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Author Topic: Repairing a lifting bridge  (Read 1361 times)

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Offline Rivers

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Repairing a lifting bridge
« on: June 01, 2021, 08:11:44 AM »
Hi all,

Just wondering whether I could consider doing this repair to my Tonk American myself. After I first got it in 2012 I took it in to a luthier's shop in Austin for a neck reset and various smaller fixes and improvements. It's all still fine except for the bridge, which has lifted off the top along its back edge.

Luthiers are scarcer than hen's teeth out here in the country and I don't know any. Plus I've gotten pretty comfortable fixing things myself whenever possible. Interested to hear your comments and experiences with this type of repair.

Offline Stuart

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Re: Repairing a lifting bridge
« Reply #1 on: June 01, 2021, 09:15:49 AM »
Hi Rivers: I've never done it, but I'm comfortable enough working with wood that I'd probably do it myself if there was no one I trusted in the area. There are plenty of videos available on YouTube and Stew-Mac has the clamps and other tools for the job. Surface prep and using the right glue are important in any glue up, but I'm sure that's covered as well. And I'd stay away from quick fixes since if the glue joint is failing, you want to start over from square zero.

Offline Slack

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Re: Repairing a lifting bridge
« Reply #2 on: June 01, 2021, 10:27:08 AM »
You can do it.   ...and I agree 100% with Stuart on surface prep, youtube is a good resource for the how to's.  It could be the start of a new career.

Offline Rivers

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Re: Repairing a lifting bridge
« Reply #3 on: June 01, 2021, 12:27:08 PM »
Thanks guys. Yes, I'm planning to do it right if I do do it. I'd take the bridge off, prep everything and reglue it. And yes, I figured I'd need those purpose built clamps.

Offline Stuart

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Re: Repairing a lifting bridge
« Reply #4 on: June 01, 2021, 01:34:29 PM »
Hi Rivers: Keep us posted on how things go.

Offline waxwing

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Re: Repairing a lifting bridge
« Reply #5 on: June 01, 2021, 01:39:57 PM »
Hey Riv,

One issue you want to plan for is intonation. When bridge was re-glued on my little Stella the luthier (Gary Brawer in SF) filled the saddle slot before re-gluing, then he recut the slot after assessing intonation requirements. Stewmac has a tool for doing this that adjusts for each string. You might also need a pin router. and a jig to cut slot.

Of course, it is possible that intonation will be correct (or close enough) if you glue it back in the same place, but if not, filling the slot becomes a lot more fiddly.

There's always something.

Wax
« Last Edit: June 01, 2021, 01:42:12 PM by waxwing »
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Offline harriet

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Re: Repairing a lifting bridge
« Reply #6 on: June 01, 2021, 04:26:49 PM »
Hi Rivers,

I've replaced a bridge on a vintage 30's supertone - I got the Stewmac "Bridge Spatula", to lift the bridge, two soundhole clamps 7" with leveler, and used titebond glue, a variety of exacto knives, dental mirror,small gooseneck light. I'm sure youtube has videos with options for protecting the finish around the area. if you want to consider any of the stewmac tools...

https://www.stewmac.com/luthier-tools-and-supplies/types-of-tools/chisels-and-knives/bridge-spatula.html

https://www.stewmac.com/luthier-tools-and-supplies/types-of-tools/clamps/soundhole-clamps.html

https://www.stewmac.com/luthier-tools-and-supplies/supplies/glue-and-adhesive/glues/wood-glues/titebond-original-wood-glue.html






Offline Rivers

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Re: Repairing a lifting bridge
« Reply #7 on: June 01, 2021, 06:49:01 PM »
Excellent feedback as always guys.

Harriet, thanks, I was wondering whether using Titebond (and which of the three varieties they produce) was a good idea, since I don't think I'm a traditional hide glue kind of a guy. I have all the other tools or their equivalents except for the clamps which I will order.

Wax, good point re intonation. Better make sure it goes back exactly where it was. The intonation was/is pretty good (for an old Regal-produced guitar) where it is now.

I will keep you posted on how it goes, fun project.
« Last Edit: June 01, 2021, 06:54:49 PM by Rivers »

Offline waxwing

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Re: Repairing a lifting bridge
« Reply #8 on: June 01, 2021, 10:10:06 PM »
Titebond II is "water resistant" and Titebond III is "waterproof", which means neither would likely be easily softened by steam if you needed to lift bridge at a later time. I think Titebond Original would be the best bet, providing a bond stronger than the wood.

Wax
"People who say it cannot be done should not interrupt those who are doing it."
George Bernard Shaw

“Just because you're paranoid doesn't mean they aren't after you.”
Joseph Heller, Catch-22

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CD on YT

Offline Slack

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Re: Repairing a lifting bridge
« Reply #9 on: June 01, 2021, 10:50:40 PM »
I agree with Wax, use Titebond original... good tip.  Stewmac stuff is nice but price-y, you can always find alternatives deep C clamps and a $10 kitchen spatula or putty blade works fine.

Offline Stuart

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Re: Repairing a lifting bridge
« Reply #10 on: June 01, 2021, 10:55:40 PM »
Hi Rivers: I agree with Wax. I've used Titebond for decades, as have woodworking friends of mine. II and III are solid products, but I wouldn't use them on guitars for the reason Wax mentions. I have a shop project that I made 60 years ago and glued up with Elmer's Glue-All, which was the standard for wood shop class way back when. The joints are still tight.

Offline Norfolk Slim

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Re: Repairing a lifting bridge
« Reply #11 on: June 02, 2021, 12:05:43 AM »
Definitely titebond 1 if not going for hide glue. 

For spatulas, I bought a set of artists spatulas from ebay for a couple of pounds, which work just fine.  I would not want to get steam around the bridge for fear of damaging the finish.  Rest the spatulas in boiuling water until they are hot and then just ease your way under the bridge, a bit at a time.  Its the same process one uses for removing hte fretboard extension for neck work.

Also- it is fairly simple to make a clamp / caul for the bridge.  You have the advantage of being able to put small screws through the bridge pin holes and to tighten them as a main clamp.  The purpose made bridge clamps are costly.

Offline Rivers

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Re: Repairing a lifting bridge
« Reply #12 on: June 02, 2021, 10:37:04 AM »
Also- it is fairly simple to make a clamp / caul for the bridge.  You have the advantage of being able to put small screws through the bridge pin holes and to tighten them as a main clamp.  The purpose made bridge clamps are costly.

We have a store called Harbor Freight over here. It's fabulous and cheap. I see they have a wide range of deep throat clamps in various sizes, that'll be my first stop I think.

Offline harriet

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Re: Repairing a lifting bridge
« Reply #13 on: June 02, 2021, 12:41:13 PM »
You might find it useful to take a look at the photos for both the soundhole clamp with leveler and the bridge spatula to adapt what you get if you need to.

The spatula has felt at the end to make it easy to slide level without scratching, besides the rounded edges. The clamp leveler prevents drifting down of the clamp.



Offline Rivers

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Re: Repairing a lifting bridge
« Reply #14 on: June 02, 2021, 05:25:19 PM »
Good idea Harriet. I find myself adapting a lot of tools to the myriad tasks I find myself tackling daily. The clamps look very like the Harbor Freight ones, without the leveler screw, and the adjustable 'anvil' screw that goes inside underneath. It may be better to buy 3 for 10% discount from StewMac. Is three enough do you think?

I see I need to measure the distance from sound hole to each target position on the bridge to be able to order the right sizes(s). And I'll get their cool spatula while I'm at it.
« Last Edit: June 02, 2021, 05:38:18 PM by Rivers »

Offline harriet

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Re: Repairing a lifting bridge
« Reply #15 on: June 03, 2021, 06:02:17 AM »
Rivers, I don't know the Tonk or if there is obstructive bracing involved you'll have to work around. . It could be helpful or it might be difficult to put three in.  I think I did a dry run before gluing and worked out any problems, with the two.

The little flat wood pieces on the top the way they have it was helpful , I used craft basswood and cut to size.



 
« Last Edit: June 03, 2021, 06:06:26 AM by harriet »

Offline Stuart

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Re: Repairing a lifting bridge
« Reply #16 on: June 03, 2021, 04:29:06 PM »
Hi Rivers: As Harriet mentioned, there will probably be bracing to contend with so a dry run that will reveal any potential problems is a good idea. One thing you could do once you have the bridge off, is make a template using the bridge on a piece of thin, but stiff, cardboard. You could mark and cut the holes for the 1st and 6th strings, put something--maybe nails or screws though the 1st & 6th holes in the top and align the template from inside the guitar. That will give you an idea of where the bridge is--from the underside. Even pressure is important when gluing and although the bridge plate will do a good job of distributing it, there are going to be areas beyond it that you'll want to apply clamping pressure to--as Harriet has mentioned. Of course you could simply use the bridge, but a template will allow you to mark it up if necessary.

There's a woodworkers' trick that will come in handy. There's going to be some squeeze out. Get a few plastic straws and crease them so they are square with 90 degree corners. Then trim them at the end at a 45 degree angle, corner to corner. The pointed end will fit in tight where the bridge meets the top and you can go around the bridge to remove (scoop off) any excess glue. Works like a charm. I'm not a fan of using a wet rag--or any rag--for removing excess glue because it can "size" the wood (act as a wash coat) which can cause problems when staining.

Decades ago my woodworking friends lent me a copy of Patrick Spielman's "Gluing and Clamping." It contains a treasure trove of information. I eventually bought my own copy. I checked and it's available dirt cheat from the used booksellers.
 

Offline Rivers

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Re: Repairing a lifting bridge
« Reply #17 on: June 04, 2021, 04:12:55 PM »
Excellent information guys, thank you very much.

 


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