Bridge failure - how do I remove a damaged bridge??

[Quinny]

Hi,

The tie-on part of my bridge cracked off from the front section. It cracked in the channel between the ramp and the block the strings tie-on to. On closer inspection, I didn't mask enough area for spraying and the failed section was glued onto the lacquer - bugger.

I want to remove the remaining 2/3 of the bridge to glue on another. I get now that I better sand off all the varnish over the full foot print of the bridge!!

1) The bridge is glued on with Titebond glue and the lacquer is nitro-cellulose gloss. Do I mask the soundboard - what with? - and heat gun the bridge, then repair the finish??

2) I made the bridge with walnut as that was what the neck and rosette was made from. Is that part of the problem - wrong function for this wood??

Any advice is very appreciated. I just started uke lessons so my skill development is now arrested!!

Thanks

Andrew

[kiwigeo]

For getting bridges off I heat up an artist's palette knife with a heat gun and start by getting he knife in n under the bridge wings. I then gently work the knife around under the rest of the bridge and lift it off. The rear of your bridge has already come away so simply go in with the knife from the rear of what's left of the bridge to minimize damage to the finish.

Walnut shouldn't be a problem. My current build classical has a walnut bridge...mind you it's a Gore style bridge so it has two layers of CF weave..its not going to split even if you drop an atom bomb on it

[Allen]

Since the bridge is going to be replaced, then I'd recommend that you plane down the majority of what's left. If all you have left is a thin veneer of the old bridge, then any heat that you apply to release the glue will be much more effective. You will have a lot better chance of removing the remainder without excess heat an potential damage to the surrounding finish.

When I heat up a bridge for removal (ones that I have to save) I make a cardboard mask that protects the top. I wrap this with al-foil. All you will see is the bridge surrounded by the mask. Then use a heat gun to gently heat up only the bridge. The Al-Foil covered cardboard protects the top and the finish. The rest of the procedure as per Martins instructions hold.

[Eric Reid]

No need to heat the knife, and less chance of finish damage if you don't. Mask the top with cardboard and foil as described. (I like to use a layer of styrofoam covered with foil). Heat with a heat lamp. It will take a while to get hot (maybe 10-15 minutes?). Pay attention to runout. This is crucial. If you can see the runout, then come into the bridge from the side that looks lighter. If you can't see it, then you'll have to go by feel. Either way, you need to come in from opposite directions on either side of the center seam. Get this wrong, and you can do serious damage to the top. The suggestion of planing the bridge down to a thin veneer is a good one. A little slower, but a lot safer.

[Hard Road]

I mask the area just like mentioned above, then i lay a small piece of wet towel over the bridge and place a hot clothes iron on it, works for me. Planing the bridge down lower will certainly result in less heat needed to remove the remainder as well.

[Quinny]

Thanks for the advice Martin, Allen, Eric and 'hard road'. It is reassuring to know how to mask effectively against heat. I will plane down the bridge, mask around it and apply heat. Luckily as the back section is broken I can gently pry away from there without worrying about damage as it will be under my replacement bridge.

Any advice on the wood I used?

I used walnut as I used it for the neck and bridge. Obviously the bridge cracked as the back third was glued to lacquer, but I am wondering if walnut isn't appropriate for a bridge. My local timber yard has New Guinea Ebony in stock so I can get some Saturday. I can't find ebony uke bridges for sale online either, they don't seem to be available.

Thanks

Andrew

[Trevor Gore]

I've used some pretty high tensions on American black walnut bridges on classical guitars without any problems (thick fluorocarbon strings). They do have the CF in, as Martin indicated, but the CF doesn't prevent a split that could, for example, run horizontally through the string holes. So I don't think Walnut as a species is a problem from that point of view. Maybe a problem with that specific piece, or maybe the gluing, as you mentioned.

[kiwigeo]

My local timber yard has New Guinea Ebony in stock so I can get some Saturday. I can't find ebony uke bridges for sale online either, they don't seem to be available.

Thanks

Andrew

Ebony _looks_ nice on a bridge...but that's about it.

[charangohabsburg]

Any advice on the wood I used?

I used walnut as I used it for the neck and bridge. Obviously the bridge cracked as the back third was glued to lacquer, but I am wondering if walnut isn't appropriate for a bridge.

Walnut is just fine for a bridge, as many other wood species are. I have seen dozens of Spanish cedar bridges (cheap guitars) that had held up well since decades (not counting in the sometimes excessive wear on string-holes and unprotected tie-blocks, nonetheless those bridges were still structurally sound), and I also have seen a couple of rosewood bridges that split on almost new guitars (less than 1 year old). It is more about bad luck than the wood species. And yes, as Martin alludes to, ebony is a bit heavy for a bridge.

[Quinny]

Thanks Trevor, Martin and Marcus - it is pretty clear now from your advice. I am not sure if can all think back to your early inexperienced days, but this type of advice is so incredibly reassuring and stops all the worry and perseverating of what to do.

This morning the bridge came off easily once I planed it down, masked it, heated gently and levered it off with a pallet knife. Now to get to making my new bridge - in walnut - before it gets too hot in the shed today!!

Thanks guys

Andrew