SKBarbour wrote:
Thanks for the answer Todd. Do you think bracing with adi, which from what I understand is stiffer, would help? Along with going a little heavy on the x brace and bridge plate?
Brian, you didn't indicate but I assume these Breedloves were figured redwood tops?
Brian, you didn't indicate but I assume these Breedloves were figured redwood tops?
Adi will indeed generally be stiffer at a given size, but you can also just leave the braces a little taller to get the same stiffness increase with sitka or lutz or whatever.
I'd also go on the large side for glue area, like 5/16" X brace, since you're gluing to a lot of endgrain.
I suspect dealing with the low stiffness would be somewhat similar to my quest to make rosewood topped guitars... except instead of going super thin to get the weight to just a little above normal and ending up with lower stiffness that way, you go thicker and end up with the weight a little above normal but still lower stiffness due to the runout
Here are the tricks I've developed so far to deal with it:
1. Use more braces. 3 fingers, for example, so the unsupported spans of top are smaller and thus not so squishy.
2. Notch braces into eachother, so you can control the stiffness at the junctions rather than having it be purely defined by the stiffness of the plate.
3. Support behind the bridge. Either make the bridge plate much larger, or use a pattern like lattice or fan braces in the lower quadrant. I'm currently liking 5 fans.
4. Strong upper bout structure is a must. I like the L shaped headblock style, glued to the upper transverse brace, not just coming close to it. A-frame should be fine too, if sufficiently tall and notched into the headblock and UTB (again, don't leave high flexibility points at brace junctions).
Here's the latest incarnation, although used with super stiff straight grained redwood on my harp guitar:
Attachment:
Bracing8.jpg
It's about .100" thick and still quite stiff by itself, but with 300lbs of tension on it so relative to that it's pretty thin. I probably could have gotten away with 2 fingers since it's stiff enough that it wouldn't be squishy between them, but I think 3 taller fans would show more localized distortion around them than these 5 shorter fans, and the 3 fingers make it all nice and even. I've had strings on it since Friday and it's holding up like a champ, and sounds pretty darn good. I'll be using this exact pattern on my next rosewood top (adjusting for differences in body shape and bridge position, of course), and would most likely do the same for curly redwood.