Botched the first half of a bridge re-glue. Help!

Chicago · #1 04-08-2017, 09:30 PM

I may be over exaggerating (or maybe not) in the title. So I noticed that the bridge on my Seagull was lifting and I decided that this was a good opportunity to attempt my first bridge removal/reglue. I spent about 25 minutes removing the bridge, constantly using an iron to heat the bridge and my drywall knives. It felt like the removal was going smoothly until the bridge actually came off. I didn't feel like I was forcing it, but apparently I was. The bridge came off with a whole lot if cedar attached to the bottom. Looks like I pryed a layer of wood off the top rather than break the glue joint over the majority of the bridge. I'm wondering how you guys think I should proceed to avoid trashing the guitar. My plan is to proceed as normal-scrape away the wood/glue from the bottom of the bridge and then scrape a (mostly) even surface into the guitar top prior to gluing. This will probably require removing a little more wood the planned from the top, but I think that with a little over-scraping, I might be able to have a good gluing surface with only a few small chips/gouges. That being said, I'm concerned that I might have completely fudged this bridge job. What do you guys think I could do to rectify this botched removal?

Chicago · #2 04-08-2017, 09:44 PM

*THIS POST PREVIOUSLY CONTAINED PICTURES. THEY WERE HUGE SO I REPOSTED SOME SMALLER PICTURES BELOW*

Hyoung · #3 04-08-2017, 09:51 PM

I think someone more experienced than I is going to come along and advise you to fill the low spots on the top with CA superglue, then sand the underside of the bridge smooth and glue it down. But what do I know, that's just what I would do...

mirwa · #4 04-08-2017, 11:44 PM

Any chance you can resize those pictures and then link them back in, they are huge.

Those that do it all the time, make it look easy, but we all started somewhere and most if not everyone has at some stage ended up with what you have there.

When you use your spatula for separating its important to feel the glue area, it's like pushing against a foam mattress and your not forcing them apart your simply stretching the glue bond until it finally gives way.

I personally would not clean the fibres off, simply make sure they are straight and nothing is in the way for a re-attach, normally I also prefer titebond, but in this instance I would use hide glue.

The other option is clean both surfaces up of all loose fibres, get it super clean and use an epoxy glue.

Steve

Ned Milburn · #5 04-09-2017, 05:53 AM

Often, (certainly not always) guitars that need bridges removed & reglued can benefit from a SLIGHTLY lower bridge (0.5mm to 1.0mm lower max, during this operation). So, scraping the wood from the bridge and resurfacing the top wood are well warranted to create a proper wood to wood glue joint.

Your photo looks fairly standard, although Steve makes a good point about the tool use and wedging action. I use artists putty knives with the tip ever-so-slightly bent up to avoid tear-out as much as possible.

Do NOT touch up with CA then glue the bridge on.

If any minor fill is ever needed, I usually make some saw-dust (sanding dust actually) and make a paste with wood glue, then use this "live" as I glue the bridge on - not before.

Make certain to scribe and scrape carefully the footprint of the bridge so you get a 100% glue to glue joint. This is NOT usually done in factory builds, and this is one of the main reasons bridges begin to lift.

Chicago · #6 04-09-2017, 07:42 AM

Thanks for the great replies thus far. I resized these pictures on Imgur and Im also adding a few more pictures to the bunch

Chicago · #7 04-09-2017, 07:52 AM

So after some deep thought, this is what I think I would like to do-

1) Use heat and steam to break the glue joint between the bottom of the bridge and the cedar tear-out.

2) Use a chisel or plane blade to remove the cedar from the bridge in one solid strip

3) Steam the guitar top to remove any dents/digs caused by the drywall knife on the gluing surface

4) Glue the strip of cedar tear-out back onto the top

5) Scrape/sand the guitar top gluing surface

6) Sand the proper radius into the bridge

7) Glue the bridge to the guitar top

8) Order a pizza and have a few beers

How do you guys feel about these steps. Would you do anything differently? I feel that step 8 is really critical in making the repair successful.

Frank Ford · #8 04-09-2017, 08:57 AM

I'd:

1. Carefully remove all that masking tape.
2. Hold bridge back in correct location, and LIGHTLY scribe a line EXACTLY at the perimeter all around (X-Acto knife blade or some such).
3. Carefully scrape all top finish off from scribed line to old gluing surface.
4. Toss bridge into boiling water for a couple of minutes - take out and scrape off residual cedar and/or glue.
5. Block sand bottom of bridge to flatten, even it up and clean it. Don't round edges or corners, and don't try to sand a radius. It should be flat.
6. Lightly sand the top gluing surface with a tiny block and sandpaper to even it out a bit.
7. Glue and clamp the bridge as normal.
8. Crack open that IPA. . .

Chicago · #9 04-09-2017, 11:55 AM

Frank, thanks for your input. If you don't mind me asking, why should the bottom of the bridge be flat? My understanding was that the bottom of the bridge should match the radius of the top, but manufacturers usually skip this step on lower end models. That being said, if I really knew my stuff I wouldn't be in this predicament in the first place

Ned Milburn · #10 04-09-2017, 12:55 PM

Quote:

Originally Posted by Chicago

Frank, thanks for your input. If you don't mind me asking, why should the bottom of the bridge be flat? My understanding was that the bottom of the bridge should match the radius of the top, but manufacturers usually skip this step on lower end models. That being said, if I really knew my stuff I wouldn't be in this predicament in the first place

Some guitars are built flat, others with a radius. Designer's choice. If a guitar is flat, I re-mate the bridge flat. If it is/was radiused, I re-mate the bridge with a radius.

Frank Ford · #11 04-09-2017, 02:12 PM

The bridge is stong and stiff, and by clamping the top to it, you might flatten the top a bit in that area. We're talking just a tiny amount here. By clamping a flat bridge to a top with a slight radius you may induce a bit of stress in that area, stress that will, if anything, help resist the pull of strings trying to bend things into a bit of a curve. I fugre that's likley to be good rather than detrimental.

A bridge tends to come off as the top bends underneath, and "peels" away, starting at the back edge, so it's that back edge really doing the heavy work to resist string tension.

Now, there's nothing really wrong with carefully radius-ing the bottom of a bridge to match the top, but in most cases it's unnecessary.

redir · #12 04-09-2017, 04:12 PM

That's actually not as bad as you think. If I get big tear out then I will chisel off the top wood that is stuck to the bridge and then glue it in place. Otherwise just follow Frank's advice. Make sure to get rid of all the finish, most likely that's why you have cedar stuck to the bridge because your knife actually went under the finish which the bridge was directly glued too. Always should be wood on wood but on cheap guitars they glue right to the finish and that's what you get.