I'm a newb to the world of lutherie , but looking to make this my retirement hobby. A long time player and tinkerer on my own stuff I realized I enjoyed doing this and thought I'd work start slow and work up to building things. I started with my own collection (dozen basses, guitars, etc) and some yard sale rejects. However, this big opportunity fell into my lap when I was back home for a visit this summer.
My brothers prized '73 Guild F112 had the bridge pulled up on the bass side and the top has a slight belly bulge. Apparently, it had been that way for many years. I offered to take a crack at it (free of course) which my brother agreed to, so I brought it home to California (I live not far from Franks shop, Gryphon Instruments.) When I removed the bridge the top underneath the loose side had fine wood 'hairs' - not typical tear-out from what I can tell <see photo>. As I said, I'm new to this, so maybe you've all seen this type of damage.
My first question to everyone is, do I try to glue that stuff back down first, or just clean it up and start fresh, hoping there's enough top left for support? Or do I have to patch in some new wood?
I also found a loose brace which may be the root cause of the bridge problem. Its the one behind and right up against the bridge plate and really hard to get to, so I reasoned it might be easier to remove it altogether and clean then reglue rather than try to work it in place. I was able to use a hot palette knife to loosen it. However, working blind I also poked the knife right through and split it. Real rooky move, but then I'm a real rooky. The other end also split a little.
So can I get away with gluing that back together, or is it new brace time? I'm assuming I'll have to solve the brace problem first before regluing the bridge.
I also intend to put a Bridge Doctor in.
Thanks in advance.
I have not done a repair like this myself (so disregard my opinion when a more experienced one comes along) but it looks like there is a quite a bit of rotted/decayed spruce there. I would be guessing some moisture has got into that. It is not going to be any good trying to reglue the bridge onto that rotten stuff. I think you will need to remove some material until you are back to solid timber, and that probably means needing to graft in some new spruce to fill the defect. Could be tricky, but not impossible. Lets see what other people say. If the brace is split but still in place you can glue and clamp it. If a bit of it has come right out it might be harder to get it together. Are we talking about the main x-brace, or one of the secondary ones?
Thanks Mark. Yes, it a secondary brace that sits right behind the bridge plate. I'll have to see whats left after getting rid of the rot.
It does look fairly typical, and I presume the dark discoloration is staining, not decomposition. Offhand, I suspect it's a reasonable candidate for standard regluing technique, after careful block sanding to smooth the ragged bits. Of course, you'll want to scribe to the very edge of the bridge and remove any finish that could impede glue adhesion.
Thank you Frank. I was hoping it was not going to be major surgery.
I also found that the bridge has twisted or warped a bit - I suppose from being only part way pulled up and under tension for so long. I think I can sand it flat, or should I replace it?
OK. That is the kind of expert opinion that I was refering to that trumps mine! If Frank says it is not so bad, you can feel a whole lot better.
When it comes to regluing a bridge it is essential to have a good fit of the contour of the top with the underside of the bridge. So you will need to fix the brace issue and restore the appropriate shape of the soundboard, and then see if the bridge can sit nicely on that with no gaps. While the bridge is off, and you are working on the soundboard, try clamping the bridge down to a solid piece of timber which is slightly domed to approximate the radius of the guitar top. It is probably not dead flat - more likely a 30' radius or thereabouts. See if the bridge wants to flatten out with some gentle persuasion. If it does, you will later marry the bottom of the bridge to the shape of the soundboard by sanding it on a piece of sandpaper that is actually lying on the soundboard itself. There are lots of tutorials and repair blogs on the internet you could look at to guide you through that (with frets.com being the first place to start). If that bridge is really curled up, and doesn't want to resume a normal shape, you will need to make a new one.
Yes, it great when a master speaks. I appreciate your input also Mark. Once I figure out the top thing I'll know what, if any, radius I'm working with. If I need to flatten the bridge I'm thinking of warming it up and clamping it to my sanding beams.
Don't sand the bridge to flatten it. I assume it pulled up behind the pins- sanding to flatten it would thin the wings, which looks bad and weakens it.
Heat it and clamp flat, or even with a reverse curve. Also don't shape the bridge to match the top dome. The bridge was flat when Guild built the guitar. The rigidity of the bridge will help flatten the top.
I'll second that, Greg. In 50 years of guitar work, I have yet to scrape, sand or otherwise contour the bottom of a bridge to fit the radius of a flat top guitar. I (and others) believe that since the pull of the strings tends to bend the bridge up in the middle, a little extra tension in the other direction is a good idea.
Well, I just learned something important then. I have always operated on the assumption that the bribge should be contoured to the slight curve of the soundboard. It is interesting to hear the that it works OK or better if flat.
That's a good tip. I will keep the bridge flat from now on even on slightly domed tops (unless it's a cylindrical Howe-Ormes). Less work and better result!
does this imply that if a bridge isn't flat (mine might be slightly twisted) that I should sand it flat?
You have to determine how much you'd have to take off to get it flat. Certainly try to heat it and flatten it first [even clamp it twisted a little in the other direction]. Guild bridges can have pretty hefty wings, so you could sand some without it looking weird. Whaddaya say, Frank?