Thread: Suehiro Gokumyo 20K

Been thinking about this 1200 stripping diamonds on the 20k. Going by the unfortunate experience of Sham with his DMT 1200 (which Dia-Sharp did replace BTW) I was figuring that because of the different construction of the Atoma it was probably alright to lap waterstones.

Dia-Sharp specifies (after the problem with Sham's) no higher grit than 325 and that under running water. Before Sham posted his warning I was using a DMT D8C 325 at home, and a DMT 1200 at work. I noticed that the Norton 4 had grey streaks on it when I lapped it with the 1200. Curious. Fortunately Sham posted his experience and I realized the grey was the diamond and substrate nickel stripping off of my plate. I say fortunately because I hadn't ruined the thing.

So...... cutting to the chase .......... if the 1200 isn't good for lapping the 20k, is it alright for other waterstones ? I realize the 20k is super hard. The next question ........ if the 1200 will strip diamonds on the 20k, what plate won't ? Maybe I'm stuck with the loose grit on a ceramic tile ? If I had it to do over I'd just stick with the Naniwa Superstone and the hell with it.

I've looked at the 20k under magnification and it appears okay. Going by the aforementioned experience with the grey streaking on the DMT I note that I've seen none of that on the 20k. I've always lapped under running water, and always the tail end of the job. So maybe I've dodged the bullet. Examining the plate (magnification) the diamonds are consistent, and not badly worn.

Makes sense that the finer the diamonds the more difficult it is to anchor the little beasties on the plate. So goes without saying high grit diamond plates are fragile to begin with and treating them to rough will ruin them. That said I do dress my SG-20k with a trend 1K diamond plate but with very light pressure being mindful of the possibility of disaster. As Mainaman mentioned its just being used to smooth out the marks made by the rougher 300 plate and in no way is taking a role in lapping the stone. I have been lucky so far I guess but lapping a Suehiro for me is just not done that often.

I fully understand the reasons for using the Atoma 1200 on the Suehiro Gokumyo 20k. When I 1st got it, I used the Atoma 400 and I didn't like the striations it left on this supposedly 'Finest' hone, so i ran it over some 1500 wet/dry. It worked fine, but I decided then to buy an Atoma 1200 so I could maintain what I believed was a better finished hone. Thats where Tools of Japan came in. Now many members know Stuart, and he doesn't mince words, and when I sent an email to obtain a Atoma 1200 from him, he said,(I won't sell it to you if your going to lap the G 20K with it), so I have since then (Over a year ago) I've mentally ignored any stria from the 400 and haven't had an issue with the result, it gives the same great edge as it did after 1500 w/d which also is banned. So guys, put a mental blindfold on and use the DMT 325 or the Atoma 400. Once you cross the mental battle it's plain sailing from there.Every couple of razors on the G20 I give it a half a dozen figure 8's with the 400 just because I believe that a slightly disrupted surface gives me a better result.

Originally Posted by bobski

I fully understand the reasons for using the Atoma 1200 on the Suehiro Gokumyo 20k. When I 1st got it, I used the Atoma 400 and I didn't like the striations it left on this supposedly 'Finest' hone, so i ran it over some 1500 wet/dry. It worked fine, but I decided then to buy an Atoma 1200 so I could maintain what I believed was a better finished hone. Thats where Tools of Japan came in. Now many members know Stuart, and he doesn't mince words, and when I sent an email to obtain a Atoma 1200 from him, he said,(I won't sell it to you if your going to lap the G 20K with it), so I have since then (Over a year ago) I've mentally ignored any stria from the 400 and haven't had an issue with the result, it gives the same great edge as it did after 1500 w/d which also is banned. So guys, put a mental blindfold on and use the DMT 325 or the Atoma 400. Once you cross the mental battle it's plain sailing from there.Every couple of razors on the G20 I give it a half a dozen figure 8's with the 400 just because I believe that a slightly disrupted surface gives me a better result.

I just wonder if the coarser grits on the plates might not suffer the same 'stripping' of diamonds & embedding in the surface of the 20k. Also irritated that there is nothing on anyone's website that warns anyone of this possibility. I'm going to email Stuart and ask him about this, and about my cracked Chosera 10 & 5K. Not a happy customer.

Originally Posted by JimmyHAD

Been thinking about this 1200 stripping diamonds on the 20k. Going by the unfortunate experience of Sham with his DMT 1200 (which Dia-Sharp did replace BTW) I was figuring that because of the different construction of the Atoma it was probably alright to lap waterstones.

I have found this to be the case & I lap harder stones than the 20k. In fact when I first met So & he suggested these plates to me, he had used his already for 7 or 8 years on his Jnats.

Dia-Sharp specifies (after the problem with Sham's) no higher grit than 325 and that under running water. Before Sham posted his warning I was using a DMT D8C 325 at home, and a DMT 1200 at work. I noticed that the Norton 4 had grey streaks on it when I lapped it with the 1200. Curious. Fortunately Sham posted his experience and I realized the grey was the diamond and substrate nickel stripping off of my plate. I say fortunately because I hadn't ruined the thing.

So...... cutting to the chase .......... if the 1200 isn't good for lapping the 20k, is it alright for other waterstones ? I realize the 20k is super hard. The next question ........ if the 1200 will strip diamonds on the 20k, what plate won't ?
As above.
Maybe I'm stuck with the loose grit on a ceramic tile ? If I had it to do over I'd just stick with the Naniwa Superstone and the hell with it.

Flattening stones of differing warp requires different tools. SiC on glass etc is easy & effective. For daily maintenance & slurry making I use the 1200 Atoma on all stones 8k & up.
Below that, ie 1k-5k I use my 400. For my 320 Pro I use a 140 Atoma. I would not use a 1200 Atoma on a 1k stone any more than setting a bevel on a razor with a 12k stone.
Horses for courses.

There is one stone that will destroy most diamond plates in short order & that is the Spyderco UF. 2 mins max with a 1200 Atoma will see it adequately "broke in" beyond that , well, its your plate .

I've looked at the 20k under magnification and it appears okay. Going by the aforementioned experience with the grey streaking on the DMT I note that I've seen none of that on the 20k. I've always lapped under running water, and always the tail end of the job. So maybe I've dodged the bullet. Examining the plate (magnification) the diamonds are consistent, and not badly worn.
I think that says it all.

~~~~~~~~~~~~~~~~~~~~~~

Jimmy, you'll find Stuart has dealth with this a few times, and from memory it is the fact that the finer clusters on the 1200 are more likely to break off, thus embedding in the stone. Why they do it I don't know, but I do believe he is of the view that don't use it (1200) on any stones. I think it becomes more apparent on a stone the hardness of the G 20. As I mentioned mate, I am not a heavy user of the G 20 as a hobbyist, but I only became aware of the issue when I tried to buy a 1200 off him thus the warning. Cheers Bob

Forgive me Jimmy, what went wrong with your choceras, I have a couple I use the Atoma 400 on?

Using a diamond plate finer than the hone being lapped to do more than a very light lapping is not a good idea as it's very easy for the removed abrasive particles to build up thick enough to bite into the nickel plate that holds the diamonds in. When they are near the same grit or when the diamond plate is finer than the hone, the abrasive particles removed from the hone during lapping are often larger than the distance from the top of the diamonds to the nickel plating, so they can very easily dig into the nickel and remove diamonds.

Personally I've never had any diamond grit embed in any stone I've lapped with a diamond plate, but that's not to say it isn't possible. Most of the time this is much more likely with softer stones. Abrasive lapping using loose grit is based upon this fact - copper is often used as a lap due to its softness - the grit is distributed across the copper surface then embedded with a hardened steel roller or pressed in with a hardened steel block.

Originally Posted by bobski

Forgive me Jimmy, what went wrong with your choceras, I have a couple I use the Atoma 400 on?

Bob, a picture is worth a thousand words. It is difficult to capture the extent of the cracking. Suffice to say that it covers the surface of the stones, sort of like photos of the Sahara desert terrain in the driest areas.

Wow that's unfortunate. I dont see how lapping played a role in the detriment of those stones. I heard Choseras are somewhat sensitive to being left wet too long and that binder breakdown can be a cause of this. I guess this is why they do not recommend soaking for any length of time and I wouldn't use any honing solutions or soap on em either. Not saying this is the case for your stones but it seems the binder has a wonky nature and might be rather unstable depending the conditions they are exposed to. I understand you reside in Florida Jimmy, maybe heat and humidity also played a role in their demise. Just a thought but more of guess considering I have heard others suffer a similar outcome.

Originally Posted by Razorfaust

Wow that's unfortunate. I dont see how lapping played a role in the detriment of those stones. I heard Choseras are somewhat sensitive to being left wet too long and that binder breakdown can be a cause of this. I guess this is why they do not recommend soaking for any length of time and I wouldn't use any honing solutions or soap on em either. Not saying this is the case for your stones but it seems the binder has a wonky nature and might be rather unstable depending the conditions they are exposed to. I understand you reside in Florida Jimmy, maybe heat and humidity also played a role in their demise. Just a thought but more of guess considering I have heard others suffer a similar outcome.

I don't think lapping had anything to do with the cracking. Not at all. As for living in FL. The stones have been in a climate controlled environment and have never soaked them more than 5 minutes. Anyway ........ tis what it is.