X Bracing planning

[Peter Lynch]

Hi
This is another beginners question , I am building a small acoustic ( slightly larger than 0 size ) I have the specs such as , Length , Upper Bout , Waist , Lower Bout
Scale length etc so have drawn the body shape and am happy with that .
I now have to draw a bracing plan ( x bracing ) and I am wondering if there is a rule of thumb where the bracing ends in the lower bout . For instance does the x bracing finish just beneath the widest part of the lower bout ?
Sorry if this is a dumb question , but I can’t find any reference to brace planning in any of my books or on line

Thanks
Peter Lynch

[johnparchem]

I decide how close I want the X to the sound hole and then I make sure I clip the wings of the bridge. Extending the the lines place the ends of the braces.

[kiwigeo]

As John notes....run cross braces under end of bridge wings.

[Peter Lynch]

Thank you John and Martin , information gratefully received
Peter

[Mark McLean]

Other variables to decide are the angle of the x, and how to place it relative to the sound hole and the bridge. Most larger body guitars like 000 or D have an x angle around 95 to 98 degrees, but a smaller body guitar might want the main x-braces in the lower bout brought a bit closer together - maybe 90 degrees or even a little less. Opening the angle up makes the top less stiff in the longitudinal axis and allows a bit more bridge rotation under string tension. Similarly, forward-shifting the x-brace (moving the x joint closer to the sound hole) does the same, and makes the main centre section of the soundboard more mobile.

You probably don’t want to depart too much from plans of proven models. Take a look at a few available plans for similar size guitars (check the plans section of this forum). Whatever you do - the rule that Martin mentioned is very important. The main x-braces must pass under the bridge area. If you forward shift too far, or open the angle too much, the braces will pass outside the ends of the bridge which will leave the bridge area unsupported and prone to rotation or bulging.

[Peter Lynch]

Thank you Mark
I have a fair few plans here and why I didn’t realise that all the X brace plans pass the lower legs of the braces under the wings of the bridge I don’t know ! Once I looked it was obvious . The angle of the x brace is interesting and I do notice that in the smaller guitar plans the angle reduces . Thanks for pointing me in the right direction Mark
Thank you
Peter Lynch

[kiwigeo]

I have a fair few plans here and why I didn’t realise that all the X brace plans pass the lower legs of the braces under the wings of the bridge I don’t know ! Once I looked it was obvious .

Missing the obvious isn't hard to do....the stuff that you've been doing since you started building but you just haven't bothered to stop and think "why?". I think quite a few of us spend years merrily building and then reach a point where we do start asking "why?". I've reached a point where I find myself going back to basics on a lot of aspects of my builds and looking hard at why things are done a certain way and if they necessarily have to be done that way. I call it maturing as a builder.