Bridge repair on Freshman acoustic - advice appreciated!

[Andrew Hann]

Hi all,

I'm a recently trained luthier ( just completed Masters course at Galloup school) based in the UK. Just got a job to re glue a bridge which popped right off when the customer left his guitar in a hot car. A chunk of the spruce fibres were torn from the top - see photo for extent of damage.

My question is , what is the best method of filling the top to get a adequate/flat gluing surface. I was thinking of trying to chisel off the main missing chunk from the bottom of the bridge and glue that down and perhaps fill the smaller missing areas with wood dust mixed with a few drops of super glue, then scraping flat. Just want to make sure it holds.

Clearly there's a margin all round of finish where the bridge wasn't glued at all and I'll scrape that back to the edge of the bridge. I'll be using Titebond (not yet versed with hide glue)

Its not an expensive guitar, probably $500 new.

Any advice appreciated!

Andy

[Roger Häggström]

I think you can go ahead with your plan. As you probably know hot hide glue is the best glue for a bridge, so why not take the opportunity to get versed! You need to clean both surfaces from the old glue in that case :-) Titebond will do fine on a cheap guitar.

[Andrew Hann]

Sorry Roger, only saw part of your message initially.... re - hide glue - it is my plan to get versed with hide glue. I  need to source a glue pot or something that will do the job that isn't too expensive. I've only just set up the workshop on return from the US and I'm still accumulating tools/ materials etc. For this job I don't have time so will use Titebond on this occasion. Cheers

[Andrew Hann]

Thanks Roger - that makes me feel better! It is my first bridge repair job.

The other minor problem I'm thinking about is how to make a caul to go over the braces and how one can get the caul the right shape. Tried a light inside the guitar but it doesn't show up the braces as top is too thick. Looking at one of Dan Erlewines solutions ( shown on Stewmac online) - i.e. getting some styrofoam , backed with 1/8' plywood, use magnets to position, and making an imprint, then cutting out the sections where the braces are, and using this as the caul. 

Do  you know of any other methods of getting the correct shape for cauls to go inside the body to fit over the braces etc?

Many thanks for your help

Andy

[Roger Häggström]

Dan Erlewine's method is pretty much it. Just do it like in the video and it will work out fine :-)

[Andrew Hann]

That's great, your help is much appreciated Roger, thanks 

[Thomas James]

In some situations I use plane shavings to fill voids. It allows control on thickness. They can be sized to fit.
Also, I have used a bunch of small magnets to outline the brace structure, then connect the dots to make a drawing. Add that to depth measurements. It doesn't take long. Cheers, Tom

[Andrew Hann]

Hi Tom. That sounds a good idea too.... much appreciated Andy