adding a glued bridge to a flat top

[stephen jeffery]

Hi i'm new so beware of naievity and poor spelling. I have an old worco parlor i would like to add a bridge to to replace the floater for intonation purposes and to possibly lower the action. the belly is fractionally sunk. I thought of a spanish type that wouldn't need drilling. what's involved please?

steve

perhaps the following photos help

[stephen jeffery]

[Ron Frazier]

I don't know if those old parlor guitars are worth doing that . If it is yours go for it. I some times bore 2 holes one on each side of the tail piece and screw it to the top. then you can shave the bridge down to lower the action. It doesn't seem to heart the sound.

Ron

[stephen jeffery]

Hi Ron. Yes it is mine. screwing to the top would increase the downward pressure. And then I could shave the bridge a tad. great idea. I have also ordered a spanish bridge and a bone saddle from stew-mac. I intend to pass the strings through the back holes of the bridge from the tail piece to create the pressure and then glue the bridge in place if i'm satisfied. I might just try your suggestion in the meantime. takes a while to get from stew-mac to Greece

steve

[Ned Knepp]

I would guess the guitar is ladder braced. You might want to see if there are any loose braces inside or any reinforcement where the bridge will be glued down. You have to consider that shifting from a tail piece to a glued bridge changes the forces on the guitar face radically. It may not last for long.

Ned

[stephen jeffery]

do you mean it might destroy the face? Is it better to place the bridge over a brace?

[Tim Mace]

Send me the guitar and find one w/a bridge you like w/a glued on bridge!I like tail.

[stephen jeffery]

i sense tongue in cheek over the tail

[Ned Knepp]

The point that I was making is that the guitar was built to use the tailpiece to take up the lifting forces the strings exert on the body and transfer them to the base and sides of the instrument . The guitar bracing is probably lighter because of this. The bridge handles down forces but no lifting forces. Once the tailpiece is taken out of the mix, ALL of the pressures are exerted on the bridge and top, which creates rotational forces on the bridge, lifting the back while depressing the front. Without some reinforcement, the result is often a hump in the top below the bridge and a dip in the top above the bridge.

You can't just "place the bridge over a brace" unless the brace happens to be in the position that the bridge needs to maintain correct intonation. In other word, you don't really have much choice over the saddle placement. That position is determined by the scale length and proper compensation to play in tune. If you look at some examples of bracing for guitars, You will find that most if not all are designed to reinforce and support the bridge in some way. Even ukulele's, with their small width and light string load usually have a bridge plate on the inside under the bridge position. I think it's very possible that your guitar has something like this too. The question is; can it support the sort of twisting stress a fixed bridge will exert on the face?

I guess that this all boils down to the idea that a the bridge type that a guitar is designed for is usually related to the bracing used for the top. A classical guitar is braced in a much different way than most of these parlors are braced so adding that style of bridge probably won't make it sound like a classical guitar but it will change the focus of the string tension forces. That doesn't mean that it can't be changed but you should consider what sort of bracing you are working with and the possibility that you may need to make some modification to that when you make the bridge change.

Personally, I've never liked the use of tail pieces on flat top guitars BUT there are people (Tim, for one) that like them very much. There are some other threads here that also address this question and the idea that it might be better to purchase another guitar that is more to your liking rather than making extensive modification to a guitar that someone else may like as it is. I have run into a few people that made these sorts of mods only to find that the result isn't what they thought it would be and found that it's not so easy to go back.

If the issue is that the face is sinking, you might want to address that first anyway ( the bracing again) then decide. ( I think this may actually become a bigger issue if you switch to a fixed bridge without making this repair first. ) Once the face is restored to it's original position, you may find that you like the guitar better. A little bit of sinkage here can effect the sound quite a bit because you loose string pressure on the bridge and impart less energy to the top.

You mentioned intonation which should be easily fixed with a sliding bridge. Just reposition it to the correct location. Once you find it, you can always make some small pencil marks on two of the corners so you can easily relocate that point as needed.

My disclaimer: I am not an expert or even "in the business". I do this sort of thing as a hobby. It is possible that others here, with more expertise and experience will come along and show that my thoughts and opinions are bunk. If I come across as condescending, boring you with things you already know, I apologize. In the end, of course, it's your guitar and you can do what you want with it.

Ned

[stephen jeffery]

i was referring (with humor i hope) to Tim Mace, Ned. I really appreciate your - anyone's - advice.

[Tim Mace]

I reluctantly add the word "piece"to my comment.

[stephen jeffery]

Have just checked inside the guitar and there is no brace across the area where the bridge can sit - only an extra piece of wood glued on. there is a brace at the back and one just before the soundhole. I'm at a loss as to how to continue. What would you recommend as a simple answer?

[Ron Frazier]

The top will distort with a glued bridge. It would fix the problem with that by using a bridge doctor. I understand that with a bridge doctor you would not need bracing but bracing would keep the top from destroying it self.

Ron