Charango, how to prevent neck bowing and twisting?

This isn't really a ukulele question but I thought some of the ukulele builders would probably be able to answer this question as there aren't many charango forums. I do have a ukulele by the way.

A charango is a 10 stringed (nylon) instrument with a body about the size of a soprano ukulele but the headstock is almost the same size (large) due to having 10 tuning pegs.

It's traditionally made out of one piece of wood and at least with the cheaper version (which I have) it's common for the neck to twist and bow. It has no truss rod (and no bridge saddle for that matter).

I assume that more expensive ones don't do that but I can't get a lot of information on models listed on ebay. So I'm just wondering, in general, how would this be prevented on the more expensive models. Some May have separate necks but most do not. I'm sure more expensive ones use wood that has a lower water content at the time of the build.

How else would builders prevent this? I can't image someone spending $300 on one would accept such defects but with their manner of construction how would this be prevented?

Firstly its about selecting the correct wood type, light, strong and stable, then ensuring its straight grained and ideally quarter sawn. Depending on the load on the neck, it's possible to make it more resistant to bending and twisting by having a laminated neck, ie 3 or more pieces of wood glued together. Other techniques involve use of a truss rod or more recently reinforcing the neck with a carbon fibre rod.

I'm sure there's lots of info on the internet about neck reinforcement irrespective of instrument. Its something that's often discussed on this forum too so you could search here.

One way would be to take off the fingerboard and inlay a chunk of unidirectional carbon fiber composite in the neck.

greenscoe said:

Firstly its about selecting the correct wood type, light, strong and stable, then ensuring its straight grained and ideally quarter sawn. Depending on the load on the neck, it's possible to make it more resistant to bending and twisting by having a laminated neck, ie 3 or more pieces of wood glued together. Other techniques involve use of a truss rod or more recently reinforcing the neck with a carbon fibre rod.

I'm sure there's lots of info on the internet about neck reinforcement irrespective of instrument. Its something that's often discussed on this forum too so you could search here.

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Yes, I'm aware of the general ways that this has been accomplished with other instruments but charango's are one piece (so, no lamination), don't have truss rods so considering all that I'm wondering how any of them would be twist free.

Selection of wood must be the difference I guess.

Well, since they are one piece and they are cheap instruments to begin with, I would say the only thing to prevent twist and warping is sheer luck. You could do as others have mentioned and re-build this thing and spend some money doing it, but you are still left with a cheap instrument that is now more stable. I deal with cheap Mexican instruments all the time and there is no winning some times, just luck.

seattle said:

Yes, I'm aware of the general ways that this has been accomplished with other instruments but charango's are one piece (so, no lamination), don't have truss rods so considering all that I'm wondering how any of them would be twist free.

Selection of wood must be the difference I guess.

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I have no intention of rebuilding or trying to fix this instrument. I can play it and that's about all I expect out of this one. I probably won't buy another one if I do I wanted to know a bit more about what to expect even from an expensive one since they all are made from a single piece of wood.

I think the answer must be that the more expensive ones are made with properly dried wood and out of the right wood and right cuts for this purpose.

It's a very short neck, so less chance of it warping/twisting. You also need to know the actual tension each string is at. If they are at around 4 Kg each they are exerting no more than your average 6 course Lute and they don't have any form of reinforcement. They do tend to use hard woods for the neck though. So a dense, quarter sawn example of Mahogany, Sapele or Maple should work fine. A 6 course Vihuela has 11 strings, total string tension of around 38 - 40 Kg but it has a much longer neck than a Charango but perhaps a neck that is a bit deeper in cross section. The necks aren't known for warping.