How to Find the Sweet Spot of a Katana for Cutting

In Japanese swordsmanship, we’re taught to cut with a part of the katana called the monouchi, which is loosely defined as one third of the blade from the tip. But where exactly on the monouchi is the sweet spot?

Dojo etiquette disclaimer: if your sensei teaches you a different way, please follow the instruction of your own sensei.

[CraigHocker]

As another science nerd and Iaidō practitioner, I appreciate this video very much. Nicely demonstrated. Thank you.

[gardehusar]

I really really love that you are so scientific and technical about the aproach to this ☺

[charlescarr]

Great video and I will definitely be keeping this in consideration during my next cuts. Truly amazing how much power these can focus on such a small area.

[grndragon]

The trick with the finding The Sweet Spot with a stick was awesome when I tried it

[ronin]

Great video, excellent instruction and information, thank you very much for sharing your knowledge

[stejada]

Very interesting.
There is an outstanding improvement on the use of the audio-visual component. Very didactic.
Congratulations Paul Shin! Keep them coming...
Santiago

[wishicouldshowmyname]

Very interesting and very good directions.

[jimshady]

Thank you for the very helpful information i really enjoyed learning more about the Katana. Atb - Jim

[yeaman]

Great video! The scientific side interests me greatly. I'd love to see more videos like this one dealing with actual information that will help my tameshigiri form and such. Nice tsuba on your iai, you have good taste. I have the same on my iai and shinken.

[arikukatoyamasaki]

Very interesting and well made video! Keep up the outstanding work and progress.

[seraphik]

3:19 my eyes popped at that. it's like that blade came alive in that instant.

[boojizog]

Really nice video! Love the links to nerd out on. I am curious is there a method where one can find the sweet spot on shinai as well more out of curiosity than anything else.

[gordonhall]

I love you geeked out on this. Put all that physics to use. :)

[luongkevin]

Thank you for a great and very informative video.

[space_time]

Very informative thank you for the video. You also have some of the most well made katanas I’ve seen. Can you tell me where you got them from?

[erichusayn]

Thanks for the info. Been wanting to use a marker for similar reasons and was unsure if it would wipe off...

[MrCopcon]

Thank you very much for very useful information.

[humanyang]

Thanks a lot. I'm asking about if the theory is right for the daito and shoto of Nito-ryu. Cause the player is using only one hand to hold the daito and shoto, so the weight of hand and arm is halved. I guess the weight center is far from the normal position. Should the sweet spot be closer to the tip of the sword? Should the right sweet spot change from 1/3 to 1/4 when holding the sword with one hand?
[Edited]
I think about your video again. I think your test is to find the first point of the edge behind the weight center of the sword. Cutting the target behind the weight center will let the impact force turn the sword toward the cutting direction automatically which stables the sword. This is the benefit of cutting with a curving sword or knife. If testing with a straight sword or knife, it should never stand up.

[akioutsunomiya]

thakyou for that information that is good for me thankyou

[ryanvella]

Hi Paul, great video. Thanks for sharing. What does it mean if the sweet spot is all the way at the tip? Thanks