#1
I found this neat Sakura 12 String guitar, nearly complete with everything for next to nothing. The only problem is over the year the bridge has been pulling up on the top of the guitar. It is pretty dramatic slope 4 degree as seen in the photos.
Right now I have about 20 lbs of weights on the the bulge but I am not sure if it is working.

My question is, what is the best way to flatten the bulge so I can make it useable again? I am open to any suggestion, I got it for super cheap guitar so I am willing to use any suggestion, even drastic ones!

Thanks!





Last edited by niceties55 at May 19, 2016,
#2
Some top bellying and bridge rotation is normal, but it can be really bad on inexpensive 12-strings. I've seen them where the rotation has lifted the strings from the back pins right off the addle.

Here are some ideas that could be maybe used in combination.

Shave the bridge to get more working space on the saddle.

Cut ramps in the pin holes to increase string break angle on the saddle.

Get the top steamed down

Use a flying brace, eg a JLD Bridge Doctor, to hold it in place. I have a home-made one in my old Gibson to stop the action deteriorating. Don't try to use it to crank the bridge down though, I've split a bridge trying that.

Use a tailpiece for some or all the strings.

Use lighter strings and/or tune down.

Que mas?
Last edited by Tony Done at May 19, 2016,
#3
You can always go in through the back of the guitar. It's a lot of work but it's a proper repair and depending on how confident you are with wood working you can also fix other issues like cracked/loose braces if their are any.
You will have to spend a bit of money on a few tools and any other bits you may want to replace along the way.
I will post up a proper how to tomorrow. It's gunna take a while.
#4
^^^^^The repairer who fixed up my old Gibson rebraced the lower bout to lower the action through the soundhole. He had welts on his (big) forearm for a couple of days afterwards. That takes both skill and fortitude.

But it reminds me that you can do a hack fix by resetting the neck angle:



I did this by cutting a thick slot down the heel, gluing it bent back with epoxy, then hiding the repair with pseudo binding made of black bog, epoxy mixed with kid's powder (tempera) paint). This one didn't have a truss rod, but the same method might be feasible with a truss rod if a little ingenuity is used to get rid of the timber on either side of it.

The nail and white bog are original, that's typical Colombian luthery.
#5
Right I will give a summised version of what to do with the in through the back method. If it's something you think you can do and you need more specifics holler at me and I will do my best to guide you.

You will need to buy a thin flush cut saw stew Mac sell a whole variety of them. Get a thin one so your not removing too much material.

You will need to heat up the binding to release the glue and allow you to remove it from the guitar.
You then need to locate the seam between back and sides.
With the guitar face down use the flush cut saw to make a cut just under the seam all the way around the body. DONT cut in too deep, it's inevitable you will cut into the back bracing a bit but you want to try and limit this as much as possible.
One that's done you should be able to lift the back off the guitar. Thus gaining access to the innards.
Gently heat the bridge reinforcement plate until you can lift it from the sound board.
That's the thin piece of wood directly under the bridge between the bracing of the guitar. I would make a new one that is a centimeter larger than the original both forwards and backwards.
Next take 1cm wide strip of paper and try and feed that under the braces to see if any have come loose.
If any are loose then you will need to re glue them which will be a complete pig to do.
You will need a large thick board and some very deep clamps to this.
You then need to fix the new bridge plate in.

Once your all done inside the guitar you need to re attaché the back,
You will need a thick wooden board, 3/4-1 inch thick and load of heavy duty frame hanging hooks and a couple of bike inner tubes with the valves cut off.
The board needs to be atleast 6 inches bigger than the body of the guitar in all directions.
Draw an outline of the guitar on the board and then screw the hooks in at a 2-3 inch spacing about 2-3 inches away from the body outline.
Also cut a hole in the board where the sound hole will sit. This allows you clamp the body in place.
Clean up the glueing edge of the back of the guitar and then run a bead of glue over them purfling in the body. Place the back on the guitar and then stretch the inner tube over two opposing hooks cross them over the guitar and repeat down the whole body. It should look like a shoelace. This applies even pressure over the back whilst the glue sets. Leave it like that for 24-48 hours.
You will probably need to re cut the grove for the binding to be glued to. To hold the binding during gluing use strips of masking tape at 1 inch intervals.
You will then need to clean up and level where the bridge will sit and re glue the bridge. You can buy or make a bridge clamp.
You will also need to re drill and ream the bridge pin holes. You can buy a reamer from stew Mac.
I advise buying new bridge pins aswell so they are the correct taper.

Hope thats of use to you.

Just remember to be patient. Give all glue 24-48 hours to set under clamps.
#7
I've made a start on it on my 12 which started to lift the bridge. I'm having to take it slow though as I don't have much money to put into the tools I need. The soundboard hadn't distorted anywhere near as much as the OP's but one of the main braces has shifted.
It's a horrible thing cutting apart a guitar and I'm no wood worker but if you take it slow and be careful then you should be all good.