Loose Guitar Braces
Loose Back Brace
Braces reinforce and strengthen the top and back of most acoustic instruments. The braces on an acoustic instrument bare the brunt of string tension placed on the instrument and it is essential that they be securely glued in place. Because most acoustic flat tops are no more than say .100+/- of an inch, braces play a huge role in keeping everything together.
Signs of Loose Bracing:
- Top rotation (dip in front of bridge, hump behind)
- Ripples / Waviness on flat panels
- Rattling/vibration/changes in tone
- Stress to glue seams
Some times we aren't aware of loose braces. They are usually discovered by inspection after a bulge is noticed, a rattle is heard or perhaps a bridge repeatedly comes loose.
A thin feeler gauge will slide under
a loose brace.
I start by inspecting the interior of the guitar with a light and mirror, but sometimes that isn't enough. Loose and split braces that have no visible gap can be difficult to spot.
After eyeballing it I turn to my favourite brace checker, a simple feeler gauge. A thin feeler gauge will easily slip between a loose brace and the top or back.
Cracked / Split Braces
A cracked/split brace can elude even the best eagle eyes. While inspecting the braces with an interior light and mirror a split brace may give no cosmetic clue as to it's whereabouts. Handling each brace is sometimes necessary to locate the mystery brace as the crack can be very fine with no gap or separation.
Paper strip shows location of a hidden crack
Even though these braces are radiused (shaped to render the top/back slightly arched) this one has begun to curl up excessively. Warping can occur when a brace is left loose for a long period of time or the instrument is subjected to a dry environment.
Gluing Loose Braces
Before gluing the brace, old glue must first be removed to insure good adhesion. I go to great lengths to avoid leaving glue behind which would make these kinds of repairs most obvious.
Loose top braces are often glued using deep c-shaped clamps available thru luthier supply companies.
Back braces are often glued with the use of interior "jacks". On occasion I may use an interior jack in combination with an exterior clamp. This allows me to place greater pressure on a back brace without the risk of damaging the instrument.
I use a small nylon wedge to lift the brace away from the panel and permit glue application.
"Jacks" are often used to glue loose back braces
When left un repaired a loose brace can actually come completely free from the top or back. On many occasions I have inspected a guitar only to find a missing brace, one can only wonder where it got off to.
As seen in a previous photo, a loose brace can warp over time. Excessive warping can make the brace far to stiff to be clamped back into position. In such cases removal and/or replacement is often necessary.
I have successfully made an installed many top and back braces without removing the back. This excludes the X brace, it is two braces where one lies over another. This is tedious work as the radius must be copied and the brace positioned while placing ones hand, clamps, mirror and light inside the sound hole all at once. Difficult access does require the back to be removed for some repairs.
Acoustic Guitar Repairs
- Action / Set Up
- Bridge Plate
- Bridge Pins
- Buzzing - Noise
- Care / Maintenance
- Convert Rt. to Lt.
- Fret Replacement
- Fret Types
- Neck Damage / Issues
- Neck Angle
- Neck Resets
- Part Glossary
- Strap Buttons
- String Changing
- String Choices / Effects
- Truss Rod
- Tuning Machines
- Tuning Troubles