Will constantly changing tuning twist/warp a guitar neck?

The answer is no, if the tensions are not extreme in variation and the guitar is properly maintained otherwise.

My best suggestion is to tell your band to stop changing the $&*@( tunings! Speaking as someone who has performed in a number of them (and as an audience member who has suffered through it), one of the biggest mood killers is having to wait while the guitarist and bassist retune in between songs. Its lame! Pick one tuning, or at most two (ie Standard and Drop D) and just use them... and do whatever you can to only retune *once* during a show, if you absolutely *must*.

Part of the reason to not change tunings is that when you alter the tension on your neck, you throw your intonation slightly off. That means that strings are more likely to buzz, notes higher up the neck won't sound in tune with the notes lower down the neck, and that overall your playing experience will suffer a little. It only gets worse with greater differences in tuning. So while going from standard to Drop D isn't too bad, going from standard to drop d to standard c is just ridiculous - your tension will be thrown off, your strings will be more likely to buzz, and you'll actually lose sustain and tone.

Pick one tuning and stick with it. Rewrite or transpose songs/riffs, if you have to, to make it work. Pick a tuning that your singer has an easy time singing in, and stick with it.

One of the nice things about this is that as long as you take care of your guitar, do the maintenance, etc, that you won't need a second guitar for a different tuning! (which is kind of a PITA itself, actually)

Neck twisting is more likely to happen with humidity and temperature changes. After all, the neck has a bloody steel rod in it to counter the pull of your strings... but even a steel rod can't help wood cells from deforming due to dehumidification or from absorbing extra moisture from the air.

Your guitar should be in a relatively constant temperature and humidity environment, should be properly set up and intonated for a specific tuning, and preferably the fretboard should be conditioned once a year or so to keep the neck from being affected by weather/environmental changes.

Saul

Guitars are set up for a certain tuning. When you alter that you change the tension of the string, you change the distance from the string to the neck, and also the bridge position will be wrong, so your high E on the 12th string, may not match the note of the open E string. While you most likely won't be snap or break anything from down tuning, you are changing the tension on a piece of wood, which WILL cause changes over time. Not to mention your guitar will not be properly "set up". This could potentially warp the wood, which you don't want. Some floyd royse bridges have a device that will let you drop the low E string. Just make sure you get the guitar SET UP for whatever tuning you want. Also, think about a second guitar for alternate tunings, if you go back and forth that much. That way you can easily do this live.

1

Guitar Neck Warp

Well, eventually, yes it can warp the neck and wear on the other hardware. It's a 'tension over time' thing. This can be mitigated by regular neck maintenance, but still does take potential years off the life of the guitar, if you are constantly retuning.

Best practice if you play in many different tunings (I do) is to have a guitar for each tuning. This way, the intonation is always specifically set, the action is always specifically set, and your instrument only has one kind of tension to adapt to.

Granted, guitars are built to handle various tunings, and you won't 'break' your guitar doing this, but you WILL wear on it. If it was less than top quality, you only bring the necessary maintenance periods closer. If it IS a top quality instrument, many years of this kind of treatment will begin to show.

I would say that what you are doing is UNLIKELY to do any damage. Harm could only be done if the neck was actually being pulled backwards and forwards as you changed tunings - you would notice this.

If you has a guitar that was say tuned a semi-tone flat and had very light gauge strings on it, changing to standard tuning and using really heavy strings might cause problems but what tou describe should be ok.

Yes it can cause neck problems.

It was suggested to me that you tune the outside strings first 1 & 6 then 2 & 5 then 3 & 4.

This would cause the least twist to the neck.

You need an excellent ear or an electronic tuner.