Incredible video

To get the concave grind, it looks obvious (but we could be totally wrong) they allow for extra maybe 1mm-2mm thickness on the flat side, do the hollow grind all the way up to the tip/edges, and then thin it by grinding the flat side, resulting in a frypan shape and a very even hollow. Only say obvious because we use yanagibas as fishmongers a lot and the hollow runs all the way until almost the tip.

now I understand why they say the honyaki is much harder than the laminated blade. When it's laminated you can tweak it any time with a bit of bending , and with a piece of mono steel you just have to be perfect. Very interesting and helpful video , thank you for documenting and sharing your learning process.

I'm super duper excited! Can't wait for it 😱 I'm curious how you make the Ura. 💪

Awesome video man, it really helped me understand single bevels. Time to practice ura grinding some more :>

A couple of South African grinder manufacturers have table that sit under the wheel which allows you to use the table as a work rest and also to see what you're grinding. That setup might help you with the Ura.

Don just spitballing here but what about using a radiused platen to get the middle section done, then a smaller wheel like you have, or maybe in 4 inches to get the edge and spine then going back to something like a felt radius platen to blend it? all while using a pivoting work rest that's not too wide (like as wide as the belt) so you can pivot the knife as you get towards the tip. Edit: I'm just now realizing we have no idea how "in the past" this video is and you may already have a solution

Great video, thanks for sharing your knowledge ✌️ pretty excited about the interview with Jon Broida. Thought I saw it in the past but can't find it anymore 😔

straightening technique on the little hammer by luciano dorneles from Brazil

First.

This is great seeing the process after handling the finished piece at Travis'. Thanks for sharing your process.

日本の庖丁に興味を持っていただき誠に嬉しい限りです！ 和包丁の名産地、大阪は堺市に是非行ってみて頂きたいです。 I’m so impressed and happy that you are interested in Japanese knives. I really want you to visit the most famous Japanese knife industry place in Sakai-city in Osaka prefecture. I’m working in a knife shop which is located in Kappabashi in Tokyo so if you ever think of coming to Tokyo, you should visit our shop!

I know by now you already completed the project (I am a bit late on this serie of videos) so I don't know if it will be helpful but in razor making we start the compound grind using a wider radius first to set the bevel width, then we change the wheel cutting the diameter in half for each pass (for example 8", 4", 2"). That gives us crispy lines and a very uniform compound hollow. Granted, razors are a lot smaller and thicker and the hollow is not in the middle of the bevel... thank you for sharing your journey!!

Heat treat the blade blank before bevel grinding and use Norton blaze ceramic abrasive belts dip in water often each pass keep cool 36g then 50 or 60 grit next 120 can go finer with aluminum oxide or Norton norax belts then cork belt then scotch bright finish belts and if want polished go on to buffer

Super excited for this!!

Hollow ground backsides are seen in high end chisels and knives. It allows the maker and user of the knife to be able to make the backside super flat without having to deal with or grind alot of real estate. You just have to flatten a small surface area to help you make the sharpest edge possible One downside if that if that perimeter gets too narrow from use or sharpened incorrectly then the knife is trash as there is no way to recreate the hollow ground backside once the perimeter is gone....it is impossible to repair The ability to release any suction on the flesh of the fish is also likely important as these knives are specifically made long to be able to cut the fish in one pulling stroke rather then sawing and the decrease resistance to the pulling due to a sharp edge, small surface area contact due to its thin profile and hollow ground all play into the design.

There's been a ton of talk on BladeForums about carbide hammers for straightening too. I'll have to try making one too! Thanks for taking the time to put this together and document your process. It's super helpful and interesting!

Another great video (also really good job on keeping the video at Jon Broida's shop consistent visually with video at your shop (like, remote video spots often look fucking blair witch in comparison visually because the lighting is completely different then your staged home lighting rig)) looking forward to ep2!

Looks like a yanagiba any% there, actually about the warp you have to undestand that they grind it on huge round spinning wetstones wich minimise te warp, in addition to that, they have wooden "platens" that hold the knife in place and baking it up at its fill contour, the compound grind is done just liek you did there, the deep part is horizontal to the wheel and the more shallow and wider part is diagonally to the wet stone. Im taking a guess here but im pretty positive that the grind the hollow part fully, from the spine to the edge but then just put it on sharpening stones to make that flat spot. Also the sick hollow grind also helps to prolong the wetstones life, because theyre not cheap, and never actually were (the natural ones) so in addition to air pocket that was another reason :)) great work keep it up!

I've only made two, so take that into consideration. But, in doing my research and comparing, I noticed the same semi-stepped Ura on the back of the blade. I made mine by using a wheel to set the central / deeper ridge. I then followed up with a 36 inch radius platen to bring the Ura closer to the spine and edge creating a full convex on the rear of the blade. I finished and blended/dialed it in by hand with paper and stone to get about 1/16 off the edge and slightly less from the spine. Might not be the perfect way to do it but, it seemed to provide the best overall order of operations in my practice and final attempts. I'm sure you've figured out a better way by now that we'll see in future videos but, thought I'd share just in case.

Maybe some of my comments might be obsoleted by watching your other videos I made 2 yanigaba in my life (mono steell full py hardened) Knife 1 I could finish successfully. I warped a bit but I could straighted it). I muts admit my ura sucked (I gotvit blended in but not very fine) but I got the knife sharp. Knife 2 warped significantly. It was more like a banana. I tried to straighten it but during that procees it cracked. Knife 3 is in the making, raw blade is shaped and heat treated but no other grinding done yet. About straightening of a warped blade. I made an apprenticeship as a tool aand die maker. Most of thin tool parts came warped out if heat treatment. Before further grinding we straitended them by hammering. We used small ball pen hammers, same principle as a carbide chissel hammer but not as aggressive. As you learned by yourself there is a limit you can fix with this. As for hollow ground. It needs a lot of practice. For my first ura I established a center hollow grind with a smaller wheel then then switched to a curved platen and widended the grind gardually. You are right you can’t see it but with practice you can feel it. As practice try some hollow ground hunting knives. I also made two straight razors, both is a good practice. And I always gring standing, sitting down tenses my body two much and I loose control.

Have you tried lapping in the Ura with a wet stone or granite block and sandpaper?

You Used It!?!

Wouldn't it be easier, to first do the urasuki from edge to edge and then make the edges flat for the uraoshi?

I love the unga-bunga caveman hammer! Years ago I got a commission for a Kiritsuke which is basically something I never make out here in the backwoods of Australia. Its got the same sort of weird hollow-compound in the back and single bevel setup. Hmm I thunks to myself, how I into this geometry without making boomerang? So using the greatest western minds which aren't mine, I just grabbed the most dimensional stable billet of steel I had in the whole shed- big ol lump of D6 ledeburitic which is just heaps of carbon, tungsten and chromium that just turns into crazy lumps of carbides to the point its just god-awful to sharpen, but it never really gets blunt either. I think it took 3 x 2h tempers just to get it a bit tougher at 62HRC but it didn't warp! No way in hell even at about 80% done to shape at the air quench it hung in there somehow and all the subsequent grinding after that. Anyway, that's all I've got to add and good luck!

There is a pretty good amount of information out there.

You‘ll need a bigger hammer 😅 all joking aside, the carbide hammers we use for straightening blades are a lot heavier and you basically just use the weight of the hammer and the bounce of the anvil to set your marks. Think about one kg/ two pounds of weight of the head. You‘ll get marks that you‘ll need to grind out but the effect goes pretty deep…

Super interesting build, and very informative video! I wonder if there is a way of using a mill or CNC to carve out the back of the knife before heat treat?

7:30 seems to be the key here, i never seen a mono-steel single bevel knife from japan. i wonder if it will make your life easier if you start here. and japanese smiths definitely grind with jigs on whetstones, i cannot imagine free handing that kind of geometry.

I'm no knife grinding expert... but I have a suggestion, you can take it as a grain of salt.. If you used a press with a "Jig set up".. I.e.. some round stock, that was the right size, that was parallel to the metal being worked, to mash your metal, into the "U" shape, your wanting, BEFORE you start grinding on it, , then you could just gently nudge the metal into the "U" shape your wanting... And then just go to town, removing material.. on your belt grind on the flat part.. That would automatically give you your desired outcome, at least that's how it'd work out in my imagination. So maybe you already thought of this? maybe you didn't? but that's how I'd tackle it... rather than trying to do it AFTER the fact.. Hope this suggestion gets the creative juices flowing for you?

how useful do you think a metal scraper would be? say a really hard W2 blade. I think sword makers used them

Get u a 10 or 14 inch wheel

You're doing the hammering wrong. You hammer to the inside of the warp and the metal spread by the peining corrects the warp. It works because you're hammering on a flat and hard surface, but it's going to keep warping unless you do it correctly. You'd be better off hammering with a mallet on something like a wood block, which shouldn't be as dangerous as hammering on a monosteel blade.

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