Sunday, February 20, 2011

Slow and Steady Wins the Race!

I often rue the fact that I have insufficient time to spend on my hobbies, but the picture below suggests otherwise.  The secret seems to be in looking ahead, determining as best as I can what spare time I might have on my hands and planning in advance how best to make use of it.

The back and soundboard halves were joined and thicknessed on separate days some weeks ago, while the braces, bridge patch, cross-grain back reinforcement and headblock have been laying around in readiness having been prepared in short bursts of activity over the past few months.

With higher humidity on several days over the last two weeks, the dehumidifier in the spare room has been running continuously and I've been able to maintain a relative humidity of around 45% - ideal for gluing braces to the soundboard and back.  The temperature in my workshop has been bearable too, and the neck I began yesterday reached its current state of completion this afternoon.  I'm on a roll!


Sunday, February 13, 2011

Voicing the Top - Intuition and Technology

Shaving the soundboard braces to bring out the guitar's tonal potential is one of the more intuitive and mysterious aspects of guitar construction.  For me, it's also one of the more tactile and enjoyable stages when the use of hand tools is mandatory and the senses come strongly into play.  A cycle of tapping, flexing and brace shaving is involved, with a somewhat nebulous goal in mind despite having read everything I can on the subject!

Unfortunately, my hobby builder status dictates that it's often many months after voicing a top then going on to complete and evaluate the instrument before I'm able to repeat the exercise - hardly an ideal situation in terms of being able to build any sort of muscle memory or draw meaningful conclusions. The pertinent questions whose answers seem elusive in terms of being able to adequately articulate them are:
  • What did the top feel like as I flexed it, i.e., how much resistance was there when bending it across the grain and with the grain?
  • How did the top ring as I tapped it and how was the response influenced by the way the top was held or suspended and where it was tapped?
  • What was the correlation between those very subjective assessments and the success of the completed instrument from a tonal perspective?  
  • To what extent did the materials, density and stiffness of the guitar's other components combine with those of the top and contribute to the outcome?
As I review that list of questions, it strikes me that the challenges they pose seem almost insurmountable.  It's obvious that relying on my memory from one instrument to the next isn't a satisfactory approach given the subjective nature of the assessments involved and how infrequently I'm able to repeat this part of the process.

Perhaps the use of technology offers a way forward and can lend a degree of objectivity to what would otherwise be limited to some vague, transient sensory experience. Measuring top deflection both parallel to and across the grain prior to gluing the braces, photographing the top bracing and noting brace heights, recording tap tones with a decent microphone (or perhaps one of the hand-held Zoom recorders) or even videoing myself as I hold the top and tap it seem likely candidates as I seek to minimise the guesswork involved in the voicing process and develop a baseline for subsequent instruments.  Or perhaps I should learn to trust my senses and develop a greater appreciation for the delightful uncertainties inherent in wooden instrument construction!


Friday, February 11, 2011

Glue Clean Up

With the advent of the soundport, the standard of workmanship inside the guitar body is more easily scrutinized and there's perhaps an even greater incentive to clean up surplus glue as the various component parts are assembled - not that I've neglected this previously. If some vintage instruments can be taken as a guide, it seems this wasn't always a priority, even for well-respected manufacturers. Times change though, and as I inspected a new Martin in a local music shop not long ago, I must say I was impressed by the meticulous attention to detail within the guitar body including the fact that all traces of excess glue had been carefully removed from the intersection of the back plate with the linings and back braces. I vowed then and there to emulate this in my own instruments to the best of my ability in recognition of the fact that it's often the little things that make a big impression.

There are several approaches to cleaning up excess glue once clamping pressure is applied to a freshly-glued joint. Regardless of the method used, I always try to plan ahead and give some thought to the arrangement of clamps to ensure unhindered access to glue squeeze-out after they're in place. I'm also careful not to apply an excessive amount of glue in the first place. A 1-inch foam roller is helpful in that regard, with the added advantage that an even coverage of glue is more quickly and easily achieved.

I know that the preferred approach for many builders, whichever glue is used, is to leave glue squeeze-out undisturbed, letting it partially set or gel before attempting to remove the excess. I use Titebond for the majority of gluing tasks, and find that a flattened plastic drinking straw with the end cut at something like a 45 degree angle is a good first step towards removing unwanted glue as soon as clamps are in place. This approach works particularly well when gluing braces to the soundboard or back. The straw is pushed cut-end-first along the freshly-glued joint and much of the surplus glue finds its way inside the straw which is then discarded. It helps of course to have several pre-prepared sections of drinking straw on hand.  Chisel-shaped slivers of spruce or cedar, moistened Q-Tips (cotton buds or ear buds) or a moistened sponge can also be useful as a follow-up and, using a combination of these methods, it's usually possible to remove every last vestige of excess glue without compromising the joint itself.

When gluing braces to the back and soundboard, I exercise patience and generally glue one - or perhaps two - braces at a time. Not only does this slow and steady approach give me ample time to clean up after myself, but I have the luxury of a clear view and unobstructed access to squeeze-out.

Another strategy which contributes to a clean look inside the guitar body is to attach the rim assembly to the back first, rather than to the top. I find it helpful to have a second chance to tidy things up before the top is attached and while the various nooks and crannies which will remain visible after final assembly are still easily accessible.


Tuesday, February 1, 2011

Two Rosettes

The finished rosettes:

I'm pretty happy with them both, and they provide an attractive alternative to my more usual abalone rosettes.

Click on the image for a better view.