Thread: Bridge plate placement

Hi Dom, this could be one of things that there is no definite answer too and you end up favouring one way or another after having a few goes at it...but heres what I reckon.
I generally avoid leaving small gaps between struts and other soundboard components, like the bridge plate. The reason being that over time these gaps can allow small distortions in the soundboard that show up as unsightly lines or kinks on the top. ( assuming its a gloss finish, a flat finish would not have the same problem)
Its possible maybe that the book you're using advises leaving a 1mm gap in order to avoid very narrow spaces being created that might cause a buzz noise. If thats the case, I reckon a better way to avoid the risk of buzzing is to chamfer the edges of the pieces where they touch. So in the case of the bridge plate, butt it right up to the braces, and then chamfer the edges of the bridge plate right down to the soundboard. That way the soundboard should still be supported right up the the brace without the risk of the two pieces rubbing against each other and buzzing. Hope that makes sence!
jack

Yup, butt it up against the X brace.

Personal choice I guess but anytime I have two braces butting against each other I drop in some hot stuff CA glue just to ensure there's no chance of buzzing. I do the same between sides of bridge plate and abutting braces.

Jack, I like the idea of not butting a square edge up against the X which I think would have some impact on the way the area responds. And I like your idea baout chamfering the edge to help against long term changes in the top. I have only made a few guitars and at this stage am just happy to finish them but I also hope they will be around for while so things like protecting the top are good tips.
Here are a few pics of my latest. It is a sitka top dred with nice curly narra B&S with 3 piece back. It has a rosewood strip between each piece and you might be able to see that I have zig zagged the curl. The rosette is walnut with blue and green and black and white purfling. I am thinking of going with black trim (ebony) as the wood is quite golden and I recon it would look cool. The last shot is of the guts of a guitar my partner Julie is making with a bit of my help.
Dom

Love that rosette Dom, very simple and clean, a great look.
Julie's guitar looks pretty speccy too.

Thanks Andrew, I had 4 tops to put rosettes in, a few walnut and Koa rings from LMI and some coloured strips and a few beers and went at it.

Here are a few more pics of what I ended up with. Everything looks dusty and gluey in pics and will look better once it has a finish on it. I'll post more pics as I go.

The last one is a finished OM that is ready to have its bridge fitted and strung up. But as you can see I fighting on a number of fronts at the moment.
Cheers
Dom

Looks great Dom, good to see some intersting designs, and I like the zig zag back!

Looking good Dom.

The brace running along the back of the bridge plate is an interesting modification. Ive seen it used by a few of the guys on the OLF forum.

Cheers Martin

Thanks guys, The OLF'ers call it a 'magic tone enhancing super bar or something impressively American. In Australia we are happy to call it a brace running along the back of the bridge. I saw it explained in one of the Big Red Books.
I suppose its use is to tie one leg of the X to the upper tone bar and it would keep them stiff across the grain and help prevent that area pinching in under tension. A bit like the triangle bracing on some guitars. And as I mentioned above, the plans I am using suggests not to butt the bridge plate up against the X so this would help across this area.
Dom

Hi Dom and Martin, I'm a convert to the triangle kind of bracing. I started using it on the bouzoukis coz its good to keep a high tension soundboard flat. I've got to like it on guitars though, it seems to be a reasonable way to bring up the bass volume without loosing volume in the treble, and controls the bark in the mids which I like
Jack

Interesting bracing on the lower bout Jack.

Jack, do you think that having a more symmetrical bracing pattern like yours makes it easier to control the sound? I read as much as I can find about this stuff and it seems that one of the benefits of lattice bracing it just that, and you get balanced defined notes across the range. It makes sense. After all, you really want the whole sound board to respond as one and in structural terms you don’t want weaker areas next to stronger areas.

But maybe it is the asymmetry that give guitars their flavor.
Dom

It does for me Dom, but I think its a very personal thing. I don't think its supierior to any other design except that I really like the sound it gives and it suits me.
I think I agree with the general idea that it's not so important which design to use, its more important to pick one and stick with it for a while and get a feel for it.
As I said I started using the strut flat behind the bridge plate for bouzoukis and 12 string guitars as it seemed an effective solution to keeping the back of the bridge down on high tension instruments.
I also reached a point where I could look back over quite a few guitars that I'd made, to try and figure out if the ones I liked and the ones I didn't like had any things in common. I was then able to notice that of the guitars I didn't like the sound of, most had struts, including the X brace, that were at an angle closer to in line with the grain of the top. Conversly, the guitars that I did like the sound of the X braces and the other braces were flatter, meaning closer toward perpendicular to the grain of the top. So thats what led me in this direction. I never specificly went for a symetrical design it just kind of works out that way. I've tried breaking up the symetry a bit but havn't noticed any diference in the sound. It doesn't seem to matter exactly where the struts go.
Thats just me though, and I'm sure you've discovered already that two people making the same thing get different results!
Jack