Thread: Learning Jnats with Microscope

The Tsushima is a very nice and aggressive stone, I use it in place of a Botan to make the transition from synthetic to a Jnat finish. It quickly cuts synthetic stria.

The other day I was honing a special knife, a Jody Sampson, custom fighter with Sampson. Pacific Cutlery and Bench made stamps. On special collector knives I often hone knives on an Edge Pro to produce even bevels.

I had profiled the bevel on a 600-diamond plate and had transitioned to a Shapton 1k, glass stone. I used a small piece of Tsushima to clean the Shapton and honed on the slurry on the 1k to see what would happen.

It quickly removed all the deep 600 grit stria and left a hazy finish on the bevels and a straight keen edge. I honed 6 of my wife’s kitchen knives using the same Shapton 1k with Tsushima slurry and it quickly produced a keen edge leaving a satin finished bevel. On all but 2 of them it brought the edges back, 2 with small chips I dropped to the 600 diamond then polished on the 1k with Tsushima slurry.

The Tsushima is a good stone for cleaning the Shapton’s that get dirty and are difficult to clean. It would probably be a good stone for cleaning the swarf load up on the Naniwia Super Stones, that load up worst than the Shapton Glass.

I was really surprised at how quickly the stone cleaned up and the Kasumi finish it left on the bevel and a keen edge.

Originally Posted by Euclid440

The Tsushima is a good stone for cleaning the Shapton’s that get dirty and are difficult to clean. It would probably be a good stone for cleaning the swarf load up on the Naniwia Super Stones, that load up worst than the Shapton Glass.

I was really surprised at how quickly the stone cleaned up and the Kasumi finish it left on the bevel and a keen edge.

Actually I'm using a Naniwa dressing stone to clean the SS 3K (and king 1K too)... but still don't like that stone too much...

Originally Posted by Skorpio58

Actually I'm using a Naniwa dressing stone to clean the SS 3K (and king 1K too)... but still don't like that stone too much...

That's because it was designed more for the 1K Chosera.

The slurry produced with the dressing stone, and Chosera, makes it a turbo charged, bevel setter.

One of the first thing a newbie (as I am) has to understand about Jnats, is he has to compare different naguras on different honzen stones and see how these works. Microscope can help for sure, but shaving is the final judge.

As I got a lot of Naguras, I'm starting to test each one on my Nakayama Kiita Koppa, Ozuku Koppa and (maybe) Aiiwatani Karasu too. So, working with different combinations on each stone, hopefully I'll be able to evaluate how these works and how the microscopic aspects will be related to their shaving behavior.

Just to become familiar with these Naguras I made a quick test to fine tune the operation schedule.

Used a Solingen Vintage Razor, 6/8" FH, the Nakayama, a Black Tsushima Nagura and a Nakayama Tomo.

The chips on the images are not noticeable at thumbnail test, but will be removed before the real Test Series will start.

Timestamp on images will help to define the approximate working time on each step.




[Edit: Below ->Tsushima Nagura instead of Tomo]

Looks better, looking at depth of the chip, you can see how much steel is removed across the whole bevel. Quite a bit.

The Tsushima with a bit of pressure should remove all the stria on the right side and the chip.
How many laps are you doing on Tsushima?

If you joint the edge a single stroke or two, that will remove much of the chip and straighten the edge. You want a good edge because the final test is to shave with the edge. How it looks can tell you a lot, but how it shaves is what counts.

You can pluck a hair and take a micrograph with the hair next to the chip. That will keep you in perspective, how small some defects really are.

Joint, more laps on Tsushima and start with pressure as the stria disappears lighten up on pressure.

Once you remove the chip, use that double stria railroad track, on the razor belly as your witness/registration mark, so each time you photograph each nagura stone, so you are comparing the same section of the razor each time.

If you highlight it with some colored sharpie ink it will be easier to find quickly.

Originally Posted by Euclid440

Looks better, looking at depth of the chip, you can see how much steel is removed across the whole bevel. Quite a bit.

The Tsushima with a bit of pressure should remove all the stria on the right side and the chip.
How many laps are you doing on Tsushima?

Joint, more laps on Tsushima and start with pressure as the stria disappears lighten up on pressure.

I've to learn to recognize better microscopic evidences as the stria you're talking about. I use the microscope with a smartphone... so it's a litte bit difficult for me to see (and understand) well what's happening. Better after honing session when I look at images on my laptop...
Anyway, next time I'll try to apply more pressure when working with Tsushima. As you know, I don't count laps, but worked on it for about 12 minutes.

Just saw this video in which he resets the edge of a cheap Chinese razor and then follows a progression that ends with a Jnat progression with naguras. He also shows microscope images as the edge progresses.

Seems to be a new video. You have to listen carefully as he has a French accent and the English subtitles don’t always match what he is actually saying.

https://youtu.be/00EyMg_uCDY

A lot to learn from this video. A Titan is not much different from a Gold Dollar. The spines are thick and seriously in need of heel correction.

His first few laps on the 400-diamond plate and you can see and hear him honing on the stabilizer. Ouch.

At 4:27 when he switched to the Shapton you can see, the heel was not touched by the 400-diamond plate.

1K hair test does not cut hair except at the toe and even that is weak. The heel half of the razor is off the stone. The video does not show the heel with the 1k, but 4:43 shows no 1k stria about an inch or so from the heel corner.

The bevel is not fully set.

At 8:15 Hair test. “We’re Good”. And that is why hair test is not reliable, half of the edge never touches the stones. and he declares “We’re Good!”

At 10:36, Jump to the Jnat, notice how quickly the heel falls off the stone with his X stroke. Keep the heel on the stone at least halfway through the stroke. The heel gets no time on the stone. The stroke is bad, but it does not matter in this case the stabilizer would keep the heel from making contact anyway.

Notice at 11:36 that half of the razor is not honed to the edge. Lots of synthetic stria visible, and no edge at the heel. The heel/stabilizer is keeping half of the razor off the stone.

At 13:40, he needs to shape the tomo nagura. Because it is not rounded smooth at the edges, he is grinding the flat part and creating a thin sharp edge on the tomo. If flakes, stop. Wash off the stone, round the edges of the tomo and make a new chip free slurry.

Note at 15:28 the edge is not honed, he does not do a hair test on the heel. Had he corrected the heel, and kept the heel on the stone, he probably could have got a good edge on it.

He did all the right test, ink the bevel, microscope, but never looked at the bevel and edge to see if he was honing to the edge.

You must look, to see if you are making progress and are honing to the edge, if not, why not?

You can learn a lot from this video. He has nice stones, needs to slow down, and look at the bevel and edge.

Update: The Razor delivered a very good shave. Deep & Smooth

Of course this result will have to be parameterized in comparison to the other Tomos & Naguras

1) Nakayama kiita koppa + Tsushima Black Nagura + Nakayama (1) Tomo Nagura = Shave Test OK