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Warped soundboard and strange bridge/saddle combo

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Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Fri Mar 24, 2017 3:52 pm

As a favor, I've taken on the repair of a laminated guitar with a loose bridge. The Guitar is a "Carlos" model 240 made in Korea and besides having a problem with the top, the saddle is different and I need some help figuring it out.

First question: how to I get the soundboard flattened out?

Second question: The saddle is embedded in a metal strip and has adjustment screws on both ends. The saddle's plastic strip is higher on one end than the other. Which end goes on the low "E" side?

Carlos Guitar Saddle.JPG
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Re: Warped soundboard and strange bridge/saddle combo

Postby Mark Swanson » Fri Mar 24, 2017 4:00 pm

Consider taking that junk off the guitar, and making a new saddle. You can glue shims into the slot to thin it out and make a real saddle to fit in there. those metal pieces really kill the tone.
The guitar may need repair inside, you'll have to look for loose braces. If none are loose and the top is badly warped you may need to replace the bridge plate.
    Mark Swanson, guitarist, MIMForum Staff
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Fri Mar 24, 2017 10:52 pm

this guitar doesn't have a bridge plate. I'll put one in.
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Sat Mar 25, 2017 5:38 pm

whoops! after feeling around inside, I found a bridge plate.
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Thu Mar 30, 2017 1:38 am

I'm in the process of shimming the bridge so I can install a better saddle. I've tried to flatten the soundboard, especially in the area occupied by the bridge. When I place a 12" straight edge across the soundboard, spanning the area through the location where the bridge will be attached, I can see that the the bridge footprint is around a mm low on either end. At either end of the ruler, the soundtop is about 2.5 mm lower than the center. This is a cheap laminated plywood guitar and I'm wondering if I can glue the bridge down and be done with it.

I took this job on as a "learning experience" and I am, indeed, learning.

Guitar top.JPG
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Re: Warped soundboard and strange bridge/saddle combo

Postby Beate Ritzert » Thu Mar 30, 2017 7:06 am

Which means the top came up by 2.5 mm or the arching had been built into the top in the factory. In order to understand please follow Mark's advice to check the braces. Either the old fashioned way with a small lamp and a mirror or with an endoscopic lamp / camera or whatever else You can reach. Your effort will fail if there is a problem with the bracing.

Even if You find that everything is ok, You will have learned something (learning does include doing things which are economically inefficient like the things i am just doing with the warped plates of my old archtops).

Back to the top: if You try to egalize that deformation on the top You will cut through the outer laminate layer.

What happens when You clamp the new bridge?
Will the gaps close? If Yes i might be tempted to just glue the bridge with either HHG or fish glue. Both glues give You the chance to remove the bridge relatively cleanly and easily in case of problems.
But only if that was my own guitar and not a paid repair for someone else.
Or myabe i would adapt the surfaces just in order to practice that.

But if the gap will not close You'll have to adapt the surfaces before glueing.
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Fri Mar 31, 2017 11:17 am

Beate writes:
"Back to the top: if You try to egalize that deformation on the top You will cut through the outer laminate layer"

The bridge footprint is somewhat egalized after I sanded down to bare wood. I can put the bridge in place and it fits pretty well. Think I'll glue it down with HHG.

What happens when You clamp the new bridge?
Doesn't look too bad.

Will the gaps close?
Seem to close pretty well

If Yes i might be tempted to just glue the bridge with either HHG or fish glue. Both glues give You the chance to remove the bridge relatively cleanly and easily in case of problems.
But only if that was my own guitar and not a paid repair for someone else.
Yes, the gaps close. This is not a paid repair, but a freebie. The owner wants to give this axe to a nephew as a practice guitar. Think I'll Glue the bridge back down and call it good.

Or myabe i would adapt the surfaces just in order to practice that.
Don't quite understand what this process would be, but I think I'll just glue that bridge back down and be done with it.
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Re: Warped soundboard and strange bridge/saddle combo

Postby Doug Shaker » Fri Mar 31, 2017 1:39 pm

Or myabe i would adapt the surfaces just in order to practice that.
Don't quite understand what this process would be, but I think I'll just glue that bridge back down and be done with it.


Before I glue a bridge to a soundboard, I make the bridge conform to the soundboard surface by putting a piece of sandpaper on the soundboard at the bridge location. Then I chalk the bottom of the bridge and sand the bridge on the soundboard until all of the chalk disappears.
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Fri Mar 31, 2017 7:03 pm

I adapted the bridge by working the footprint. This is just the opposite of what was suggested here. Anyway, that's what I did and I got the bridge more or less fitted. Today, I just decided to glue the bridge on and am including a picture here. I used HHG as suggested. Time will tell how successful I've been when I get the new saddle and strings installed.

Guitar bridge glue job.JPG
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Re: Warped soundboard and strange bridge/saddle combo

Postby Beate Ritzert » Fri Mar 31, 2017 7:10 pm

Nice. But why are You frustrated (... Your signature...)
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Re: Warped soundboard and strange bridge/saddle combo

Postby Ron Daves » Tue Apr 11, 2017 10:39 pm

Why am I a frustrated Luthier wanna-be? Every stringed instrument project has disappointments and it is frustrating. I spend time on every build covering up mistakes and I can always see them when the
build is done.

Anyway, this guitar with the strange saddle and warped soundboard is now done. I managed to get the bridge removed using a hot knife, but did mess up the finish in a couple places...lesson learned.
I removed the original saddle, shimmed the bridge and installed a new bone saddle. This was a labor of love and the guitar was old and was going to be given away. Thus I was willing to take on the
repair for the experience. The biggest lesson that I learned was to make sure the finish is well protected and that you use a curved blade to work the glue loose. Also, there needs to be a mark on the
blade so that you don't extend it beyond the edge of the bridge.
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