Tough Question, Easy Answer Department

RonMartin(deceased)

Funny but the most often asked question I get when doing a class has nothing to do with care, watering or even the dreaded "can I keep a juniper inside". It is about that little piece of wire that we use to bend branches.
Just how big should that wire be in order to do the job.
At one time I patiently explained the standard response.
1. Aluminum wire = about 1/2 the thickness of the branch to be bent
2. Copper = about 1/3 the thickness of the branch to be bent

But it seems even armed with this information people still use too small a wire and it will simply not hold that branch.

A while back I came up with what I think is a better answer to that question.
Grab a piece of wire as shown in the picture below. Leave about 2 inches sticking out. Push the wire down on the branch. If the branch moves then the wire will hold it. If the wire bends, guess what, It wont.
An easy solution and it will work no matter what kind of wire you use.
But even after they do the test they still ask. Is this wire ................
So how many of you will now run to the wire rack to see if it works or not ;o)

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stonemonkey

Lovely Thesis Ron.

And if the branch bends your wire.....give up!

Andy

Cre8tive

So you're saying I can keep my juniper indoors?!!!

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Carl_Bergstrom

Perhaps I'm overanalyzing, but I don't see how this same rule could work for both aluminum and copper.

The holding power of the former is roughly the same during the "Ron test" before wiring and after wiring. Not so the copper, which hardens once bent.

Is the difference that negligible?

(An easy fix: different lengths extending beyond the fingertips for the two types of wire.)


Cheers,
Carl

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RonMartin(deceased)

Basically the difference between the two doesn't matter in this case.
I have over the years I have used both copper and aluminum. The test has always worked on either one.
If the annealed copper wire will bend the branch when soft it will definitely do so when it work hardens.
No sense in complicating things. ;o)

heymikey(deceased)

heyOldMisterCrow; Perhaps your not analyzing the situation enough. In Ron's example the wire, whether it be aluminum or copper is resisting the bending force of the branch by flexing up to it's elastic limit at which time it "bends" or undergoes plastic deformation. Because the wire in this test is acting like a cantilever, the amount sticking out beyond the fingers is important because the stress causing the wire to bend is proportional to the square of the length ( so that a wire sticking out 2 inches is subjected to twice the stress as a wire sticking out 1.41 inches and how many people can estimate either of those two lengths accurately). Secondly, a wire half the diameter of the branch has a moment of inertia ~2.25 that of a wire 1/3 the branch diameter (a function of the square of their diameters) which means the larger wire in this case has ~ 2.25 times the holding power for bending the branch. Ergo, and hertofore, the best solution as I see it is to use aluminum wire about 1/3 the diameter of the branch to be bent based on the diameter of the branch in the middle of it's length. This wire runs nearly the entire length of the branch and subsequently is a little undersized where the branch meets the trunk and maybe a little oversized out near the end. If the branch needs to be bent near the trunk a second wire is installed that runs parallel with the first but only ~ halfway down the branch. In actuality I haven't looked at my engineering books on this subject in 30 years and I probably have everything a$$-Backwards, BUT, it works for me and I like aluminum wire better.

RonMartin(deceased)

Wow, guess I had better go back and change the name of this thread.
Sonehow "Tough question, easy answer " doesn't seem to apply anymore ;o)

dbz12fan

I learned this tip at the first bonsai meeting tha I attended from Boon Manikivitivipart (sp?). It has been one of the most useful things related to bonsai that I have learned to this day.

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JTriptow

I have never felt more stupid than after reading heymikey's post above. And I think I'm pretty darned intelligent. ~Scratching head~

Jennifer

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