Classical guitar repair help

A few months ago my daughter's guitar took a bit of a tumble when someone forgot to zip the case up on the way to school. We looked into getting it repaired, but the quotes that came back were as much as the guitar itself ($300+). At the time I was about to just go and buy a new one, but got out the duct tape out and did emergency repairs instead. Surprisingly, it has held its tone well, and it generally stays in tune.

https://i.imgur.com/nvNz4Nh.jpg

It's tricky to see in the photo, but the top has come away from the side for about 15cm, and there is about a 6cm split on the top.

School holidays are coming up, and I'm tempted to have a shot at doing the repairs myself while it's not required for a bit. I'm not looking to make it showroom perfect, but would like to have a crack at making it somewhat whole again.

I guess my first questions are:

• What sort of glue do I need?
• How long will it need to cure?

Traditional classical guitars would use hide glue. But a $300 one is more likely to use Titebond or PVA in its construction.

Your best bet is to prise the top off as much as you can, and use sanding sticks or sandpaper taped to thin bits of wood to sand as much of the existing glue off as you can, or use a small sharp edge to scrape it away.

Ideally you'd remove the top completely (which also requires removing the fretboard), sticking a patch over the split on the underside, and then gluing the top and the fingerboard back on (which is why the repair would cost so much).

You may be able to glue a thin wooden patch over the split on the inside if someone with thin arms can hold it inside, but clamping it in place cold be an issue unless you've got a specialist clamp. Otherwise a wood patch and some CA gel would allow some strengthening for the split and would set without needing clamping.

Then use a brush to apply Titebond to both sides of the gap, and clamp the top back on, wiping off any excess glue with a damp cloth.

Traditional classicals would be French polished, but that looks more like a Poly finish. If the finish needs repairing, then you'll need to sand the area around the split and join to key it, but could then use wipe-on or spray poly to finish the job.

Ok great, that all makes sense, particularly cleaning up the area and applying titebond. I'm not so keen on removing the whole top for this project (something for practicing on an op-shop find or the busted uke I've got laying around...). I'll have a think about how I can get in under the split on the top though. That sounds worth doing if I can I figure out a way.

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Thin knife and some thin wooden wedges. It's one of those cases where it's better to increase the amount of 'damage' so that it can be better repaired. It may also be worthwhile watering down some Titebond to say 70:30 Titebond:water so that is penetrates the remaining crack areas at the ends that you can't get a small artist paint brush and full-strength Titebond in. It all helps. And if it really is a very small crack and you don't feel happy about opening it up, then you could mask off around it and wick in some thin CA and then clamp it down.

Simon has offered good advice and I'm certain has way more acoustic repair experience than me.

I'd be interested in seeing what's under the "100 mile an hour tape" (that's what we called it back the car racing days) just to put the damage and repair next to each other in my head.

Not a huge amount of acoustic guitar repair experience, but a friend makes classical guitars (and is now branching out into steel-strung as there is a limited market for £3k+ classical guitars), and posts lots of pictures and explanations on Facebook, so I've got a good idea of what goes on inside them.

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Originally Posted by McCreed

I'd be interested in seeing what's under the "100 mile an hour tape" (that's what we called it back the car racing days) just to put the damage and repair next to each other in my head.

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School holidays coming up. I'll do the big reveal then XD


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Not a huge amount of acoustic guitar repair experience, but a friend makes classical guitars (and is now branching out into steel-strung as there is a limited market for £3k+ classical guitars), and posts lots of pictures and explanations on Facebook, so I've got a good idea of what goes on inside them.

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That's a good friend to have and I understand those market limitations. I 've owned cars that didn't cost £3k!
I have great admiration for anyone that undertakes building any acoustic instruments. Give me solid slabs o'timber anyday! :o

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Originally Posted by McCreed

Simon has offered good advice

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When it comes to guitars Simon is the most clued-up guy on the forum by a long way, he's better than google

Revealing photos as promised:

https://i.imgur.com/LgyZ2uB.jpg
https://i.imgur.com/9Q3C4R5.jpg
https://i.imgur.com/hqL8uB6.jpg
https://i.imgur.com/MLzzlk9.jpg

This also shows a smaller split about 2 cm on the top, and also that the top has popped out over the top of the binding at one section. So I'm assuming I'm going to have to apply a bit of brute force somewhere to get it back inside the side. Just not sure how much "give" it has.

(Also, for the Perth crew, I went to Timbecon in Canning Vale yesterday, to buy some Titebond. That place is bloody dangerous...)

you are going to need to be very careful trying to get that edge to sit back down. it appears as though the top has fractured from the purfling ledge as well as split.
Forcing it back down may cause further fracturing if you can't get the binding to 'give' enough to set that exposed purfling back to where it should be.
I would think that the way to tackle this involves all sorts of stripping back, top removal and stabilisation and then re-setting it on the box and re-binding, if you can get the binding/purfling to move enough to get the top to sit down you might get away with wicking some thin CA into the fractures and splits and getting it all to hold together.

It's certainly going to be a tester. Is there anything rattling around inside it? DO you havee a mirror or one of those little scope cameras that you could use to check what that all looks like inside the box?

No, nothing rattling around (other than what appears to be part of my daughter's school recess :rolleyes: ).

I'm going to have a go at doing this very very carefully without taking the top off, and back off at the first sign of stress on the body.

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Originally Posted by dozymuppet

I'm going to have a go at doing this very very carefully without taking the top off, and back off at the first sign of stress on the body.

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Yep, that's probably the best plan. The alternative is a very big endeavour.

You're definitely going to need an inspection mirror to see what on earth is going on inside.

It may be that removing the binding is the easiest way to get too the bits you need to get at. Which means that you'll need to be prepared to replace it. And removing it may not be that easy.

Yep. the binding is very much at play here. I managed to do a bit of exploration with a (gasp) Swiss Army Knife lever, getting a little bit of purchase to be able to see at least some of what was going on. Then I used the tweezers from said SAK, and was able to pull the white binding out enough for the top to drop back into place, and the binding to sit back on top (albeit a bit out of kilter).

https://i.imgur.com/CvZdMFL.jpg
https://i.imgur.com/720zN9f.jpg
https://i.imgur.com/RQKTCZJ.jpg

So I'm in a better place now, but I still need to get in there and clean things up, before applying glue.

Looking a lot better there. But you'll certainly need to stick something on the underside to hold it all together.

Looks like that might be a bit tricky. I realised that as well as having the sum of human knowledge in my pocket, I've also got a decent camera with a flash, and relatively skinny wrists.

https://i.imgur.com/D0FMQUQ.jpg

The damage isn't too bad from what I can tell, but I'd still like to see what I can do. I can probably get some kind of prop in there to provide the pressure required to hold a fix in place.

That looks and sounds promising!
I also have "relatively skinny wrists" but it never fails that they go into places a lot easier than coming out for some reason!

Nice MacGuyvering mate! You can see that the top has split laterally across from the break at that section of purfling ledge.
As Simon says you’ll probably need to fix something on the underside. It might be possible to fabricate a small thin plate to cover it but you’d need to also find a way to clamp it accurately in place.
you could make some basic f style clamps with hardwood and all thread to get in there and clamp it all securely together.

Not too bad underneath, though some of the top parts of the wood are creased.

Maybe you could turn it upside down and spread some epoxy over the crack on the inside? Push it into the crack and then pile a bit on top.

If all else fails, there's always the John Belushi Method...

https://www.youtube.com/watch?v=8V_hCqO6UQs

Yes, I have been to Timbecon To buy titebond. Worth the trip just to have a look around.

Update: I ended up cleaning up the visible damage by sliding some sandpaper in, then liberally applied titebond before gently clamping. I decided to see what the result of that would be before attempting to patch the inside.

I also applied some Birchwood Casey Sealer & Filler, then a couple coats of Tru-oil. Will probably do some more Tru-oil and polishing next school holidays. (Might also look at wax filler sticks.)

Seems to have done the trick, and it's staying in tune and the tone is still nice. Even my daughter's guitar teacher was impressed with the handiwork.

https://i.imgur.com/5tRFDMa.jpg

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And zoomed out, "barely" noticeable

https://i.imgur.com/Y6qcLRf.jpg

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Should you ever choose to open it up and do more extensive repairs. Here is a video (4 mins 34 seconds if you want to jump straight to it) that touches on how splits in the tops of Violins are repaired.

https://www.youtube.com/watch?v=cJhmCzm2NYo

Damage doesn't look too bad at all. So the next task is to strip off the finish on the top and re-do it so that it looks like new. Or go with the full heavy relic look.

I'd better build her ST first before she lets me at it again...

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As I have said elsewhere - battle scars. Shows it isn't guitar stand princess.