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How to fix a split bridge on an acoustic guitar
View of damaged bridge
Doing what seemed impossible
This Johnson dreadnaught guitar was acquired for free from a posting on Craigslist. The picture shown in the posting displayed a guitar that was almost intact and in relatively good condition except for the split bridge. I had never made this kind of repair before even though I have a lot of experience with woodcraft. I am not a Luthier.
I went to the library and took out a few books on guitar repair. The best one I found was Guitar Player Repair Guide : how to set up, maintain and repair electrics and acoustics / by Dan Erlewine. At first glance, the task seemed impossible without destroying the top of the guitar. After close examination I discovered the split went right through the top wood.
Here is an illustrated step by step chronicle of how I managed to save this guitar.
How to begin:
By following these steps and the advise from the manual on guitar repair mentioned above, I managed to restore the bridge on this guitar.
STEP ONE: I pulled the pegs and removed the strings. I managed to save the strings by loosening the tension on the keys so that they became almost slack.
STEP TWO: I carefully removed the broken parts of the bridge from the guitar top using Xacto tools, long blades and thin saw to avoid damaging the guitar top which was pulled upward and split by the force of the break of the bridge. This particular guitar did have a laminated spruce top which was an advantage in this case. A solid top might have split open and the repair would have been a lot more difficult or maybe impossible. ( I do not know what caused the damage to the bridge.)
STEP THREE: After removing the bridge parts, I was able to glue the bridge back together with yellow carpenter's glue. I clamped the bridge for over a week to allow the glue to cure. I have always had good luck with this glue in my other woodcraft projects but I had no idea how it might affect the sound of a musical instrument.
STEP FOUR: The top of the guitar did suffer some damage and the shape of the top was pulled and curved upward almost like a violin. I used a very fine 180 grit sandpaper to smooth out the undersurface and remove the old glue.
STEP FIVE: After the bridge was repaired, I used a Dremel Tool to remove material from the underside of the bridge to make it fit the contour of the top.
Restored bridge and exposed guitar top
Replacing the bridge
The next stage of the restoration process was to re-attach the bridge to the guitar making sure that the bridge was installed to the exact position before removal or the guitar would not work correctly.
STEP SIX: To replace the bridge, I used bolts and wing nuts slipped through the string holes to re-mount the bridge onto the guitar and I used a placement clamp to insure that that bridge was put in the right place otherwise the guitar would not work properly.
STEP SEVEN: Restoring the string pad. The damage to the guitar went deep into the top and the pad so I decided to augment the pad with a piece of thin hardwood. I used white oak. I had no idea how that type of wood might effect the sound of the guitar but it was all I had available to me. I used screws and wing nuts to hold the pad up to position so I could measure and make the holes for the pad.
STEP EIGHT: After drilling the holes in the pad to match the string holes on the bridge, I used a thin file to refine the holes so that the string pegs would fit snugly. After the holes were finished, I glued the pad in place using the same bolts and wing nuts. I allowed the glue to cure for more than a week.
After re-attaching the bridge and the new string pad, I took additional steps to clean and prepare the guitar to be restringed.
Re-attaching the bridge
Final steps to making guitar playable
These are the final steps I took to clean and prepare the guitar for restringing
STEP NINE: Before restringing, I thoroughly cleaned the rosewood parts of the guitar using olive oil rubbed into a soft flannel cloth on the fret board and bridge which was covered with grime. The body of the guitar was cleaned with light buffing with the same flannel but no oil.
STEP TEN: I was ready to re-string the guitar. I went to the Guitar Center and bought Elixir ultra light polymer coated bronze strings. I did my string research online first. I learned that the polymer covering extends the life of the strings. I had no real idea what this guitar was going to sound like because there was no way to play the guitar when it was damaged. I had to hope all the repairs I made would work. I had to refine the string holes a little more with a thin file before restringing to fit the strings and pegs.
STEP ELEVEN: Restringing the guitar. I have to say I am a novice and this was my first experience restringing a guitar. The instruction book I used really didn’t show me all the things that can go wrong. Take your time and be patient. I managed to re-string starting with the high E then B, G, D, A and low E. I did not tune each string as I installed them. After the initial winding of each string, I turned the keys slowly, increasing tension. The guitar creaked like an old ship. The tuning keys were in good shape and the bridge and pegs were secure again, the new hardwood pad put a strong hold on the string beads so the strings held their tension well.
Set-up and Action
I was lucky that the replacement of the bridge did not adversely affect the set up. The action was just right. Action is the distance from the string to the fret board. You can measure the action of guitar by using a long yardstick and laying it along the nut and the bridge saddle so I knew before I performed the restringing that the action would not be too high but almost perfect. Fretting was very clear and clean with no buzz.
STEP TWELVE: Tuning the guitar. I used an Intellitouch PT10 battery operated tuner with a color screen that records the vibration of each string and reads the scale flat to sharp with a dial.
To my great relief, the guitar was tunable and in fact, after three successive tunings, over a few days, this guitar remains in tune and in fact the sound of the guitar is rich, mellow and sweet. The action is fine and the fretting is smooth with almost no buzz.
Not bad for a freebee. I have my practice guitar. All it cost me was a bit of glue, handicraft ingenuity, some book research, a bit of frustration and anticipation, and a new set of strings.
NOTE: After three months of use, the guitar continues to hold to tune very well.