Course Stones

Currently I have Nubatama but I see Naniwa do two types GC-grain & C-grain does anyone have experience of these the price of these stones is half the price of the Nubatamas .
I use the course stones for thinning & re-profiling tips etc since I prefer to stick to sharpening purely with whetstones.

 

What steels are you sharpening? I have not used the nubatama stones so cant compare but I have used the naniwa stones... which grits exactly are you considering? btw I think there are better choices then naniwa but some to consider...
chosera, the pink brick, cerax 320, matukusuyama 300, japanese knife imports has a few options as well
anyway feel free to ask more questions I have used most of those. Thinning by hand is a labor of love but it's way easier when you have tools that both cut faster and don't dish... a good feel is just icing on the cake.

 

I am thinking of sub 150 grit stones I use them to remove hollows from bad use of steels and general knife repairs usually on good knives either Japanese , mid to high end German or knives from people like Cut.
I do occasionally use a belt sander for radical repairs.

 

i have tried a number of stones in the sub 220 grit range, and very few, if any, are worthwhile to me.

 

Hello Jon I take it you use that wonderful Japanese Water Wheel ps still thinking about JNATS although I can't imagine that you would recommend them for extensive repairs .
Currently I will repair tips on a Nubatama 26 grit I use the side of the stone for this & then generally thin on an Aotoma 140 whilst sharpening on the hop.
I will use a belt sander at home and dip the blade in water after every pass but generally I reserve this for very big repairs the last been on a Mac which had a hooked point & a big hollow by the heel and was way too thick -not been laminated these are hard work.
How do your Gesshin compare to say the Aotoma 140 ?

 

you can always try abrasive powders on a cinder block or some other brick like thing.
http://sandblastingabrasives.com/Diamond-Powders-Lapping-Slurry-Compounds-Synthetic.html
the link is to diamond powder but silicone carbide would also work. Mostly I have no experience this low on stones nor do I like using dmt ec or atoma 140.. heck I barely enjoy using the 220 pink brick but the brick is much better/cheaper then the atoma or dmt.
Jon also has a nice variable speed belt grinder.
anyway goodluck in your search.

figured I would look up what you were using and I also assume they no longer sell the 24 grit or the 60 grit nubatama stones which is why you are looking for a replacement? the 24 grits looked to be made from silicone carbide so the powder might be something you would enjoy.

 

naturals are not going to work well for that kind of work... there is a 3m 200micron diamond stone i've used that i enjoy for really serious work (similar to an atoma). I also enjoy the atoma, but really prefer the 220 type stones in terms of how quick followup work is.

Anyways, which gesshin are you trying to compare with the atoma?

For what its worth, i've tried almost every stone in japan under 220 grit, and i have yet to find any that i have been happy with. I have stones ranging from about 14 grit up to 180 (maybe about 30-40 different ones).

 

Currently I have the Nubatama course stones xxx course -60 I find the side of the xxx is good for tip or hollow repairs but it does very little as does the 60 for thinning the Nubatama 150 is pretty good but quite fast wearing as is the 400 . I have yet to try Gesshin stones it is so easy to spend a lot on stones .
Currently I find the Aotoma 140 & the Nubatama 150 good for initial thinning . Do the finer Gesshins give a finish more like a natural stone?

 

depends on the stone

 

Leo Barr,

If you really talking extensive thinning reprofiling and tip repairs, then a belt sander is what you want to use. After the finest belt you should have a decent finish too.

Saves a lot of time. Doin it by hand is pointless

 

This reminds me a lot of our last conversation Jon. The end result for me was better belts that could be run wet and slow (the Norton Norax series vs the 3m Gators). Those might be hard to find though for a hobbyist type sander which also isn't adjustable in speed. I did buy a couple different stones, but so far nothing matches the cutting and blending abilities of the belts (as bieniek) said) when used properly. Diamond plates are probably the most effective, but all it takes is one diamond that pulls out and cuts a 2" furrow in the work to ruin your entire day.

 

yeah... for coarse work when you dont have a rotary water wheel, i totally agree... the koolmist system is really cool too

 

Jon is there ant sort of horizontal water wheel system that although not as good as yours is worth the while I see some quite cheap ones by Ryobi or Shinko I would be looking to use such a machine for heavy thinning on single bevel knives I would be finishing by hand but both of these machines look a little light weight . I did have a Tormec at one time but I found it awfully slow and been vertical the point of contact was more critical than I imagine on a horizontal wheel and therefore easier to loose the angle particularly on the slow speed the Tormec is(I think it is a good machine for carpenters but not nearly as good for knives)
I am not in a rush to get such a machine but it will make sense for major works on a knife. I think a slow system can lead to errors since so much longer is spent on the machine this is where I do not mind doing it by hand especially if there is no hurry so that the job can be done over more than one session.

 

the one i have isnt even commercially sold at all... it was custom made for me by one the guys i train under in japan. Not even sure where i would get one without that. There are some premade systems, but none worthwhile i have seen in the US, and the premade ones in japan are even more expensive than what i have for the most part.

 

This is the main question I had for Jon when we talked as I mentioned above, lol. About the only thing I think might work myself, is a variable speed disc sander setup vertically with a basin, and affixed grinder wheels of varying grits. If setup properly with a containment system under it, it could be run wet or dry. 10" wheels run $30-$150, 12" wheels seem to be substantially more expensive, though I found some of unknown grit on Grizzly's site for $60-$100. Dressing them could be problematic as well if you allowed any grooves to form, and finding appropriate grits for various jobs could be difficult as well.

Just some ideas I put together while doing my own search for a wet wheel setup. I gave up the whole concept simply because it was much, much more cost effective to pick up a half dozen $10 belts that will last years and learn how to make them work to my intended purpose, then it was to build a frankensteined horizontal grinder/wheel setup that may or may not have worked anyway.

 

I find it interesting that the thread took this turn. I haven't been really happy with any solution at the very coarse end, so I had decided that I would next try a belt sander with a speed control and a spray bottle. I've already purchased a Harbor Freight 1x30 belt, a Harbor Freight speed controller, and a wide variety of 1x30 belts (not Harbor Freight). I wish I could tell you how great it is, but I bought that setup just after using stones for my last heavy thinning project, and I haven't had a reason to try my new setup yet.

 

I have a HF 1x30. There was a reason I was looking for coarse stones or a water wheel when I talked to Jon. I can grab the belt and stall the motor bare-handed. In addition, the lack of appropriate belts will be prohibitive. The available 1x30 belts run hot and wear quickly at full speed, and don't cut at low speeds because you stall thr motor if you use enough pressure. I mean, I have a 3hp fully variable 2x72, and until I found the norax belts, thinning was more efficient on stones.

Something to think about there.

 

Thanks for the warning. I'l have to write up a post if/when I ever get to trying it out.

 

Absolutely, and since you already have it, don't be discouraged by my words. I was mostly saying it so you'll know some of the limitations you'll face. I still use mine for other things..but for grinding steel, not so much. If I HAD to use it for that purpose, one of the things I'd do is make a better (more sturdy) platen setup, and setup some sort of cooling system. The cork and scotch brite belts from supergrit would also be invaluable, as they last MUCH longer than standards belts, and can (SHOULD!) be run wet. In addition you can use the cork belts with buffing compounds once you wear all of the grit off of them, and continue polishing with them indefinitely.

http://www.supergrit.com/products/products_belts-misc

The scotch brite (they call them 'surface conditioning') belts alone might work for many thinning jobs, if you can keep them wet. Just run through the progression (ALWAYS edge trailing with scotch brite!), using the coarse belt to cut...then finish by hand. They are surprisingly aggressive for what they're made of if you can keep the heat down...and by nature blend their cut, making for a prettier end result on double bevel stuff.

Anyhow, there's some more ideas to throw out there. When I made my earlier post I'd forgotten the 1x30 cork and surface conditioning stuff at Supergrit...which will help your cause tremendously. You should only need one belt of each grit to last a good long while. My 2x72 cork and scotch brite belts have been used on half a dozen blades now (knives and razors), and show zero signs of wear.

 

Jon's 300 diamond stone is a great stone. I also like the 220 shapton pro.