Spine and choil rounding/polishing questions

[Gongoozler]

I have a Teruyasu Fujiwara Nashiji Gyuto 210mm. I love the performance of the knife, but the sharp edges on the spine and choil are no bueno, especially since the ones on my other Gyutos are very nicely rounded.

I have never done anything other than basic edge sharpening and handle swaps.

I have reservations about learning how to do spine and choil rounding on a somewhat expensive knife like this one, so I'm considering it sending it to someone to have the work done.

Soooo

1. Is it something fairly easy to do myself? I have a vise. What grits of sandpaper would I need to buy?
2. If I decide to send it to someone, who would you all recommend (preferably someone US based)

Thanks!

 

[Cliff]

It's pretty easy. I've never used a vice. I just hold the knife, carefully. I'm sure a vice would make it easier. You'll also want some kind of backing. For the choil, something like a screwdriver or a pen can work

 

[KasumiJLA]

Since this is your first time it will take you a little longer but you will see that it is still quite simple. Even if you do not finish your project you will still be able to use your knife and finish it another day at your own pace.

Since you already have a vice it's gonna be handy. Use a soft material to clamp between the knife and the vice, I personally use a rubber mat but you can use a thick fabric or something that won't scratch the knife. Secure the knife tight, but not too tight..! I'm sure you understand why.

You can use a dremel to speed up the process or you can do everything by hand. 90% of the time I do it by hand. For the progression I would go like this: 220-400-600. Then you can add some more finer grits and finish with diamond polishing paste for a mirror effect. It's totally up to you! A 600 grit finish will look glossy and reflective on a small area like a spine and choil. This entire project is done dry without using any lubricant while sanding.

For the choil
I use a dowel and/or a chopsticks to wrap the sandpaper around it. Work from the outside in, giving a nice rounded shape. Try to refresh your abrasive when you start to feel like it's not cutting anymore to speed up the process. For such a small part you don't really have to alternate the direction of the sanding. In the end it won't show scratches and the result should be uniform.

For the spine
You can use a hard backing wider than a dowel since you'll want to cover more area. I personally use a piece of wood of 2 inches wide and I wrap the sandpaper around. It's the same technique as previous by rounding the corners at 45° and then blending everything together so that everything is rounded. When everything is done on your coarser grit (220) and the spine is now rounded, you can use the shoe polishing technique for the rest of the work to be done. Just take your time and avoid to putt too much pressure to prevent the sandpaper for breaking. If you see a spot that isn't to your liking, simply go back to the previous sandpaper and rework the section until it's perfect.

And voila! You should have a pimped Fujiwara to your liking. It's honestly not that hard to make. Just understand that you have to remove material at the right place with the coarser grit and then it's the polishing process with finer grit.

Bonus : I found this old video of me doing some choil work. And this old video about an usuba restoration.

 

[kdizzog6]

A semi soft sanding block will work good for the spine too, it is soft enough to round the edges without flattening the sanding.

 

[pitted_soul]

I just cut thin pieces of sandpaper with increasing grit levels, no blocks or dowels. Put painters tape on the main blade and blade face of the end of the handle. I put the knife handle in a vise with padding and the spine edge facing upwards. I start by doing oblique sanding of the edges of the spine and then I get another piece and then pull it downward and slightly taught over the spine and work it back and forth. Everything done is with the same movements so it's consistent. They will wear out and then I grab a new one. Start with 80 grit and then work your way up, 120, 220, 320, 400, 600, and 1000. You can stop at 600. I do the same technique but altered for shape with the choil.

I just did this last night on a Shinkiro 240 and it came out great. It's tedious but not especially difficult. I've done it on a few others but my last endeavor looked the best. I can shoot some pics. The spine isn't crowned, per se, but nicely, uniformly rounded and softened.

 

[dAtron]

I use a small file first then sandpaper wrapped around pencil later. The files significantly speed up the process

 

[Benuser]

Perfectly rounded spines and choils do look very nice. But practically, all you need is easing the edge of the choil's right side, and the same for the section of the spine your index comes into contact with. I certainly wouldn't round the spine's left side, as a sharp spine is useful for removing meat from a bone or moving produce on the board.
I feel little difference between a somewhat eased spine or choil and a really rounded, polished one.
I like these abrasive sponges. They are sold in sets of three grits, without an exact indication — has to do with FEPA norms — but my guess is between 400 and 800 as you know from sandpaper. Very convenient, cheap and lasting.

One warning: when easing the choil don't do it over it's entire length. There's no need to, as your middelfinger never touches the heel. And you want to have problems with the heel's geometry when sharpening.

 

[CLouie2]

In considering options (ie for spine/choil rounding and polishing as stated above), could someone please recommend a dremel and the necessary attachments??
For some reason I think I’d have a better results with that route.
Thx!

 

[aporigine]

In considering options (ie for spine/choil rounding and polishing as stated above), could someone please recommend a dremel and the necessary attachments??
For some reason I think I’d have a better results with that route.
Thx!

A Dremel can get you into big trouble fast. Ask me how I know

I have enjoyed this thread dealing with questions I have often had. For spine and choil work, the paper-and-dowels approach is the one I choose.

 

[Luminaire]

I just rounded spine/choil on my new watanabe gyuto. It really goes pretty quickly when you start with 80 grit + duct tape.
Also don't recommend Dremel it's way too easy to make an ugly mark and then you have to hand sand the entire blade which is way more work.....I speak from experience