A better coarse waterstone

B

bgentry

Joined
Aug 3, 2009
Messages
1,575
I've only got a collection of 3 waterstones, all Nubatama. The coarse is the Nubatama bamboo 150 grit. The one that's brick colored and very thick. This stone works, and definitely grinds steel sort of fast. But I have several quibbles with it: It's really porous and hard to keep wet, even after some mud is produced. The noise it makes while grinding is loud and off putting. When it's wet, it makes WAY less noise, but as I said, it's very hard to keep it wet. Once it produces mud, I think it grinds faster, but the mud is thick and sticks to the blade, so when I'm trying to evaluate the edge, I have to first clean the mud off, which means extra time and getting my fingers more wet and more dirty more often. Finally, it's sort of fast, but honestly the DMT XXC seems to grind quite a bit faster.

So I guess I want a quieter stone that grinds faster, stays wet more easily, and has either thin mud that doesn't stick, or no mud at all. Which seems to point directly to the Shapton GS 120. But that's just my first blush at this and I'm still pretty new to waterstones.

Any ideas?

Thanks,

Brian.
 
I've had some luck using dishsoap in my waterstone bath - seems to keep it from drying out so fast. On my Norton 220 have come to just use it dry and brush it off every so often. The mud it forms appears to slow it down.
 
Ken's Corner has a nubatama rated at 24 grit. I'm sure that'll grind like a grinder.
 
Hmm , well one option is to have Ken get you a Nagura Stone to help develop a thicker mud to help the stone hold its water better. I am sure he would have a small piece of 150 Nubatama leftover from cutting EP piece that he could sell you.

Are you soaking the stone at all before use?

Also use more pressure , a waterstone wont dig as deep as quickly as a comparable diamond plate. However the 150 Nubatama will make quick work of those DMT XXC scratches.

Also if you live in a climate like I do where the air is really dry from the winter (hovering around 0-20% RH right now , my humidor is running lots) then it wont matter what stone you go to it wont hold its water well , but a splash and go stone such as a shapton could actually make the problem worse (provided ambient humidity is part of the problem)
 
Thanks for the review of the stone. I'll go over your concerns.

" But I have several quibbles with it: It's really porous and hard to keep wet, even after some mud is produced."

It is porous. Most really coarse stones are. Soak the stone and develop some mud on it and keep some more water on it as necessary. It's physics - the particles are bigger, so the space inbetween them is bigger.


" The noise it makes while grinding is loud and off putting. "

If it wasn't making some noise, it would be doing less cutting. All stones this coarse make a lot of noise - Shaptons included. The 150 wears but not quite as fast as the Shaptons in this grit. But it's MUCH thicker. For a coarse stone it is relatively slow wearing. If you want to see a fast wearing stone, try the Naniwa Lobster stones. You'll wear through MOST of the stone in one session!


"When it's wet, it makes WAY less noise, but as I said, it's very hard to keep it wet."

USually the second time you use it, it dries out less quickly. Again the nature of coarse stones.

" Once it produces mud, I think it grinds faster, but the mud is thick and sticks to the blade, so when I'm trying to evaluate the edge, I have to first clean the mud off, which means extra time and getting my fingers more wet and more dirty more often. "

Keep it a bit more wet :) Rinse your fingers over the stone to not waste mud.

"Finally, it's sort of fast, but honestly the DMT XXC seems to grind quite a bit faster."

Depends on the steel. But the scratches from the DMT XXC are deeper. Use the Bamboo 150 to get the DMT XXC scratches out. Works perfectly for this.

Hope this helps you enjoy the stone more.

You should be able to use the stone well without excessive pressure or a separate slurry stone.

---
Ken
 
Of the 4-5 coarse Nubatama stones I have used and tested there was not one that really stood out. The black 180 I have used the most was the most well rounded but muddy and kinda slow for its grit. The stones were also all different in binder hardness releasing abrasive at different rates which caused inconsistent cutting speeds that often did not relate well to the grit numbers.

I think a Shapton or Chosera stone would be more along the lines of what you are looking for.

What will be your main use? And do you need a very coarse stone often?
 
Addressing a few random points:

1. Yes, I soak the stone before use. At least 5 minutes, and as much as 15 to 20. It makes a little difference if I go over 5 minutes, but not a huge difference.
2. I'm in Florida, so it's always rather humid and water doesn't evaporate very fast unless it's in direct sunlight.
3. I do wash my fingers over the stone to try to preserve the mud. It's still thick and sticky.
4. This wasn't intended as a review. I'm not trying to be negative. I'm asking for help with a product I might like better. This is a good product, it's just different that what I think I'm looking for.
5. I use a coarse stone fairly often: Sometimes for reestablishing an edge that is very very blunt; in which case I'll use the stone a lot. Other times it's just a starter to make initial bevel grinding quick and to insure that all previous grind marks from factory or otherwise are ground away.
6. I do use quite a bit of pressure when doing a regrind. Way more than I would use on a diamond plate, but not exactly "leaning into it" either. Enough that it definitely produces mud after a few back and forth strokes.

Thanks for the help so far. Any specific stones anyone would recommend? Or should I just stick with DMT XXC and perhaps C before jumping to my 1000 grit Nubatama Ume? Seems weird to switch from diamonds to waterstones. When going from 150 bamboo to 1000 Ume the 1000 erases the scratches from the 150 rather quickly. Much more quickly than you might expect from the simple grit numbers. Going from XXC straight to 1000 probably isn't going to be similar. Which is why I'm considering another waterstone instead.

Brian.
 
Thanks for the additional feedback, Brian. Very informative. I'd suggest using a slightly different approach with the 150. Do your initial bevel setting with the DMT XXC (or an Atoma 140) and FOLLOW with the 150 Bamboo. This should serve you well for several reasons:

This will quickly convert your scratch pattern from a diamond scratch pattern to a stone scratch pattern. It is one of the quicker 'converters' out there and , as you've experienced, the jump to the 1k Nubatama ume speckled is easily accomplished in most instances. Coarser Nubatamas will leave a coarser scratch pattern than this and be harder to 'jump' to a 1k.

The amount of time on the 150 will be lessened considerably. You should be finished with the 150 before even developing much mud and be ready to move on to your 1k stone.

During this shorter session, your stone will stay even flatter.

A more extreme stone like the 60 grit is Very noisy and MUCH harder to convert although quicker.

The 60 grit loves high pressure use. The 150 really doesn't require the degree of pressure it sounds like you are using. Let the mud do more work and if it gets 'sticky, just dilute it a bit until you are in the right range. Less pressure will help here. In my experience, the Nubatama stones give a finish pretty consistent with the specified grits in my hands, but I don't use very heavy pressure and don't leave the stones permasoaked. Of course YMMV. If you wanted something slower and finer the 220 grit Nubatamas might do well for you, but it sounds like you want more aggression. The 400 Chocera is a finer stone and will not cut as quick as the 150 Nubatama at all. It is more comparable to the 400 Nubatama and not as aggressive as the 320 Nubatama ume. The 320 bamboo is more aggressive but more expensive. If you are wanting more aggression the 400 stones just don't match the 150 at all.

The Shaptons are less aggressive in the 220 and 320 Pro and Chocera stones. The 120 Shapton pro stones and GlassStones are roughly ( :) ) equivalent to the Nubatama stones in aggressiveness, however the GlassStones wear at least as quickly as the Bamboo but are only ~6mm thick, so they don't last long - nowhere as long as the other glassstones as they are a different formulation than the rest of the glassstones. The 220 GlassStones are not very aggressive and REQUIRE that you use a very rough stone or plate to make them cut aggressively. The 220 and 320 Pro stones are good aggressive stones appropriate for their stated grits.

Another approach is to go with a 400 Atoma or DMT Coarse (or the extra cosrse) stone after the XXC or 140 Atoma and then switch over a bit later to something less coarse than the 150 Bamboo in the 400 grit range. I use this sort of approach on very abrasion resistant steels, but for most steels, this is not necessary.

Don't be too concerned with soaking more than a few minutes on the 150, but just keeping the surface wet during use.

There is a Naniwa synthetic Ohmura that is ~ 150 grit and a stone Hida tool carries at 150 grit. Both of these are considerably softer and the Hida tool stone is not very aggressive for it's stated grit (I'd surmise a low grit density)

Hope this helps.

---
Ken
 
Ken,

Thanks for all the information; you covered a lot of stones I didn't know existed actually. :) I like your idea of XXC followed by 150. I might try that on my next beater blade to see how it works.

You keep mentioning wear and I haven't really addressed that. With the amount of work I've done on the 150 I've definitely worn it some and I'm not all that sure it was flat when I started. It seemed dished in the long dimension with a high "shelf" at one end.

I've never properly flattened a stone before. I tried on the 150 for about 10 minutes using a "tile rubbing stone". It *definitely* cut the 150, but I think I made it worse. The tile rubbing stone is much smaller than the 150 and I wasn't consistent or something. It just never got flat and I think I made the "high end" lower than the rest of the stone. It's not exactly a mess right now, but it's definitely worse than when I got it and I should fix it, or get it fixed. I'm very hesitant to use the DMT XXC on it.

I've seen others using the bottom of 12" x 12" household tile, rubbing the stone on the tile to flatten. I'd like to try that method, as it's cheap and looks easy. But I don't want to make things even worse. Any suggestions on how to properly flatten this and other coarse waterstones?

Thanks,

Brian.
 
Well you can use the DMT XXC or the Atoma 140. The Nubatama stones come quite flat. Impressively so. Contact me directly and I can help you out if it is REALLY dished badly. Like a half inch or more of dishing.

Keep in mind that when you flatten a stone you can get a flat surface but you should also strive to get a flat surface parallel to the back side. If you have really got the stone way off I can redo the stone for you and get it trued up and parallel, using equipment I've designed for that purpose.

The DMT and Atomas will work well. I've literally done thousands of stones on my Atoma plate - first one and going strong - and have gone through a few DMT XXC plates.

Alternatively you can get a 60 or 24 grit Nubatama to flatten the 150, but eventually you will need to flatten them. The 24 grit Nubatama gives the most aggressive surface finish for stone flattening. On knives, you would use the DMT XXC or Atoma 140 to clean up the 24 grit scratches. Yea, it's that coarse :)

Let us know what you think of the DMT XXC followed by the 150 combination.

---
Ken
 
Brian - pass on the household tile idea. The stone will grind the tile. The tile isn't abrasive enough to be effective. Also pass on using your sidewalk or a masonary brick. This just contaminates the stone with concrete and is a bigger mess. The Norton flattening stone is too fine. Naniwa makes some flattening stones, but my bias - being honest here - is towards the Nubatama. There is a large 24 grit Naniwa stone.

It is best to use a stone as big or bigger for flattening to keep things level.

---
Ken
 
Ken and I just had a long-ish conversation via voice. I'm going to try flattening my 150 with the DMT XXC and hopefully have a flatter stone. I'm also going to try XXC -> 150 -> 1000 Ume as a progression and see how that works out. Finally, I'm strongly considering adding the Nubatama 24 grit stone to my collection. I'll post back here with any significant findings.

Thanks to Ken for the conversation and all the advice.

Brian.
 
My favorite coarse stone I've used is my gesshin 400. Not so muddy, but a joy to use.
 
I wouldn't recommend the Naniwa Omura for 'stock removal' type stone work from trying that this week. Tried it by itself this week (having fun with a Byrd Cara Cara and an Opinel #8) and it was slow. Did a vintage Ken Schwartz technique of adding extra grit to the surface (have a bunch of 80 grit SiC from Lee Valley) and it sped things up a teensy bit.

My 'ah-ha' stock-removal came from adding the 80 grit SiC to the surface of a coarse Crystolon stone with a few drops of honing oil. Got the hollow grind removed from one side of the Cara Cara (now I want a navel blood orange) and 2/3 from the other side. Even the stone with just oil and no extra is fairly quick, but the bump of 80 grit made it that much quicker. It's not a waterstone, but a $5.47USD oilstone might be worth trying.
 
Today I did some flattening of the Nubatama 150 with my DMT XXC, using some suggestions that Ken made. I used the weight of the plate, which almost seemed like too much, but I went with it. It cut the stone with seemingly no issues. Since the XXC is almost the same size as the 150, I think it did a good job flattening it. Ken had mentioned to me to try working mostly on the flattest portion of the stone and to not try to get it perfect the first time. When describing how dished it was, I told Ken it might be as bad as 1/4" off in one area. Turns out I was way off.

I don't think the lowest spot was any worse than *maybe* 1/8"... really probably less. Easy to see with a ruler on top of the stone, but not really too bad. Though I swear I can *really* feel it when sharpening a blade. Maybe it's just psychological, but I swear I could feel the low spots. Apparently my attempt at flattening using a tile rubbing stone (about a month or so ago) was pretty awful. I made the sides lower than the middle and *both* ends lower than the middle. The XXC plate fixed the side to side pretty much 100%. About 10 minutes of effort also fixed the front to back problem almost all the way. There's about 3/4" at one end and 1/2" at the other that's still lower than the rest. I'll just keep using and flattening the stone periodically and I think it will work itself out.

The flattening also seems to have mildly smoothed out the stone. It's subtle, but you can see and feel the difference. Finally, the XXC seems to be mostly unaffected. Probably completely unaffected, but of course when you start scrutinizing anything you find things that don't look right. In this case, the middle 2" x 3" of the plate looks slightly different than the rest and feels a little different too. But I'm thinking that's from all my previous use of the plate and I just didn't look at it closely until now. I'm going to keep using the XXC to flatten this stone unless I notice a *real* problem.

Thanks to Ken and to the others that responded here. I'll post more after I've sharpened a blade on the 150 now that it's mostly flat again.

Thanks,

Brian.
 
I would recommend a cheaper diamond hone or SiC powder on a lapping plate. Using the DMT on such coarse waterstones will dull the diamonds significantly. Speaking from experience.
 
I wouldn't recommend the DMT XXC on the 24 or 64 grit stones, but you will be fine on the 150. Cheaper diamond hones will just wear faster and the Atomas will last longer.

Some also use coarse SIC powder on 24 grit stone. Naniwa in particular recommends doing just this.

The DMT XXC coarse will leave a less aggressive surface on the 150 than surface conditioning or flattening against the 24 grit stone, so the resultant finish will be slightly more aggressive.

---
Ken
 
You must log in or register to reply here.
Back
Top