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Repair or Re-top?
http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=27462		 Page 1 of 1
Author:  hnuuhiwa [ Wed May 19, 2010 12:52 pm ]
Post subject:  Repair or Re-top?
Although this is not regarding a guitar, I thought it best to post here for the collective brain trust.

My wife completed her second ukulele in her ukulele building class a few weeks ago. It's a purpleheart B/S, sinker redwood topped six-string tenor uke. After a few days of having strung it up, the bridge started coming up in the middle and the tips. Her instructor didn't see a major problem, and felt it just needed to be re-glued/re-clamped, which they were going to do this week. By this weekend, the bridge started pulling on the top, causing a 1/2" crease/crack to appear from the center of the bridge towards the tail. The crease ran alongside one of the braces that ran under the bridge from the bridge towards the tail.

Anyway, yesterday she opened the uke case to find the following: :o

Image

Image

Obviously the strings should have been slacked while awaiting repair, but that's now in hindsight....she was devastated :cry: , but her instructor said that it could be repaired. When I looked at it last night, I kept thinking that it would be a difficult repair with access inside the box limited/non-existent due to the size of the sound hole. there's no way to "reach" into the box and work under the bridge area.

My thought was that it may be "easier" to take off the existing top and put a new one on.... What do you folks think?

I'm also not sure that she should stay with the typical "pinless" uke bridge design, and maybe she should use a pin bridge design with a bridge plate, given that she'll want to use sinker redwood for the top again. Thoughts or opinions??

BTW - when it was strung up, it certainly sounded great...much fuller ringing tones and wonderful sustains compared to her 1st 6 string uke, which was an all-Koa. But those that know me, know I have a heavy bias towards sinker redwood [:Y:]
Author:  Michael.N. [ Wed May 19, 2010 1:12 pm ]
Post subject:  Re: Repair or Re-top?
Repair it - but there seems to be a rather thick film of white glue on that bridge. Even with the tie bridge it should be able to withstand much more tension than 4 strings. Look at a Lute and the number of strings the bridge holds and that very bridge has a tiny footprint.
Author:  Jon L. Nixon [ Wed May 19, 2010 1:33 pm ]
Post subject:  Re: Repair or Re-top?
It looks to me like there was little or no wood-to-wood contact when the bridge was glued and the small area that was glued correctly had short grain, took all of the pull from the strings, and finally was overcome by shear stress and let go. It does seem strange that the low tension of nylon uke strings would do this, but unless you have a poltergeist I don't know how else it could have happened. It wasn't left in a hot car, was it?
You could put in a straight-grained patch under the hole. release the fragment from the bridge using a heat lamp or blanket and reglue it using a gap-filling glue. Level the area and then reglue the bridge after it has been correctly fitted. You don't have much to lose by giving it a try.

A new top is really not as scary as it sounds- there is lots of info here.
Good luck!!!
Author:  Howard Klepper [ Wed May 19, 2010 1:37 pm ]
Post subject:  Re: Repair or Re-top?
It's not that this kind of damage isn't a fairly straightforward repair--it is, and you can find instructions on Frank Ford's site.

BUT. That top appears to have an extremely high degree of runout, and I would expect more trouble with it in the future. Could you post who sold her the top? Whoever it is needs to understand something about runout.
Author:  Alain Moisan [ Wed May 19, 2010 1:41 pm ]
Post subject:  Re: Repair or Re-top?
Howard Klepper wrote:
That top appears to have an extremely high degree of runout, and I would expect more trouble with it in the future.


Indeed.
Author:  WaddyThomson [ Wed May 19, 2010 1:51 pm ]
Post subject:  Re: Repair or Re-top?
Looking at it, I was wondering if the wood was scored too deeply when marking around the bridge to scrape the finish off the top. It sure did break off in a clean line
Author:  Daniel Minard [ Wed May 19, 2010 2:20 pm ]
Post subject:  Re: Repair or Re-top?
With that much runout, I'm surprised that top was sold as tonewood.
Speaking strictly personally, I'd put on a new top... In spite of all the attendant hassles.
Author:  jfmckenna [ Wed May 19, 2010 2:44 pm ]
Post subject:  Re: Repair or Re-top?
My experience with figured redwood is that it's very brittle and breaks in that manor. That top doesn't look particularly figured but I've seen concoidal type breaks like that one in redwood. It's repairable with a bridge patch underneath IMO.
Author:  truckjohn [ Wed May 19, 2010 2:48 pm ]
Post subject:  Re: Repair or Re-top?
I was thinking..... Curly figure soundboard rears it's ugly head.

That beautiful curl is probably the culprit... especially since Redwood is already skewed towards the splitty end of the spectrum....

Think -- it broke loose with the pull of 4 nylon strings... Say you glue it back together with some sort of reinforcement veneer from behind... Will it hold then, or will it just yank out a bigger chunk of the curly figure from that top?

I second the vote for Retop... I would pick a nice, straighter grained piece piece that comes out of a split billet... Choice of material is up to you.

Thanks

John
Author:  hnuuhiwa [ Wed May 19, 2010 6:55 pm ]
Post subject:  Re: Repair or Re-top?
Thanks for all the input everyone...I think that it might be a good learning experience to patch it and if down the road it has issues again, then a re-top can be done (maybe by then I'll have enough experience that I could do the re-top with/for her). ;) Hen...
Author:  jfmckenna [ Wed May 19, 2010 7:56 pm ]
Post subject:  Re: Repair or Re-top?
hnuuhiwa wrote:
Thanks for all the input everyone...I think that it might be a good learning experience to patch it and if down the road it has issues again, then a re-top can be done (maybe by then I'll have enough experience that I could do the re-top with/for her). ;) Hen...

I think that is a good plan and I think you will be ok. A bridge patch that surrounds the hole by 5mm or so ought to suffice and you may as well just install a patch across the whole bridge while you are at it like you would for a steel string guitar.

Here is a similar repair I did to illustrate my point about the bridge patch: http://ww2.hereweare.us:8080/guitars/parlor.html
Author:  unkabob [ Wed May 19, 2010 8:22 pm ]
Post subject:  Re: Repair or Re-top?
I would go for a full bridge patch.

I would go for a Hana Lima style tie-down. The string goes through the bridge and bridge-patch and is knotted with a bead inside the ukulele. It is a little more trouble fishing the string out of the sound-hole to add the bead and knot it but it works well. The best bead that I have found are coco beads from Michals craft store.

Bob
Author:  Daniel Minard [ Thu May 20, 2010 1:55 am ]
Post subject:  Re: Repair or Re-top?
Good plan Henderson. You can always replace the top later if you need to. If it works, you'll have saved yourself a lot of work. If it doesn't, you've lost only a few hours & gained some good experience.
Author:  John Hale [ Thu May 20, 2010 3:19 am ]
Post subject:  Re: Repair or Re-top?
My first uke bridge pulled off in a similar way I replaced it with a steel string style pinned bridge and 18 months down the line the top hasn't bellied anymore and it played almost daily
Author:  hnuuhiwa [ Sat May 22, 2010 1:51 am ]
Post subject:  Re: Repair or Re-top?
Well...I finally had sometime to take a real close look at my wife's Uke, and I don't think a patch is going to work. There is a crack that extends above and below the bridge, as well as a cross grain fracture next to the fretboard. eek
Image

Image

I looked into the possibility of running the patch to support the crack, but found that the crack runs so closely alongside the brace that extends from the bridge to the tail, I wasn't confident that I could get the patch to properly support across the crack.

Image

With the crack and the fracture, I don't think its worth trying to save this top...I'm now heavily leaning toward making this a retopping project. idunno
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