There are primarily two ways in which a log of wood is cut – flat sawn and quarter sawn – to be used for construction purposes or to build musical instruments.
In flat-sawing, the log is passed through the blade cutting off plank after plank without changing the orientation of the blade or log. The resulting planks have different annual ring orientations when viewed from the end. The relative angle of the rings to the surface goes from almost zero degrees in the external planks to almost ninety degrees at the core of the log.
Quarter-sawing gets its name from the fact that the log is first quartered lengthwise, resulting in wedges with a right angle ending at approximately the center of the original log. Each quarter is then cut separately by tipping it up on its point and sawing boards successively along the axis. That results in boards with the annual rings mostly perpendicular to the faces. Quarter-sawing yields boards with straight, striped grain lines, greater stability than flat sawn wood, and a distinctive ray and fleck figure. It also yields narrower boards, because the log is first quartered, which is more wasteful.
Because there is greater wastage when quarter-sawing, timber merchants – supplying to both builders and instrument makers – avoid quarter-sawing, or charge a higher rate for quarter-sawn timber. And when even instrument makers are targeting only the profit margin and not instrument quality, who cares about what wood is used and how it was sawn?
But then, when you are building a musical instrument, you want all wood on it to be quarter sawn and not just the main surface: for reasons of stability.
I worked on my first ukulele, here in India, recently. It was a pretty, all-mahogany, satin-finish instrument.
But the reason why it was in was because not only was the bridge lifting, it was also cracked along the line linking the holes through which the strings were fed.
Unfortunately, some cheap wood dyed a dark colour had been used for both the fretboard and the bridge, and I am pretty sure it was a flat-sawn piece.
Now that the inevitable had taken place, it was my job to figure out how to make ‘The Li’l Guy’ whole again.
Before, each glue-up job, it is a good idea to do a dry-run of the clamping process. It throws up the problems that you are likely to face when you do the actual thing. Because it was a ukulele, the soundhole was too tiny to get regular guitar soundhole clamps to fit. The only option left was to clamp it from outside.
But in doing so, it was apparent that ‘The Li’l Guy’ would be unable to withstand the pressure of the clamps and would require support from within. There exist something called brace clamps, which can move up and down and support the back and top (from inside the instrument). However, they are a huge investment for a small fry like me.
After wracking my brains some, I came up with the idea of pieces of wood that would work as brace clamps.
Now, the problem arose of how to get it inside the instrument! Some more head-scratching and I drilled a hole in the centre of each piece of wood, put in a screw, and holding its head with a needle-nose pair of pliers, stood them up on either end (approximately) of where the bridge was.
With my handy-dandy brace clamps in place, I pushed glue under the bridge, where it was lifting, and where it had cracked, and clamped the entire bridge.
And while it was clamped I decided to pay some attention to the fretboard and fretwires. The fretboard looked like this when I started.
Midway, it looked like this
Can you see the colour disappearing? And by the time I finished, it looked like this
Clean, oiled, though lighter in colour, and fretwires burnished.
48 hours later, the clamps came off and ‘The Li’l Guy’ was healed. Since it was a satin finish, I decided to rub some oil on the instrument to make it look better. The effects were very encouraging.
Stringing it up was another pain, but eventually, I got it done.
ADDENDUM: The latest news from the owner is that string tension broke the bridge again from the same spot, like earlier. I have requested the owner to bring it in and I will have a look at it afresh.