mas4t0

No need to oil a tsuba, just be sure to store it properly; a kiribako is best.

Thank you all. I'll join once I know I can somewhat consistently commit some time. That'll probably be a few more years, unless I drop something else.

The same law applies. Be sure to declare it and to have all relevant documentation with the blade. You'll need to persuade the Border Force officer that it's covered by one of the exemptions and is legal in the UK. If you have a JSA licence, this will be helpful to keep with you too as it provides an additional exemption. I've found that they tend to be quite trusting of almost anything in writing. I like to write or print out anything I'm going to say about the blade and keep those documents with it. It's well worth the preparation, if the officer isn't convinced and decides to seize it, you'll be without the blade while you appeal the seizure. This document has more detail and I believe is the guidance referred to by the Border Force.

Exactly Jeremy. There's also the issue of the form, weight and strength of the user, and the nature of the cutting medium; which will determine the magnitude of the forces exerted and the proportion of those forces acting along the y-axis. Lots of variables, and if we were doing this properly, we'd want quite a large safety factor to help account for the uncertainty. I realise that in all these posts I never answered your initial question, but hopefully some clarity has been provided all the same.

Barrett, I'm still confused as to why you want to use an antique blade in this way. I just don't understand why you would want to, given what you know of the risks and cost implications. It's not that: you think that antiques are functionally superior. you think that antiques are somehow magical and impervious to damage. So is it that: you're a risk taker and the possibility of losing $10k+ on a single swing excites you? you like the idea of leaving your mark on an antique blade? you're not actually intending to, but like the reactions you get? I'm genuinely curious of the motivation.

Barrett, I'm sorry you feel that way. It might not feel like it, but people genuinely are doing their best to assist you. There's a thread here from a member who's unfortunately had issues with his shinken bending when cutting after having a bohi carved in it. An art sword may be more prone to bending from the day you get it. The first bend, after professional straightening, could easily wipe more than 90% off the value of the blade depending on the marks (kizu) left on the metal and it can never be repaired. This particular forum is focused on the study and preservation of Nihonto, so you will get responses along those lines. I notice that your mentioned at some point being stabbed with an improvised weapon. I was too. A little under a year ago I almost died while protecting an old man and a young woman from a lunatic who armed himself with a broken bottle after I'd disarmed him of his knife. Many others here have similar experiences and there are many military veterans here too. You have the wrong impression of the members here. Please trust me that we are genuinely trying to help you avoid a costly mistake, a mistake that some members here have no doubt made.

Thank you Ian, the information provided clarifies a number of things. Regarding groups... I have no proper background in the humanities, so would likely waste a lot of everyone's time asking things which would be expected pre-requisite knowledge; online it's easier for people to ignore me if I'm bothering them. Books also feel much more efficient. I can get though several hundred pages per day, but I'd waste countless hours of someone's time to get the same understanding. I also rarely have enough time on my hands to attend things. I have quite a bit of time at the moment, but that's unusual for me and won't last more than a few more months; I generally struggle to maintain decent attendance at any of the groups I am part of.

Thank you Michael.

Ian, I'd love to hear more of your thoughts and experience on museums, especially regarding their proper role and how different priorities are (or ought to be) weighted. If you've ever discussed this in a book could you please point me towards it?

The craftsman carving the bo-hi is (presumably) not an engineer, so there's no way he'd be accurately taking account of the engineering mechanics. When you cut with the blade, you're exerting a bending moment on the blade. The stiffer the blade is, the less it'll flex, and the less it flexes, the more likely you are to remain in the elastic region and not plastically deform (permeantly bend) the blade. Had you consulted an engineer ahead of time you could have optimised the depth and width to remove the necessary amount of weight or change the dynamics of the blade as required, with minimal y-axis loss of strength and stiffness. A deeper bohi will make a louder sound during Iaido practice. The hi could have been wider but cut more shallow or otherwise cut differently to better optimise for your needs. It may have been that through engineering analysis it would have been determined that the blade could not be lightened to your requirements without compromising it to too great of an extent. This kind of analysis is not standard when carving a bo-hi and would be prone to inaccuracy due to the metal not being homogenous and the internal lamination structure of the blade along with the specifics of the heat treat and metallurgy being unknown. With an iron core, the loss of overall strength and stiffness when removing the steel is greater than you would expect for a homogenous piece of metal, as the steel contributes disproportionally to the overall strength and stiffness of the blade. If you cut a bo-hi on a blade with an iron core, you'll have lost much more strength than the loss of web-thickness would lead us to expect (on a homogenous blade). I assumed that the blade did not have an iron core, as you would presumably have reached it at this depth of carving. All the same, analysing it geometrically would help understand the likely effects of altering the geometry (by carving a bohi). I would guess that the craftsman carving the bohi carved it at a standard width and the depth was determined by the weight of metal to be removed. It sounds like you now have an ideal Iaito and will be well served by a separate shinken. It's not particularly uncommon for horimono to pierce all the way though the blade as part of the design. I certainly wouldn't recommend this on anything other than an art sword. The person who carved it will be able to tell you more about the decisions made than we ever will. How did the carving come about, what was the brief and which questions were asked at the time? What purpose would it serve to know the depth of other bohi? Even for a blade used in a cutting test, which had a bohi at the time (likely unverifiable), you'd need to know the complete geometry of the blade (at the time), the metallurgy and the internal lamination structure. Even this wouldn't be particularly helpful as you don't know if it was a fluke or a case of perfect tenouchi reducing the need for high y-axis strength.

Great result! But where'd the breadknife go?!

I'll PM you Barrett.

Barrett, I'd advise a shinken made from modern steel. Modern steel will give better edge holding, higher strength and higher toughness. It's not really a matter of safety. Cutting with a blade is putting miles on it; you're using it as a tool instead of an art object, so you're not preserving it. At best you'll scratch the polish and blunt the blade, necessitating further polishes which remove metal. In all likelihood you'll bend the blade of a Nihonto by cutting with it; causing kizu and you might might eventually break the blade. If you're fine with damaging and maybe destroying the blade, you can use anything you like. If you want the best tool for the job, with the best edge holding, strength and toughness, you want modern steel. Is there any particular reason you want to use a gendaito or shinsakuto for tameshigiri? If you do go that route, be sure to refer to the guidance of Nakamura Taisaburo (or your sensei) to ensure that you commission a blade well suited for cutting and sized appropriately for you. Many katana are not well suited to tameshigiri or to Iaido more generally. For tameshigiri I use a custom made hira-zukuri katana in 1086 steel and many other practitioners of JSA here make use of production swords from China. In any case, be sure that you're buying a suitable shinken and not a blade intended primarily for aesthetic appreciation. Nakamura's Spirit of the Sword will help you find your bearings.

Hi Jeremy, Thank you for clarifying. I was unsure if you were enquiring about an art sword or a shinken. I'm sorry to hear that, but with that in mind it seems that you've proven experimentally that the blade has been perhaps compromised too much. I don't have all the measurements needed to calculate it, but I would guess that the bo-hi described would weaken the blade by less than 20% along the horizonal axis, but perhaps more than 60% along the vertical axis. I use a thin, modern steel hira-zukuri for tameshigiri. I've never had any issues with bending and the blade is very light. Maybe something along the same lines would be a suitable option and this blade could be reserved for kata?

Too deeply in what sense? Are there shinae (ripples or wrinkles in the skin steel) due to bending in the past? If not it's likely not a problem. Are you using the blade for tameshigiri and concerned about it bending in use? If not, it doesn't really matter unless it interferes with your aesthetic appreciation of the blade. A deep hi could have been cut to remove a flaw from the blade; there's likely a reason if it is unusually deep. You can use the calculator above to see how significantly the bo-hi affects the capacity of the blade to resist bending, but you'll need some more measurements. That'll give you a quantitative understanding of the extent to which it's been weakened. Nihonto without a bo-hi will easily bend on an off-angle cut and a bo-hi will invariably weaken it further.

I don't have any examples for you, but it makes less of a difference than you might expect. From a mechanical perspective, a bo-hi effectively creates an I-beam with quite significant flange-thickness. Even when the web-thickness is quite thin, a significant proportion of the original strength and stiffness are maintained. The losses in strength are only particularly relevant on an off-angle cut. This calculator will let you compare the second moment of area for an I-beam Vs a solid rectangle and the diagram will give an indication of all the relevant measurements.

My apologies Adam, I notice that you said as much in your initial post and I missed it somehow. I understand the difficulty of finding places for things, it's always difficult. While an unconventional display, it's clear that you put a lot of time and effort into arranging the room. I think it works nicely as an overall composition. There's someone a little strange about how the armour is sitting, the neck looks quite elongated and the sode are touching the neck; can it be adjusted a little on the stand?

I have to ask; is the armour on your side of the bed or your partner's?

How'd you end up here 2 years late?

Antler and bone are primarily ossein, and have a Mohs hardness of around 5. Ivory, tusk and tooth are primarily dentin, and have a Mohs hardness of around 3.5. Horns and claws are made up primarily of keratin (the protein found in hair, fingernails, and animal hooves), surrounding a core of live bone. Keratin has a Mohs hardness of around 2.5.

"Nanban tsuba" literally "Southern barbarian sword-guards" is a catch-all for tsuba that show foreign influence. I would assume they're much rarer at Juyo level as they're much less likely to be culturally significant to Japan. As with Nihonto; history, traditions, schools, makers, development, etc are all important factors. For a nanban tsuba to present all of these factors to such a level that the NBTHK determined the preservation of the tsuba to be of historical importance (for Japan) is quite unexpected and unusual. That's not to say that they aren't exceptional pieces of work, along with many other nanban tsuba, just that other tsuba would seem to have an advantage when it comes to receiving Juyo papers. Clearly the examples here are truly exceptional, given that they were awarded Juyo papers.

The issue is generally workmanship and artistry rather than how elaborate the piece is. You could start by comparing the piece for sale here with the one in this thread: Perhaps this article will be helpful: https://blog.yuhindo.com/fungible/

I agree that they're massively underpriced in general, especially compared to their manufacturing cost. I think it's worth defining what you mean by high prices. I've rarely seen a tsuba below $1k which I would care to own, but the value is undeniable when you consider it to be a centuries old hand made art object. I think pieces at this level of the market see a lot of volatility (proportionally) as the amounts involved are quite small. Someone paying a few hundred dollars above the going rate for a piece they happen to notice and take a liking to can skew things quite significantly. In the $5k-10k range, I've often seen pieces which were technically masterful but in many cases are somewhat of an acquired taste due to subject matter; Dragon turtles, Japanese tigers, etc. When we get up into the range of $20k plus, there are few pieces I've come across that I wouldn't consider a masterpiece. These tend to align well with our sensibilities and I'm sure they would be worth many times more if they were not such an obscure art form. At any level though I think it's best categorised purely in terms of supply and demand. I don't think it's an art market, as I'm doubtful that anyone is seriously investing in tsuba.

I always buy my supplies from the site I linked above: http://www16.plala.or.jp/katana-iimura/kiriteiregu-e.html I go with the Extra special : domestic "Kozo" I don't think the cost difference is enough to justify the use of lower grade niguiami. Abrasives in the paper could easily damage the polish, so it isn't worth skimping to save a few $. As for oil, I buy it from the same place, but you can also use pure mineral oil (the type you can buy from pharmacists in the UK). Choji is a mineral oil and clove oil blend. Mineral oil works just as well but it's unscented.

I use a kit from here: http://www16.plala.or.jp/katana-iimura/index2.english.html#Care tools This one specifically: http://www16.plala.or.jp/katana-iimura/kiriteiregu-e.html But I only use Uchiko on shinken (swords for martial arts use). They also sell the supplies and tools individually. Edit: Seth linked to the same kit, being sold by a different seller. It's a good kit, I'd go with whoever is more convenient for you.