More 12-string disintegrating blues...

[yug]

I found this box in a pawn shop and decided I could fix it. The bridge had separated from the top and needs to be re-mounted. I removed the bridge rather effortlessly but discovered 2 probs:

The hot putty knife bubbled the finish in a couple places.(I know, should have put a hot pad between the knife and the box). Is there a way to spot-refinish the laquer?

Some of the wood on the guitar top was damaged when the bridge separated. This guitar is a Japanese copy of a Hummingbird 12-string. The damage isn't deep. Just need to know if I should level the area or float the bridge onto the surface with the hide glue.I don't think wood putty or filler would be advisable as I don't trust the holding qualities of either. I don't want to keep shaving away with the exacto-knife til I have nothing but a second sound hole.

Thanks for the forum,

Yug...

[cynical1]

yug -

First off, greetings and welcomed to the Nutz house.

Let me try and answer a few questions before I start asking you a few...

If the guitar is finished in lacquer you can re-coat\repair it at any time. Lacquer will always melt the previous coats and blend well after sanding and buffing.

If the guitar isn't lacquer then spraying lacquer over it could prove problematic. I'd suggest finding an inconspicuous spot and testing a drop or two of lacquer on it to see if it blends or lifts.

Now for the questions...

When you say that some of the wood on the top is damaged, can you post a picture or two to qualify that? Reason being is that on a 12 string you really don't want to remove any more material from the top then absolutely necessary.

I'd hate to give you bad advice by guessing at what you're trying to accomplish...and what you've got to work with...

And as far as re-gluing the bridge, make sure you have a clean wood to wood bonding area. One of the big reasons acoustic bridges let go is that the bridge was glued over a finished top.

Finally, on most 12 strings the bridge will have pins to locate the bridge. Are those still left?

Happy Trails

Cynical One

[yug]

The top appears to be 1/8 in. thick. I have removed about 1/32 in that was pulled away from the top underneath the bridge. I don't think that's a significant amount of wood, but as you say it is a 12-string and subject to greater stress than a 6-string.

Found a fragment of the finish for testing. I'll let you know how that comes out.

Can't figure out how to add a pic but I'm working on it.

[cynical1]

1/32" is probably not the end of the world. Crack or splits are a bigger issue, but since you didn't mention any I'll keep moving.

Something you may want to look into, if you don't have them already, are sound hole clamps.





These are from Stewart MacDonald, but there are other variations on a theme out there. They make a really expensive one, but I figure you could buy another guitar before you paid those off...

Like I said before, ensuring there is no lacquer or poly finish in the gluing area for the bridge is more important the a little missing wood. The bridge also needs to be cleaned up and all glue residue removed and should be dead flat. Use a straight edge to confirm. If you find out that too much material needs to be removed to accomplish this then the wise move would be to replace the old bridge with a new one.

If you wanted to fill in the missing wood I would suggest epoxy wood filler. This is what I use:



It's a two part system that gives you about 30 minutes to work with before it begins to set up. It does shrink, and it's a bh to sand if you got too happy applying it. However, once you let it set up for a few days and sand it down the stuff is tougher then the original wood and I've never had it pop out on me.

As far as glue...well...everyone has an opinion here, but for all practical purposes, I've been using TiteBond II for years.



It's waterproof and stronger then the wood once it dries. They have a Titebond III, but I've never used it and can't speak from experience on it.


For Reference

I asked before, but never got a confirmation. Does your bridge have locating pins?

Happy Trails

Cynical One

[yug]

Trying to keep this short and sweet. I have a couple of 5" C-clamps that will work to clamp the bridge. I only use Tite-Bond Hide glue for the joining of wood-work. I use Elmer's white glue for some repairs. I will try to find the filler you suggested for leveling the bridge site.The bridge pins and the side screws are helping to hold everything in place, so, no problems there. Thanks for all your cynical suggestions. I mean that in the best possible way, one cynic to another. I'm sure we'll talk again. I have other projects...

yug...

[cynical1]

You're entirely welcome. Good luck with the repair. As you probably know, getting a good tight glue bond is the trick here. Much easier said then done.

And be careful with the 5" c-clamps. It's very easy to over-tighten them and split your top all to Hell. That was one of my first colossal screw ups 30+ years ago and what kept me away from acoustic repairs for a long time.

Take the extra time and make up some wood blocks to protect the underside of the top and the bridge from the clamps. They'll also help distribute the pressure from the clamps better.

Too bad Double Yoi isn't around...he's currently apprenticing with an acoustic guitar luthier and would probably be a better resource then I am.

And I'll be here down the road when your other projects crop up.

Good luck.

Happy Trails

Cynical One

[yug]

Cynical One,

I have finished the 12-string. Doing some research on the web about this manufacturer I found that other guitars have shed some of their finish when re-setting the bridge. The issue is cosmetic and does not affect the playabilty.

The P.C. Woody was interesting to work with. I globbed it on thick and deep.I let the Woody cure. I sanded and sanded. Then I sanded some more. Then I took an X-acto chisel blade and removed about 93% of what I globbed into the guitar and sanded that smooth. Let that sit and cure for a few days then glued the bridge onto the guitar with the Tite-bond II. After all was siad and done, I now have a nicely seated and glued bridge. Thanks for all your help.

Still working on pix for the Silvertone and a Harmony arch-top I recently acquired. And my first build...

Thanks so much,

yug...

[cynical1]

Yug -

Glad it all turned out well and your 12 string is back in business.

And you learn quick about how thick to apply the epoxy wood filler. Once it cures, though, it's better then the original wood. And with the Tite-Bond glue you should be finished with the bridge on that guitar.

Even though there's no pictures, I'm still gonna give you a +1 for the repair...and for all the sanding on the epoxy filler...

So, I still can't talk you out rehabbing of that Silvertone, huh?

Happy Trails

Cynical One