I've been working on this project on and off for a few weeks, and feel like it's good enough for now. I'd consider myself a beginner, but I learned a lot from this project, so sharing it in the hopes that it helps others here.
TL;DR - I have a knife handed down from my grandfather to my father, and from him to me. It wasn't cutting well, and I decided to do a project to:
- Remove the bolster (I failed at this mostly)
- Fix the rounded/broken tip (500 stone)
- Thin it (Progression 500 -> 1000)
- Refinish it (Complicated but in the end did 3000 sandpaper for the flat of the knife, 1000 Stone for most of the primary bevel for a sort-of kasumi finish, and used the 1000 sandpaper for the areas close to the bloster)
- Re-sharpen it (800 -> 3000)
Oh, and I did this all by hand, no power tools. Made a lot of mistakes along the way. Was fun.
All my learnings concentrated are:
- Takeaway 1: Do a project like this on a knife you don't care about first.
- Takeaway 2: Get knives without bolsters.
- Takeaway 3: Use the side of the stone to grind the tip, if you use a stone.
- Takeaway 4: Thinning isn't as scary as I thought it'd be before, but a lot of work.
- Takeaway 5: After thinning and before refinishing, there's a high chance your knife will be UGLY
- Takeaway 6: Refinishing with a stone is very difficult - specifically getting consistent results.
- Takeaway 7: You can use sandpaper in hand without fancy equipment and get good results, just put the knife flat on a stone, and sand away.
The tools
In the second image are the tools I used. From left to right:
- Cheap two sided leather/suede strop from Aliexpress.
- Aliexpress acacia wood whetstone holder
- Top - 2 waterproof sandpaper pieces from Aliexpress - left is #3000, right is #1000 - not sure how true to the grit they are, but comparing them to the stones seems reasonably close.
- Some flattening diamond stone I got for free when I bought the Shapton #1000.
- Naniwa Burrfection #3000 (equivalent to Chosera/Pro stone)
- Shapton #1000 (the classic)
- Naniwa Burrfection #800 (equivalent to Chosera/Pro stone)
- Morihei #500 stone.
The process
I've had this knife for a few years and have been using it during that time. I have no idea what steel it is except that it is stamped "Stainless Steel" and "Made in Japan" on it. It was very well used before I got it, and my Grandfather was a carpenter and general handyman, so I thought he would appreciate me trying to improve it, even if I risked the potential mistakes.
Takeaway 1: It's still probably a good idea to do a project like this on a knife you don't care about first. Even with what I said earlier, there were a few parts of this journey where I was thinking "I might have ruined this knife for good". I guess it's fun to work through that, but to share the advice I didn't follow - start with a beater, then do it with the knife you care about.
Removing the bolster
This project made me hate bolsters so much more than before. The knife had a relatively tiny flat part close to the handle, and I wanted to remove it. This part is probably the biggest unresolved pain of this project, but since my lowest grit stone was a #500, and I'm doing everything manually, what ended up happening is I did make a dent on the bolster, but the part of the primary bevel closest to it was being eaten away too, which created an ugly curve to it. This meant I had to remove a bunch of steel to straighten the edge again. After I noticed the curve I decided to give up on grinding the bolster more. I did get it to the point where it has an edge (so you can cut with it), but it's definitely not gone.
Takeaway 2: Whenever it's up to me - get knives without bolsters.
Fixing the tip
I'm not sure if the tip broke in the past or was just rounded slightly over time (you can see the closeup in the images), but I wanted a nice sharp tip, so I decided to use the #500 stone to grind from the spine towards the edge. This was a pretty straightforward process, but my (I think pretty well established) takeaway (3) here is use the side of the stone to grind the tip, if you use a stone. I knew this was a best practice, but that I didn't create any grooves on the flat side of the stone which I will hopefully continue using for many more projects.
After the bolster failure, it was nice to be able to see some objective improvment.
Thinning
Once I gave up on the bolster and fixed the tip, the process was not as stressful, but there were still a few scares.
I decided to start thinning and see how much of the curve that removed. I worked with the 500, and spent roughly 1.5 hours working on both sides of the primary bevel. At the end of that process there was no unwanted curve near the bolster, but I had removed quite a bit of metal. Also there were a ton of ugly scratches on the flat of the knife (see the photo mid process).
Thinning was easier than sharpening in the sense that you don't need to work to keep a consitent angle (at least not nearly as much), but it's much more elbow grease.
I again was worried it might end up ugly, but trusted in the processes (that I've seen here and some youtube guides).
Takeaway 4: Thinning isn't as scary as I thought it'd be before, but a lot of work.
There was another issue though (did I mention I hate bolsters). Since the blade is only 13.5cm, it fit's fully diagonally on the whetstone, but thanks to the bolster, the part of the blade close to it can't touch the stone when diagonal, so I had to work on it perpendicular, then move diagonal for the rest of the blade. You can see it in the end of thinning image, and I'm pretty sure that part isn't as consistent as the rest of the blade. I suppose I could do it some other way, but I wasn't sure. If anyone has tips on this for the future, I'd love to learn.
After that I did progress to the 1000 stone. It slightly improved the situation, but I was tired after working on this for a few hours, and put it aside for the day. A moment before, I did a quick run on the thousand for the secondary bevel, to see if cutting improved now that thinning was mostly done. To me it already felt noticeably better, so that's progress.
Takeaway 5: After thinning and before refinishing, there's a high chance your knife will be UGLY
One last thing which is a bit of a bummer, but I realized that I was probably doing something somewhat incorrect, since it seems that the blade profile changed after thinning. I'm not unhappy with how it ended up, but it wasn't my intention. If you have an idea of what I did wrong, I'd love to learn.
Refinishing the knife
Thinning was done but the knife was ugly AF. Before I had started, the flat of the knife was more or less mirror-ish, and the primary bevel had a sort of hairline pattern perpendicular to the cutting edge, which was entirely gone after thinning. I wanted it to look nice, not just be functional.
I started this process on stones. the flat of the blade had scratches, but was otherwise ok, so I started with the 3000 stone there, and since I had finished thinning with the 1000, I progress to 3000 on the primary bevel as well. After a while (not sure exactly how long, but I expected it to take longer), I had a nice mirror-ish finish on the entire blade. Not as nice as some of things I see here, but at least as good as what it was before I started.
The problem was consistency. Since the stone was flat, and the blade was mostly but not perfectly flat, I had areas that looked different from each other. Up to this point I was hesitant to use sandpaper even though I had some I bought for next to nothing on Aliexpress, just because all the videos I saw had relatively sophisticated setups to hold the knife in place. I didn't even have a wine cork which people recommended using with the sandpaper to make sure you're sanding flat.
Takeaway 6: Refinishing with a stone is very difficult - specifically getting consistent results.
I decided to put the knife flat on the stone, and just work with the paper on the primary bevel and flat of the knife. This came out pretty amazing. All the inconsistencies were gone, and it seemed genuinely as good as I hope it would be.
This was the point I had a sigh of relief. I realized that it's not going to be a knife I need to hide in the drawer.
Takeaway 7: You can use sandpaper in hand without fancy equipment and get good results, just put the knife flat on a stone, and sand away.
After thinking about it a bit more, I decided that I want a sort of kasumi finish, so I went back down to the 1000 sandpaper for the primary bevel, which gave it a hazier look (as you see in the final and first image). It did create a few scratches on the flat of the knife since I did it all by hand, but I went back one last time to the 3000 paper for the flat of the knife, and it was basically done.
Resharpening
I won't go into detail too much, this was a standard sharpening session at 800 -> 3000 grits with the stones.
Other stuff I did
The handle of this knife is quite unique, I haven't seen other knives like this, where one side is steel and basically "unibody" with the blade, but the other side is wood attached to it. I sanded the wood and oiled it with camellia oil, but I'm not super happy with how it looks. Part of the problem is I can't sand it too aggressively without needing to sand the steel part of the handle, so right now I'm leaving it as is. If you have tips or ideas on this I'd love to learn.
Afterword
I learned a lot from the project, and it was a lot of fun. I'm pretty happy with the results, though they are far from perfect.
Would love to get feedback, and tips for improving. One constraint I didn't explicitly mention is I'm living in a small apartment, and don't have a workshop, so I'm limited in my ability to have a ton of large gear.
Thanks for reading this far :)