12 string Sigma with bellied top

[Eugen C]

Hello

 

I live in Bucharest, Romania.

I am not a luthier, I just like to use tools and make things with my own hands.

I have read Mr. Ford frets.com and also all the discussions here and I found a lot of invaluable information and I thank you for this.

I did some minor repairs to my guitars and I repaired a broken peghead on an EKO Ranger.

Now, my problem: I bought a Sigma 12 strings from Ebay with a broken peghead that was profesionaly repaired previously. Is in very good cosmetic condition, with very litle wear but the bridge is rotated and the top is bellied.

All the braces are glued and the bridgeplate is in good shape. The bridgeplate is laminated with 4 or 5 layers, only the first layer is missing some wood between pin holes.

You can see in the pictures how much is the top bellied. In these pictures the guitar is without strings.

The action is a little too high, it can be reduced by shaving the saddle but the problem is the intonation that is sharp on all strings because of the bridge rotation.

As I can't afford to buy an expensive guitar and I like very much how this one sounds, I would like to flaten the top. And because I want to do all the work by myself, the costs and the time wouldn't be a problem. That would be also a very good way to learn.

I know about JLD Bridge Doctor but I hope to receive advice from you.

[Greg Mirken]

After looking at your pictures I have to say I was expecting much worse! Is the belly noticeably worse when the guitar is under tension?

Do you have an electronic tuner so you can tell us how far the intonation is off? 12-string guitars are tough because the skinny octave strings always go sharp unless the saddle has individual compensation steps for them. A wider saddle may help your intonation problem.

Is this a laminated top Sigma? You can tell by the edge of the soundhole.

[Eugen C]

Thank you for your answer.

Is a Sigma DR12-7. From what I have found on the web that means that is a Dreadnought Rosewood 12 strings and 7 means the best model. It is all laminated, including the top but it sounds very good.

The belly without strings is the same as on my other guitar with strings on, 6 string Ibanez Humming bird replica with almost the same construction.
With strings, the belly is just a bit more.
If I move my hand over the soundboard, I can feel the point where are the X-braces near the bridge ends, is the point where the belly starts.

Regarding the intonation, I don't have a tuner but I have a good ear, and I think that all strings are aproximately a half semitone sharp.

My fear is that the belly not to get much worse with the time.
Another problem is that the bridge is a little unglued behind the bridge pins, you can see in the pictures that my feeler gouge under the bridge but just in that part and just that much.

I started to make a Bridge Doctor device but I want to use the two already existing screws, I don't want to make a third hole in the bridge. I want to make a "Y" shaped piece to connect the bridge with the block of wood.

Do you think that this device will reduce the rotation of the bridge?
Do you think that I must try to flaten the top using heat or other method?

Sorry for long post.

[Bob Steinarsson]

Have a look here: http://fretsnet.ning.com/forum/topics/warped-flat-top-tops

Why afraid of making a third hole? It will be much easier to make a standard one-hole bridge doctor, and a little MOP dot in the bridge is just nice!

[Eugen C]

I'm not afraid, I just don't like the ideea to make a new hole if I already have two.

[Eugen C]

I remember your message. I have the same situation, the belly is hard, I can't flaten it if pushing with my hand.
When I clamp the top, I clamp it against the back edges?
Can I use a wet sponge instead of towel?
Should I be careful not to spill water on the wood?

[Bob Steinarsson]

My case sounds similar to yours. Belly was hard as concrete. No movement at all with hand or with clamping. After some hours with clamps and wet towel (se pictures), it was possible to squeeze the clamps a litte, and after two days, the belly was flat as a pancake. Then I installed the BD, and the belly has not occured again. If it starts bellying again, I think that a little twist on the BD nut will solve the problem.

I see no reason to use a sponge. You don't want to soak the wood in water. You just want to make it a little humid, and the water towel worked perfectly in my case. In my case one bracing loosened, but as also the bracing had become softer like the rest of the area around the bridge, it was easy to glue it back again using a syringe and Titebond's yellow glue

However, I have done this only once, and I cannot promise success in all cases. I would be more afraid of doing it on a solid top guitar than on a laminated top. Neither would I do it on someone else's expensive guitar before I get more experience with it. But I see no real danger as long as the wood doesn't get soaked, and I think that it is only the area under the plastic bag that gets humid. (I read somewhere in this forum about a humidfier used for this purpose, but I don't know where)

If you try the method mentioned here, please tell how it works! Good luck!

[Eugen C]

Thank you very much! I will keep you informed.

[Lee Gendvilas]

Did you flatten the top with the strings on (to pitch) or off? Did you have to keep re-wetting the towel?

[Bob Steinarsson]

The strings were off. The strings being on would have worked negative, I think. I did not need to rewet the towel, but I think that this i a question related to the humidity of the air and the time needed to flatten the top.

[Eugen C]

Two days ago I have clamped the guitar.
Because of the belly, there was a 3-4mm gap between the top sides an the big plate I have used for clamping.
This morning the gap was gone!
The top is flat.
Now, question: should I leave the clamps on for few more days?
I will be out of town from tomorow evening and I was thinking to let it clamped till Saturday night.
I don't want it to be too flat :D

[Ned Knepp]

If it were mine to do, I think I would remove source of moisture and keep the clamp just tight enough to hold things but not tight enough to really stress the assembly. Without strings, the top should stay in place it I don't think it would hurt to allow the moisture to stabilize for a day or two before completely removing the clamp and stringing it up.

Ned

[Eugen C]

Here some pictures. First and third are "before", the second is "after".