It’s not a big deal until the sharpening particles become smaller than the carbides. I have not been interested in PM steels for a while so I can’t remember what the actual grit of the stone is when you have to worry about it. Seems like it’s over 2k but that’s a guess.

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lsboogy
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Re: Diamond stones

Post by lsboogy » Tue Feb 26, 2019 10:14 pm

Most fcc/bcc carbides are on the order of 50nm and will be significantly smaller than a whetstone grain. They are bound with something like -55ev/atom (cohesive force) and cannot be separated by human induced force. If they are properly dissolved in alloy steel, it would take an act of God to remove them. Carbon will precipitate
First stage, excess carbon segregates into defects. Second stage, cementite forms or iron carbides form (in high carbon alloys), third (final stage) leads to crystallization of ferrite plates and equiaxed grains.
If you knife heat treat only gets to first stage, you will have big clumps (3-400nm or larger) of carbon in the steel - you might be able to get those out with a stone. Anything else and it will be impossible to remove carbide in white steel with your hands

Wjhunt
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Re: Diamond stones

Post by Wjhunt » Wed Feb 27, 2019 5:46 am

https://knifesteelnerds.com/2018/08/27/ ... stability/
I prefer carbon (especially blue #2) for a gyuto but I do like S30v for a folder. For the folders I use a 400 grit stone and strop with 1 micron diamond. You would need access to a SEM to prove carbide pullout and I’m just not that concerned about it.

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lsboogy
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Re: Diamond stones

Post by lsboogy » Wed Feb 27, 2019 9:16 am

http://www.phase-trans.msm.cam.ac.uk/20 ... nsite.html

food for thought - shows why only defects (big hinks of carbon) could be stripped. Properly done steel will have the carbon diffused (dissolved) into the lattice structure of the steel -

if you look towards the bottom of the doc, you can start to see some of the particles at the 50nm level - how well your steel is cooked is a function of heat treat, metallurgy, hammering, sintering etc.

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Otaku19
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Re: Diamond stones

Post by Otaku19 » Tue Mar 05, 2019 8:55 pm

Intriguing theory from a very accomplished sharpener: https://www.youtube.com/watch?v=WBoA8VI6koE

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lsboogy
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Re: Diamond stones

Post by lsboogy » Sat Mar 09, 2019 12:56 am

Otaku19 wrote:
Tue Mar 05, 2019 8:55 pm
Intriguing theory from a very accomplished sharpener: https://www.youtube.com/watch?v=WBoA8VI6koE
I wish that a lab could back him up. I see many people who probably have valid points (sometimes known as craftspeople) who know more than the lab rats but have not found a way to validate what they feel. If we are talking about pulling out vanadium carbides from a well mixed steel, I would guess him wrong, but that's why steel is more than jello with bits in it. Metallurgy is still not an exact science - even VIMVAR stuff is not always uniform - we still get stringers in crucible melts where there should be none.

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Otaku19
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Re: Diamond stones

Post by Otaku19 » Tue Mar 12, 2019 5:17 am

I would really like to see the results from a very high powered microscope. I'm wondering if it's possible that the carbides are actually being dulled by softer stones versus being sharpened by the diamonds

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lsboogy
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Re: Diamond stones

Post by lsboogy » Tue Mar 12, 2019 9:17 pm

Otaku19 wrote:
Tue Mar 12, 2019 5:17 am
I would really like to see the results from a very high powered microscope. I'm wondering if it's possible that the carbides are actually being dulled by softer stones versus being sharpened by the diamonds
There are images of said in link above. I would not say that the no lab rats are wrong, but the lab rats have evidence of what they are talking about. If you look, carbides are about 50nm (vanadium carbides) in size. They are not well bonded in steel, but iron carbides (martensite, austentite, cementite) are not going anywhere, I think the idea that you pull carbides off a surface selectively near impossible - I'm not a metallurgist, but have a lot of surface science background and do a fair bit of metallurgy at work (physicist, with good background in material science). If your grain structures are bigger than 100nm mesh (where good powder steels start) you might have a case.

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