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Old 12-06-2017, 03:52 PM
Chicago Chicago is offline
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Talking Bridge re-glue affected tone. Trying to find a fix

My Seagull S6 Folk has always been my "experimental" guitar for trying new luthier related projects. The bridge was lifting and I decided that this would be a good time to learn about bridge removal/regluing. Well it's a good thing that I used a Seagull instead of something more valuable for my first attempt, as I have some problems that I need to fix. After the repair, the high strings sound slightly dead, and the lower strings sound tinny compared to how they used to sound. All around, the guitar has lost some richness and power. I have a few ideas as to the cause and how to fix it, but I wanted to run my thoughts by the folks on this forum to get your two cents before I proceed.

During the removal process, I didn't go slowly enough and I ended up ripping out a thin piece of cedar from the top (it remained attached to the bottom of the bridge). I opted to use heat and steam to remove this section, and regule it to the top prior to prepping the surface to accept the bridge. In the pictures, you can see the footprint of the re-glued cedar. I suspect that this could have something to do with the issues, but I'm not totally sure.

I also had to remove about .01 inches of wood from the top to smooth out the surrounding damage from the cedar tear-out that occured when I removed the bridge- i.e. the bridge is inlaid about .01 into the surface of the guitar.

Because I had to remove some extra wood from the top under the bridge footprint, I was unable to achieve a perfectly flat gluing surface. The sides on the bridge footprint were nice and level, but the center of the footprint dipped by about .015 in the center. I figured it would be best to leave it be, as I wanted to remove as little material as possible, and the top could easily flex to close up that .015 gap under the pressure of the clamps.

This guitar also had an under saddle pickup at one point, and some glue seeped into the the saddle slot through the hole that the pickup wire ran through. I cleaned the glue out of the slot using water, paper towels, and q-tips, but I'm thinking that perhaps there could still be some residue that is raising the side of the saddle, not allowing it to seat properly, or that the wood on that side may have swelled and remained enlarged due to the mixture of water and wood glue (again, causing the bridge to not seat properly).


My current plan is to get one of the saddle slot files from Stewmac to see if leveling the bottom of the slot will fix the problem.

If that is ineffective, I plan to remove the bridge again (hopefully correctly this time), and shave away some wood under the bridges footprint and the surrounding area to completely remove the remnants of damage/re glued cedar that remain from my first removal attempt, and to achieve a perfectly flat surface.

What do you guys think of this analysis? Am I missing anything? Would you recommend that I do something different. I'd really like to hear your opinions so that I can dive back into this project with confidence and a solid game plan.





Last edited by Chicago; 12-06-2017 at 04:10 PM.
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  #2  
Old 12-06-2017, 04:31 PM
Earl49 Earl49 is offline
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You didn't say (or I missed it) but what kind of glue did you use? Ideally the glue will cure to a glassy hardness that will maximize the transmission of vibrations. Any soft glue like Gorilla Glue would likely act as a cushioned damping material between the surfaces, and may take a long time to cure hard. The glue should fill in any minor irregularities of the surface.

Also I assume that the strings on it now are new. Putting the old strings back on will cause them to go dead. Few things kill string tone faster than tuning up and down. Then I would finally think about checking for a perfectly flat saddle slot.

As an aside, I recall watching a fairly recent Godin factory tour video where they showed the final neck attachment station. They now use epoxy for the neck, with the neck bolts acting only as clamps until the epoxy cures. The technician measures the neck angle / height and chooses the right thickness of bridge from a parts bin to get the correct geometry. The necks will no longer be resettable, as it is usually impractical to get an epoxy joint apart. If there is a neck angle issue that occurs under warranty, they plan to replace the guitar outright.
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Old 12-06-2017, 05:55 PM
Chicago Chicago is offline
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I used Titebond 1 and it was clamped for 6 hours, then left to dry for another 42 hours before stringing it up. Also yes, the strings are a fresh set. The neck appears to be solid, and the action is as low and playable as it was before the bridge job. Intonation is also good across the board.

I'm hoping it's the saddle slot. I've read about people using the same method that I used to remedy tear-out during a botched bridge removal with good results so the saddle slot seems like a prime suspect
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Old 12-06-2017, 06:06 PM
LouieAtienza LouieAtienza is online now
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As far as I know Seagull routs a very shallow "pocket" that supposedly just breaks through the finish, and the bridge has a corresponding "rebate" of about .001" around the perimeter of its bottom. So if you've sanded the top to level it you thinned it out at the bridge area, where maybe a patch would have been the more appropriate repair.
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Old 12-06-2017, 06:22 PM
charles Tauber charles Tauber is offline
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Did you use some type of gluing caul on the inside of the guitar, against which the clamps were seated? Did that/those get removed after the clamps were removed?

If the bridge is adequately glued, there is no reason to remove it again. It is unlikely that the glue joint/how it was glued has altered the tone, given that you used Titebond. Also, you don't want to remove anymore of the top wood. Unless absolutely necessary, leave it alone.

As an aside, if a guitar top has runout, and most do, then the runout will be oriented in opposite directions on one half of the top compared to the other. When removing a bridge, that means one usually approaches the removal from opposite directions on each half of the bridge. That about half of the bridge has a fair bit of top attached to it, while the other half does not, suggests that, perhaps, you didn't approach it that way. (The half with top stuck to it, was removed in the opposite direction than it should have been.)

It is possible that a blob of glue in the saddle slot prevents the saddle from sitting flat. This would be an issue for an under saddle pickup, but wouldn't likely change the un-amplified tone much, if any. "Levelling" the slot isn't appropriate, if the problem is a blob of glue in one specific location. One of the most difficult things to learn is to correctly identify a problem area and work only that area, and not everything around it. Working the entire area, rather than addressing the specific problem, often makes matters worse, not better: one hasn't addressed the cause of the problem.

None of the things you've mentioned are likely causes of a significant change in the sound of the instrument.
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Old 12-06-2017, 06:23 PM
Chicago Chicago is offline
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Louie Atienza, can you elaborate on the patch? I don't quite understand
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Old 12-06-2017, 06:29 PM
Chicago Chicago is offline
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Quote:
Originally Posted by charles Tauber View Post
Did you use some type of gluing caul on the inside of the guitar, against which the clamps were seated? Did that/those get removed after the clamps were removed?

If the bridge is adequately glued, there is no reason to remove it again. It is unlikely that the glue joint/how it was glued has altered the tone, given that you used Titebond. Also, you don't want to remove anymore of the top wood. Unless absolutely necessary, leave it alone.

As an aside, if a guitar top has runout, and most do, then the runout will be oriented in opposite directions on one half of the top compared to the other. When removing a bridge, that means one usually approaches the removal from opposite directions on each half of the bridge. That about half of the bridge has a fair bit of top attached to it, while the other half does not, suggests that, perhaps, you didn't approach it that way. (The half with top stuck to it, was removed in the opposite direction than it should have been.)

It is possible that a blob of glue in the saddle slot prevents the saddle from sitting flat. This would be an issue for an under saddle pickup, but wouldn't likely change the un-amplified tone much, if any. "Levelling" the slot isn't appropriate, if the problem is a blob of glue in one specific location. One of the most difficult things to learn is to correctly identify a problem area and work only that area, and not everything around it. Working the entire area, rather than addressing the specific problem, often makes matters worse, not better: one hasn't addressed the cause of the problem.

None of the things you've mentioned are likely causes of a significant change in the sound of the instrument.
Excellent info. I didn't even think to consider the runout on the top. Is there a way to identify why direction the runout goes prior to removing a bridge? I did use a caul, but it has been removed.

I swear, repairing instruments can sometimes but far more difficult than building them! haha
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Old 12-06-2017, 06:37 PM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by Chicago View Post
Is there a way to identify why direction the runout goes prior to removing a bridge?
No. Pay attention to what is happening while you do it. Knowing that one direction will tend to lift wood while the other won't is your guide.

Quote:
I swear, repairing instruments can sometimes but far more difficult than building them! haha
That is true.
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Old 12-06-2017, 06:40 PM
Chicago Chicago is offline
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I'm wondering if it could have something to do with the surface area of the gluing surface? As mentioned in a previous comment and shown in the pictures, the guitar came from the factory with some finish reaching under the perimeter of the bridge (up to 3/16" in some spots). Because I stripped that finish away and re-glued, the gluing surface now extends to the edges of the perimeter of the bridges footprint (rather than being up to 3/16" inside of the footprint as it came from the factory). That would affect the leverage that the bridge has over the top, and henceforth could affect how the vibrational forces are transferred to the top. Am I wrong?
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Old 12-06-2017, 06:53 PM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by Chicago View Post
Am I wrong?
Likely, yes.

It isn't uncommon to remove the finish around the perimeter of a bridge footprint and then re-glue it. Doing so doesn't cause a degradation in sound.
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Old 12-06-2017, 07:17 PM
LouieAtienza LouieAtienza is online now
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Quote:
Originally Posted by Chicago View Post
Louie Atienza, can you elaborate on the patch? I don't quite understand
Well you removed wood in the proceas of pulling the bridge. It happens. If you just merely sand the area smooth you'll create a recession in the area. So either a) you end up with a thicker film if glue than necessary at that point, or b) you cranked the clamp enough to force the join closed, and when you remove the clamps the resulting tension forces the bridge to warp slightly, possibly enough to warp the bottom of the saddle slot. In this scenario I may actually create a fissure of constant depth where the tear out was, tapering it to zero and fitting it under the bridge footprint, then gluing material hopefully of the same wood and leveling that out to the surrounding area.

Probably b is the likely scenario which can be checked. The slot can be trued but likely a new saddle would be needed. I don't think fully gluing the bridge in did harm, a lip is usually left by manufacturers to ensure a clean bridge install. But I think full bridge gluing considered more an improvementthan anything else.
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Old 12-08-2017, 07:18 AM
Ned Milburn Ned Milburn is online now
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Are you using the same saddle??

Often, not always, bridge removal can involve removing a small thickness of top wood (ie: the stuff that stuck to the bottom of the bridge, and levelling the bridge area on the top). Even if this is slight (0.25mm for example), it means your action would be lower.

Also, if you removed the UST pickup, that would lower the action as well if you are using the same saddle.

So, with lower action, your guitar very well could lose some power and richness.
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