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PostPosted: Wed Sep 20, 2023 9:34 am 
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Walnut
Walnut

Joined: Thu Aug 10, 2023 4:38 pm
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First name: Stephen
Last Name: Cleary
State: NY
Country: USA
Focus: Repair
Status: Semi-pro
Hi,

I have a bridge on a classical guitar that's lifting slightly so I was going to remove and reglue it, but the bridge has a black finish on it. Is it possible to remove this without destroying the finish? If I heat it up will it melt / bubble? Making a new bridge is probably outside of my skillset / toolset right now.

If it's too risky to remove without damage is it better to just leave it as it? My understanding was we should reglue any amount of lift. I can get an .006 feeler gauge under the bridge at the back, it goes in about 3/16" at the middle. It's only lifting under the center section and slightly on either side.

If it is safe to remove, any advice / resources on removing the pearl dots over the screws? I've seen people steam them out but I don't know the specific details so I just want to be extra careful.

Thanks!


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PostPosted: Wed Sep 20, 2023 3:55 pm 
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Koa
Koa

Joined: Tue Jan 15, 2013 10:00 pm
Posts: 985
First name: Josh
Focus: Build
Status: Amateur
You can loosen the pearl dots by applying a damp cloth or paper towel to the dot and touching it with your soldering iron to generate steam. Go slow.

Yes, you can heat a bridge without damaging the finish on the bridge - you need to heat at a lower temperature than you would on an unfinished bridge. As an example, I remove nitro-finished bridges regularly by heating at 250f. I use silicone heat blankets.

Since we don’t always know what finish is on any particular bridge there is always some risk, so go slow and check often.



These users thanked the author joshnothing for the post: Hesh (Wed Sep 20, 2023 10:45 pm)
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PostPosted: Wed Sep 20, 2023 3:59 pm 
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Koa
Koa

Joined: Tue Jan 15, 2013 10:00 pm
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First name: Josh
Focus: Build
Status: Amateur
Also: have you reglued a bridge before? If you value this guitar and this is your first rodeo it’s better to take it to a professional instead and practice on junkers to get your feet wet.

Keep in mind that you need to determine why the bridge lifted and address that too as part of the repair.



These users thanked the author joshnothing for the post: Hesh (Wed Sep 20, 2023 10:45 pm)
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PostPosted: Wed Sep 20, 2023 10:48 pm 
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Old Growth Brazilian Rosewood
Old Growth Brazilian Rosewood
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Joined: Fri Nov 02, 2007 9:49 am
Posts: 13387
Location: Ann Arbor, Michigan
First name: Hesh
Last Name: Breakstone
City: Ann Arbor
State: Michigan
Country: United States
Status: Professional
Wanted to ask what kind of guitar (brand and approx value) because that may have some bearing here too like Josh said. For a classical to have screws holding the bridge suggests it's a cheap import. Some cheap imports have had the bridge glued onto the finish intentionally (CA) and a cold removal/dull chisel, shock system of removal may be appropriate for the instrument.


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PostPosted: Thu Sep 21, 2023 3:27 am 
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Koa
Koa

Joined: Tue Jan 15, 2013 10:00 pm
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First name: Josh
Focus: Build
Status: Amateur
Hesh wrote:
Wanted to ask what kind of guitar (brand and approx value) because that may have some bearing here too like Josh said. For a classical to have screws holding the bridge suggests it's a cheap import. Some cheap imports have had the bridge glued onto the finish intentionally (CA) and a cold removal/dull chisel, shock system of removal may be appropriate for the instrument.

Is that Dave Collins bridge tomahawk video still around? :D


Sent from my iPhone using Tapatalk



These users thanked the author joshnothing for the post: Hesh (Thu Sep 21, 2023 3:52 am)
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PostPosted: Thu Sep 21, 2023 3:54 am 
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Old Growth Brazilian Rosewood
Old Growth Brazilian Rosewood
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Joined: Fri Nov 02, 2007 9:49 am
Posts: 13387
Location: Ann Arbor, Michigan
First name: Hesh
Last Name: Breakstone
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State: Michigan
Country: United States
Status: Professional
joshnothing wrote:
Hesh wrote:
Wanted to ask what kind of guitar (brand and approx value) because that may have some bearing here too like Josh said. For a classical to have screws holding the bridge suggests it's a cheap import. Some cheap imports have had the bridge glued onto the finish intentionally (CA) and a cold removal/dull chisel, shock system of removal may be appropriate for the instrument.

Is that Dave Collins bridge tomahawk video still around? :D


Sent from my iPhone using Tapatalk


laughing6-hehe He hid it I think not wanting people to think that was what we did with Martins. Everyone knows we use a sledge hammer on Martins... :)

Amazing video he hit it perfectly the first time and the bridge went flying across the room.


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PostPosted: Thu Sep 21, 2023 2:22 pm 
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Walnut
Walnut

Joined: Thu Aug 10, 2023 4:38 pm
Posts: 10
First name: Stephen
Last Name: Cleary
State: NY
Country: USA
Focus: Repair
Status: Semi-pro
It's a cheap Japanese import from the 80s or 70s. Does anyone know roughly when did it become common to start using glues that don't respond to heat on these things? I've done it before but just not with these specific details.

Anyway I've tried to steam out the dots and they don't seem to be responding to the steam. So I'm leaning towards leaving the bridge alone for the time being.

I've seen that video of him removing the bridge with a pickaxe haha


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PostPosted: Thu Sep 21, 2023 11:26 pm 
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Old Growth Brazilian Rosewood
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Joined: Fri Nov 02, 2007 9:49 am
Posts: 13387
Location: Ann Arbor, Michigan
First name: Hesh
Last Name: Breakstone
City: Ann Arbor
State: Michigan
Country: United States
Status: Professional
stephencleary3 wrote:
It's a cheap Japanese import from the 80s or 70s. Does anyone know roughly when did it become common to start using glues that don't respond to heat on these things? I've done it before but just not with these specific details.

Anyway I've tried to steam out the dots and they don't seem to be responding to the steam. So I'm leaning towards leaving the bridge alone for the time being.

I've seen that video of him removing the bridge with a pickaxe haha


Sorry to be the bringer of bad news but this guitar was never intended to be serviced, hand it back to whomever it's not your fault it was built to be pitched after it's useful life.

You have encountered what we call in the trade AMG (Asian mystery glue). It's often found on Chinese imports and none of us have any idea what it is but it does not release with heat predictably and at times at all. As such leave the bridge alone.

A proper bridge reglue is not an easy operation when you have not done it or are not equipped. It should be removed, the surfaces cleared, the bridge fitted to the top and then reglued with a quality, appropriate glue.

For a decent guitar that was intended to be serviced we charge $160ish so you can see the repair should exceed the value of this instrument making the economics not present to repair this guitar.

We always have people here though who insist on proceeding with these unserviceable guitars when they are not learning anything that translates into any valuable knowledge or skills. This is not directed at you Stephen you are learning, asking questions and exploring and that's all good.

The threads that give those of us the most pause are the recurring threads about attempting to reset a doweled neck joint. That's when we run into the folks who don't understand that for professional luthiers it's not all about what we might be able to do skill set wise. It's also all about what is wise to repair and what you should walk away from.

I've spent a goodly amount of time surveying my peers who work in the trade and it's my impression for that book I want to write and likely never will that the single most common reason why Luthiers fail and leave the trade is they attempt to be all things to all folks. Translation: they don't know when to say no and move on to the next job.

Now you know it's not a decent learning experience and to proceed and remove and repair the bridge you will be effectively reengineering the guitar into something it was not intended to be by the maker. The scope of the job may creep and once you have started it you own it and must complete it.

So danger Will Robinson your efforts and time will be much better spent on a serviceable instrument.


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PostPosted: Fri Sep 22, 2023 11:57 am 
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Walnut
Walnut

Joined: Thu Aug 10, 2023 4:38 pm
Posts: 10
First name: Stephen
Last Name: Cleary
State: NY
Country: USA
Focus: Repair
Status: Semi-pro
Thanks Hesh!



These users thanked the author stephencleary3 for the post: Hesh (Fri Sep 22, 2023 12:23 pm)
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