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jezah81
4th December 2003, 04:14
I just recenty bought a shirakashi jo, but i have found out its a little warped. will this affect my training?
Regards,

Tim Atkinson
4th December 2003, 06:13
All jo, or bokuto for the matter, will warp to some degree. Depending on your climate, how you store the jo between use and quality of the timber, are all determining actors.

If it is a slight warp you may be able to fix it by steaming the timber and then shaping.

Storing on a rack or even screwing an "eye" into the end of the jo and hanging it vertically can prevent the problem in the future.

What sort of deviation are you talking about? If you lay the jo on a flat surface, how high off that surface is the other end?

ulvulv
4th December 2003, 16:00
I got a warped jo 8-10 years ago. It is slightly curved, with maybe 1/3 inch "curvature". I have tried to put it under pressure several times without success. I laid it between two bricks, and put an 8 kilo handweight on top an left it for two months, checking now and then. :(
I have not tried to soak it, but I will try a last time, before I cut down the straightest part to tanjo-size.

Anybody actually tried to straighten a warped jo with some degree of success? We all know the theory. :D

jezah81
5th December 2003, 06:05
The deviation on my jo when i lie it flat on the ground is about 5mm. Can i still use my jo for training or does the warp affect training in any way?
Regards,

Tim Atkinson
5th December 2003, 06:27
Jeremy,

With a deviation of 5mm I would not think that it would affect your training.

If you are in Sydney or north, you will have to watch those humid summer days.

Leave it on a rack, or hang it vertically, but never leaning against the wall.

Jack B
5th December 2003, 18:45
I have a very good old jo that is several degrees warped towards one end. It doesn't seem to affect the use. I know someone who actually considers a jo better if it slightly warped; he says they have a better feel. Maybe he just likes personality.

My old jo was hung from an eyelet, religiously, but warped anyway. My feeling is that if it really wants to be warped, let it and it'll find it's happy place and be solid there. (As long as it's not too ridiculous, and a good jo shouldn't want to warp too too badly.) I've heard of people straightening jo with water and cinder blocks, but why fight it?

Brian Owens
13th December 2003, 09:29
Originally posted by ulvulv
Anybody actually tried to straighten a warped jo with some degree of success? We all know the theory.
I've done it, with great success. After seeing my results I became the resident jo (and bo) straightener at my dojo.

I bought a length of PVC pipe several inches in diameter and supported it vertically over a pot of boiling water. Using an inverted funnel from an autoparts store I channeled the vapor up through the pipe.

I suspended the jo by an eye hook inside the pipe and let it steam for two hours, adding very hot water to the pot as the level went down.

I then removed the jo, wearing oven mitts, and strapped it between two lengths of angle iron, using hose clamps to cinch the angle irons together.

Every few minutes I'd turn the screws on the hose clamps as far as I could.

Once I could tighten them no more I set the whole "sandwich" against the baseboard in my garage and left it for two days.

End result? Straighter than when I bought it.

It would have been easier (and possibly cheaper) to buy a new jo, but I like a challenge. Besides, I was attached to that one.

ulvulv
16th December 2003, 22:28
I am little by little succeeding in my "economy unwarping experience". I strapped my warped jo to my bookshelf with small plastic strips, and used a book as a wedge. two weeks with baudelaires collected poems has straightened it a bit, and after spending Christmas with James Crumley , my guess is that my old jo will be ready for action.;)
if not, its the steam and plastic tube recipe next!

Kim Taylor
17th December 2003, 23:45
To straighten a weapon fast (quick and dirty) just wait for a sunny morning, lay the weapon down on the grass with the hump upward, sun dries out the long side and moisture from the grass causes the short side to swell.

Did that with a Lignum Vitae bokuto that did straighten until it got its moisture balance back, it's now as warped as it ever was.

On leaving a weapon against a wall and having it bend: Creep is measured in wood beams in terms of years with constant heavy loads applied. Leaving your jo leaning against the wall overnight or even for a week isn't going to result in much creep of the wood. What will happen though is that the moisture will change, the wood will warp and the warp will naturally fall downward rotating the jo so that it looks like it "sagged". It's the moisture content change that makes the warp.

Kim.

ulvulv
18th December 2003, 06:30
Originally posted by Kim Taylor
To straighten a weapon fast (quick and dirty) just wait for a sunny morning, lay the weapon down on the grass with the hump upward, sun dries out the long side and moisture from the grass causes the short side to swell.
Kim.

smooth!

I would only wish we had some sun. All we have now is moisture, and we all feel very warped. I guess the sun will not straighten us out until May.
:D

ulvulv
31st December 2003, 01:09
Originally posted by ulvulv
I am little by little succeeding in my "economy unwarping experience". I strapped my warped jo to my bookshelf with small plastic strips, and used a book as a wedge. two weeks with baudelaires collected poems has straightened it a bit, and after spending Christmas with James Crumley , my guess is that my old jo will be ready for action.;)
if not, its the steam and plastic tube recipe next!

Crumley did it. My jo is back from the dead, but the one big warp transformed into two smaller ones. Sob sob. they are fortunately not so big that they will cause any practical or visual discomfort during practise.