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Marko Tsourkan

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Going to do a run of prototypes for a yanagi, garasuki, honesuki and miroshi deba in 52100
Yanagi - 270mm
Miroshi - 240mm
Garasuki - 180mm
Honesuki - ??
Honesuki/petty hybrid - 135-150mm

Need advice on honesuki length and whether to make it with a hollow ground back. What do you guys say? 135mm or 150mm? Single or double-beveled?

M
 
Excited re: the petty hybrid! My yo-honesuki is my favourite knife profile ever. And a well ground double bevel would be awesome for petty use.

For buthery, I use my honesuki *alot* and i think that a concave back would serve very little purpose. Flat-back 99-1 edge is ideal for me. 150mm gives it enough versatility to do some bigger butchery as well as just birds in my experience.
 
I made a 135mm petty/honesuki hybrid a long time ago. I shelved the project for a while, but now decided to revisit it, as my interest in single beveled knives has grown. The one I made was single-beveled and a hollow back.

The profile and geometry for traditional single-beveled knives like deba, garasuki, yanagi I will copy from my favorite makers. Basically, they should be very similar to Japanese-made, but in 52100 steel. I will harden them to 63-63.5RC.

@Dusty - flat back on honesuki sounds interesting. I think Shigefusa poultry knife is flat rather than hollow on the back.


M
 
I've never used a hollow back honesuki, what are the advantages of a hollow back? I understand with a yanagiba and deba when a large part of the blade is in contact during a slicing motion, but isn't the main action of a honesuki using the tip to separate through the joints? I don't see where there would be a problem with stiction. I may have missed the point though
 
I am not entirely sure, as I haven't really started tackling problems associated with single beveled knives, but my guess is the hollow grind on the back partially offsets the stress in steel that is created by grinding a bevel on one side only. This is just a guess, and I need to test it, but I do know for fact, when steel is removed asymmetrically, internal stresses can make steel bend or warp.

In case of my knives this will be critical, as monosteel (basically oil quenched honyaki) cannot be straightened by hand after hardening same way as kasumi.

M
 
Nice Marko, would you also be considering a smaller (180-210) miroshi deba?
 
150 for sure on honesuki. Not sure about the hollow, though.
 
Must be true single bevel. I would rather sharpen a single bevel and I prefer them in use.
 
I got a suggestion to do a flat profile and a single bevel/hollow back on honesuki/petty for ease of sharpening and use.

How critical is a curved profile for a honesuki/garasuki knives?

M
 
I got a suggestion to do a flat profile and a single bevel/hollow back on honesuki/petty for ease of sharpening and use.

How critical is a curved profile for a honesuki/garasuki knives?

M
I've used honesuki for quite a while for lots of animals, birds of all sizes, smaller (1-3#) fish and meat ranging from cleaning lamb racks and legs to trimming silverskin from strip loins. IME, just the slightest curve is necessary, and actually I think too much would take away from the great utility of the shape. That wierd triangular shape just works for its intended purpose, and more.
As far as the grind is concerned, the ones I have and use are just flat on the back and not concave. It works for me, and I usually grind the smallest little bevel on the back, although for some reason I feel like the shape probably wouldn't benefit from being 50:50.

Hope this is worth something to you.
 
Yea, I don't really see how a hollow ground back would be any easier to sharpen than the flat back. Now that I'm thinking about it, maybe it could be 165mm or so, but I wouldn't want it to be particularly long having used my 150mm.
 
Yea, I don't really see how a hollow ground back would be any easier to sharpen than the flat back. Now that I'm thinking about it, maybe it could be 165mm or so, but I wouldn't want it to be particularly long having used my 150mm.

It's easier because you're only wearing down the outside few mm of the back instead of the entire back surface area. This saves time and your stone. For a numeric comparison, lets say that we have a knife that's 6.5 in (165 mm) x 1 in (25.4 mm) = 6.5 sq inches for the entire back.

For uraoshi, lets assume that it leaves a 3 mm border around the whole of the back knife and I'm going to generously calculate the back side as if it were a square. So, if 3 mm = 0.118110236 inches then, the surface area for uraoshi sharpening is 6.5*2*0.118110236 + 1*0.118110236*2=1.77165354

So to do the flat back requires the removal of about 3.6 times the metal of a similar knife that is hollow ground.
 
It's easier because you're only wearing down the outside few mm of the back instead of the entire back surface area. This saves time and your stone. For a numeric comparison, lets say that we have a knife that's 6.5 in (165 mm) x 1 in (25.4 mm) = 6.5 sq inches for the entire back.

For uraoshi, lets assume that it leaves a 3 mm border around the whole of the back knife and I'm going to generously calculate the back side as if it were a square. So, if 3 mm = 0.118110236 inches then, the surface area for uraoshi sharpening is 6.5*2*0.118110236 + 1*0.118110236*2=1.77165354

So to do the flat back requires the removal of about 3.6 times the metal of a similar knife that is hollow ground.

Perhaps so, but in the real world nobody grinds away the entire backside.
 
You guys gave me some good ideas, thank you.

I think I am going to hollow-grind the back on the first prototype, and do the flat on the second.

If you smell more pass-arounds in the air, you are probably correct.

M
 
Perhaps so, but in the real world nobody grinds away the entire backside.

Agreed, I also just put a very slight micro bevel on the back of the blade. Mainly to assure removal of the burr and it only takes a minute.
 
Perhaps so, but in the real world nobody grinds away the entire backside.
Right, I shouldn't have implied that people are grinding away at it, but polishing to take off that burr to rezero their knife still seems easier to do on a concave back.
 
So, I took all suggestions I received from folks in this thread and ground a 150mm honesuki. I have encountered some issues, as expected and was able to work them out, and I could say that the knife is a success. It is still a prototype and I will need to get some feedback as well as grind a couple more to nail down the process, but I got to tell you, I feel encouraged. Pics tomorrow.

My next project is 275mm yanagi.

M
 
I flattened a typical honesuki profile, so it is easier to sharpen (bevel flat down on the stone), including the tip area. Back is hollow ground - I like it much better than a flat back.

I heat treated this blade the same way I do my other knives in 52100 to 62.5RC, but I might adjust hardness for later knives after I get a feedback on performance.

Knife will go out for testing for performance (geometry, edge toughness when cutting through bones, wear resistance, sharpness, etc). After I get some feedback, I will make another prototype.

My next single-beveled project - yanagi followed by mioroshi deba. All will be done in 52100 steel.

DSC_0493.jpg

DSC_0494.jpg

DSC_0495.jpg
 
Sweet. Looking forward to seeing the mioroshi deba as well.
 
nice =)

its like 52100 honyaki ?

first single bevel knife ?
if no , please link with your another one.

what spine thickness at the heel ?

i use global_g7 for allpurpose line knife on sushibar, besides cutting rolls(yoshikane suji here, yanagis is too thick for more rolls).
http://www.coltelleriacollini.it/intershop/Large800/g7.jpg

now i think about some Honesuki, he can take a seat =) for allpurpose knife.
 
Sorry, missed these questions.

Yes, you can say that 52100 is heat treated similarly to how Japanese heat treat oil-quenched monosteel blades - honyaki. It's different than mizu-honyaki (water-quenched). Also, 52100 is deeper hardening steel, so applying clay to the spine won't produce similar hamon figure as on white or blue steels.

Spine thickens at the handle will vary from 4.5 to 3mm, but over heel the spine thickness will be in the area of 3.25-3mm on all knives larger than 180mm. This is intentionally, as the knife gets a sturdy, solid feel.
 
In the next couple of weeks I will finish a prototype drop point I started some months ago, as well as a neck knife I am going to gift to a friend. Still working on design and haven't selected the steel, but leaning AEB-L or 19C27, or 52100.

Resurecting a 3 year old project of a modified honesuki/petty knife. Probably 135mm. Traditional single bevel, hollow back, fairly thin, so could be used as a petty. Will have a prototype in a couple of weeks. If well received, will offer it in carbon, stailness and damascus san mai (monosteel core, damascus front, two layers)

Changing honesuki profile. Prototype in a couple of weeks, and this one will be passed around.

Western handled scimitar prototype (modified profile of a classic scimitar), as well as Western handle gyuto (also prototype) will come sometimes in February.

Yanagi prototype 2.0 will be done sometimes in February after I receive a feedback on verions 1.0. If well received, it will be offered in 52100, and 52100 damascus san mai (two layers, plain steel in the back, damascus in the front)

That's all.
 
Your a busy man. Great stuff Marko, very exciting!
 
Marko,

You are really blazing some new and exciting trails. The single bevel really looks great. I can tell you're going to have a very busy year coming up.
 
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