Nubatama 4K

I had been looking a Nubatama 1K for knives since Ken did a video on them a couple years ago, it is a thick very cool looking, hard, aggressive stone for large knives.

I got one at the end of 2014, and it works very well on knives, leaving a shallow stria pattern, for an aggressive stone.

So, I thought I would try it on razors and was impressed, it was fast, shallow cutting and self-slurred very little, if at all.

As a result, I started looking at the Nubatama 4k (my Norton 4k was getting thin) and was thinking a lot about the Transitional Stone, I posted about it in this thread. Basically, the 1k is the grinding stone that shapes and set the angle quickly.

The next stone in the progression is a transition stone converting from grinding to polishing and transitioning to a straight edge. It is this stone that removes all the low grit stria from grinding or not. This stria will cause problems down the road at finish, chipping the edge especially with novice honers that do not put enough time in polishing a bevel and/or using too much pressure at bevel set. For that reason the Transition Stone may be the most important stone in the progression, for the novice.

CKTG had been out of stock on the 4k, so I had to wait a few months, once I decided to make the purchase, but finely it arrived.

It is a hard, Green stone that produces pea soup slurry. I lapped it with a 140, 400 & 1k diamond plates. It lapped easily enough for a hard stone.

I have been using it for a couple months now, replacing a well-worn Norton 4k and have been impressed. It’s aggressive, shallow stria easily erases 1k stria and with a much straighter edge than a Norton 4k, much more like an 8k edge. The low stria pattern is the perfect set up for the Norton 8k, that polishes the bevel quickly and nicely straightening the edge even more.

I took some Micro graphs to demonstrate first the Nubatama 1k compared to a Chosera 1k. The stria is wider but shallower than the Chosera.

I honed the razor on a Norton 4k then marked the mid-point on the razor and honed the toe end with 10 laps on the Nubatama 4K and took photos. You can see, the leading edge of the bevel is polished, but not to the top of the bevel after 10 laps. Also note how straight the edge is already, for a 4k.

After another 10 laps, the edge is super straight and the 4k stria is even throughout the bevel. Note the swarf on the stone and lack of slurry after 20 Laps total, (10, straight and 10, X laps).

From the Nubatama 4k, the Norton 8k quickly polishes the bevel and the edge gets much straighter, quicker.

Micrographs

The first two micrographs are the 1.Norton 1k and 2, Nubatama 1K. The third & fourth are, 3.Norton and, 4.Nubatama 4k, note the edge on the Nubatama 4k. and the last is of the Nubatama on the edge over the Norton 4k angled at the top, here you can see the shallower Nubatama stria, after only 10 laps the edge is pretty straight.

What the graphs don's show is the blade was completely honed to remove previous stria and lay down a complete Nubatama 1k stria pattern and then a Nubatama 4k pattern. When photos were taken only the tip half was honed by the Nubatamas.

So is it for everyone?

It is hard, aggressive and shallow cutting. It does have a gritty feel, much like a Norton 1K. If you are production honing and or looking for a new solid 4k, the Nubatama is a performer, at $98 (cheaper than a Naniwa Pro 5k and a few dollars more than a Norton 4k) and at 205mm x 75mm x 25mm, it is a good size and value.

And BTW it is also a great kitchen knife finish stone, just a few laps are all you need, (Great Knife Touch Up stone). I use one side for razors, the other for knives.

My current progression is a 1k & 4k Nubatama, Norton 8k, 12k Super Stone and then a natural stone or SG20k finish. It is a very solid, quick progression.

Nubatama 1K
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Nubatama 4K
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Norton 1K
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Nubatama 1K
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Norton 4K
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Nubatama 4K
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Nubatama 4K over Norton 4K
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Thanks for the review Marty. Been curious re these stones.

The Norton 1k looks less ragged than than the Nubatama 1k edge ?

Yes the edge on the Nubatama is more ragged, but the stone is hard and cuts a shallow but wider stria. Swarf will float on the water like in the 4k photo.

I usually, joint the edge and go to the 4k that removes the 1k stria quickly because it is not deep.

20, ½ side honing laps on the 4k also, removes the 1k stria, then lay down the 4k stria.

I did not joint or side hone for the photos in this thread. 1-2 light jointing strokes will straighten the edge and the 4k is aggressive and will bring the bevels together quickly.

Ah ! I'm wondering if it is more a burr than a ragged edge seeing it is a fast cuutter ?

I got a little time on these at the Denver meet...

I personally did not like the feedback from them to the razor, nor the stria

The guy that owned them tried out my Chosera 1-5-10 and could feel and see the advantage of the feedback from the Chosera..

I would have to hone quite a few more razors on them to make a real judgement about them