Tue Nov 27, 2012 11:08 am
I'd wanted one of these for quite a while. A friend gifted me one. I use it for setting bevels on razors. I can't get this thing to cut a decent bevel. It seems like it's shaping the steel pretty well, but then it plateaus a bit. I take it to lapping film and the bevel pops right on up, however staying on the Nubatama, I get nowhere. What's the trick with this stone? I've heard it compared to a Chosera 1k, but I can get my Chosera to cut a bevel at a fairly decent rate of speed.
Tue Nov 27, 2012 9:43 pm
i'd love to know as well.
Tue Nov 27, 2012 11:04 pm
Nubatama Ume stones in my experience are a harder stone. I don't have the 1k but have the bamboo 1k gold, its a hard stone too IMO but has a high grit density and cuts extremely fast.... To a point.
When the stone builds mud the mud becomes finer and starts polishing the bevel and the stone will slow down considerably if not flushed with water. This is great if you want to be finished and ready for the next stone but if using it to set a bevel it may make things difficult.
Tue Nov 27, 2012 11:45 pm
thanks for the comment jason. was thinking on the ume because of the size of it.
i love harder stones. would anyone with experience with both stones care to chime in just how much harder would it be compared to the chosera?
Wed Nov 28, 2012 2:02 am
Well if we go from 800 to 1200 grit, between the two series there are 9 stones available. In the Ume series there is the larger dark brick and the spotted stone - available in three hardness levels - so 4 Ume stones. Why do this? Well the answer is that IMO the 1k level of finish expecially needs to be VERSATIlLE as it is a transition from shaping a blade or determining geometry to polishing a blade or refining existing geometry. So a 1200 Bamboo is very soft-perfect for interacting with a less than geometrically precisely defined surface. The 800 is much firmer and probably closest to the 1k chocera (IMO) A bit harder is the speckled 1k ume then the 1k gold bamboo. Harder still is the 1k speckled hard formulation - comparable to a Shapton 1k. Then there is the double hard or 'hard hard' which is even harder than the Shapton 1k. If you have an interest in the Hard or 'Hard hard' spotted Ume stones just contact me directly via PM, as they are not currently listed on CKTG
Wed Nov 28, 2012 2:23 am
thank you ken for your input. will put that into consideration.
and apologies for hijacking the thread.
Wed Nov 28, 2012 3:26 am
Jason B. wrote:When the stone builds mud the mud becomes finer and starts polishing the bevel and the stone will slow down considerably if not flushed with water. This is great if you want to be finished and ready for the next stone but if using it to set a bevel it may make things difficult.
When sharpening on the 1K hard Ume I see very different result with mud and without. Without mud I experience a gliding, slippery sensation that abrades finely without producing much mud from sharpening process. When I use a diamond slurry stone to build mud (I think importantly mud of the same 1K grit) there is almost a rosin bag type effect of instant traction and the fine stone particles grip the stone and edge very aggressively(I can hear the difference: from smooth to almost sandy). Much faster cutting speed and no dishing of the stone.
Since this stone doesn't produce much mud, it eventually rinses away during a long session. higher grit nagura not much help speeding things up but softens the scratches a little.
Fri Nov 30, 2012 12:48 am
Makes sense. The 'hard hard' will be even more like that - even less mud and a harder surface. By abrading the mud with a slurry stone, you get more mud so expecting more cushioning, higher grit density and more traction makes perfect sense. This isn't unique to this stone. For instance, by abrading a Shapton glassstone, you also get a more aggressive cutting rate. When you flatten a stone you can use this removed stone or mud for this purpose rather than just rinsing it off.
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