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Any Suggestions for reparing this bridge?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=48539		 Page 1 of 1
Author:  WaddyThomson [ Mon Nov 14, 2016 11:51 pm ]
Post subject:  Any Suggestions for reparing this bridge?
I know this is probably a lost cause, but this bass classical guitar bridge came off after 20 years. Production guitar, initial cost about $1,000 but now would be something like $2,500 to replace. Owned by a teacher at one of the programs in the Winston Salem NC area, and he doesn't have the money to replace it. It's used in guitar orchestra performances.

I know there is too much wood pulled out to make a really good repair, but I felt like a try would be worth it. Even if it doesn't last a long time. It looks to me like the scoring under the bridge went into the wood, I'm amazed it lasted 20 years. The guy knows there is no guarantee on this, and I'm not going to charge for the work. I don't really do repairs, or try not to!

Anyway, any suggestions on this? Couple of other builders looked at it and one finally suggested epoxy. Not the best thing for a bridge, but it does have some gap filling properties that might be beneficial. The owner doesn't really care if the guitar loses some of it's high end - "it's a bass guitar", he said. Other guitars take care of the treble. I originally thought hide glue, but with the missing fiber, it might not be the best thing. I'd appreciate any thoughts. Also, any thoughts on what epoxy, if that's the right stuff to use. You can see in the picture that the bridge sits on the finish a little at each end. Also doesn't help.

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Obviously I'm still having problems getting pictures from my phone to work right! Stupid phone! Please disregard the upsidedownness of the pictures!
Author:  meddlingfool [ Mon Nov 14, 2016 11:57 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Is there something wrong with the bridge? Does it need replacing?
Author:  Chris Pile [ Tue Nov 15, 2016 1:10 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
That's not as bad as you think. Clean both surfaces up a bit, and glue it down with Titebond or hide glue. It will work.
Author:  Pmaj7 [ Tue Nov 15, 2016 1:14 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Get rid of any fibers that wont match then use wood glue with a little added water, hide or epoxy. As long as there is a lot of contact I think it will all work fine.
Author:  George L [ Tue Nov 15, 2016 1:28 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
I'm no repair expert and fixed one worse than that once with plain old Titebond. It's been holding up just fine.
Author:  meddlingfool [ Tue Nov 15, 2016 2:09 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Lee Valley GF2002 might be worth a think. Good gap filling properties. A certain company I used to know used it all the time for that purpose...
Author:  Hesh [ Tue Nov 15, 2016 5:28 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Hey Waddy Bro - this is a good example of why repair guys hate WRC tops.... at times. When they decide to shed a bridge the top can shred.... much like this one has. As you rightly noticed scoring the finish too deep is also a time bomb of sorts that contributes greatly to this kind of failure. I've built with WRC anyway but we pays our dues and takes our chances....:)

There are two approaches that we might use.

First typically cleaning up both bridge and bridge patch to like-new, smooth, clean surfaces with hopefully 80% wood-to- wood direct contact and HHG. 80% is arbitrary but a bit of a guide for how I approach these things and we are gluing on bridges often, just did one yesterday on a Martin GE model with a through saddle and a stupid hole routed in the top..... Rabbeting the edges as we discuss from time to time here would be something that we might do too.

If a decent 80% or more wood-to-wood matching surfaces is not likely or possible sometimes not cleaning up the fibers from either the bridge or the top and only removing fibers obstructing a complete and decent mating of the two pieces is also a viable approach. Especially if this is not a heirloom instrument as well and then you guessed it, the dreaded e*oxy with quality, structural e*oxy such as West, System III, even Bob Smiths but with a long open time such as an hour or more. You still want a very decent fit though even with e*oxy.

If going the HHG method the bridge bottom gets cleaned up on the belt sander, know your platen so that you can exploit the curves to match the bridge bottom and top. Sharp chisels work too once you secure the bridge and have your hands never down range. The same is true for the guitar top. Single edged razor blades can be used as scrapers to refine the shape of the bridge bottom to match the top.

In any event avoid HHG if you need to fill lots of gaps, there are better choices for inferior glue joints.

Believe it or not it's completely repairable, is done every day, no big deal, and again this is why beyond tone and a pretty face WRC is not the fav of repair guys for guitar tops. If you want to call me, numbers on our site, Ann Arbor Guitars, I'm happy to walk you through it.
Author:  jfmckenna [ Tue Nov 15, 2016 8:46 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Yeah I agree that it's not as bad as you think unless the picture is not showing it all (the lower left area of the bridge patch is either a shadow or a crack through the top, if it's the latter then you got problems). Just try and scrape off as mush of the top would you can under the brdige and glue it back into it's place on the sound board. Then clean it up and glue it with Titebond.
Author:  Robert Lak [ Tue Nov 15, 2016 9:05 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Hesh, in your opinion, is the failure 90% fault of the poor install (scoring of the wood) or 90% fault of WRC?

- a concerned owner of a WRC top yet to be used. :shock:
Author:  TRein [ Tue Nov 15, 2016 9:38 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
I recently repaired a similar catastrophe on a deeply-scored around the bridge, cedar top classical (not one of mine!) I consulted with the builder on the West Coast on how he would repair it. Pry off any stray fibers and use LMI glue without cleaning either surface he advised. So I ordered some LMI glue, which in its newer formulation appears to me no different from Titebond. It was easy to register the bridge and soundboard and so far it is holding.
It is hard to say exactly what causes this shearing of the bridge on cedar tops. On all that I have seen fail like this the bridge outline has been deeply scored, which effectively concentrates all the bridge tension to the footprint of the bridge. If the cedar fibers were more continuous I can visualize some of the tension could be spread out over a wider area around the bridge. It is obvious from Waddy's pic that the wood failed rather than the glue, with the exception of the 1" or so on the end of the bass side of the bridge. This is not surprising since there is still some finish under the outside wings of the bridge which would yield a thicker than optimal glue joint at this area.
If I were fixing it I would scrape the glue off the bridge and soundboard on the bass side, leave as much of the cedar in place as possible while removing loose fibers, remove the last bit of finish under the edges of the wings, and use Titebond original or LMI glue. I don't think it overly optimistic to think such a repair might last another 20 years.
Author:  david farmer [ Tue Nov 15, 2016 11:07 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Looks like the wing sitting on the finish never got brought into clamped, wood to wood contact. From there, things just unzipped.
Part of the decision process would take into account the thickness/ bracing of the top originally. Was it wispy and already rotating?, or Factory overbuilt?
Going forward, keep in mind, those two clean surfaces have dried glue in the fibers. Most likely some AR. I think I see yellowish saturated Cedar fibers in that area. What ever glue used will be trying to stick to that glue sized zone. By many accounts new glues don't stick to cured AR well. That might put you right back with an identical week spot there.
Reason number 65256 why hide is still the best for sticking bridges on to begin with.
I use a tiny rabbet for finish when I feel I absolutely have no choice. But I don't like it. I think it's the worst concession of function to visual perfection luthiers have adopted. On WRC I think it's malpractice unless you at least enlarge the footprint of the bridge to compensate for the lost real estate.
Author:  Pmaj7 [ Tue Nov 15, 2016 11:35 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
david farmer wrote:
I use a tiny rabbet for finish when I feel I absolutely have no choice. But I don't like it. I think it's the worst concession of function to visual perfection luthiers have adopted. On WRC I think it's malpractice unless you at least enlarge the footprint of the bridge to compensate for the lost real estate.

Thanks David. Somebody had to say it! Lol

And other than getting rid of the stray fibers, I would only start removing wood if you plan to remove it all and start with a new joint. Unless a lot of it looks compromised. I agree with removing more finish on ends.
Author:  Clay S. [ Tue Nov 15, 2016 1:05 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
I agree with Pat Macaluso - remove any loose fibers that impede a good fit and reglue with the fibers that match up on the top and bridge. I would use HHG and enough to "wet out" any fibers not firmly attached to the top or bridge.
Author:  WaddyThomson [ Tue Nov 15, 2016 2:29 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
I think removing fibers would be a bad idea! The fit is nearly perfect when you put the bridge in place. It will not move at all. The depth of wood loss precludes leveling both surfaces, unless I put in a 1.5 mm shim to compensate for the depth of lost wood in the top. The deepest place is about that. The top is flat, and it's a 5 fan, with a bridge patch. There is some missing wood. Don't know where, but not a lot. I'm certain there are some gaps under there. I have some "All Wood" Epoxy I got from LMII that has a long open time and cure time. Can't recall what brand. I have never used it, so I don't know the properties. I would be afraid of HHG or Titebond with the missing fibers. I'm not sure about the Lee Valley Glue. Is that the stuff with a 20 minute open time. I have some, but it dries to a rubbery consistency that I don't like much, though if I use epoxy, I'm giving in anyway.
Author:  ernie [ Tue Nov 15, 2016 2:45 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
FWIW depending on the glue used I would use de glue goo(woodcraft) to remove as much of the old glue as you can, I use q tips and a sharp razor blade to clean up old glue. Also you will want to double tape around the bridge to get all the excess epoxy.Since you have a good match between bridge and top.Keeping as many of the torn pieces of WRC is imperative in getting a good fit , that will hold up. Good luck !
Author:  WaddyThomson [ Tue Nov 15, 2016 4:55 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Thanks, Ernie, that makes sense to me. The only place there is glue to remove is where there are no fibers on the bridge. There is no glue on the top where the bridge tore off.

Thanks to all of you, who responded! All reasonable ideas from what you can see in a photo, a poor one at that, and upside down too! Darn phone! gaah
Author:  ernie [ Tue Nov 15, 2016 5:31 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
a man has got to do what he needs to do,Don/t sweat it Bridge clamping is tough on my nerves Only do it when I am calm.
Author:  Hesh [ Wed Nov 16, 2016 9:18 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Robert Lak wrote:
Hesh, in your opinion, is the failure 90% fault of the poor install (scoring of the wood) or 90% fault of WRC?

- a concerned owner of a WRC top yet to be used. :shock:


Hi Robert: I'v built with WRC lots of times and the last guitar that I ever built before my allergies got the best of me and I had to buy a nebulizer and become friends with a pulmonologist was also WRC. It's a great tone wood, superb for finger style instruments IME and pretty as can be IMO as well. I really like that dark chocolate WRC and it matches some rosewoods for a very cool look.

Where is the blame for these kinds of failures?

Certainly scoring too deeply and into the wood fibers is often something we see with lifted bridges and runout from tops that should have never been deemed suitable contributes too. WRC does have a demonstrated tendency to fail in a more dramatic manner IME as well. I've seem them rip completely off and not just lift at the wings.

Here's where service people and some builders, not all.... mind you may part ways. In my way of thinking a guitar is ultimately a tool for a musician. This means that building for the "real world" of musicians is critical to any builder's success AND to the stewardship experience of the player as well. If what we built cannot withstand the ravages of how guitars are typically used additional thought, engineering, and consideration may be warranted.

In other words players let guitars dry out, keep them in hot cars, may be gigging at a venue that's dry as a bone, etc. Guitars have to endure less than perfect care - an understatement.

With moves these days by more and more manufacturers toward torifaction and not just for possible... tonal reasons but for greater resistance to RH swings as well I do think that it's important to consider materials that we use for the intended function.

With this said and considering what guitars have to endure, typically, personally I would not be building WRC instruments for steel string. YMMV.... And again folks should do what ever they want and I'll always do the same as well.

I can't ignore though that when a WRC top sheds a bridge it's usually more dramatic to the point of being catastrophic in some cases.... If we have to use e*poxy or piece in an entirely new "scoop" of wood to repair something that commonly happens I would not call that instrument "serviceable" in the sense that material selection was optimal for what the thing is intended to be and do...

Again YMMV. I would be less reserved about WRC on classical tops because of the lower tension but still we see classical WRC tops shedding bridges too as we see here.

In a perfect world, perfect finish scoring, perfect wood selection (no runout), perfect care of the instrument for all of time after it's built WRC would likely be fine.

The world or at least my world is just not that perfect though.
Author:  david farmer [ Wed Nov 16, 2016 2:47 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Into the shop moments ago. :(

If we are going to strip our planet of old growth, lets at least make things with it that will last through the weekend. :(

Hey Waddy, just mix up a double batch of epoxy would ya?

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Author:  Hesh [ Thu Nov 17, 2016 5:12 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
David at least it's not an Ov*tion.... ;)
Author:  WaddyThomson [ Thu Nov 17, 2016 10:12 am ]
Post subject:  Re: Any Suggestions for reparing this bridge?
I can do that. Smith's "All Wood Epoxy" has a 2 hour pot time. When will you pick it up?
Author:  david farmer [ Thu Nov 17, 2016 1:08 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Durango to charlotte. hmm.... just put it in the fridge. I might have to put the mountain bike in the shed and use the road bike. :)
Author:  Bryan Bear [ Thu Nov 17, 2016 1:16 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
You could save some time by bringing the guitar and clamps with you so you don't have to ride it all the way home before you clamp up. Just a suggestion. . .
Author:  Hesh [ Thu Nov 17, 2016 5:27 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
What do they say about bad things happening in threes....

Found this in our shop this morning.....

This bridge was lifting at the wing, the one with the wood still on it from the top.... so it's carefully remove, clean up, expand wood-to-wood gluing area if possible and reglue with HHG.

As you can see Taylor likes to use pins too so they can stay if they want, I don't care....;) A word of caution though I have had guitars where the bridge lifted and the reason was the pins were too long and prevented the bridge from being clamped all the way down.... Dry runs are your friend, not to be confused with, well you know....

Anyway I was hoping that this one would be shredded too because they usually are but no such luck, my removal technique didn't lift any fibers that were't already lifted.

Also you can see the rabbit that we were talking about too around the bridge bottom. David Farmer taught us that Taylor was doing this and of course Collings does it too. So do we. It makes for a nice locating pocket when working with short open time glues such as HHG.

Back to work here, this is our busy time of year.
Author:  david farmer [ Thu Nov 17, 2016 7:50 pm ]
Post subject:  Re: Any Suggestions for reparing this bridge?
Makes a nice pencil and smells good in the wood stove though. laughing6-hehe

On bridge re-glues like that I figure they had their chance now I get mine. I score around the very outside with the back of a new #11 blade and HHG that whole SOB down. Looks perfect and I can be sure if someone comes back with the bridge off again, the bridge plate will still be glued to the bottom!
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