Bridge repair glue
 

Hello, all. Great forum, lots of useful info and some nice guitars for sale that I wish I could justify! One day...

A question about glue. Here in Europe you can buy white (looks white, dries transparent) PVA glues that are sold in varying strengths for general woodworking applications. Is this the same as Titebond (haven't seen the brand here), or should I get the real thing from StewMac?

Reason is I'm replacing a bridge on a 70s Yasuma 130D. The old one is lifting slightly, no damage so I suspect excess string tension. Plus it has one of those adjustable saddles with a heavy metal holder in a wide slot (see pic). I plan to fit a regular bridge and saddle.

In another pic you can see the chewed-up bridge plate. It's solidly glued, no cracks, so when the bridge is off, I will fill that with wood dust, glue, clamp up and redrill. Again, is Titebond the best choice here?

Finally, and just out of interest, I notice one of the X braces (the non-continous one) has a slight gap at the joint. It's tiny, just enough to get a fingernail in. It doesn't look repaired and isn't loose - in fact all the internal bracing is totally sound. Is that to allow for expansion?

http://wordsforit.com/pics/yasuma1.JPG
http://wordsforit.com/pics/bridge2.JPG
http://wordsforit.com/pics/xbrace1.JPG
http://wordsforit.com/pics/xbrace2.JPG

Thats a very sloppy lap joint, you could glue in a properly fitted filler, and is the bridge plate spruce? thats what it looks like in your pic. If its spruce you might want to replace it with maple.

Don't know anything about european pva glues but original titebond or HHG (my choice) I believe super glue is the preferred matrix for filling in the bridge pin holes. Good luck

long term maintenance
 

Looks to me as if the x-brace gaps could benefit from being filled with shims, glued in, and the 'x' also capped with spruce to bridge the part of the 'x' that is interrupted with a notch. I think that would immeasurably stiffen the 'x' for the long term. Real luthiers might speak up here.

Not really. Its a gamble. TB does not stick well to itself, and worse to other glues.


I just went through this and tried filling with sawdust and TB and did not get the level surface I wanted, and I had a compromised deck for glue to hold.


You have 2 choices here. Fill with glue sawdust and use TB and gamble.

Or use 90 minute epoxy and be done.



I went the epoxy route on my 12 string and have no regrets other then better clean up to make the glue line look better. Its not bad but I'm a perfectionist.


I read every post and reply here on the topic before making my decision, as well as emails to some of the best.

TB and sawdust works great for this application as well.



What has not been addressed is how chewed up the bridge deck is when it gets removed. That is what I was addressing in my reply.


With that being the case, I would use the same material when regluing bridge.


So if epoxy was used, a piece of tape on the bridge plate would work great. You do need a 5 or 3 degree reamer after redrilling pin holes.

Thanks for chiming in. I'm getting the distinct impression that Titebond is maybe not the way to go here. Things are coming along. I left the bridge plate in situ and repaired it top and bottom with CA/wood dust. Looks good now.

The bridge came off fairly cleanly using the iron/foil/hot knife technique. You can probably tell from the pic that it wasn't a great joint, which I suppose is a stroke of luck! Not really a knife, I used a really thin palette scraper that I filed the corners off, bent it so that it lays flat under wiggling pressure, and
then honed a slight edge on the top (thank you frets.com). I plan to use hot hide glue and the E/E bolt-through and caul method to affix the new bridge, but here's where I could do with some expert advice.

The old bridge took some material with it and there are a couple of areas where I've slightly nicked the top, leaving semi-attached wafer-thin shavings. So I need to repair that damage, gluing back the shavings and filling the tiny indents where the bridge removed some fibres. Bearing in mind this will be a new bridge, so I'll also be scraping/sanding down the top to match the surfaces.

Looking at Frank Ford's glue chart, and from other posts here, I get that epoxy and CA are the best choices for filling small gaps like this, but will the hide glue stick to that? Is hide glue even the best solution here? Would you advise mixing glues like this, or sticking with one - HHG or epoxy - and using it for the whole shebang? It's a solid spruce top BTW, if that makes any difference.

The new bridge hasn't arrived yet, and I need to have it here to check the pin/saddle geometry etc, so at the moment all I can do is a bit of prep, but I don't want to go off half-assed gluing things using the wrong stuff.

http://wordsforit.com/pics/bridge%20off1.JPG
http://wordsforit.com/pics/bridge%20off2.JPG
http://wordsforit.com/pics/bridge%20off3.JPG

Judging by the lifting fibres, I conjecture that you removed the bridge with the spatula only from the side of the bridge furthest from the sound hole. For a solid wood top that has runout, the lay of the wood fibers changes directions from one half of the top to the other (i.e. about the center seam). Thus, when removing a bridge on a top with runout, one usually needs to go at it from the opposite direction of the bridge when changing from one half of the top to the other.

My advice is to not glue the lifting pieces separately. Instead, ensure that all of the old glue is removed and then use your preferred glue to glue the bridge and the slivers in one shot. Just ensure that you get glue under the slivers and that they lie flat.

Opinions vary on whether or not the bottom of a bridge should be contoured to follow the curvature of a "flat top" guitar. I do not contour the bottoms of bridges: they are flat and then clamped to the top. String tension will move the assembly where it wants to go. Of course the surface of the top must be suitably prepared to provide a good mating surface. A chisel used like a scraper works well for that.

Thanks Charles, really helpful. You are totally correct. When removing the bridge I tried to work from the outside in, but I didn't know about runout, or the lay of the wood fibre changing direction. I wondered why one half came off cleanly and the other less so.

I wasn't intending to contour the bridge. I realise that the clamps will pull up the top to match the harder (flat) rosewood. As for preparing the top, remove glue, chisel, scrape, replace slivers - I think I got it.

You Sir, are a genius.

Thank you, but it is information known to any experienced luthier or repair person.

As for the X brace, I'd just put a cap across it about 3/32in thick and sanded flush at the ends. That will give it a huge bump up in strength.

Thanks redir,

I'll do as you suggest