guitar repair

[Jacob]

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?

 

[thick_mike]

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

 

[Setch]

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.

 

[Jacob]

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

Excellent links, thanks thick-mike.

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.

 

[MIGNAL]

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.

 

[thick_mike]

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/

 

[thick_mike]

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

 

[Jacob]

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.

 

[thick_mike]

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.

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

 

[Jacob]

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.

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

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?

 

[thick_mike]

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.

 

[Kalimna]

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

 

[Jacob]

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.

 

[thick_mike]

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!

 

[Jacob]

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

....

More of a Blind Lemon Jefferson.

 

[bugbear]

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

 

[Jacob]

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

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:

 

[marcros]

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

 

[Phil Pascoe]

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

 

[marcros]

neigh, surely not