MACHO123 wrote:Blavonski;
Well said; I totally understand what you're talking about, although I have no experience with physics. What Jorge is saying makes sense as well, but I don't think it applies to what is being discussed. Well, unless you tune your congas to an unreasonable tension (Requintos), then leave them that way for long periods of time, then what Jorge is saying applies. That's common sense though, you don't need physics to figure out what happened. You only need physics to explain WHY it happened.
Hello Macho123,
yes, I agree to a certain point. One doesn't need physics to figure what happens when a structure fails, because one can see the result. However that
what is also the
how and
why of it failing. And often common sense isn't enough. And one can apply physics to figure out
how and
why it
can’t happen inspite of what it appears to be able to do. This is the reason, in my opinion, why Jorges argument, that Conga staves will creep up and out of position makes no practical sense. And to prove any physical fact one has to have examples.
MACHO123 wrote:
I've restored many Congas (approx. 30) using Titebond II with great results and no creeping. But I always de-tune my congas when I'm done playing them.
I guess if you're lazy, and don't de-tune them, well then you would have to worry about what Jorge is saying no matter what glue you use. Eventually with time and force the staves will pull apart.
I disagree, for the reason I mentioned earlier.
In order for this to happen, there would have to be, along with the constant stress & strain of being left highly tuned under tension, active lateral, push & pull movement, forces acting on, (between) the individual staves against one another to loosen them. Like if you are trying to retrieve your wallet that is tightly stuffed in your pocket, for the right reasons; well simply pullin on it isn't always enough, you have to wiggle it from side to side. Because as you are pulling, your jeans pocket is likewise pulling to keep in inside.
At any rate, eventually with time, a conga skin and or it's lugs will creep to find a balance of reduced tension stress that they both can live with, a compromise so to speak. Or, as an example of no compromise, and as we have seen often with skins on bongos and less often on congas because they are thicker, the skin will tear. Or on congas the lug hooks will bend backwards, increasing its radius, or the threads will strip. The movement that is taking place among the staves, (and there is movement, everything moves and deflects under external forces), is microscopic and extremely minimal. And this is why
creep is, in my humble opinion, an irrelevant factor here in deciding what type of quality, PVA ,rated D3 wood glue to use in such a construction, and especially when it's only about repairing cracks.
Also, I would like to add that, the old Cuban Quinto that I'm restoring (and that is taking longer than I planned), was stored tuned in a basement here in Berlin, Germany for well over 20 years. And as mentioned in my opening post regarding that drum, the bearing edge and lug- plate area Stave Joints were all still in perfect alignment with one another. And this drum was most certainly played outdoors and definately not treated with kid gloves and most likely even left tuned most of the time when not being played. The separations that were there in the staves were due to the glue becoming brittle and deteriorating over time. And even with those seperations, (which were mostly at the bottom where it took the most abuse), there was no evidence of the staves pulling out at the lug-plate areas or being pulled up and beyond the adjoining staves. However, although the skin was still in tact, it had surface tears all around the rims bearing edge.
I know I broke my promise.