# guitar repair



## Jacob (18 May 2012)

Acquired a guitar wreck freeby. Stagg dreadnought with 3 broken/missing struts and cracked soundboard. Looks like a classy guitar in spite of being cheap/Chinese. And it sounded nice and I quite fancy it, so looking to repair it. 
The struts and soundboard would be dead easy, cracks neat enough for an invisible repair, but only with the back off.
Any hints?
I thought I'd start removing the binding with a cutting gauge perhaps.
Gluing the back back would require spool clamps it seems. Lengths of m8 stud plus nuts? Don't want to buy any special kit as it's a one off (most likely).
Wheezes? Wangles?


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## thick_mike (19 May 2012)

Frets.com is a mine of guitar repair information. The guy there has a very creative attitude to his work.

E.g.

http://www.frets.com/FretsPages/Luthier/Technique/Structural/LongPipette/longpipette01.html

http://www.frets.com/FretsPages/Luthier/Technique/Guitar/Structural/XBraceWrinkle/xwrinkle2.html

http://www.frets.com/FretsPages/Lut...tructural/Cracks/LG2TopCrack/lg2topcrack.html

Loads more in a great big list of ideas and information...

http://www.frets.com/FretsPages/pagelist.html#Luthier


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## Setch (19 May 2012)

Taking the back off on a chinese acoustic will be tough, not least dealing with inch thick, diamond-hard poly lacquer. Through the sound hole is the way to go - as linked above frets is the place to go for info and tool tips.

If you really want to pull the back, rope and wedges are a traditional low teck approach to clamping, or surgical tubing or long lengths of inner tube. Another approach is a go-bar deck, pretty easy to knock together and disassemble from scrap.


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## Jacob (19 May 2012)

thick_mike":3auvl93c said:


> Frets.com is a mine of guitar repair information. The guy there has a very creative attitude to his work.
> 
> E.g.
> 
> ...


Excellent links, thanks thick-mike.


Setch":3auvl93c said:


> Taking the back off on a chinese acoustic will be tough, not least dealing with inch thick, diamond-hard poly lacquer. Through the sound hole is the way to go - as linked above frets is the place to go for info and tool tips.


Three braces need fixing which suggests to me that there may be other damage - it's had a big thump, so I'll go the back way I think. Yes the lacquer certainly does look thick and the back and sides are in very good clean condition. But it's a scrap guitar and I'm more interested in playability than appearance. If I manage to do a neat job it will be a very good guitar I think.


> If you really want to pull the back, rope and wedges are a traditional low teck approach to clamping, or surgical tubing or long lengths of inner tube. Another approach is a go-bar deck, pretty easy to knock together and disassemble from scrap.


OK thanks setch. What's a go-bar deck? (I'll google it).

PS Googled it http://liutaiomottola.com/Tools/Go.htm
Brilliant. I've done the same on other jobs with bits of cane for the bars e.g. sticking a drip rail into a window opening where clamps and other fixings were impossible.


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## MIGNAL (19 May 2012)

Trouble with taking the Back off (besides all the extra work) is that you get into the realms of altering Neck angles, which you don't really want to do. Back off is a last resort but maybe the only option.


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## thick_mike (19 May 2012)

MIGNAL":10i4tz17 said:


> Trouble with taking the Back off (besides all the extra work) is that you get into the realms of altering Neck angles, which you don't really want to do. Back off is a last resort but maybe the only option.



Agree with this ^^

The struts are called bracing (which might help you to search for information on the net).

E.g.

http://www.fretnotguitarrepair.com/repair/acoustic-guitar/braces.php

http://acguitar.com/article/default.aspx?articleid=24027

If the braces are in situ, but have become loose, it's pretty straightforward to repair. If the braces are missing then you should be able to whittle something suitable from spruce billets. All of this is achievable thought the sound hole (unless you've got a guitar with f holes or an ovation type guitar). A lamp or torch and a mirror inside the guitar will help.

The Stewart McDonald website has lots of ideas for useful tools, although I would imagine the tool worship contained in it will drive you mad Jacob. See what they're selling, then make your own tool to do the same job for considerably less. There are lots of videos and repair tips too.

http://www.stewmac.com/


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## thick_mike (19 May 2012)

Here's a step by step of a similar repair with some clever use of rare earth magnets:

http://www.frets.com/FretsPages/Lut...tural/Cracks/D45FBTopCrack/d45fbtopcrack.html


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## Jacob (19 May 2012)

Some clever stuff there!!
OK I'll go for the hole instead. 
I'd got as far as using a round powder compact mirror and a torch - but I see that using lengths of mirror, side by side, gives a better view, so that's a step forwards. I wondered about a mirror on a retort stand but the clamp would get in the way in the hole.
I'm off to cut up a mirror!

Thanks for that.


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## thick_mike (19 May 2012)

Jacob":24oe3bhj said:


> Some clever stuff there!!
> OK I'll go for the hole instead.
> I'd got as far as using a round powder compact mirror and a torch - but I see that using lengths of mirror, side by side, gives a better view, so that's a step forwards. I wondered about a mirror on a retort stand but the clamp would get in the way in the hole.
> I'm off to cut up a mirror!
> ...



A mirror triptych (!) with taped joints so you can pass it through the hole, then open out inside.


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## Jacob (28 May 2012)

thick_mike":1h4zg81y said:


> Jacob":1h4zg81y said:
> 
> 
> > Some clever stuff there!!
> ...


Good idea! Could also be used as a Kaleidoscope, in between guitar repairs.

I've had a good look. Only one short strut broken, the ones that felt rough look as though that's how they were from new. So it's easy to mend without buying any kit except glue for the sound board cracks. Cyano Acrylate? Is that the same as super glue? Can it run into the cracks _after_ the strut is glued in? I'll peruse the links you've given. Any other particular suggestions on this?


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## thick_mike (28 May 2012)

Cyano acrylate is superglue.

You need the low viscosity (thin) stuff for cracks. It helps to flex them to open the crack up a bit, so probably best to glue the soundboard cracks first, then sort the brace out. CA glue isn't any good for gap filling, so you need good contact between the surfaces.


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## Kalimna (28 May 2012)

Jacob - further to the above info, check out www.mimf.com - it's a superlative source of info on all things guitar. There is a forum there which has recently moved to new software, so there isnt a huge amount of archived material, but the folk who post are extremely knowledgable and free with their good advice.
Having taken the back (and neck) off an acoustic guitar, I can tell you it's a royal pain. I would advise against using a cutting gauge to remove the binding, and if there is no alternative to removing the back, you may have to replace the linings too (trinagular bits o wood as a kerfed strip or singular block - search for tentellones) that provide extra gluing surface for the back-side join.
The rubber strip/cord method of 'clamping' the back to the rest of the soundbox is certainly te way forward - low tech and easy to control tension, though a workboard/caul-type-thing with a raised edge is important so as not to put tension on the arch off either the back or the front. 
Speaking of the arch, if you need to replace any of the braces, be aware that nearly all acoustic guitars (particularly steel string ones) have an arch (in the region of a 25 foot radius), and this would need to be replicated to prevent undue stress being placed on the back.
The guitar may have be very playable prior to the damage (and may indeed be playable now), but a repair missing out on a few important points will make the guitar quite unplayable in the future, or at least sound flippin awful 

Good luck,
Adam


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## Jacob (30 May 2012)

Dunnit. The easy way - I decided the cracks would never be made invisible so I rubbed PVA in, rather than superglue.
Clearing off the remains of the brace was a problem. If I was doing it more often I'd wonder about some sort of cranked draw knife/chisel to pull towards me so I could see what I was doing in the mirror.
Biggest problem was to get it into position in one go, without dropping it and getting glue all over the place. Did it by careful dry run rehearsals until I go the movement right every time. Doing it again I'd wonder about having it pinned on the end of a bit of coat hanger wire with some sort of clamp (retort stand?) so as to manoeuvre it under control.
Seems OK s far, bit of a conspicuous glue fillet, but better too much rather than too little.
I wondered about adding a bit of extra reinforcement but perhaps not - might over do it and spoil the sound.

Thanks for all the excellent advice.


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## thick_mike (30 May 2012)

Luthiers often use single edged razor blades as scrapers to remove excess glue. To prevent damage to the soundboard finish, you can Sellotape over most of the razor edge, just leaving sufficient exposed to deal with the glue.

Most modern acoustic guitars at this end of the price range are over engineered from the point of view of bracing anyway so that the manufacturer has fewer customer claims. As you say, adding extra bracing will likely deaden the sound. As long as you don't intend to do a Pete Townsend, you should be ok.

It fits with your tool philosophy anyway...function over form!


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## Jacob (30 May 2012)

thick_mike":3u6rxx4p said:


> .... As long as you don't intend to do a Pete Townsend, you should be ok.
> 
> ....


More of a Blind Lemon Jefferson.


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## bugbear (30 May 2012)

thick_mike":12kzlzsd said:


> Most modern acoustic guitars at this end of the price range are over engineered from the point of view of bracing anyway so that the manufacturer has fewer customer claims.



Also the plywood tops on cheap guitars are likely to be stronger than the solid tops on finer guitars.

Making a sturdy box is easy - it's making a good guitar that's hard!

BugBear


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## Jacob (30 May 2012)

bugbear":3odi37qi said:


> thick_mike":3odi37qi said:
> 
> 
> > Most modern acoustic guitars at this end of the price range are over engineered from the point of view of bracing anyway so that the manufacturer has fewer customer claims.
> ...


This one (Stagg SW503) has solid spruce top and appears to be properly made close replica of a Martin. Also sounds good and has good action. But seems to have been less than £100 new! It's the Quansheng factor. The Chinese have hit on the formula - find out what people really want and make it as cheaply as possible with as little compromise over quality as possible.
Or is it a Belgian factor? Stagg are Belgian firm. Brian tells me that they still know how to make chips in Belgium! A lost art here - though there used to be a little chippy on the A7 south of Edinburgh but I bet it's gone now. There's a pub in Buxton which does good chips. Only two places spring to mind from a lifetime of chip eating. :roll:


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## marcros (30 May 2012)

you can still get good chips in Leeds if you know where to look Jacob. Still fried in dripping...


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## Phil Pascoe (30 May 2012)

The best chips were reckoned to be Belgian, apparently because they were fried in horse fat.


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## marcros (30 May 2012)

neigh, surely not


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## Jacob (31 May 2012)

Finishing the chips and back to the guitar. 
Looking at it has been giving me that deja-vu feeling, but I couldn't think why. 
Got it now - it's got something very much in common with the hand made but cheap "production line" furniture so common before the machine age. That is that everything is done "properly"; dovetails and other details, as if by experts, the economy being in cheaper materials and speed - resulting in less careful cutting, finishing, glue splodges, particularly where out of sight.
The result being very good value _at the price_ and a conclusion that these same people could produce the very highest quality, if they had to.
Also they are obeying the first (only?) essential rule of design - if you want to make something good then copy something good.


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## Modernist (31 May 2012)

I did enjoy the chips  I only wonder why the art eludes so many over here.

Re the guitar braces. Why is it not a problem gluing (spelling corrected by Google but I'm not convinced (glueing)) cross grain. Why don't the tops and backs split asunder?


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## thick_mike (31 May 2012)

Got to say the quality of cheap guitars now vastly exceeds that of the budget guitars available when I started playing in the early 80's. I can buy a better guitar now, for the same price, than I could then. Given inflation that's incredible! Can't say the same for a pint of beer or a ticket to a football match (or a bag of chips!).


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## Setch (31 May 2012)

Good quality instruments are assembled under scrupulous controlled conditions, and are intended to be stored and used in similar conditions. If they were exposed to the same shifts in humidty which most furniture endures they would (and sometimes do) suffer splits and structural failures.

The tops of acoustic guitars are arched, so that any cross grain expansion of the top just increases the arch - the top of the arch goes up, rather than the sides pushing out. This helps the instruments ride out minor changes in humidty and temperature.


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## Eric The Viking (8 Jun 2012)

Whatever you do, Jacob, just don't take it on United...


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## Jacob (8 Jun 2012)

Eric The Viking":ayyhramb said:


> Whatever you do, Jacob, just don't take it on United...


Er - woss that then?


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## Kalimna (8 Jun 2012)

Setch - I had not considered the arching having a side benefit of humidity change stability. All the info I have read on the matter suggests that it is for structural rigidity, but what you mention makes sense too. Backs tend to be arched also.

Jacob - there was a YouTube thingy about United Airlines wrecking a (correct me if Im wrong) Taylor acoustic. United wouldnt admit fault (again, this is all from memory!) and Taylor got so much 'free' press that they gave the poster of the video a guitar in 'compensation'. That's the gist of it, but google it to confirm 

Cheers,
Adam


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## Eric The Viking (9 Jun 2012)

Spot on. The poor chap who had his guitar wrecked spent months trying to get United to 'fess up. Eventually he said he'd write a song about it, to which United basically said 'Fine, do your worst!*' He now has a second career as a customer advocacy expert, his music business is doing really well, and United probably bitterly regret not training their baggage handlers better. Over 30m people have watched the video apparently, even though the hit count doesn't indicate that.

Enjoy - it's really well done!

*paraphrased, obviously.


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## thick_mike (9 Jun 2012)

Jacob":3pa2t630 said:


> Finishing the chips and back to the guitar.
> Looking at it has been giving me that deja-vu feeling, but I couldn't think why.
> Got it now - it's got something very much in common with the hand made but cheap "production line" furniture so common before the machine age. That is that everything is done "properly"; dovetails and other details, as if by experts, the economy being in cheaper materials and speed - resulting in less careful cutting, finishing, glue splodges, particularly where out of sight.
> The result being very good value _at the price_ and a conclusion that these same people could produce the very highest quality, if they had to.
> Also they are obeying the first (only?) essential rule of design - if you want to make something good then copy something good.



Budget guitars are often built in the same factories as the more prestigious guitars. The difference being material specification and QC, both of which come from the brand. Another influence on how good the guitar "feels" is the retailer. Good retailers will adjust neck relief, action and nut and saddle heights prior to selling. This can really make a guitar feel great to play, even if it doesn't sound that good. These final tweaks being done in the country of retail means that small movements in the wood due to humidity differentials are accommodated. 

Lots of these guitars are made in very humid countries and yet are very stable over here. To be honest, humidity doesn't really seem to be much of a problem in the UK. I don't think we get enough seasonal variation to cause guitars major structural issues. Americans seem to have much bigger problems going from very dry winters to humid summers. They're always banging on about humidification being essential to stop frets lifting and tuning problems, but as long as you don't keep your guitar in the garden pond or in the airing cupboard, you're pretty much OK over here.


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## Kalimna (9 Jun 2012)

Mike - unfortunately my experience suggests that humidity can be a problem over here. I made an acoustic out of macassar ebony B&S (at a course run by Mark Bailey at Bailey Guitars in Ayr), and whilst kept in humidity controlled conditions at the workshop, over a couple of years of being at home, developed a couple of splits along the grain in the back (can post piccies if anyone interested). We put this down to the wood perhaps not being too stable, and not quite at equilibrium when purchased. However, it then became an interesting exercise in repair, and evidence of exactly why you want a glue that gives under heat. The guitar now has a new back and sounds flippin amazing!
I have now bought a humidifier and meter which seems to read a constant 45-46% relative humidity in my house, which I think is spot on.
Cheers,
Adam


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## thick_mike (9 Jun 2012)

Kalimna":7hxy03vh said:


> Mike - unfortunately my experience suggests that humidity can be a problem over here. I made an acoustic out of macassar ebony B&S (at a course run by Mark Bailey at Bailey Guitars in Ayr), and whilst kept in humidity controlled conditions at the workshop, over a couple of years of being at home, developed a couple of splits along the grain in the back (can post piccies if anyone interested). We put this down to the wood perhaps not being too stable, and not quite at equilibrium when purchased. However, it then became an interesting exercise in repair, and evidence of exactly why you want a glue that gives under heat. The guitar now has a new back and sounds flippin amazing!
> I have now bought a humidifier and meter which seems to read a constant 45-46% relative humidity in my house, which I think is spot on.
> Cheers,
> Adam



Fair enough, admittedly, my acoustics are pretty basic. I've only got a couple with solid tops and sides. The cheaper guitars which get the most abuse are ply, which will be more stable any way I guess. Also, although my house is centrally heated, it's pretty old with no DPC, so I guess acts as its own humidifier!

Oh and...pics please!!


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## bugbear (11 Jun 2012)

thick_mike":38urjbjb said:


> Lots of these guitars are made in very humid countries and yet are very stable over here. To be honest, humidity doesn't really seem to be much of a problem in the UK. I don't think we get enough seasonal variation to cause guitars major structural issues. Americans seem to have much bigger problems going from very dry winters to humid summers. They're always banging on about humidification being essential to stop frets lifting and tuning problems, but as long as you don't keep your guitar in the garden pond or in the airing cupboard, you're pretty much OK over here.



Yes - if you read American furniture making history, the first immigrant cabinetmakers were forced to update the "traditional" English/European techniques they bought with them, due to the extreme seasonal swings in the USA.

BugBear


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