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Motohaba According To Nbthk


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Recently i been studying some Juyo papers and i found out something odd, it seems that NBTHK considers the measure of motohaba from the ha to the base of the mune, not like i've always been told, from the ha to the top of the mune. In some older paper it appears to be as mine, but in last years seems something changed.
Did someone else notice that too? Or have an explanation?

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Actually also in the bulletin by NBTHK  it seems that they apply this method of measurement. I checked the last Shijo Kantei To No. 742, the same one released in October 2012, in which the oshigata are in 1:1 scale, in both it is reported "Motohaba: 6 bu 9 rin (2.1 cm)", measuring with the caliper we understand that Manuel is right..

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Do you have certain examples to share Manuel?


I have been documenting the swords from NBTHK magazine issues as well as from other written sources I have and I have noticed there is often a slight differences in the measurements between sources. It gets difficult when multiple sources have some millimeters of gap between each other. I have used NBTHK's measurements as the ones I trust as on some occasion sword might have slightly different stats in 5 references for example... And there has been few times when NBTHK's monthly kantei sword has had slightly differing measurements on a second appearance.


For example one such example that has varying measurements by NBTHK is Jūyō Bijutsuhin tachi by Ohara Sanemori. So far I have documented this sword appearing 6 times in Tōken Bijutsu magazine in the last bit over 20 years.


When it was the famous sword (issue 706) it had following measurements. Nagasa 70,2 cm / sori 2,2 cm / motohaba 2,55 cm / sakihaba 1,65 cm / motokasane 0,45 cm / sakikasane 0,3 cm / kissaki 2,4 cm / nakago 21,95 cm / sori 0,3 cm

When it was up for kantei (issues 590 & 628) the measurements were. Nagasa 70,3 cm / sori 2,12 cm / motohaba 2,6 cm / sakihaba 1,6 cm / motokasane 0,65 cm / sakikasane 0,25 cm / kissaki 2,4 cm / nakago 21,97 cm / sori 0,3 cm

Then the same tachi is in Meihin Katanaezu Shusei with measurements. Nagasa 70,3 cm / sori 2,3 cm / motohaba 2,6 cm / sakihaba 1,7 cm / motokasane 0,5 cm / kissaki 2,4 cm / nakago 22,6 cm / sori 0,3 cm


Another tricky one would be famous Kokuhō Meitō Koryu Kagemitsu. It is featured in several references that have slightly differing measurements.


Tōken Bijutsu 487 has Nagasa 73,9 cm / sori 3,0 cm / motohaba 2,9 cm / sakihaba 2,0 cm / motokasane 0,7 cm / sakikasane 0,5 cm / kissaki 3,0 cm / nakago 17,5 cm / sori 0,3 cm

Meihin Katanaezu Shusei has Nagasa 73,9 cm / sori 3,0 cm / motohaba 2,9 cm / sakihaba 2,0 cm / motokasane 0,7 cm / sakikasane 0,5 cm / kissaki 3,0 cm / nakago 17,5 cm / sori 0,3 cm

Nihon no Bi by Gakken has Nagasa 73,6 cm / sori 3,0 cm / motohaba 3,0 cm / sakihaba 2,0 cm / kissaki 3,2 cm / nakago 17,3 cm

eKokuho database has Nagasa 80,6 cm / sori 2,7 cm

Most other references I have this in have Nagasa 73,9 cm / sori 3,0 cm


While the differences are minor it is really frustrating when trying to document the measurements of the sword. I am not exactly sure how the experts actually measure the swords but few millimeters might be easily mistaken. There have been many times I've seen that measurements on a Jūyō paper and measurements of the website selling the sword are different sometimes on all measurements. On those occasions I have trusted the Jūyō paper over dealers measurements.

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Sorry for the late reply Jussi, i was looking for a good example.
This is a famous tanto by Ryosai, it's also been proposed as kantei by NBTHK with the following dimensions:

Type: tanto
Length: 7 sun 2 bu (22. 0 cm)
Sori: slight uchizori
Motohaba: 5 bu 6 rin (1.7 cm)
Motokasane: 2 bu 1 rin (0.65 cm)
Nakago length: 3 sun 4 rin (9.2 cm)
Nakago sori: very slight

This is what i measure from the scan took from http://www.sho-shin.com/sai.htm


Even considrering a conversion approximation and a possible parallax error from the picture the difference is too obvious for me, especially the other dimensions are much closer to what NBTHK states
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I have that tanto also in the Tantō book and it is listed with following dimensions there


Nagasa 22,0 cm, motohaba 1,9 cm, motokasane 0,6 cm, nakago 9,0 cm


And Sho-shin website seems to have


Nagasa 22,1 cm, motohaba 1,8 cm. nakago 9,4 cm


While these are miniscule differences in the big picture they are troubling me a lot.

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and another one, this one is a katana from https://www.aoijapan.com/katana-bizen-suke-fujiwara-munetsugu-saku30th-nbthk-juyo-paper/


Aoi's measures:

Blade length(nagasa) : 72.0 cm or 28.34 inches.
Width at the hamachi : 3.20 cm or 1.25 inches.
Width at the Kissaki : 2.50 cm or 0.98 inches.

Juyo paper's:
Nagasa: 72.0
Motohaba: 3.05
Sakihaba: 2.2

here's my measure from the scan:

Now appears clear to me that they measure from ha to the base of mune, not like i always been told from ha to the top of mune
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For Kinmichi I think Jūyō paper states: Nagasa: 41,65 cm Sori 0,9 cm Motohaba 3,3 cm Nakago 12,0 cm

Aoi art gives these measurements: Nagasa: 41,6 cm Sori 0,4 cm Motohaba 3,4 cm


In these the 0,5 cm difference in sori measurement is troubling me.


For Munetsugu the difference between sakihaba measurements is a mystery to me. In NBTHK measurements there is 0,9 cm change between moto & saki where as Aoi's measurement only show 0,7 cm change? Motohaba measurement being lot closer to each other than sakihaba measurement.


Aoi measured this sword 74,1 cm while NBTHK paper states 73,6 cm. https://www.aoijapan.com/katana-mumeisa-hiroyuki62nd-nbthk-juyo-paper/ 0,5 cm difference in length is a lot but moto & saki on this one are just slightly different from the paper.


Here there are only minor differences in sori and length but motohaba & sakihaba match by Nipponto measures (yet in some of their measurements there might be 1mm difference in width which I think is just tiny measuring difference)


http://www.nipponto.co.jp/swords3/KT326740.htm(I am pretty sure the sori is supposed to be 1,3 cm but they mistyped in 2,3)


Taiseido tends to have exact measurements that are in papers




Samurai-Nippon only has under 1mm differences to papers usually



https://www.samurai-nippon.net/SHOP/V-1726.html(except for this one)


I cannot really explain why there are so big differences in measurements, my gut feeling is that either the sellers or the NBTHK are not stressing the millimeter accuracy of their measurements (even though it really seems like they are as NBTHK can give 0,05 cm accuracy and some dealers give 0,01 cm accuracy measurements).

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I was doing some pixel analysis by photos and in general the measurements seem to be pretty close to Jūyō papers by pictures of some sellers. However I noticed that Aoi Art generally enhances the mune way too much in their pictures. As I have purchased one tachi from them and did pixel analysis on their picture, it didn't match and I have the accurate measurement as I can take it by caliper.


Every other measurement about matched the Aoi picture except the measurements which included the mune. For example for my tachi the mune in reality is very small I had about 1mm difference at motohaba and at sakihaba the difference is so small that I cannot properly measure it. Mune height at that point is most likely under 0,5 mm, as I couldn't get really measurable difference trying to measure on top of mune or without mune. However when I did pixel analysis on the Aoi picture they have greatly enhanced the mune. The mune alone at sakihaba is 15 pixels in their picture which will alter the actual measuments of the sword. I measured the sakihaba being 1,9 cm as that point the sword will fit between the caliper. But from the pixel measurement from Aoi Art picture it would give me about 2,1 cm sakihaba. Aoi Art had exactly correct measurements in their sales description for my sword though 3,0 cm motohaba and 1,9 cm sakihaba.


But I wouldn't trust their pictures for fine measurements by pixels as they do enhance the mune of their swords for pictures.

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i guess then only someone with a juyo blade that can actually measure it with his hands could solve this mistery, tho to me this situation is really bothering (probably cause i work in the mechanical industry), how hard can it be to use a caliper??

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