Thread: Jnat finishing

Originally Posted by aa1192

I was using my 1k DMT credit card, but it seems to be bleeding diamonds. I guess either it is too fine for the job or maybe I got a dud, but even on my coti it releases grit into the slurry. I can always go back to my DMT 325 but that seems overly aggressive and a pain to slurry with.

Yes. Fine DMT's do not survive lapping so you probably got a few more miles using it only as a slurry stone.
DMT recommends nothing finer than their DMT C or 325 as some call it.
The only reason one can get away with an Atoma 1200 is that the diamond coat is on a pimpled surface which does not lock onto the stone destrying the nickel matrix. DMT's being a continuous coat are more susceptible to damage.
http://straightrazorpalace.com/advan...w-problem.html

Originally Posted by bill3152

Thanks for the comment. Well Im not a scientist but Ive used many different materials to do some scratch tests. I used glass at first but realizing that glass is as hard or harder than most stone even though alot of whats in a Jnat is silicate. Anyway, I used a piece of plexiglass, ran a dmt on it , then I took a tomo nagura rounded corner as I use and ran it on the plexi. Big difference in scratch patterns in the 2 samples. Now what are scratches? These are marks made by an abrasive. Ive tried this on the side of a coke bottle, same thing and a scrap of marble as well. I used the material being scratched held vertical so as not to say the plate is heavier than the tomo. Many tomo naguras are at the same level particle wise as finishing stones, which is probably 6-10k maximum. I think the rapid breaking of slurry is occuring with dia plate slurry as a result of the abrasiveness of the larger particles on each other. A dmt or atoma is made to cut into steel or stone, thus the teeth and orientation of these diamonds, stones while they can break off large particles if your not careful, IMO release smaller particles. Again Im not a scientist but I feel these observations make sense to me. I welcome any other comments or experiments any others have done. If what Im saying doesnt make sense, thats ok. It just makes sense to me.

How much slurry you make & how hard you press & how worn your diamond plate is will all make a difference to your honing results. What I call a final slurry most would call clear water. I know Jimbo has a similar Asagi to me & works his the same. I'm also sure I've posted enough of my cosmetically polished edges using Atoma "slurry" that are not scratched or chipped. The particle size theory may well be a moot point if the tools are handled correctly.

Originally Posted by bill3152

Thanks for the comment. Well Im not a scientist but Ive used many different materials to do some scratch tests. I used glass at first but realizing that glass is as hard or harder than most stone even though alot of whats in a Jnat is silicate. Anyway, I used a piece of plexiglass, ran a dmt on it , then I took a tomo nagura rounded corner as I use and ran it on the plexi. Big difference in scratch patterns in the 2 samples. Now what are scratches? These are marks made by an abrasive. Ive tried this on the side of a coke bottle, same thing and a scrap of marble as well. I used the material being scratched held vertical so as not to say the plate is heavier than the tomo. Many tomo naguras are at the same level particle wise as finishing stones, which is probably 6-10k maximum. I think the rapid breaking of slurry is occuring with dia plate slurry as a result of the abrasiveness of the larger particles on each other. A dmt or atoma is made to cut into steel or stone, thus the teeth and orientation of these diamonds, stones while they can break off large particles if your not careful, IMO release smaller particles. Again Im not a scientist but I feel these observations make sense to me. I welcome any other comments or experiments any others have done. If what Im saying doesnt make sense, thats ok. It just makes sense to me.

Sorry but the logic of testing the scratch pattern of the DMT vs Nagura evades me completely..

Now please understand that personally I have used both systems and I think both are viable, I feel the difference in edges are coming from the Base Stone and the Techniques used by the guy pushing the edge..

But I do think that saying that a quality Diamond Plate releases some kind of "huge chunks" of base stone while the Nagura does not, is something that I just have a bit of trouble digesting... The results on both styles of edges just haven't ever proved that out to me...


I accept the statements "I get the best results from using a "Blank" Nagura on my J-Nat"
I accept the statement "I get the best results my using the slurry raised from my J-Nat and working from there"


But every time I read that part about the size of the grit released especially as it gets more and more "descriptive" "thus the teeth and orientation of these diamonds, stones while they can break off large particles" I just SMH and think that I haven't found that to be true..


In closing, I am not saying either one is a better system, I am saying it is dependent on the Base Stone and the Operator...

My 1k never did lapping duty and was purchased just as a slurry maker, but something is wrong. Looks like the nickel is coming off in the slurry; my coti slurry is turned grey. I thought maybe it was old swarf caught in the grit but after many rounds of scrubbing still it happens.... Very frustrating when a purpose bought tool can't fulfill it's purpose.

The smaller diamonds are more susceptible to being pulled off, even on the pimpled surface of an Atoma according to Stu @ ToolsFrom Japan. We talked & agreed on a 600 Atoma (rather than a 1200) for that reason. And yes, I'm also going to be using it for slurry on hard naturals, which is why he recommended (strongly) the 600 instead.

1200 DMT shedding nickel from the plating is a bad sign. The diamonds being pulled off will wreck your edge & could break the stone attempting to pull them apart if they get stuck together. It is not suited at all for slurry making. Even that would count as lapping, which DMT says should be done no higher than 325.

As for the DMT 325 working, my guess is the diamonds, being bigger, are buried deeper in the nickel matrix & the fact that it's not a completely flat surface for that reason (diamonds still sticking up, creating a slightly interrupted surface).

Originally Posted by aa1192

My 1k never did lapping duty and was purchased just as a slurry maker, but something is wrong. Looks like the nickel is coming off in the slurry; my coti slurry is turned grey. I thought maybe it was old swarf caught in the grit but after many rounds of scrubbing still it happens.... Very frustrating when a purpose bought tool can't fulfill it's purpose.

As I said slurrying is simply a lighter form of lapping so will just take longer to to strip the nickel off.
DMT did not make that tool for that purpose so you can't blame the tool.

Originally Posted by PA23-250

As for the DMT 325 working, my guess is the diamonds, being bigger, are buried deeper in the nickel matrix & the fact that it's not a completely flat surface for that reason (diamonds still sticking up, creating a slightly interrupted surface).

Makes sense & this is why a 1200 Atoma can be used as opposed to a 1 k DMT.

Personally have not had any issue with diamond loss on the Atoma 1200 so long as you are not silly with what you try to lap with it - I use it to lap everything from my 4K Norton up to my whatever K Jnat finishers, with no problems. I even use the 1.2K Atoma for my bevel setter and it has worked fine for the past (cannot remember) years since I bought it.

James.

IMO, the main ingredient and consideration is the difference in fraility between slurry from a base stone and a nagura as opposed to the fraility of slurry generated by a diamond plate from the base stone alone.

Interesting topic with some heated opinions. I have been avoiding diamond plate for use of slurry until recently. I have found it's not scoring my surface as I thigh it would, however it is now well worn from lapping. My stone seems to work much better with slurry as it's a bit scratchy without.

Originally Posted by Seumas

Interesting topic with some heated opinions. I have been avoiding diamond plate for use of slurry until recently. I have found it's not scoring my surface as I thigh it would, however it is now well worn from lapping. My stone seems to work much better with slurry as it's a bit scratchy without.

We have differing opinions, but its not heated. These discussions are many times the best ones as we present our opinions and let the viewers decide. It seems most things have different approaches, and most would tend to pick one side, although both are viable.

Originally Posted by Bayamontate

IMO, the main ingredient and consideration is the difference in fraility between slurry from a base stone and a nagura as opposed to the fraility of slurry generated by a diamond plate from the base stone alone.

Originally Posted by gssixgun

Then we have to discuss breakdown since most of us do believe that all our J-nat slurries are Friable we must therefore believe that the slurry break down. I have a bit more of a hard time believing that two separate and distinct grits from two stones breaks down finer then one grit from a very fine stone...

Originally Posted by bill3152

We have differing opinions, but its not heated. These discussions are many times the best ones as we present our opinions and let the viewers decide. It seems most things have different approaches, and most would tend to pick one side, although both are viable.

There was a time that I actually used a Hard Arkie to generate slurry off my Nakayama thus eliminating the perceived notion of the Diamond plates releasing bigger particles in the slurry.. It just did not show any difference in the final feel to the edge or the finish on the bevel.. Since my 525 DMT is always on the table I went back to using it..
I find both systems to be fun and the results are both smooth shaving edges off of my stone so I guess it doesn't matter to me..

Try both ways see what works best with your Technique and Base stone and go from there,,, -BUT- I am still of the notion that "Huge Particles" are released when using a Quality Diamond Plate and that there is somehow a disadvantage to using one is simply not proved.. At least not to me and my base stone

I agree Bill these very discussions that delve into the minutia are fun and many times get the Experimentation juices flowing out there...