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I've been getting wonderfully smooth edges using an Ozuku asagi jnat. I am wondering how to lap it. I've lapped my norton 4k/8k and coticule with a DMT 325 with great success. Will the the DMT325 work well on a hard Jnat? It seems that the 325 would be too coarse for the smooth jnat. Should I lap with a DMT 1200 or something finer? Any recommendations are much appreciated.
Tnx,
Charlie
I use the 325 dmt, then i spent some time rubbing my coticule slurry stone over the surface, a good 20 minutes, thenthe same with my tommonagura stone, job a good an.
gary
i just got the same stone and had some great smooth edges also
I have used a DMT 325 for initial lapping on my JNats.
However, I usually also go thru a progression of flattening using a DMT 600 and a DMT 1200 before finishing it with a good 10-15 mins of rubbing it with an equally hard JNat.
I have flattened a few very hard jnats with my dmt, I didn't encounter any problems. After a few uses with the slurry stone, it was as smooth as it could be. I didn't find any performane differences between the two, but I didn't even bother to find out if there is a difference. If you don't push too hard, it won't leave too big scratches in the stone, it is too hard to really dig in with a lot of water and almost no pressure.
Just out of curiosity: is it necessary to flatten your ohzuku or is it still in good shape?
No, not necessary. I just like to obsess about technique. Perhaps I will never hone it. It kind of makes my stomach squirm at the thought of taking a diamond plate to this stone. On the other hand, it is just a rock that we've somehow elevated to mythical status. And then I convince myself that the edge is somehow smoother than what I get on a manmade stone.
-Charlie
On my Japanese natural stones I use my Atoma 400 exclusively for both lapping and raising a slurry. On all of my synthetic stones, Naniwa's, etc. I use my DMT 325.
I've been using a dmt 325, then a BBW, then my coti, gives it a mirror finish on it if you look at it at a 5-10 degree angle
[QUOTE=instantcrow;871438]I've been getting wonderfully smooth edges using an Ozuku asagi jnat. I am wondering how to lap it. I've lapped my norton 4k/8k and coticule with a DMT 325 with great success. Will the the DMT325 work well on a hard Jnat? It seems that the 325 would be too coarse for the smooth jnat. Should I lap with a DMT 1200 or something finer? Any recommendations are much appreciated.
Tnx,
The DMT 325 will work fine for lapping. If you wish to smooth the surface even more with DMT 1200 that is OK too.. The main thing is that your stone surface has to be FLAT. If your stone surface is un-even or dished out you will get a frowning edge.
MIke
I lap all of my stones with older worn out 600 Atoma plates, they probably act more like a 1000 though because I have had them so long. I also normally use these same Atoma to raise a slurry from this host stone instead of a tomonagura, it is easier, quicker and then I know for sure that my expensive Oozuku or Nakayama or whatever host stone, supposedly my finest, is actually supplying the grit making up the slurry. Granted, there are some excellent pieces of tomonagura out there, but if it was a junk stone to begin with, and that is why it got cut up, then what is the point of interjecting some unknown grit or rogue particles into the slurry. If the host stone if fine enough for finishing a razor, I like the idea that the slurry grit is also of the same material, fewer unknowns. Any little scratches from the Atoma get ground down within minutes if not seconds from the razor/slurry action anyhow. Alx
The thing to remember with DMT's is that they don't recommend using anything finer than the 325 for flattening. In fact they recommend the extra extra coarse for hard Arkansas stones. The 1200 DMT can be easily turned into plain steel bar with excess use on hard stones.
On the other hand the 1200 Atoma plate works great as a slurry stone & light lapper. I have personally seen a 1200 Atoma which is still in use after approx 10 years.
alx!
How good do Atoma plates hold up with time? I would suspect you use yours regularly, how long does it take to totally wear out one? I have an Atoma 400 on the way for flattening, and heavy bevel work on problem razors.
So Yamashita told me that he only uses his Atoma (600 or 1000) for lapping and generating slurry.
And the thing with such stones is that they are finishers.
In other words, if you spend all that time lapping it, and then 20 minutes rubbing it with other stones, you're spending a whole lot of time just wasting time for no purpose at all.
Scratch lines in a hone do not matter, so that's not an issue, and if you just use it as a finisher, it will stay more or less flat and only needs a couple of laps to stay flat. Everything you do more, you're just wasting precious stone and precious time.
If not abused and under normal everyday useage they will hold up for years and years, but they do wear down over time through attrition and the cutting action mellows out somewhat. The diamonds are mechanically fixed onto the plate by a heavy deposit of electroplated nickel which surrounds the diamonds like a bezel as they lay flat on the plate in the electrolytic bath. The plates are designed to grind flat items flatter and the diamonds take the brunt of the labor when used like this. It is when you try to grind a 3 dimensional items like I did with an axe head, this is when the nickel base can be compromised and you can end up with a bald spot on the plate devoid of diamonds. I still use the baldy plate for somethings.Quote:
Originally Posted by jeness
Beyond exotic alloys like tungsten carbide there are no harder simple carbon steels used in edge tools then those of the Japanese and I wore out the center area an Atoma reshaping the face of an old japanese axe. It was the corner angle grinding work that ate up by undercutting the nickel base of the plate. But for flattening stones which are already generally flat or even for beveling the edges of a stone the Atoma hold up as well or better than most. I think it comes down to the thickness and quality of the nickel deposit holding the diamonds in place. Alx
For those that don't know the Atoma surface is very different to the DMT. Atoma pic below:
It's kinda raspy for want of a better word. I don't like the 400 Atoma on razors even badly damaged ones but it laps Shaptons pretty quick.