Tanaka Deba modification

Hi guys,
It is the time to move this forum a little bit so it's the time for another WIP. I know that everybody enjoy them, so there we go:
I got Tanaka some time ago but I was very busy to play with it. Owner of that knife told me that he already spent about an hour on 400 grit stone, trying to flatten the blade road and that he had a hard time to remove all low spots.






Before I start doing other things I decided to check back of the knife - ''ura''. As most of you know this is crucial because if there are any problems with ura then we will definitely have problems with sharpening. If ''ura'' is damaged too much then it is equivalent to broken knife and only experienced blacksmith, owning a big grinding wheel, is able to repair it. And maybe I am wrong but I think that it is not always possible.
You can see with naked eye that ura side heel is not grounded properly.

U used red marker pen to see where am I removing metal.


I started with JNS 6000. It will remove marker pen and reveal some secrets but won't remove too much steel.
We can see that there is unsharpened part on the heel and space between tip and next 3cm of the spine is not touching the stone.


I spent some time on it trying to remove steel on JNS 800 and I didn't know why I cannot remove metal from that part. I have checked straightness before by looking on knife and it looked ok. This time I used Atoma 140 as a reference.



You can clearly see that tip is not in contact with Atoma plate. It is very bad sign. Because the knife is to thick and it is single bevel I can't repair it. My skills will never be good enough to repair it. I change my stone to JNS 1000 and try different angle of aproach and pressure.



Here you can see that steel is evenly removed in all places except those mentioned before.


On picture below you can see that slowly I am getting there.


Quick polish on 6000 to check how does it look like.




The secret was hidden in knife position on the stone. Instead of polishing with knife laying perpendicularly to the stone I layed only the tip on the back of the stone. Move was back and forth. My fingers were placed on the spine. Also I lift a handle a little bit. Maybe lifting is big word to descript what I have done. I intend to lift without lifting. It's hard to explain.


Later I moved my fingers a little bit backward with left finger on the beginning of the shinogi line still pretending that I lift the handle.



Rest was sharpened normally with finger under shinogi line and with pressure only on move forward.

This is the moment where I leave ura side because I have more plans for it later on. I just wanted to see what is going on there.
There is another thing which is worrying me.


On the picture you can notice some scratch or crack. It is weird because it's polishing nicely and easily to the crack and after that it is not that nice. Also sound after crack is different.


Here I marked crack with yellow arrow and place where it should be with red one. At least it is not on the spine.

It's time to see what is going on on the front bevel. As usual I marked everything with red marker pen. This time I started with JNS 800 straight away.



After few passes we can see...


...we can see that almost whole bevel is straight. There is low spot on the heel but actually I saw this on almost every deba I have ever sharpened. There is another one on the tip but this is not surprise for me as well. There is another thing. If this knife was previously sharpened properly we should see marker pen on 1/3 from the edge to shinogi line. We can see that there is clearly marked cutting edge like in gyuto or something. I spent more time with JNS 800. Next picture shows a little bit more.


I don't care about low spots on the heel and the tip. Maybe they will dissappear on the next sharpening sessions. There are not affecting cutting performance. The most important is to have straight and even ''ura'' and edge. We ca also clearly see cutting edge which must be removed.



Here you can see cutting edge I mentioned before.



At the end of todays session I strop the knife on the leather just to clean it.

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJR2f2l84rXBhMW8aUzZUfm50gqGHpKAAJDDwprtau0AomntPn-waSPy5N6L-f9AvTx7FkmcAXZZNMcwKi7boIh8U_DA7Eab55A94lpMFIKgbFffvAS1ZFH56SNFS4zluRS4ZAKkoiYw/s512/20141003_104952.jpg

Let's keep going. Last Friday I worked a little bit more on the blade road. Fingers on shinogi line like before and pressure only on move forward .
Then I started sharpening the edge. This time my fingers were placed over the edge (as close to the edge as possible) and my pressure was directed backwards.




You should also remember about using the whole stone. I have a problems with using some points on the stone. You can draw the net with pencil on the stone. This will show you places on the stone which are not used.


Now everything look like this. I think that it is quite even. I also removed unwanted cutting edge.

You can clearly see the burr.


I didn't want to sharpen or polish this knife today. There will be time for that later on. I just wanted to see how this steel behave on the stones.
Red Aoto

Binsui


Very small pocket Hakka.




I really love my Hakka. The cutting edge feel really sharpened and polished but in the same time very toothy. This is what you want on deba I suppose. It took me maybe 2 minutes and I even didn't try to do that nicely. I even didn't remove jns 800 scratches before and here you can see that Hakka gave me a nice polish. I think that any sand paper will ever be able to compete with J-nats.

This is the ura at the moment.


I will keep working on the ura side. There is still something wrong with it. I've done all of this on Friday. Today (Sunday) I wanted to check something and I placed deba on my atoma 140 to check for flatness. There is another thing which I haven't seen before and it's worrying me now. I will update pictures later on.

TBC...


I have found out why I can't sharpen heel of the ura side. The knife is not touching flat surface not only on the tip but also on the heel as well. This is very bad thing and I think that it is not possible to repair.



Also I took off this awful handle. It was easy because handle wasn't glued it.




Even tang is ground strange. I will correct it on belt grinder later on.




After sharpening the blade road and the edge you must connect these two angles. To do that place your fingers between shinogi line and the edge and use pressure only on move forward. Also with every move lift knife a little bit to round whole bevel. If you do that properly your will get hamaguriba edge.



At that point I finished sharpening and polishing on Red Aoto. It is not the time to properly sharpen and polish the blade. To make the finish even I used Red Aoto mud. Do not waste mud from your stones. When you flattening them collect mud and put it to jar or some container. You will be able to use it later on.






One can use champagne cork or ultra hard felt to polish.


And this is effect. It took me 2 minutes. You can spend more time to remove all vertical scratched and create horizontal ones. I will work on the bevel even more so I decide to leave it as it is.





''Ura'' side




Next step was to polish flat face of the blade. I used very hard sponge as a base for sanding paper. Grits: 180, 400, 600, 800, 1000. Instead of using water use WD-40.



Before:




I could get better finish but the gap between 180 and 400 was to big. Maybe I will correct it tomorrow.





Here you can see that I removed that ankward cutting edge.



To be continued...



The next step is to repolish ura side a little bit. I don't want to achieve super polish. Just clean the back side.




If somebody don't have a super hard sponge, then he can use trick which I have learned in Denmark. Just glue 4 - 5 layers of masking tape to sanding paper. This will harden paper but will also make it flexible.






Now it's time for the front flat face of the blade. I will use my friend - the fingerstone


It will be Hakka. It is soft but also quick and leaves a uniform finish. It is exactly same as with the sanding paper. You must fit the stone to unevenes of the blade.




Just thinn the stone to about 1mm and glue the rice paper on it. If you don't have a rice paper you can use one layer of tissue.



Glue should be waterproof and flexible. The best for that is Pattex but I had no time to order it.




Cut the stone to size of your thumb...


... and break it. The rice paper will hold everything together.







You can also use it on ura side. Here you can see some scratches from 180 grit sand paper. It is harder to do on back side because you must be careful about edge.




Glueing handle back to the blade.




I should finish tomorrow. I have only to resharpen it and nicely polish.

TBC...

Just to remind you.

Before:





After:

https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJR2f2l84rXBhMW8aUzZUfm50gqGHpKAAJDDwprtau0AomntPn-waSPy5N6L-f9AvTx7FkmcAXZZNMcwKi7boIh8U_DA7Eab55A94lpMFIKgbFffvAS1ZFH56SNFS4zluRS4ZAKkoiYw/s512/20141003_104952.jpg