Wednesday, December 26, 2012

Claro Walnut - Not So Subtle!

With the luxury a few days off over the Christmas/New Year period, I'm proceeding steadily with the pore-filling process while I wait for delivery of the KTM-SV top-coat material. I'm perpetually amazed at the figure in this guitar's Claro Walnut back and sides, hence the repeated attempt at a photograph that will do this wood justice. Thanks Allied Lutherie!


Saturday, December 22, 2012

Pore Filling With Epoxy

After installing purflings and bindings, it's very rewarding to scrape them level, carefully round over the edges, then sand the top, back and sides in readiness for the first steps in the finishing process. It feels like the end of a journey while at the same time signifying the beginning of another equally challenging one.

With final sanding on this guitar complete, I've taken the first steps towards pore-filling the back and sides with epoxy, a process that finally reveals the true beauty of the wood. As a hobby builder, many months have inevitably elapsed before I get to this stage, but the rewards make the effort and the wait worthwhile. Along with stringing a completed guitar up for the first time, seeing the figure and colour of the wood magically appear as the first coat of epoxy is applied is surely one of the highlights of the building process.

On a cautionary note, a problem with some epoxies is that of amine blush, a waxy residue that forms as the epoxy cures that can interfere with adhesion and curing of subsequent top coats. From what I've read on the topic, spending a little more on a good quality epoxy is worth considering as they're less likely to be susceptible to blushing. Whichever product you choose, once the epoxy has fully cured a thorough rub down with a damp cloth - or, better still, one dampened with a 50/50 mixture of water and denatured alcohol - is a simple precaution that eliminates potential problems. There's wisdom too in avoiding the application of epoxy when the ambient temperature is falling and relative humidity is therefore likely to be rising - conditions said to exacerbate blushing.

Sunday, December 16, 2012

The Secret's Out!

A friend contacted me yesterday seeking advice about a suitable guitar upgrade for her daughter. As I've secretly had plans all along to make a gift to her of one of the guitars I currently have under construction, it seemed like a good time to reveal my intentions. As a result, I've decided to prioritise the completion of this guitar with a view to presenting it to her as soon as I can.

As luck would have it, I finalised the construction stage only a week ago - the task of finishing therefore begins in earnest. The first step is to fill the pores with epoxy after which two coats of Ilva TF23 sealer will be applied immediately prior to the first of the KTM-SV top coats.

I'll document the process here for the recipient's benefit and in the hope that it's of some interest to others as well.


Monday, December 10, 2012

Guitar Necks: A Recent Improvement

I had time to daydream about guitar building over the last few months even if I didn't have opportunities to make progress in any practical sense. Among other things, my ruminations concerned construction of the neck in terms of how I might improve the design and produce more consistent results. Finally, with the university year over, I'm in a position to turn those thoughts into actions. 

In keeping with my usual method, two knock-down bolts extend through the headblock into threaded plugs embedded in the neck tenon. Although this is a popular and proven design, I've come to realise that there's an inherent weakness: if the bolts are overtightened through the soundhole by an inquisitive or over-zealous owner for some unknown reason, there's a chance that the force they exert on the plugs could eventually split the neck at the extremity of the tenon. However remote this possibility might be, it seems prudent to provide some reinforcement. With that in mind, I've modified my routing jig so that the tenon it produces is narrower than it once was, the idea being that I can build it back up to the desired width of 20mm by gluing a 2mm layer of wood to either side of the tenon as shown in the picture below. Crucially, the grain direction of these outer layers is at right angles to that of the neck shaft which provides good protection against splitting.

I'd like to achnowledge the luthier who came up with this idea; if I could only remember who they are I'd certainly do so!

I'll report on further improvements to my neck construction methods in an upcoming post.