String gauge, scale, and tuning relationship? (Guitar in particular)

Question

Does anyone have general guidance or a good resource on this, specifically considering scale length, string tension, string gauge, and tuning? I've found loads of anecdotal research and a even few calculators, but while these are often useful they don't actually explain the technical aspects or anything. I suppose I'm either looking for some sort of guide/explanation, the math behind it, and any helpful extraneous information you might have.

If it helps at all, I'm starting to get into non-standard tunings (major thirds in particular) and I'm trying to figure out why specific string gauges feel and/or sound 'better' than others from a technical standpoint.

Answer 1

If you want a really technical discussion that uses serious math, you can get Richard Mark French, Engineering the Guitar. (It's available as an ebook on Kindle.) He deals with scale length, intonation, the physics of ideal and real strings, etc., etc. The math is, frankly, beyond me, but it is an exhaustive treatment.

Answer 2

See this previous post of mine.

And this one from @slim.

They both refer you to a PDF guide published by the D'Addario String Company which provides a comprehensive resource for determining which gauges strings to use for different guitar-family instruments of different scale lengths and tuning schemes. It also takes into account different types of strings, such as steel-string and nylon. The charts and measurements generally can be used for any brand of strings, not just D'Addario's. This is a gold mine of information.