Why are dizis made using 2 bamboo segments?

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I have always wondered about something on dizis that are made with bitter bamboo (especially the lower keys , e.g qudi and below). Why are most of them always made using 2 parts?.

When I say two parts, I do not mean copper tuning joints style, I mean, even for "unjointed" dizis, they are in reality 2 pieces of bamboo glued together. (first part is from the blow hole to the end of the flute, the other is the part above the blow hole where poems are carved). This use of 2 separate bamboo parts seems very evident when transparent bindings are used, or usually because the grain of the bamboo is different suddenly.

I know this does not affect the acoustics of the flute at all, I can saw the poem part of the dizi off and still it will blow as well (may not balance that well)

Why not just use one same piece of bitter bamboo for the dizi? The dizi is already made with 1 segment, why not preserve the part after the blow hole for poem carving instead of chopping it off, and then gluing another seperate segment on ( I know this happens because I sent a few dizis back for repair on cracks, some came back with completely different "poem" segments because the initial ones had cracks there too)?

Anyone know of any reasons?

[YouLanFengChune]

Actually, I thought the same way as you. However, I realised that its not easy.

for bitter bamboo, its not easy having a very straight bamboo with no nodes all the way. Sometimes, different segments may have different thickness, even if its from the same bamboo. To ensure that weight/shape is not affected, it may be the only way.

However, sadly, many times, its for mass productions. while the shifu is craving the holes, someone can be doing the decor. When all is done, assemble, voila!

[YouLanFengChune]

the segment above the blowhole AFFECTS...

the weight factor is there. I am doing this study on instrument weight, and i realised that the CG of the instrument affcets the node and antinode of the transverse waves formed within the instrument. hence, the resonance, and the amplitude, as well as overtones and and harmonics are determined to an extent by weight and centre of gravity of the instru

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Ahh, I c, I always thought that the only reason was mainly for the separateness was increasing the production efficiency as you mentioned.

It is interesting that you say that the centre of gravity actually affects this. I always thought that the only problem an unbalanced flute will cause is more discomfort for the player, since he has to balance the flute rather unnaturally.

It is also interesting that bansuris which are also made from one segment of a bamboo do not have the additional poem part, and have many keys similar to all dizis (large and small) but still play good too.