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DMT 4000 grit / 6 micron

Posted by CliffStamp 
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DMT 4000 grit / 6 micron
May 06, 2013 02:24AM
This is the new medium extra fine 4000 grit, 6 micron stone. To start prepare an edge with a 1000 grit king (14 microns) :



I stopped when the edge was just stopping reflecting light (20-40 microns), this means just just a little work more is needed to get a sharp edge (on the order of a micron). I left it not fully sharp to check the cutting ability of the stone and this is a polishing stone. It took 100 pps to get the edge to start to shave. Now this is freehand but still it feels very fine, but there is also a very random high coarse behavior. Checking the dge under magnification (50X) it is nor surprising what is seen :



It is arguable if the polish is increasing at all, but there are infrequent, but huge scratches along the edge which are not spaced in a regular pattern and are just clumps of abrasive on the stone. Now DMT does warn of this very clearly, but if you don't read the packaging be prepared for a surprise :



You can see where those scratches hit the edge and knock pieces out of it. In comparison this edge is actually more coarse then the 600 grit / fine DMT which is kind of amusing, but again DMT warns of that.

In short, as-boxed it is pretty spastic, I would use it to put on some micro-bevels or otherwise work it in a bit before you attempt to use it seriously and make any judgments on it.

Two minor asides :

-the knife is a Boker Rhino, 12C27

-I wonder if this is why Murray Carter thinks diamond hones don't work well
Re: DMT 4000 grit / 6 micron
May 06, 2013 05:51AM
Cliif,

Do you think that we may have a quality control issue here?

I ask because in 2009 I bought some EEF 3u plates that were superb, but a more recent purchase has been disappointing, exhibiting similar scratch pattern as yours.

Cheers
John
JBN
Re: DMT 4000 grit / 6 micron
May 06, 2013 09:33AM
I don't like the diamond stones either. Having said that; i did not try them again for the last 3 years or so. Maybe they are better now. Even then i would not use them quickly. Maybe the very very finest grit thats available.
Re: DMT 4000 grit / 6 micron
May 06, 2013 07:59PM
It is possible, however I have seen this behavior before with many types of stones, though I don't think it would be expected on the Atoma's due to the way they are made. I will revisit this one after I use it for awhile.
JBN
Re: DMT 4000 grit / 6 micron
May 06, 2013 08:33PM
Quote
CliffStamp
It is possible, however I have seen this behavior before with many types of stones, though I don't think it would be expected on the Atoma's due to the way they are made. I will revisit this one after I use it for awhile.

Did you ever try a Coticule? A Belgium sharpening stone with a variable grit?
Re: DMT 4000 grit / 6 micron
May 06, 2013 09:59PM
No, I don't have much experience with naturals aside from some Chinese stones, Arkansas, and some Japanese (mainly cut offs).
Re: DMT 4000 grit / 6 micron
May 06, 2013 10:34PM
Did you try lapping one of your harder stones to break it in? My Ez-lap 250 broke in very well, but at first it was just a clumply mess of abrasive. I did use my DMT 120-150 X-coarse to lap a large hard stone, but I didn't see or feel a considerably difference. My DMT came pretty well honed, but still with occasionally high spots that will scratch deep.
Re: DMT 4000 grit / 6 micron
May 07, 2013 12:17AM
I generally just sharpen to wear them in, gives me information about how they behave as they wear in :



This is the scratch pattern of a 600 grit (25 micron) DMT, same as before right over a 1000 grit waterstone. It is clear :

-it is much more coarse than the 1000 grit
-it is much finer than the 6 micron DMT

The 600 grit DMT is well used, it has been used to sharpen literally 1000's of times, the vast majority are micro-bevels, 10-20 pps.
Re: DMT 4000 grit / 6 micron
May 07, 2013 01:24AM
Just to show how fast it breaks in. This is a MBS-26 Santoku from Spyderco which is one of the most trivial blades to sharpen I have seen, it gets sharp pretty much by accident, again prep the edge on a 1000 grit King :



See the snaggle at the very edge, I stopped it at the shaping, that is all the burr that this forms and it is trival to remove with a true micro-bevel but I didn't do it and instead just used the 6-micron DMT :



There are still those large scratches but immediately you can see :

-it can easily remove that burr and refine the edge
-it is already finer than the 600 grit DMT
-the deep scratches are being reduced in frequency
Re: DMT 4000 grit / 6 micron
May 07, 2013 01:27AM
As an side, it still has extremely high aggression on the slice and with literally no effort this blade is at the point where it can hint at a true 90 degree push cut on newsprint. At the stage it is right now it looks like a very nice finish for a kitchen knife, however I expect it to wear in more than this which might leave it too polished outside of just chopping - time will tell in either case.
Re: DMT 4000 grit / 6 micron
May 07, 2013 03:15AM
Thanks for the update Cliff. Appreciate the magnified views.
Re: DMT 4000 grit / 6 micron
May 07, 2013 11:58AM
Quote
JBN
Quote
CliffStamp
It is possible, however I have seen this behavior before with many types of stones, though I don't think it would be expected on the Atoma's due to the way they are made. I will revisit this one after I use it for awhile.

Did you ever try a Coticule? A Belgium sharpening stone with a variable grit?

Variable grit???
JBN
Re: DMT 4000 grit / 6 micron
May 07, 2013 12:30PM
Quote
thiswayup
Quote
JBN
Quote
CliffStamp
It is possible, however I have seen this behavior before with many types of stones, though I don't think it would be expected on the Atoma's due to the way they are made. I will revisit this one after I use it for awhile.

Did you ever try a Coticule? A Belgium sharpening stone with a variable grit?

Variable grit???


Yes variable grit.

It works like this:

Blade touching the stone = 8000 grit
Blade not touching the stone = 0 grit

Sorry, Dutch humor. the finger smiley



The Coticule is a slurry stone and the average grit is compared with 8000 Japanese waterstones.
But actually the grit is variable. When you make a thick creamy slurry it is coarser, lets say around 4000. If you dilute the slurry it gets finer, and when only honing on water and no slurry you could compare it to 15000 or so.

The abrasive in the relatively soft stone is an generous amount of garnets (up to 42%) with an size between 5 - 15 micron. The shape however from these garnets is dodecahedron, so no very sharp edges or needle points sticking out.

They work fine, and are mostly used in the strait razor scene.

There is a sister stone in the picture: The blue Belgium. it is found in the same layers, the grit is lower, around 4000 and the stone is harder as well.


You can read all about it at: [www.ardennes-coticule.be]
Re: DMT 4000 grit / 6 micron
May 07, 2013 02:32PM
Nice information. I do believe these stones can be relatively costly much like traditional Japanese stones? (And this isn't a comment critiquing them...just curiosity).
Re: DMT 4000 grit / 6 micron
May 07, 2013 02:48PM
The 4000 grit ones can be found for a fairly inexpensive price
JBN
Re: DMT 4000 grit / 6 micron
May 07, 2013 03:00PM
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Cashmore
Nice information. I do believe these stones can be relatively costly much like traditional Japanese stones? (And this isn't a comment critiquing them...just curiosity).

The prices are much lower than the original Japanese stones.
The Coticule is the more expensive one, and comes generally in smaller sizes. It works better though. They are sold here for between 30 and 100 Euro. If you want real big sizes like 250 x 90 mm than the price would be several hundred euro.

The blue ones are cheaper indeed. You can see a few of them at this website: [www.baptist.nl]

and here at the web shop of the company that makes them: [www.ardennes-coticule.be]
Re: DMT 4000 grit / 6 micron
May 07, 2013 03:35PM
Ok, that's what I thought in terms of the prices. I had seen them a while back somewhere. I was thinking of the large stones and how expensive they are. The smaller ones don't seem to badly priced at all. Thank you for the info.
JBN
Re: DMT 4000 grit / 6 micron
May 07, 2013 03:56PM
I was under the impression that Japanese original natural waterstones had a pricelevel from many hundreds to thousands of $ ?
Re: DMT 4000 grit / 6 micron
May 07, 2013 04:14PM
I believe you are correct. I just consider any stone over $150 to be rather pricey I guess
Re: DMT 4000 grit / 6 micron
May 09, 2013 02:24AM
Update, here is a used RSK, this is one of the early S30V models and it is a replacement for a defect which had the same defects (extremely brittle to the point it was impossible to sharpen, horrible edge retention). It has gradually improved over the years but still it at best ok because it blunts by fragmentation :



This is 50X, but it is just cardboard cutting, the edge just chips like glass, I have never seen an edge this fragile at that angle :



The wear resistance is there though, very hard to grind, this is after 5 passes right into a fine india stone :



and 10 :



This is after 400 pps on the 6 micron DMT :



My concern here is twofold :

-the dark line at the top of the edge
-the unevenness in the apex

These are signs of burnishing and stress at the edge. This edge will :

-shave, but is scratchy
-easily slices newsprint, does fancy swirls - but isn't push cutting
-0.35 to 0.45 cm on the Bergia thread



That is on the 600 grit DMT, note how :

-no dark lines
-edge is perfectly even
-push cuts newsprint
-0.05 to 0.10 on the Bergia thread

I kind of wonder why DMT doesn't simply lap the stones before sending them out as this kind of poor initial performance is simply going to lose customers who either :

-don't read the fine instructions
-don't have the patience if they did

I am getting a bit concerned though as I expected a bit more of a rapid response than I am seeing to the stone leveling in.
Re: DMT 4000 grit / 6 micron
May 09, 2013 11:42AM
Quote
CliffStamp
My concern here is twofold :

-the dark line at the top of the edge
-the unevenness in the apex

These are signs of burnishing and stress at the edge. This edge will :

-shave, but is scratchy
-easily slices newsprint, does fancy swirls - but isn't push cutting
-0.35 to 0.45 cm on the Bergia thread

Hi Cliff,
A few questions
1. Can you explain how the 6 micron stone is creating stress at the edge? It is because it's not really cutting but just burnishing/pushing the steel around?
2. When you cut into the stones to destress the edge, can you describe how hard you do it?
3. I can often get my knives to easily slice newsprint, but especially on thicker grinds like my Mora, my CS Machete, they are no where near push cutting...since youc an do this on the 600 grit it's not a refinement issue. Is there just inconsistency in my strokes that leads to a less and perfect apex?
Re: DMT 4000 grit / 6 micron
May 09, 2013 07:55PM
Quote
Cashmore
1. Can you explain how the 6 micron stone is creating stress at the edge? It is because it's not really cutting but just burnishing/pushing the steel around?

I believe the issue is that the grit is not close to uniform and what is happening is the high points are just making gouges and are preventing the finer grit from even abrading fully which may be being masked by the filings from the deep scratches as well.

However the thing that jumps to mind is that the grit is unevenly coated and the substrate is making contact with the steel, if that is the case it will not improve as the stone breaks-in, so I hope that isn't the case. Experimentation will tell.

Quote

2. When you cut into the stones to destress the edge, can you describe how hard you do it?

It is just a very light cut as if you were trying to saw the stone in half. Check the edge after each slice and ensure that you get an even light line, if you don't then you are not hitting all the edge, parts may have be chipped or dented in and you are skipping over them (you can see that in the above pictures).

Quote

3. I can often get my knives to easily slice newsprint, but especially on thicker grinds like my Mora, my CS Machete, they are no where near push cutting...since youc an do this on the 600 grit it's not a refinement issue. Is there just inconsistency in my strokes that leads to a less and perfect apex?

Yes, it is simply the width of the burr and the main things which cause it to be too large are :

-too much force
-loaded stone
-non-flat stone
-sharp corners /edges on the stone
-stressed metal on the edge

Of course the steel could also be a bit junky (blown aus-grain, embrittled, not properly tempered, etc.) but that is usually much more rare.
Re: DMT 4000 grit / 6 micron
May 09, 2013 08:05PM
Ok. Thank you Cliff. I'll try to keep those things in mind and see if my edges get any better.
Re: DMT 4000 grit / 6 micron
May 10, 2013 01:23AM
This is a Bushman off of a very cheap stone :



It is one of the reasons why many people end up with poor impressions of this steel and its types as see how snaggly the edge forms. It is not easy to keep a burr off of this steel and if you don't the edge retention will be non-existant.



This is a macro-bevel with the 6 micron DMT, five passes per side. It produces a much more refined edge which is not only much better at push cutting but is still very aggressive on a slice.
Re: DMT 4000 grit / 6 micron
May 12, 2013 01:23AM
This is a utility kitchen knife in a plan carbon steel with the edge destressed and then reformed on the 6 micron DMT only :



This push cuts newsprint on a true 90 easily now. Note though there are still the occasional large scratches, if they happen to hit the edge they still gauge it and repeated polishing removes them SLOWLY.

This stone also cuts far slower than I would have expected, for example these are similar in resetting an edge :

-1000 grit King, 14 micron : 25-50 pps
-medium extra fine DMT, 6 micron : 250-500 pps

Now I am pressing lighter on the King but still I would have expected a ratio closer to 5 but it is much closer to 10.
Re: DMT 4000 grit / 6 micron
May 22, 2013 08:41PM
On a related note there are diamond water stones being sold by Naniwa. Still trying to figure out what they are exactly as that phrase doesn't exactly make a lot of sense. However they are 2-3 times the cost of the DMT's.
Re: DMT 4000 grit / 6 micron
May 22, 2013 11:54PM
Quote
CliffStamp
On a related note there are diamond water stones being sold by Naniwa. Still trying to figure out what they are exactly as that phrase doesn't exactly make a lot of sense. However they are 2-3 times the cost of the DMT's.

I saw these the other day as I was looking at stones...the cost however quickly turned me off.
JBN
Re: DMT 4000 grit / 6 micron
May 23, 2013 11:22AM
Next week i have to visit a company that actually makes diamond honing wheels and abrasive tools, slurries, and those kind of things. I prepared a lot of questions for them. Especially i am interested in the way they let the crystals fracture. The artificial diamond is actually designed to brake in a certain way that is tuned on a specific grinding or honing system.
This is a more expensive way though. I expect therefore that the cheap diamond plates you use have the (cheap) diamond particles that erode or break in a uncontrolled way. In combination with a bad sieving system (all sizes through each other) you end up with the almost useless things you can buy for little. We will see though. I look forward to this meeting. I'll guess i take home a pound or so on diamond grit and give it to my girlfriend saying: "well, they are not big, but there are many".



Edited 1 time(s). Last edit at 05/23/2013 11:41AM by JBN.
Re: DMT 4000 grit / 6 micron
May 23, 2013 01:19PM
Quote
JBN
I'll guess i take home a pound or so on diamond grit and give it to my girlfriend saying: "well, they are not big, but there are many".

Ha, there can be a very obvious reply to that.

I was speaking to Ken Schwartz about the Diamond plates, in his experience the Atoma is free of many of the problems of the finer DMT's which he also believes to have issues with swarf from the actual substrate developing on the extremely high grits.

Experience with the Naniwa's doesn't look common, at least with the english speaking guys as the big guns in the abrasive/knife field like Ken and Tom Blodgett even don't have a lot of experience with them.

From what I can tell, and again this is based on very sparse information so may be all nonsense, the Naniwa "diamond waterstones" :

-do wear and have to be lapped
-have issues with initial flatness
-no one is praising them due to the cost

The universal response to wanting a high diamond finish is use a film on float glass or a spray on balsa or rigid leather (or nano-cloth on a rigid media).It looks like I may have to turn to stropping.
JBN
Re: DMT 4000 grit / 6 micron
May 23, 2013 01:57PM
Quote
CliffStamp
Quote
JBN
I'll guess i take home a pound or so on diamond grit and give it to my girlfriend saying: "well, they are not big, but there are many".

Ha, there can be a very obvious reply to that.

Thats probably a good way to direct the conversation in the right direction.


Quote

From what I can tell, and again this is based on very sparse information so may be all nonsense, the Naniwa "diamond waterstones" :

-do wear and have to be lapped
-have issues with initial flatness
-no one is praising them due to the cost

The universal response to wanting a high diamond finish is use a film on float glass or a spray on balsa or rigid leather (or nano-cloth on a rigid media).It looks like I may have to turn to stropping.

Why would anybody want a "diamond" finish in the first place?

A super finish is a super finish. Whatever you use to get it. Diamond is not the best tool for steel to begin with. The Diamond (carbon) reacts with the steel (carbon) and causes more heat and more wear. (wear in the diamond)
In the industrial scene very few are using diamond to grind carbon containing steel. The best option here is Boron Nitride, which is just a little bit softer (9 Mohs) but will stand longer, grind better and faster, stays cooler and can be programmed much better in relation to fraction behavior and fixation to the matrix material.

The diamonds that are used in sharpening stones/plates are not designed for this purpose. They are used because they are cheap and with using them they can use the D word in their advertising. Not because they make a good tool in any perspective. If you would use diamonds that are actually designed for the job it wouldn't still make the best tool for the job, but much better than they are made now. (to use on Tungsten carbide or something like that) Price would be raised with a factor 10 though at least.

It might be interesting to have a microscopic image from a edge that is polished with a 30,000 grit stone and compare it with a stropped edge. I would predict not much difference. When we start the honing stone experiment i will try to order some 200 NM CBN powder to make a true polishing stone by mixing it fifty fifty with Kaolin clay.

Edit: Regarding the Naniwa water-stones; with all those disadvantages they still might be doing better than the diamond plates i think. IF, they use the right diamond type for it.



Edited 2 time(s). Last edit at 05/23/2013 02:04PM by JBN.