Today I’d like to shine a light on a problem that many steel string acoustic guitars have, yet most people don’t notice: worn out bridge plates. The bridge plate is a flat piece of wood that sits inside the guitar, underneath the bridge, which helps support the top and is where the string’s ball ends anchor. Over time, the metal ball ends wear through the bridge plate, causing the strings to sit a lot higher in the bridge. Oftentimes, the looser windings at the string’s end wind up resting on the saddle, causing intonation problems, uneven action, and tonal weirdness. While the bad news is that a lot of acoustic guitars suffer from this malady, the good new is that it’s a rather simple thing to repair, and isn’t that expensive to fix. Check it out:
This guitar belongs to my friend Kip, who drove this guitar all the way from Tyler, TX to get fixed up. A couple of weeks ago I blogged about how I repaired his bellied top and bridge, which turned out beautifully, but his guitar also needed a bridge plate repair. The tell tale sign is that the strings were sitting very high in the bridge, and some of the loose windings were sitting on top of the saddle:
This bridge plate had seen better days, and definitely needed to be repaired. Since this is a 1951 Gibson, I didn’t want to completely remove and replace the original bridge plate – I like to respect the vintage value of the instrument where I can, and keep things as original as possible. Besides, there’s a much easier way to go about it:
Guitar Bridge Plate Metal High Strength Standard 4 String Bridge Board Ids
One of my favorite and most often used tools in the shop is my StewMac Bridge Saver, which is worth it’s weight in gold in a busy repair shop, and is quite frankly, a lot of fun to use. The basic gist of how it works is that it cuts away the worn out parts of the bridge plate, which are then filled back in – basically patching the bridge plate.
First I start by cutting out the bridge plate around the E, D, and B strings, skipping strings on each pass because the cutting bit overlaps the subsequent plugs a bit. This bit goes inside the guitar, and cuts away the bad wood around the string holes:
I turn the cutting bit by hand from the top of the guitar, just up to the point where the bits collar stops against the bridge plate:
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Next, I use a special bit to make plugs for the newly cut out holes. My bridge plate stock is starting to look like swiss cheese – you can tell I do this kind of job a lot!
The next day I repeat the process for the A, G, and E strings, and again let that sit overnight. When it’s all done, it looks like this on the inside:
I had adjusted the collar on the bit to perfectly match the plug’s depth, so that these were sitting almost perfectly flush without even sanding. This is really important – trying to sand things flat on the inside of a guitar ain’t fun.
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Then I drilled out the holes, while holding a backer inside so that I wouldn’t accidentally knock the plugs out, and then did a tiny bit of sanding to clean it up.
And that’s it! A simple, but necessary repair. The strings are now sitting much lower in the bridge, and are resting on the saddle properly:
I am a bassist, guitar tech, and founder of Strange Guitarworks. When not working on guitars, I create experimental music under the moniker of UFO Death Cult, utilizing microtonal instruments of my own design.This is a classic repair. The bridge had become loose while this 1964 Martin 0-16NY sat in its case, unnoticed by its owner. Months or years of relentless pull by the strings slowly deformed the top, which was no longer supported by the strength of the bridge.
D 21 Rosewood Bridgeplate
The bridge plate bent under the load, and began to crack through the bridge pin holes, and the top developed cross grain cracks in the same area.
The area was so badly warped there was no hope of gluing the bridge back on without flattening and reinforcing the top.
While it would be possible to heat and flatten the bridge area of the top, the broken bridge plate and spruce would not be nearly as strong as they were when the instrument was made. I decided it was time to replace the bridge plate.
Restoration/transformation: A 1970 Martin D 18
In order to remove the bridge plate safely, I needed to heat it up in order to weaken the glue bond while I pried it off.
I have a 1/2 thick aluminum block the size and shape of the bridge plate, and I heated it on my hotplate:
Because the top was so deformed, it was necessary for me to clamp the block tightly to flatten the bridge plate to get good heat transfer:
Tool For Bridge Plate Removal
Notice the aluminum caul on top. It helps keep the finished surface cool while I apply heat from the inside. This is tricky work, and I moved quickly to release the clamp and feel the temperature of the finish to avoid blistering or other heat damage.
To catch the back edge of the bridge plate and pry it loose. Actually, I didn't pry so much as pull straight downward toward the back of the guitar. I had to work fast before the bridge plate cooled off, so I wasn't able to take progress photos of this operation.
Notice the date and initials on the inside of the top near the bass cross brace. For a short while in the 60s, they were signed in this way. (The only other period I know when this was the custom was from about 1880 to 1900.)This week I had the pleasure of working on a vintage Gibson LG-1 acoustic guitar, owned by the fantastic musician Seth Walker. These were considered beginner guitars back in the day (the LG stands for “learning guitar”), but now they are starting to command increasingly higher prices as their perceived vintage value rises. It’s not surprising, as they are really great sounding instruments – but this one in particular had a somewhat mushy tone, which I attributed to it’s worn out bridge plate. The bridge plate is a piece of wood (usually spruce or maple) that sits under the bridge on the inside of the guitar, and helps support the bridge and top against the constant pull of the strings. Bridge plates tend to wear out over time, as the metal ball end of the guitar string rests directly against it, and slowly digs into the wood. This results in the string sitting higher and higher in the bridge, so that eventually the loose windings of the string near the end are resting directly on the saddle, like so:
Repairing An Acoustic Bridge Plate
This particular guitar had a very mushy sounding low E string, which isn’t surprising seeing that the string isn’t properly contacting the saddle. Using a mirror and a flashlight, I inspected the damage from the inside – it was looking pretty rough:
This particular bridge plate was worn out enough to warrant a complete replacement, but I opted to repair it rather than replace it completely. Why? Well, this is a vintage instrument, and I believe that they should be kept as close to original as possible (unless I’m specifically asked to modify them, in which case all bets are off). Replacing this bridge plate would not only require an entirely new plate, but would since it’s bolted down through the bridge, I would also have to drill out and replace the pearl dots on the bridge that hide the bolt heads. I felt that replacing the bridge plate would be too invasive, so I decided to repair the existing plate.
To repair the bridge plate from within, without removing it first, requires a specialized set of tools. This one is one of my favorites: my Stewmac Bridge Saver. First, I use the this bit to carve a dome out around the damaged area of the bridge plate from inside:
Top 5 Bridge Mods For Better Playability
The bit is reverse threaded, and is turned by hand against it’s threaded counterpart on the top of the bridge, which slowly brings it up into the bridge plate below, carving away a dome shape:
Next I use a special bit designed to make dome plugs corresponding to the shape I just cut into the bridge plate, like so:
These dome plugs are then covered in glue, and pressed and clamped into the bridge plate, and allowed to sit over night:
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With the plugs firmly in place, I drilled holes through them for the strings to pass through, then sanded the plugs level and cleaned up any excess glue that had squeezed out. Now the ball end of the strings have a solid anchor point, and won’t pull up too high in the bridge anymore. Now the strings correctly contact the saddle:
The mushy tone is gone! With a fairly simple, non-invasive repair, this guitar has gone from just ok
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