Wednesday, October 7, 2009

Third year begins in earnest

The summer is over, the college year has started again, albeit without the subject of Instrument Technology. The course has progressed to an ordinary degree in Business (with sound engineering as an elective). As I've not posted a picture of my completed guitar it's included here. Please excuse the size of the image, I will take some more artful shots (with my fantastic new camera) when I've put a finish on it. G'luck! 

Friday, April 17, 2009

Before actually gluing on the braces I cut and shaped a soundhole patch, this is a thin veneer of mahogany in this case, (type of wood unimportant/matter of preference) The point of this veneer is to make the soundhole surroundings stronger. The soundhole being an area where the end-grain is visible and prone to being stuck with plectrums.

I then glued the back to the side assembly and trimmed the back down almost to size. Next job was to glue on the braces to the top. Once I had all the braces in place I had to glue a maple plate to the underside of the top, over which the bridge is to be placed. This is in order to strengthen the top where the pressure of the strings will be strongest. Once I had this done I trimmed the shape of the top using the bandsaw.

Here you can see the soundhole patch and the bridge reinforcement being glued in place, notice that the top is only roughly shaped at this stage.

you can see that the braces are nearly at their final shape at this stage, I have scalloped them here, ready to be sanded clean and flush after clamping, this is a sensible thing to do as if you fully shape them before gluing you have to be very careful not to mar them with clamps.

The bracing system for the tops of most steel string guitars since the advent of steel strings has been the X bracing system, pioneered by Martin Guitars, this is the system I will be using for my guitar. The main component is the X obviously enough!

That’s not all the bracing you need though, it’s built up to allow vibrations of the top whilst being strong enough to withstand the pressure of the steel strings.

There is also another brace at the very left of the picture to be fitted, it’s a flatter brace with the grain going length-ways along it, perpendicular to the grain of the top, this is in order to stop twisting of the top under the pressure of the strings

I next installed a rosette around where the soundhole will be in the top of the guitar, I routed a channel, using a router with a base jig set up for this job, I drilled a hole where I measured the centre of the soundhole to be, then put the top on a piece of mdf on which there was a pin protruding, this pin also served as the guide for the router. Unfortunately I didn’t think to take a picture at the time, it would have come in very handy at this time!

Next job is to join the side assembly to the braced back. I used an abundance of spool clamps to do this, along with the former for the waist of the guitar and two G cramps, and two sash clamps. After I took the back and side assembly out of the clamps I realized that the guitar body had been distorted in an attempt to fir the sides to the back plate, the main problem for this, I have deduced, is that with no external former, the bent sides fought the bending over the length of time they were released from pressure, an external former would have kept this pressure on the sides until the top and back were glued thus there would be no movement, this is a mistake that I wont be making again. It has adversely effected almost every step from here on, from fitting the top, to fitting the neck, this inherent pressure will apparently also have a detrimental effect on the sustain of the guitar.

Having kerfed my sides, both back and front, I joined my back braces to my back and cut out the kerfing where the braces need to fit tightly against the sides. The picture below shows the side assembly resting on the back as it will be joined.