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Bridge removal mistake
https://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=57126		 Page 1 of 1
Author:  Geocoucou79 [ Sat Jul 12, 2025 9:29 am ]
Post subject:  Bridge removal mistake
Hi,

I made a mistake and I need advice. I was at the finishing line of this baritone and I glued the bridge yesterday. Unfortunately, the bridge shifted under clamping, beginner mistake, I should have put locating pins in the saddle slot to prevent any shifting. Anyway, I realized too late and I had to remove the very well glued bridge which I did with a heat gun and sharp spatula. Again I realized too late that the heat gun was a really bad idea. It cooked the top under the tape... I realized this only when I removed the tape and... what a mess... I'm very discouraged...

The finish is Tru-oil. I guess I need to sand the top now to bear wood and do the tru-oil again. But the fretboard extension is now glued and I would rather not remove this one too. Any smart advice?

Attachment:
Cooked top.jpg
Author:  Colin North [ Sat Jul 12, 2025 10:30 am ]
Post subject:  Re: Bridge removal mistake
Not got any advice for you, but I love the rosette. Not sure how I would go about that.
Author:  bobgramann [ Sat Jul 12, 2025 11:19 am ]
Post subject:  Re: Bridge removal mistake
The truism about cosmetics is “You can always make it worse.” Over time, the rest of the spruce will darken as it ages. You might go on from here and see how it works out, swearing never to do that again.

And, yes the rosette is beautiful and cool.
Author:  doncaparker [ Sat Jul 12, 2025 12:17 pm ]
Post subject:  Re: Bridge removal mistake
I like a heat gun for a number of tasks, including loosening glue at some parts of a guitar, but not this task at this spot. Sorry you had to learn the hard way. Yes, I would scrape/sand back and see how deep the scorching goes. Maybe you are somewhat lucky (in context) and the spruce comes clean. If not, well, you can complete this guitar, move on to the next guitar, and improve over time, like all of us. We all make more mistakes at the beginning of our building, and fewer as we go along. You should see the Frankenstein’s monster that was my first acoustic . . .
Author:  Hesh [ Sat Jul 12, 2025 12:29 pm ]
Post subject:  Re: Bridge removal mistake
Sorry Dominic that this happened to you that sucks.

So when we glue on bridges we do a dry run and clamp it in place and snug down the clamps only with no glue. Then we use masking tape butted against the leading edge and sides of the bridge to make a "well" for the bridge so that it can quickly, since we use hot hide glue be properly located and all that is left to do is snug down the clamps. I use two layers of masking tape and then in maybe a few minutes when the glue is gelling I pull the tape and that takes 75% or so of the squeeze-out up too making clean-up super easy.

Right now I don't see anyway that you can effectively access the top to sand it back without removing the neck. Is it a bolt on neck?

You can make a shield that encircles the fretboard extension and then cover the shield with aluminum foil, shiny side up and tape it all down on the back side of the shield. This is what we do in our commercial shop to release the extensions. We use a hardware store heat lamp but never, never, never leave the lamp unattended. I stand there holding it while it is on.

I place the lamp in nearly direct contact with the fretboard extension and after a minute of two I start poking around in there with my pallet knife looking for the glue to start to soften and get gummy. When I poke around I remove the lamp and the shield.

I will repeat this process maybe several times heating and poking until I can get it to separate and release. This works great and this is one of the steps we do when we reset Martin necks.

In the future as well as using a well to locate the bridge and doing dry runs Mario P. once offered on this forum that he uses a quarter sized puddle of Elmer's Carpenter glue under the extension and does not glue the entire extension. HHG or Titebond original would be fine for this too. This makes releasing the extension very fast and easy and it's all that is really necessary.

And before someone suggests with no experience with this idea that the extension can rattle it doesn't, I have over 45 in the wild with this method and Mario has hundreds and we have never had any issues with this method being a source of rattles.

Heat guns are way too hot and the heat is too concentrated for bridge or extension removal. A diffuser can help them be useful for flattening out distorted tops using water on the top under Martin pick guards when we replace them under warranty.

I hope something here helps you.
Author:  Geocoucou79 [ Sat Jul 12, 2025 1:20 pm ]
Post subject:  Re: Bridge removal mistake
Thanks all for support. This is my 3rd build and I haven't made a Frankenstein monster yet so I must be lucky with my bad luck :)! Mistakes are the hard way to learn indeed and I made a lot on this build but this one... just when I'm almost done... that really sucks.

Anyway I think I will protect the fretboard with tape, sand the top around it and redo the tru-oil. Hopefully it'll be good enough.

Here are a few pictures of this thing before attaching the neck. Yes this is a bolt-on neck and the fretboard extension is glued. Next time I would like to do a bolt-on neck extension too.

Attachment:
Front.jpg

Attachment:
Back.jpg
Author:  bobgramann [ Sat Jul 12, 2025 3:40 pm ]
Post subject:  Re: Bridge removal mistake
Be careful with the sanding. If you voiced the top and then remove wood, you will change the voicing.
Author:  Kbore [ Sat Jul 12, 2025 3:58 pm ]
Post subject:  Re: Bridge removal mistake
Very beautiful work and artistic design.
And sorry for the mishap.
I'm not a power-user of Tru_Oil; is it necessary to have to sand and refinish the entire top?
Could you do a spot sand and finish since Tru Oil is a "building" finish?
Alternately, as spoken so many times, you could turn the accident into a feature, and feather-roast the sharp edges to effect, like they roast the edges of marquetry in hot sand. Just a thought.
Author:  Hesh [ Sat Jul 12, 2025 4:02 pm ]
Post subject:  Re: Bridge removal mistake
Beautiful Dominic and we all get some warts on our builds and it's been my observation that as we fix them and move on we forget about them. I did :)

I have a hunch that sanding the top won't harm your outcomes for a number of reasons. It's your third you said so it may be over braced, we all do this so no worries. You will also be adding finish regardless of type of finish.

And the bridge will add the biggest brace of them all to the box and tighten things back up.

I have a few guitars on my walls in my condo that you can see the X brace intersection telegraphing through the top and finish. Coincidentally they are my most responsive, best sounding guitars. One is even a Martin but not from the 70's when they were massive.
Author:  rbuddy [ Sat Jul 12, 2025 5:54 pm ]
Post subject:  Re: Bridge removal mistake
I've found TruOil pretty flexible in use and touch up and I like it.

Did you put down any sealer on the top first like shellac? If so, it might be harder to fix if you sand/scrape thru to wood.

I've found with TruOil a scrapper is pretty good at shaving off a fraction of a mil of finish to fix something, and with some precision. I like the little ~ 1 1/2 x 2" flexible scrapers, and sharp. Razor blade might work OK.

I would start with that and work on the areas with the least burn. Work in to the darker areas trying not to go thru the finish if you find you are taking off the burn successfully.

You might get lucky and end up with something you can live with touching up the area and blend with the rest of the top. Right now, I don't think you know how deep the burn goes.

If you scrape down to bare wood you may have to do the whole top but you could always try and build that area back up with a few coats of TOil. Would be worth a try for me.

Let us know how it turns out.
Author:  Terence Kennedy [ Sat Jul 12, 2025 6:30 pm ]
Post subject:  Re: Bridge removal mistake
You might try finishing a spruce offcut with TruOil and then burning it with the heat gun to duplicate what you did to the guitar.
Then sand it and see how much you have to sand to get to clear wood. It may be more than expected and make you reconsider.

If you do resand I’d strongly recommend removing the neck. Might as well learn how to release an extension. You’ll have to do it someday.

I use a small heating blanket weighted down with a small sandbag. I think John Hall at Blues creek could fix you up with the blanket. I have not used Hesh’s technique but am sure it works well. Others use a clothes iron for heat.
Author:  Geocoucou79 [ Sat Jul 12, 2025 7:05 pm ]
Post subject:  Re: Bridge removal mistake
rbuddy wrote:
I've found TruOil pretty flexible in use and touch up and I like it.

Did you put down any sealer on the top first like shellac? If so, it might be harder to fix if you sand/scrape thru to wood.



No I sealed back, side and neck with aquacoat but I went straight with tru-oil for the top.

So I already sanded the top and gave a first coat of tru-oil. Like some of you recommended, I sanded the area around the bridge completely and the rest of the top more lightly. I must say I removed quite a bit of wood to get rid of the burn but it's what it is. I know I would have had better results by removing the neck and sanding the whole top equally, I can see it now. Anyway, I sanded all the way to 1000 grit this time rather than 380 or 400. I read that's the key with tru-oil, fine sanding. Now I will give it 15-20 coats of oil and repeat the bridge gluing process with locating pins this time!
Author:  phavriluk [ Sun Jul 13, 2025 9:08 am ]
Post subject:  Re: Bridge removal mistake
Geocoucou79 wrote:
rbuddy wrote:
I've found TruOil pretty flexible in use and touch up and I like it.

Did you put down any sealer on the top first like shellac? If so, it might be harder to fix if you sand/scrape thru to wood.



No I sealed back, side and neck with aquacoat but I went straight with tru-oil for the top.

So I already sanded the top and gave a first coat of tru-oil. Like some of you recommended, I sanded the area around the bridge completely and the rest of the top more lightly. I must say I removed quite a bit of wood to get rid of the burn but it's what it is. I know I would have had better results by removing the neck and sanding the whole top equally, I can see it now. Anyway, I sanded all the way to 1000 grit this time rather than 380 or 400. I read that's the key with tru-oil, fine sanding. Now I will give it 15-20 coats of oil and repeat the bridge gluing process with locating pins this time!


So what prevents that neck from coming off and the resolution get as close as possible to new construction? THERE AIN'T NO SHORTCUTS THAT WON'T LOOK LIKE A SHORTCUT.
Author:  Geocoucou79 [ Sun Jul 13, 2025 10:02 am ]
Post subject:  Re: Bridge removal mistake
Quote:
So what prevents that neck from coming off and the resolution get as close as possible to new construction? THERE AIN'T NO SHORTCUTS THAT WON'T LOOK LIKE A SHORTCUT.


I know, I gave in to my frustration this time. Most of the time I don't. But in my defense, I got many different advices, some of them were to do it that way. I think it will be fine.

By the way, capital letters in a chat are equivalent to shouting...
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