Takamine F400 bridge plate and brace issues

[John Yungbluth]

Takamine F400: Submitted for your consideration........

Looking for a little in-depth conversation on repairing a 1975 Takamine F400 12 string. Her back history is unknown. I plan to approach the body issues and finish with a neck reset if required.

I've already repaired a loose sound hole flat brace on the treble side, the traverse bar on the treble side about 3/4" and a broken out 2" piece of the top kerfing that spanned that end of the traverse bar. This is where I stopped to re-evaluate how and in what order I need to proceed.

Material:

All laminated body, spruce top, rosewood sides and back, Laminated bridge plate. Neck is mahogany, no scarf joint on headstock, 2 additional stacked pieces for the heel. Rosewood fingerboard and bridge.

Initial look at the issues:

Sinking top starts behind the end of the fingerboard and goes across the sound hole then rises back up to the X brace joint. The sinking area crosses the sound hole, flat sound hole braces, but rests between X-braces.

The bass side X-brace is sprung loose from the top at the side radial brace one, through two all the way to about the last 1 1/2 -2" length. The rest of both X-braces are still solidly attached. From what I can see under no string tension the two tone braces and the remaining radial braces are all secure.

Bridge was loose from the back edge through bridge pin holes. And the back edge rose up, off the top, above the bulge of the belly as the bridge leaned forward. The bridge has been off before, repaired and was failing again. I removed it completely. No cracks in the bridge, bridge footprint or that I can discern in the bridge plate.

Belly starting about midway through the bridge in front of the pin holes and high points at about an inch behind the bridge tailing down to the tone brace one.

***Unique issue with the bridge plate:***

The bridge plate has a unique issue. I was reaching inside and probing with my fingertip. The leading edge seemed thicker than the trailing edge. Made a crude depth gauge I could get inside. When I took thickness measurements of the bridge plate the trailing half of the bridge plate is less than the leading edge by about .13: I applied clamping pressure to the leading edge and could see the movement in the bridge plate down as I added pressure against the top. The back half of the bridge plate is solidly attached to the top, the leading part is not and sprung loose from the top.  I can't get a feeler gauge under it because of the height of the X-brace.  Not sure how to work Titebond Original into that gap to secure the plate to the top again.

HOW WOULD YOU APPROACH THIS?

And in what order of repair?

Bridge plate:

You are into the tight workspace of where the X-brace and bridge plate draw close to each other. I can't think of how to work glue into that loose end of the bridge plate and deeper into that unknown depth to stabilize the repair. Replace the bridge plate? But working inside to remove a laminate plate against a laminate top, is a potential disaster for the top if done poorly.

Opinions, alternate approach?

Sinking top, live with what has been inflicted. Bridge, bridge plate and X-brace repairs should lift a little, maybe. Add a taller bar shaped brace to stiffen each side? All these would slightly raise the top and even more necessitate a neck reset

X-brace is a repair I've done many times and comfortable doing them.

It's a juggling act to put these issues in a progression of repairs as well as how to repair that bridge plate.

Anyone ever do a neck reset on this model and have first hand experience with it being a dovetail, Mortise/Tenon or butt & Dowel joint.

[Carl Dickinson]

I'd think that removing the back would give access to all of those issues except how the neck is attached....maybe?

[Mark McLean]

I am with Carl - thinking that this work will be hard to do through the sound hole and you would have a much better time of it with the back off.  I have reshaped a collapsed top by taking the back off, spritzing the inside of the soundboard with water and then pushing it out with a hot-and-heavy sandbag (heat it up in your oven, place it inside the guitar which is sitting in a radius dish, pile more weight on top, repeat a few times). This was a Frank Ford trick illustrated on Frets.com