Gloria Medina is once again bringing great guitarists to Granada to liven up the summer.

– 16 July                 Zoran Dukic

– 23 July                 Ricardo Jesús Gallén García

– 30 July                 Rafael Aguirre Miñarro

–  6 August             Ernesto Mayhuire and Claudio Constantini

– 13 August            Javier Conde

– 20 August            Lazhar Cheruana

– 27 August            Joaquín Clerch.

– 3 September        Esther Guzmán.

The concerts will be held in the garden in front of the Manuel de Falla auditorium and if last year’s concerts are anything to judge by, this summer will be great as well.  Follow this link for more information.

I have no doubt that the best glue for instrument-making is hide glue.  It resists high temperatures, vibrations are transmitted effectively, It doesn’t dull edge tools, restorations can be effected more easily on instruments that were made with it and there are many other advantages.  In my observations, if similar instruments are made with different types of glue, the hide glue version will sound better.  The joints on a musical instrument are not glued with high pressure but at the same time it is important that the glue line be as thin as posiible.  Several factors can help us achieve this: thinning the glue appropriately, making sure the temperature of the glue does not drop too quickly so it can still flow and making sure that the excess glue has somewhere to go.  For determining the right viscosity of the glue it is a matter of experimenting with more or less water in the glue.  Heat can be maintained either by heating the pieces to be joined or in the case of thin stock, heating the joint once it is closed.  Giving the glue somewhere to go is especially important with hardwoods which might absorb less of the glue and cause a thicker layer which can separate due to its low cohesive strength.  This is done in a number of ways:  you can rub the two pieces together which will force the glue out of the joint (this doesn’t work on something like a fingerboard as full contact is not made until clamped). Hiigh, even pressure helps but you can still trap pockets of glue in the middle of a large piece.  Making a “key” on one of the pieces is useful but not for the reason that many think.  Using a toothing plane or a knife to make grooves on a piece give the excess glue somewhere to collect.  Some emulate this technique thinking that the grooves let the glue grab the wood but that is not how glue works.  Of course if you do this you have to leave plenty of wood in contact along the glue line, if you rough the surface with a heavy grit sandpaper for instance you are NOT improving adhesion.

I showed a photo a few posts back of the 100-year-old fret wire that I was to use on the “gut” guitar.  The wire has no studs because it was produced by drawing it through a hole with the typical T-shaped profile.  I have seen the tool that Manuel de la Chica used to do this and it was called a “trefilador”.  A literal translation of that word would be trifiler (as in three-way profiler) The traditional way to get the wire to wedge into the fret slots is to strike the tang with a half-round file to produce irregularities on it.  In the video you can see the process which I decided to use.  The irregularities are very irregular and next time I will either use modern fret wire or a modern tool (which I have) that crimps the wire to get the wedging effect.  The frets were noticeably deformed by this process and hammering them in straight became a bit of a challenge.  Below you can see the photo of what was left after I finished fretting, there wasn’t much extra wire.  Sorry about the blurry video, no focus on the video camera.

I glued the bridge on this morning and was nervous about doing it the same way as always.  I use string and wedges, no caul and no clamps.  I think I have posted pictures of it here before.  This is one glue joint that suffers from being clamped for too long, the pressure deforms the top slightly and must be allowed to spring back before too long.  90 minutes works for me.  Of course the more flexible the top is, the more it will deform.  In this case the guitar has the most flexible top I have ever built so I was worried about deformations and also I wanted to make the most of the bridge as a reinforcement.  In my quest to make this guitar sound better with gut strings I had not only made it more flexible but also I had used a shallower dome on it.  Obviously, the last thing I wanted to do was push the already shallow dome flatter with the glueing pressure.  I considered using clamps but my reservations about that method are even greater when it comes to a thin top so I decided against that.  As you can see from the photo the doming was preserved quite well by using a very soft prop inside the guitar which added just enough resistance so that the “give” in the top felt like it usually does on my guitars.  Sorry about the quality.  The last shot shows the top and you can see the silking indicating the vertical grain.

It is advisable to hand plane tops as opposed to putting them through the agressive drum sanders that are often used for the hardwoods.  Regardless of how you take the thickness down though, the last steps have to be taken in such a way as to guarantee the flatness and the uniformity of the top.  Even if you work the top to varying thicknesses at different points the transitions must be very gradual so that glueing surfaces can be made perfect.  Abrupt variations in thickness in a plate which is clamped between a mold and a bar will result in a joint with weak spots prone to vibration and cracking.   In short you need flat surfaces on each side of the finished top whether  these two surfaces are perfectly parallel and equidistant or not.  The best way to assure flatness is to use a toothing plane.  This tool makes marks on the high spots and leaves the low spots untouched.  The high spots are then removed with a cabinet scraper and the process is repeated.  Depending on how agressive the set of the plane is you will also be removing some material as you plane.  When the plane makes uniform marking over the entire surface it will be perfectly flat.  Careful sanding or scraping of the entire surface to remove the marks (but no more) will ensure that it remains flat.  This first surface is best achieved while the plate is still quite thick, otherwise the unevenness of the opposite side can affect the results.  Once one face is smooth and flat it can be placed on a very flat surface and the uneven side can be thicknessed and then flattened in the same way.  This photo shows a low spot which is not marked, and therefore more reflective, the surrounding area must be scraped and then the entire face planed again.  Below you can see the parallel marks from the teeth which show that the blade is registering everywhere.

The most important part of making and bracing a top is good glue joints and this technique will help you get those.