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I just had first lesson in Aikido with Jo and was surprised to see that some of the staffs were octagonal and some were round.

Can someone explain what is the difference and if there are any advantages to round or octagonal shape of the Jo?

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Could it be weight? – Sardathrion Sep 12 '12 at 8:56
We teach to think of a bo or jo as no different than a sword or a chain; you learn to lock with each, to tie with each, and, most relevant to your question, cut with each. Other claims I've heard are that it improves grip and durability; I've not looked into these claims much. – stslavik Sep 12 '12 at 15:41
up vote 7 down vote accepted

My suggestion, based purely on experience as a wood worker, would be that octagonal staffs would traditionally have been easier to make.

The machines we have available these days can bang out nice round dowel pretty easy, but once upon a time, these things would have been make by hand using tools like planes and draw knives. Using tools like that, an octagonal shape would take half the amount of time to make.

Perhaps other traditions have grown up around the use of the different shaped staffs, but in my opinion, that would be a separate issue.

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Interesting. I would think that a staff would have been traditionally round seeing that sticks and trees naturally grow in that shape. It would seem easier to smooth out the roundness of the staff rather unless the octagonal shape had a different purpose or meaning within a style. – Matt Chan Sep 14 '12 at 0:23
@Matt-Chan, that would be true if you are using a stick that is the right size, but typically you would be shaping things out of a board from a larger tree. This gives you much more control over the grain in the final weapon. The straighter the grain, the better. – nedlud Sep 14 '12 at 1:21

Fascinating question; I'd like to know the answer. I found one potential answer:"The octagonal cut of all the staffs also gives you nice surface contours for locks and submissions."

Several sources (none of which are reliable enough to quote) imply that octagonal weapons are associated with Okinawan martial arts, but that seems to be in the context of the nunchuku.

I spoke with one of my favorite jo authorities (whom I didn't obtain permission to quote/name) who relayed that one of his colleagues has an octagonal jo. Apparently,

One of my friends who does SMRJ has one. Supposedly it's "Gonnosuke style" It will cut you!! He emphasis striking with the edge of the jo's tip, like using the corner of a very small table that is moving very fast...

I've found another author who suggests that the octagonal edges can cut

The hakaku-bo, however, was octagonal, and its angular edges made it viciously effective when unleashed against an unprotected target, since they cut along with the strike. Dave Lowry also a nice, readable, survey of jo training

This provides another potential alternative answer, although it involves some inference. Apparently the "Pilgrim's staff" or Kongojo is octagonal, and there may be a separate formal school of training for combat with the kongojo.

*update: Caveat: the following is personal opinion Looking back over all the answers, I'm unconvinced by the "more wood" and even of the "Gonnosuke" answers. With respect to the "Gonnosuke appellation, although I don't deny that vendors may sell octagonal jo as "Gonnosuke style", I'm skeptical that the octagonal jo is connected to the founder of Shindo Muso Ryu Jodo in any linear fashion. (Although I studied SMRJ for a very short time, my SMRJ teacher required round weapons, and I didn't find any mention of octagonal jo's in any of the SMRJ websites I visited. I would expect that if anything were "Gonosuke style", it would be SMJR).

As far as the "more wood" goes, the only way that I can imagine that making a difference is in placing more mass on target; as others have noted, I'm not sure how much "more mass" would be involved. Furthermore if the goal is to increase the mass*velocity equation, I personally would choose a denser wood rather than an octagonal shape.

I think the most credible answer I've seen is "personal preference".

However I'm eager to see any support for any of these hypothesis, or even new hypothesis.

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@MatBanik Obviously that depends on what you consider the "radius" or "diameter" of an octagon. Normally the "radius" of a regular polyhedron is measured from its center to any of its vertices (circumradius), implying an octagonal weapon would have less wood than a round one. – Dave Newton Sep 12 '12 at 23:38
I'd say the edge would cut you no matter what shape the bo is. The edge will be sharp on either version. – Bushi Sep 25 '12 at 13:39

Octagonal weapons are less prone to torque out of your grip; same reason bolt heads aren't round–the flat edges give the weapon a means to find purchase, against the bones and skin of the hand. Whether it's enough of an advantage to prevent disarming, different issue. The disarms we practice in my FMA classes aren't turn-the-stick-on-its-axis disarms. Every little bit helps.

I hear claims they'll do more damage because you can "hit them with the pointy part", but I don't see how that would be possible in a combat situation. Even if it was possible to align a strike in that fashion, I'm skeptical the difference would be worth any effort.

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Lacrosse Sticks, which definitely do experience similar amounts of torque, have a squashed hexagonal cross section for this reason; the corners and non-round shape help you keep your orientation. You can see ovular cross sections on sword grips from many cultures as well. Once again, that is to help keep orientation, and in the case of swords, keep good edge alignment. – PipperChip Dec 15 '15 at 18:24
@PipperChip Good point about orientation, although we're talking about octagons here. – Dave Newton Dec 15 '15 at 18:30
I suppose my point is that circular objects don't have flat surfaces for you to grip; other surfaces (with edges) allow you to do so. Those examples are cases where this principle has been applied. In any case, you have a good answer. – PipperChip Dec 15 '15 at 23:20

From my experience the octagonal weapon inflicts more pain especially when incorporating the staff in joint/finger locks and throws as the edges will hurt your bone structure more than a nice round staff.

I'd say it would likely do more damage as well, as @davenewton mentioned, because of the pointy bits - but I have not seen actual evidence of this.

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If my walking staff is smooth round and shiney,then my hand is sliding up and down all over the place, the more sides to the staff the better the grasp or hold I have to steady myself as I walk.

I find the octagonal staff the best walking aid that allows my hand to stay firmly in one place on the staff or easily adjust up or down.

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Simply, smaller surface area concentrates force.

This becomes more important when your foes wear armor, as you want small surface area hits to break the bones in vital combat areas, like wrists, and feet, both which can not be armored well if mobility has to be retained, but where a hardened piece of rawhide would simply glance the blows from a round weapon because it doesn't "bite" in like an edge does.

Octagonal shape also lets you use the staff better as a mobility aid, because it doesn't roll around when using it as a bridge/ladder.

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