Gluing Bridge Back On Classical (?)

[D. Shelton]

Went to my stepson's house last week and found their guitar on it's stand, with the strings all wacky . Further investigation revealed strings still strung to bridge, but bridge disconnected from body, hence the wackiness .
I'm headed back in a week or so and I'd like to fix it for them , but I've never
repaired a guitar before, so what's a good glue for this ? Will basic wood glue work .... or what ?

TIA,
Dar

[jeff crisp]

http://www.acousticguitarforum.com/f...d.php?t=302130
http://www.acousticguitarforum.com/f...d.php?t=302130
The top thread is about glue. I would go with Titebond original.

The second thread is what you'll need to know to repair it. Post number 13 from Charles Tauber gives you a simple but effective way of avoiding the need for special clamps.

Hope this is of help.

Jeff

[charles Tauber]

Originally Posted by jeff crisp

The second thread is what you'll need to know to repair it. Post number 13 from Charles Tauber gives you a simple but effective way of avoiding the need for special clamps.

It describes a process for gluing a pin bridge with string holes through the bridge and top. It won't work for non-pin bridges, including Lowdens and classical guitars. You'll still need at least one - preferably two - long-throat clamps to reach the bridge, even if using the cauls and wedges.

There need to be clean, close-fitting surfaces on the bottom of the bridge and the top. That requires removing the old glue on both surfaces - as well as any finish that was under the bridge. If you are not experienced, it can be difficult to do so while ending up with close-fitting surfaces.

[Ned Milburn]

As Charles states, two clamps can be used to glue a classical bridge, but I prefer to use 3. One for each wing, and one for the tie-block central portion.

Also, a custom made gluing "caul" must be used with slots for each fan brace and bridge plate (or bridge bar) as required. Mine has slots for both a 5 brace pattern and a 7 brace patter. Here is a link to a photo. (Let me know if you can't view it and I'll email it to you.)

https://www.facebook.com/photo.php?f...type=1&theater

[redir]

That is a very interesting way to glue down a pinned bridge. I too use 3/16th inch bolts through the outside holes but then I use two clamps for the wings.

For classical guitar I use 3 clamps.

One thing you will have to be careful of is the bridge 'swimming' on the top as you start to apply clamping pressure. You can help prevent that by building up masking tape applied perfectly to the out line of the bridge shape. You are building a sort of trap to hold the bridge in place. It would take something like 4-5 layers of tape on all edges.

[D. Shelton]

Well, that shows how long it's been since I looked at a classical bridge . I thought I'd have smooth sailing once I got the Lowden-bridge picture out of my head

Still, I'll seriously consider doing this myself . I might have some spare clampy things hanging around that could be ... lengthened to make the necessary reach .

[Alan Carruth]

Different people use slightly different arrangements of bracing, and it's important to get the caul right. The easiest way I know to do that is to tape a piece of paper to the outside of the top, and use a couple of small rare-earth magnets to outline the brace positions. Just stick them together through the top, slide the inside one around until you bump into something, and mark it on the paper. I do this more than I would like: I'm always altering the brace layouts to account for differences in the wood, and generally forget to make the caul before I've glued the top and back to the rim. Don't forget to make the caul domed if the top or bridge bottom are (some Classical makers use a domed bridge to pull up a flat top...)

Most classical makers drill a couple of small holes in the saddle slot and pin the bridge in place to avoid it sliding around. Make sure you don't drill into the fan braces (another use for that paper pattern). Round toothpicks are Traditional, although Q-tip sticks are good too.

One maker I knew told about taking in one of his guitars in trade on a new one after it had been out for several years. It was not bad, but the sound was always a bit disappointing. When he looked inside to check that the braces were OK, he saw that the plywood caul was still taped to the top. Removing it did a world of good for the sound. I would never....

[D. Shelton]

Thanks for the tips, everyone !

[Ned Milburn]

Originally Posted by Alan Carruth

One maker I knew told about taking in one of his guitars in trade on a new one after it had been out for several years. It was not bad, but the sound was always a bit disappointing. When he looked inside to check that the braces were OK, he saw that the plywood caul was still taped to the top. Removing it did a world of good for the sound. I would never....

This story is rich! Thanks for sharing it!

[redir]

Originally Posted by Alan Carruth

One maker I knew told about taking in one of his guitars in trade on a new one after it had been out for several years. It was not bad, but the sound was always a bit disappointing. When he looked inside to check that the braces were OK, he saw that the plywood caul was still taped to the top. Removing it did a world of good for the sound. I would never....

Hahaha I could definitely see that happening.

[jeff crisp]

If you find you don't have clamps with a deep enough throat you can still use the method that Charle's uses on his steel string guitars. As mentioned you will need to stop the bridge from slipping when pressure is applied. If using the pin method to avoid this (in the saddle slot) you can substitute thin bolts (try a model shop) for the pins. Though without pins I would probably back the bolts up with a masking tape well due to the thread on a bolt not be as good a stopping point as a pin.

Simple clamps can also be cut from plywood using wedges to apply pressure at the jaws. What ever method you use do a dry run first.

[John Arnold]

If using the pin method to avoid this (in the saddle slot) you can substitute thin bolts (try a model shop) for the pins.

I use two brads and pull them out afterwards. A little soap or candle wax on the brads keeps the glue from sticking to them.
Another method for making a caul pattern is to put tracing paper on the top, and a strong light inside the guitar. Kill the room lights. If the top is spruce, the light should shine through enough to see the shadows where the fan braces are.

[jeff crisp]

I'd normally use brads or drill bits for pins myself. However depending on the width of the saddle slot and the availability of thin bolts, Charles method for steel string bridge clamping can be an option if you don't have deep throat clamps.

[Rodger Knox]

Since this is a classical with lower string tension, you can probably use Hot Hide Glue and do what is called a "rub joint".
The strength of a glue joint gennerally depends on the fit of the joint. To do a rub joint, the fit needs to be nearly perfect. HHG grabs and sets quickly, so you don't need to clamp it. Warm up the pieces a little with a hair dryer, cover the bottom of the bridge with HHG, put it in place and slide it around a bit to work it down tight. Be sure you've got it in the right spot when you stop moving it, and hold it down for a minute or two.
This_may_work with Titebond, but it doesn't grab and set as quickly as HHG.