Featured Restoration - The Screws & Holes

Screws & Holes

Hi Guitar Players,

It is a common knowledge that women worry a lot. I think it is equally true for guitar owners, especially the guys. They really know how to worry about their guitars… well this is a story of those worrying guitar guys out there.

Structural repairs made up the majority of my guitar services. Such repairs are very important and they should be carried out before other forms of repairs like functional and cosmetic. For this blog, I shall focus on re-gluing lifted guitar bridges of acoustic guitars.

The paper trick

Braces design of Small Acoustic Guitars

Re-gluing lifted bridges of acoustic guitars used to be rare. I didn't have to do too much of it until the dawn of "small sized" acoustic guitars. Many big brands jumped into producing such small guitars because they are very popular among youngsters. Small and light, great for lugging around whilst commuting.

In the aspect of volume projection, it is a basic logic that smaller guitars are not as loud as regular sized guitars. For musical instruments, volume projection is a significant indicator of quality. The designers overcome this barrier by "lightening" the bracing design on top boards by numbers. With the bracing design lightened, the volume projection was retained.

How do I know? Just toss a mirror into your small guitars, snap some pictures. Do the same to your regular sized guitars. Compare the pictures. The differences are obvious.

Guitar braces are like the pillars and columns of our houses. They give structural rigidity and stability to our roof and walls. In acoustic guitars, the braces on top boards function like house pillars. In additional, they also regulate the tonal qualities of acoustic guitars. Contemplate removing a few columns in your house… the same effects would apply on acoustic guitars as well.

In my blog post "Guitar Myths #002 - Are acoustic guitars' tops really flat?", I mentioned about the unavoidable bulging effects about acoustic guitars' bridge areas. If the regular guitars are suffering from this bulging effects, how much more would it affect the smaller guitar?

Bridge Lifting; How did that happened?

Many reasons contribute to bridge lift. In this blog I would be illuminating the structural rigidity of acoustic guitars' top boards, specifically small acoustic guitars.

As discussed earlier, small acoustic guitars' give volume projection more weight than structural rigidity of their top boards in design. One could easily imagine that when bulging effects set in, small acoustic guitars' top boards would get more of it. Another words, their top boards should bulge more than regular sized acoustic guitars.

Analogy of bridge lift

All new guitar bridges are made with flat base. They are glued to new acoustic guitars' top boards which were flat before loading strings on them. As bulging sets in, the curvature of the top boards increase. Invariably, the base of the new guitar bridges remain flat while the top boards changes in curvatures. As soon as the bridges could not keep up with the curvature (see picture above), the extreme ends of the bridges detached from the top boards. This detachment would appear like the bridges have lifted to our naked eyes. When left unchecked, the detachment grows until the guitars are unable to be tuned, or the bridges get ripped off.

Re-gluing Small Acoustic Guitars' Bridges; 2 Screws 2 Holes

There is actually no difference between re-gluing small acoustic guitars' bridges and regular acoustic guitars. However the difference in their respective life-spans cannot be more obvious. I have enough returning customers coming back for the same repair job, that is re-gluing small acoustic guitars' bridges that set me thinking of approaches to make this repair job more enduring.

A while ago I repaired a guitar that was of non-wood composition. Its bridge has detached and I made 4 attempts but they were in vain. Each attempt I tried a type of glue but nothing seems to work. The client was thankful for me trying that hard, at the same time he was very disappointed with the small guitar in question. He left that guitar in my shop.

Screws & Nuts; There is no better way than fastening the bridge to its top board by screws and nuts. So I picked up that guitar and placed screws and nuts on them. See right picture. Directly under the bridge and the underside of the top board, a piece of 3.5mm thick hardwood was glued onto the existing bridge plate as reinforcement. The nuts are secured onto the hardwood. I would like to emphasize at this point; the lifted bridge has already been re-glued properly before the screws and nuts get installed.

Since I have freely received this guitar, I too gave away this guitar freely to a deserving friend. I haven't heard anything regarding bridge lift since the guitar was given away.

Tone Affected?

Yes, FAQ from the worry guys. "Would drilling 2 mounting holes for screws and nuts affect my guitar's tonal quality?

What do you think? Personally, I have 2 replies to the above question, a simple and a elaborated one.

The simple reply; "No." Period.

The elaborated reply; "Would it affect the tone? Firstly there is one big hole in the middle of your guitar, plus another 6 smaller ones beneath your bridge pins. Adding 2 tiny holes wouldn't amount the slightest degradation to your guitar's wonderful tone."

Some small acoustic guitars use dowel pins for bridge positioning. For such design, there are already 2 tiny holes drilled onto the top board (see above picture). I simply make use of these 2 holes for my Screws & Nuts approach.

Admittedly, the Screws & Nuts approach may not be a popular solution to acoustic guitar owners. It is nevertheless an effective approach to give life-span endurance to your small acoustic guitars. Don't let the fear of unknown stop you from trying, instead take a rational view when deciding the most suitable repair jobs. Drilling your acoustic guitars isn't always bad.