Secrets to Building a Great Guitar

There is a thread over on delcamp about guitar-makers vs. mass-production.  As always the topic has a life of its own and the main conflict has become why does a guitar-maker make a better guitar than a factory.  Not all of the following is done by all of the great guitar-makers but these are some of the things that come together to make the big  difference between the “best mass-produced guitars” and the real thing.

1. Selective thicknessing of the different areas of a top is something that a maker can do and mass production cannot.

2. The same goes for working on a top or its bracing until it feels or sounds right.  Some do this pre-assembly and others post-assembly.  This affects both sound and playability.   Resonance tuning should be mentioned here in deference to those that do it.

3.  Hot hide glue is a joy to use and does not creep, does not let go when you heat it and affects the sound of the final product (Many of the traditional builders prefer sound to go in that direction).  However you must learn to use hide glue properly, it must not cool until clamped up, and it requires perfect joinery.  Those with vested interests claim that modern glues are superior for our purposes that is what the factories use.  Interesting to note that the most sought-after Martins used hide glue.

4.  Freshly worked surfaces glue better (scientifically proven) so that means that completely finishing tons of parts beforehand is not the way to go.  We usually are working on a part just before we glue it to another.  We are more inclined to use edge tools for surface preparation (also proven to be better for gluing).

5. Joinery is my next point, perfect joinery is achieved by working the surfaces, not the dimensions, to perfectly mate surfaces for gluing is not something that a machine can do better than a human.  Although plastic glues are very forgiving on bad joinery, you end up with flexible glue mass between the pieces in these cases of bad joinery.

6.    Speaking of joinery,  mating a bridge surface to the surface of the top before varnishing means no impediments to working with whichever tool is best suited to the job.  On the other hand I have never understood how you can get the same perfect surface on the top when you are scraping the varnish off one area to glue the bridge on after varnishing the instrument.   Here is a case where some mass-producers will do it one way and others another.  Curiously enough, the best factory guitars were made in a factory in Valencia using very traditional methods including Hot Hide Glue and face-down solera construction and very low-tech.  (Still nowhere near the quality of a guitar-maker).
7.  Sanding machines can work very well to a constant thickness but perfect uniformity is not what they do best.  Guitar-makers will spend a lot of time afterwards measuring with a caliper of some sort and working towards perfection by hand.  Another thing the maker can do is to prepare to perfect flatness one surface of the side or back so that the machine has a reference.  This takes time, scrapers and toothed plane to register the high spots.  This is so important not because the thickness has to be abolutely perfect but we are back to joinery again.  If the bracing fits perfectly into the gluing form (solera) the back or top must be perfectly uniform or there will be places where the contact or pressure varies and the glue joint will be weak at those points.

8.  Sanding machines are a very aggressive thing to use on a carefully seasoned softwood that is the most important part of the guitar acoustically speaking.  Many makers only use hand tools there.
9.  The traditional method of building (face down in the solera) makes for a traditional sound (which most of us want).  This method with its glue block (peones) and reliance on the delicate top-glued-to-neck stage does not lend itself well to a mass-produced setting so they do it a different way- this means a different sound.
10.  The “advantage” of mass-producing is that you can use machinery or CNC and make everything exactly the same and you do so in order to save time.  However if each guitar is exactly the same in the dimensions of all of its parts the guitars are by definition different in their sound and playability because of the variability of wood.  The advantage of the maker is that we can take into account this variability to a large degree and so vary the dimensions to get what we want.

11.  Neck reinforcements are detrimental to the playability of a nylon-string instrument.  A light cedar neck makes a guitar more flexible to play.  However to avoid twisting, warping and other undesirable effects the wood must be well-seasoned, flex-tested, and split from a larger billet to ensure that there is no run-out.  The geometry of the solera and the later planing of the fingerboard must take into account the flex of the neck.  The perfect solution to all of this in a mass-production setting is to ensure that the neck doesn’t move by laminating or re-inforcing it and then you can use any wood for the neck.  The problem is that it becomes too stiff.  Some makers re-inforce necks but hopefully they use good wood, and keep some flex in the neck and end up taking just as much time to test, flex and adjust.

12.  Wood selection is crucial to making great guitars.  But it is not about choosing the best wood but rather choosing the wood that works for you for a specific project.  It is about knowing beforehand what you can do with a certain piece of wood.  This knowledge is something that you can only achieve after making a relatively high number of guitars.  Sorry, wood buyers and wood sellers and factory owners do not have this knowledge.  Neither does the worker who works in a production setting no matter how many years he has been there.  One must take the guitar from individual bits of wood to finished instrument again and again and again to learn this.

13.  Over-building has been mentioned many times because it is the best way in a mass-production setting to ensure that you never end up with a guitar that doesn’t work with the tension of the strings.  A guitar-maker is always trying to walk the fine line between great sound and responsiveness and under-building and we get pretty good at it.

14.  One thing I learned from my teacher is to do absolutely everything you can to ensure that you achieve perfection in a given task.  Here is an example.  When gluing a bridge:  Check the fit with newsprint (put a corner under it and try to pull it out while pressing down on the bridge) at all points around the edges of the bridge.  Never touch the surfaces with those natural oils in your fingers.  Make some widely spaced grooves on the underside of the bridge only to give the glue a place to flow (makes for a thinner glue line).   Scrape the bridge surface lightly just before gluing.  Heat the top with hot blocks and apply the glue to the bridge.   Make sure that the mating surface of the bridge has a slight lateral curve which will ensure that the final joint is perfect along that axis (no separation at the edges).  Some people see all this as overkill but that is the way we work and this would be impossible in a mass-production setting.