When first learning how to restring and tune an acoustic guitar there’re a couple of annoying things we all experience, including breaking strings, keeping new strings in tune, or messing up your action by using the wrong string gauge. These are all frustrating if new to the guitar but perhaps even more so is when you notice your bridge pins popping out while tuning. In today’s article, we’re going to discuss why this happens, and how you can fix the problem once and for all.
The short answer: Why do my bridge pins pop out while tuning?
Bridge pins tend to pop out when the string’s ball end is sitting directly under the bridge pin and not against the side of the bridge pin shank as intended. If this occurs reload the string allowing enough surplus for the ball end of the string to sit well below the bottom of the bridge pin and then maintain pressure on the bridge pin by pushing down with your finger while increasing tension on the string with the tuners.
To elaborate a little further on the explanation above. If we take a look at the two diagrams below we can see the guitar string running across the top of the saddle before angling down toward the bridge pinholes. The ball end of the string passes through the bridge pinhole. The bridge pin is then installed and should then prevent the string from moving. However, as we know this isn’t always the case.
The two diagrams below demonstrate both the correct, and incorrect way to install your bridge pins and prevent them from popping out.
The wrong way to install bridge pins
In the diagram above the ball end of the string is positioned directly beneath the shank of the bridge pin. As tension is then applied to the string when tuning the ball end of the string comes into contact with the bottom of the bridge pin and exerts upward pressure (as indicated by the arrow), which, in many cases eventually leads to the bridge pin popping out.
The right way to install bridge pins
In our next example, we can see the ball end of the string sitting hard against the side of the bridge pin. This is how the ball end should sit when the string is installed to prevent the string from moving.
When the string is tightened, instead of pushing up against the bridge pin the pressure exerted from the string pushes against the side of the bridge pin, increasing stability and greatly reducing the chance of the pin popping out.
So how does one ensure this happens?
Preventing the ball end of the string from sitting under the bridge pin
If you notice your bridge pins won’t stay in place while tuning (in most cases this problem will be limited to your wound strings, usually the A and low E string) the solution is to remove the bridge pin, place a small kink in the guitar string approx. 5mm from the ball end of the string and then reload the string.
Allow sufficient surplus e.g. 5cm of guitar string going directly into the bridge pin hole before inserting the bridge pin. If your bridge pins have channels (not all do), ensure these are facing directly to the front and then push the bridge pin all the way into the bridge pinhole.
Start tightening the strings while at the same time maintaining downward pressure by placing a finger on top of the bridge pin to prevent it from moving. This will lock the pin in place and the ball end of the string will slide up against the bridge pin, eventually settling in place against the side and not the bottom.
Are your Bridge pins the wrong size?
How to measure your bridge pins for replacing
While most bridge pins are similar, bridge pins are non-standardized and come in a range of different sizes, which can be frustrating as a poorly fitting bridge pin is also likely to cause problems when pressure is applied from the strings.
Your best bet when it comes to replacing your bridge pins is to measure the pins using calipers.
First, measure the taper length. This measurement should be taken from just below the collar of the bridge pin, all the way to the bottom. Next measure the widest section of the pin shank (also just below the collar) and the narrowest section at the bottom.
Then, taking these three numbers you can then use an online calculator, like this one to calculate the taper length of the bridge pin before ordering a suitable replacement.
The tapered size of the bridge pin holes can also be adjusted using a bridge pinhole reamer but this is a specialist job and requires the skills of a luthier or someone with experience who has performed this type of job before.
While seemingly only a small and unimportant component, much like strap buttons (which keep your guitar from falling to the ground), bridge pins play a critical role and should be installed correctly. This means, ensuring you install and tune your strings as per the information presented above and also ensure (if you use them slotted bridge pins) the channel is facing directly to the front of the guitar. Once installed, remember to stretch those strings to prevent them from constantly going out of tune.