How does a cracked top get repaired?

fretie · Sep 4, 2015

So far I've seen two players, at uke jams, sit on their instruments and crack the top - ouch!
To make it more painful, both ukes very beautiful custom instruments.

So how would a luthier repair a cracked top? Glue and clamp? I doubt that taking s top off and replacing it with a new one would be an option would it?

How does a repaired top affect the integrity of the ukulele and the sound?

Pukulele Pete · Sep 4, 2015

Go to Frets.com , lots of info there . Also do a search here on this site and there is even more there. I've done it a few times , used rare earth magnets for clamps, it's not hard.
Geez , sitting on your uke ,......whew

stevepetergal · Sep 5, 2015

Generally, yes, glue and clamps. How it gets repaired depends upon the damage. If it's just a crack and none of the wood is displaced (moved or misshapen) a top may simply need to be glued. I've even seen it done without any clamping. The more extensive the damage, the more complicated the repair. Many (most?) cracked tops need a cleat attached to the underside. A cleat is like a piece of veneer that is glued to the repair site that straddles the crack, keeping it stable by actually making the two sides of the crack work like one piece of wood, again. If pieces are actually broken out, they need more extensive reassembly and larger or more cleats.
In answer to two of your questions:
Yes, a new top is an option. Maybe worth the expense for a badly damaged high quality instrument.
Yes, a repaired top does effect sound. Again a very simple crack repair without a cleat may change the sound so slightly you would never notice it. Most of the effect on the sound is caused by the added weight of the cleats on the soundboard. Cross-grain breakage will also effect the sound, as the vibrations, which make the sound, travel best along the grain lines. They move best uninterrupted.

fretie · Sep 5, 2015

stevepetergal said:
Generally, yes, glue and clamps. How it gets repaired depends upon the damage. If it's just a crack and none of the wood is displaced (moved or misshapen) a top may simply need to be glued. I've even seen it done without any clamping. The more extensive the damage, the more complicated the repair. Many (most?) cracked tops need a cleat attached to the underside. A cleat is like a piece of veneer that is glued to the repair site that straddles the crack, keeping it stable by actually making the two sides of the crack work like one piece of wood, again. If pieces are actually broken out, they need more extensive reassembly and larger or more cleats.
In answer to two of your questions:
Yes, a new top is an option. Maybe worth the expense for a badly damaged high quality instrument.
Yes, a repaired top does effect sound. Again a very simple crack repair without a cleat may change the sound so slightly you would never notice it. Most of the effect on the sound is caused by the added weight of the cleats on the soundboard. Cross-grain breakage will also effect the sound, as the vibrations, which make the sound, travel best along the grain lines. They move best uninterrupted.

Thanks for your explanation, Steve, that was very helpful.

Michael N. · Sep 5, 2015

A fresh crack is relatively easy to repair, although that doesn't necessarily mean it's a cheap job. Old cracks are somewhat more of a challenge. I doubt that a few cleats will affect the sound. I think you would have a very hard time telling any before and after difference. I can't say that I ever have been able to tell, or indeed the folk who I've repaired cracks for. One single cleat weighs around 0.1 g. That's a very insignificant amount. Compare that to the weight of the soundboard as a whole or just the weight of one single strut. There really is no comparison.

Pete Howlett · Sep 5, 2015

Leave it on the bench and the workshop elves will work their magic overnight

fretie · Sep 5, 2015

Thanks for your input, guys.

Pete, you had me smiling with your comment...were it that easy though, eh?!

Timbuck · Sep 6, 2015

Pete Howlett said:
Leave it on the bench and the workshop elves will work their magic overnight

Come on Pete ..I think it's time to tell e'm about your brown gum paper trick

sequoia · Sep 6, 2015

I actually sat on one of my ukes so I know it happens. Very unpleasant. Below is a post of my repair:

http://forum.ukuleleunderground.com...-the-Smashed-Ukulele-Part-I&highlight=cracked

fretie · Sep 6, 2015

sequoia said:
I actually sat on one of my ukes so I know it happens. Very unpleasant. Below is a post of my repair:

http://forum.ukuleleunderground.com...-the-Smashed-Ukulele-Part-I&highlight=cracked

Your repair of the damaged uke was impressive! Thanks for posting the link.

How does a cracked top get repaired?

fretie

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Pukulele Pete

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stevepetergal

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fretie

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Michael N.

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Pete Howlett

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fretie

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Timbuck

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sequoia

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fretie

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