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 Post subject: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 8:11 am 

Joined: Thu Aug 16, 2012 10:03 am
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Some time ago I asked the question here how I should flatten my high-grit stones (Shaptons and Choseras of, say, > 5K). Some people used a high-grit (about 1000 grit) diamond plate, but the majority of the people recommended a very coarse diamond plate (Atoma 140, DMT XXC).

The discussion is here: viewtopic.php?f=5&t=2150&hilit=flattening . And a similar discussion is here: viewtopic.php?f=5&t=2699&hilit=flattening

Particularly Mark stated why a high-grit diamond plate wouldn't be necessary: "I answer this question more than almost any other.
Scratches on a stone don't impart or transfer to the edge as far as I can tell. Even if they do I don't have a problem getting my knives screaming sharp without using other plates or stones to massage the surface after my dmt."

However, in a recent discussion on the Wicked Edge forum Tom Blodgett recommended using a 600 grit or 1200 grit Atoma plate for flattening high-grit stones. The discussion is here: http://www.wickededgeusa.com/index.php? ... &Itemid=63

Tom doesn't say it literally in his video, but if I'd have to summarize his words, it'd be: "Scratches on a stone do transfer to the edge."

Who can shed more light on this? Which of the opinions is the case? Is there anyone who has ever looked close-up to the edge after sharpening with a high-grit stone that was flattened on a coarse diamond plate?


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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 1:23 pm 
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That's an interesting topic.....love to see proof one way or the other. Meanwhile, I'll stick to my methods. :)



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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 1:29 pm 

Joined: Fri Mar 22, 2013 12:44 am
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I've used 140 and 220 grit diamond plates to flatten 400, 1K, 1.2K, 5K, and 6K stones.

On occasion, I've used a loop to inspect the final edge and I've not seen evidence of the scratches transferring their pattern to the blade.

Heres my logic as to why they don't transfer.

The scratches where made by the movement of the flattening plate on the stone which was pretty random.

For the scratches to transfer to the blade, ones sharpening pattern would have to track that randomness long enough to effect the blade. Not only that, as soon as that tiny portion of the blade that did not abrade comes out of the scratch trench, it will be at slightly higher pressure to the stone then the rest of the blade making it abrade faster which evens things out.

Aditionaly, the scratches quickly fill with slurry so aren't totally abradeless ( is that even a word ).

All that said, I stopped using the 140 plate to level 1K and higher stones, not because it was transferring the scratch pattern to the blade, but because dark scratches on light colored stones is just too fugly to contemplate while sharpening.... just my opinion :)


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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 2:02 pm 
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branwell wrote:.....All that said, I stopped using the 140 plate to level 1K and higher stones, not because it was transferring the scratch pattern to the blade, but because dark scratches on light colored stones is just too fugly to contemplate while sharpening.... just my opinion :)
:lol:

I stopped using lower grit diamond plates to flatten higher grit stones. It had nothing to do with scratches or transfering scratches. I use a 1.2k diamond plate only because I don't seem to remove or waste as much stone when I flatten with a higher grit stone. Takes an extra minute but who cares. For me this is just another one of those "what ever works for you" processes.



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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 5:56 pm 

Joined: Thu Aug 16, 2012 10:03 am
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I find this a very intriguing discussion... On the one hand there are people who say that it really doesn't matter with how coarse a diamond plate you lap your high-grit stones (Mark! Where are you?), on the other hand there are people who say it matters very much (Tom, Ken! where are you?).

This question popped up at another forum as well: http://www.wickededgeusa.com/index.php? ... &Itemid=63 . I "happen" to be a mod there.

It would be nice if we could join forum forces. I don't know how, but let's see.

At the end of the day it would be nice if we could get an answer to the question many ppl seem to have. I have experimented already and hoped to be able to see differences between scratches made by a 15K Shapton lapped on an Atoma 140 and a 15K Shapton lapped afterwards on a 1K WE diamond stone. The trouble is, these scratches are tiny... much too tiny for my (supposedly) 400x microscope.

So who's got empirical evidence? Or a very convincing theory?


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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 10:52 pm 
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Adam Marr wrote:"Meanwhile, I'll stick to my methods. :)"


Exactly. I'll keep doing a few biting laps on my 140 Atoma, and then a flattening finish on my 1200 Atoma.



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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Mon Jun 03, 2013 11:04 pm 
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I would split this into flattening and texturizing. Even a very fine stone needs to be flat and if it isn't it's a waste of time to just use a fine plate. Now if it is a little off, well then a finer plate is a good thing.

I haven't read Tom's posts there (and should) but somehow transferring stone scratches to knife edge scratches doesn't sound right - even from Tom :) (We quibble all the time about sharpening theory.) It doesn't match my experience at all. Now if we are talking about jagged edges on a natural then yea these can scratch up a finish.

Finer diamonds make for finer surface textures. Here a 400 600 or even 1200 Atoma slurry slurry stone makes a difference. You can see this on new stones which have a factory finish. After use the surface gets more refined and it feels nicer to sharpen on it. On the other end coarse stones benefit in aggressiveness from a coarse texturizing. So a 24 grit Aratae Nubatama will give a rough surface to a 220 Glassstone, improving it's performance for instance.

Personally I sharpen and I like to enjoy sharpening as a process, not just the result. And a well texturized stone is less 'fugly' and more sensual, so I make the surface nice to work on - once it is flat. I also rub stones together for this, so if I have a piece of stone like a 15k shapton chip, I'll rub it on my 15k Shapton to make it nicer to use.

---
Ken



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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Tue Jun 04, 2013 9:38 pm 

Joined: Thu Aug 16, 2012 10:03 am
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Hey Ken, do I interpret your post correctly by saying that “transferring stone scratches to knife edge scratches doesn't sound right” means that you think that texture differences don’t show on the sharpened edge? (And by saying that texture differences do have an impact on the feel of sharpening – finer textures feel better.)

The reason for asking, apart from Tom’s statement, is a discussion at the WE forum about the Spyderco ceramic stones. Apparently all ceramic stones have the same grit size (as told by Sal). The differences in their impact on knife edges are due to texture differences (again, according to Sal).

As phrased by Phil on the WE forum: “If we lap a waterstone with something like the 140 Atoma, or the XXC DMT plate we are going to end up with some pretty serious scratches left when we are done. In use those scratches approach the edge of the edge with sharp shoulders from many different directions (depending on the direction used when lapping). I can easily see that this will cause significantly different results than a very flat surface would. Recall the differences in the ceramics that , for instance, Spyderco sells, mostly caused by texturing. Why would the fine waterstones not be affected in a similar fashion.”

Does stone texture have and impact on the edge quality or not? That seems to be the question.


Last edited by mark76 on Tue Jun 04, 2013 11:27 pm, edited 2 times in total.

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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Tue Jun 04, 2013 9:53 pm 
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This thread makes my head hurt!! :)



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 Post subject: Re: How to flatten high grit stones? - cont'd
PostPosted: Wed Jun 05, 2013 5:38 am 

Joined: Tue May 29, 2012 12:29 am
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I sharpen knives and razors all day, I use a chosera nagura stone to clean up the surface of high grit stones after a XXC or other flattening methods that involve coarse abrasives. Why you would ever use a high grit diamond plate costing over $100 is beyond me.

Regardless if I use the sidewalk, Nubatama 60 grit, 220 leveling stone, or DMT 120 plate a nagura has always been the final step. Wrap some 2k sandpaper around the nagura if having a really fine surface is a must.

In my experience its all about the feedback from the stone and a rough surface on a fine stone feels crappy. Besides that I see no difference.


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