My revised XX back bracing

[Dennis Leahy]

OK, I am going to show this again in more detail with measurements and how I make all of the parts. Since I will be doing it for my bar fret builds, I will put the process in that thread. Should have the details there by Monday night.

G

Thank you, Grant! And, reviewing this again, I see that the final, longer pieces connect with a short double-concave piece. I had mistakenly thought this was all one piece with two different diameter holes connected together. Still, I will watch carefully and take notes. I'm especially keen to see your method for making the sloped entry into the longer braces

Hey, do you sand a radius into the bottom of the longest pieces? No need to answer here... I'll get that detail from your "2 bar fret guitars" thread. Thanks!

[whitespruce]

But, I will answer here just to get it done. Nothing is radiused, since I glue up in a dish mold and everything takes the right shape. Also note that nothing needs to have holes drilled. All quite simple.

G

[whitespruce]

Rather than cluttering up John J.s thread any more than I already have, I will just update this one. And, Steve, this gives you the link.

Here are low angle photos of a couple of guitar backs currently being worked on in the shop, One by Sandy and one by Greg (Greg actually has 2 in process). This should show the fairly even curve of the top of the shaped braces. Still a bit of cleanup left and the brace ends to shape down. To get rid of the "belly" in the center of the laminated braces, all of the "X's" have been hit a tad with the block plane, but more on the outer ones.

Sandy's back

sandybkbr.jpg

This back is TM Peruvian Walnut

Greg's back

gregbkbr.jpg

This is TM Beng. Both have TM mahogany braces.

g

[Steve Kinnaird]

Thank you, Grant! And John too, for the fresh reminder of this clever system.
One question remains (and I failed to read every particular, so I could have easily missed the explanation)-- as you tapered the brace ends toward the linings, did you worry about exposing layers of the lams? Sorta like leaf springs in appearance, but nothing to "hold together" if they take a blow?

I did one "interlaced" bracing scheme, with very thin, narrow strips of spruce glued atop each other. As they moved out toward perimeter, I wanted to carve through the layers (tapering them out) but those exposed layers worried me. This is what I came up with:

image.jpeg

There is a thin veneer glued along the spine of each brace, also overlapping each joint, but running down the tapered ends and covering each exposed layer. Does this make sense?
By the way, this is a Mango-topped, crossover classical. I wanted maximum stiffness (this piece was unbelievably floppy) and minimum weight (this "top" was disturbingly heavy). Bracing system delivered!
Thanks again,
Steve

[whitespruce]

Steve, I understand what you are asking. I have never considered it to be a potential problem any more than a regular brace that tapers to nothing before it gets to the side. My laminated top braces do the same thing. It has never been a problem.

Actually, if you think about it, there are several kinds of glue joints that do the same thing...for example the peghead scarf joint on the back of the peghead when you do not put on a "backstrap" layer. Glue joints should be stronger than the wood if done properly.

g

[Steve Kinnaird]

Yes, in theory I do agree. In practice I enjoy fretting. (Good enough place to use that term.) So, when I do a scarf joint, I cover it top, side (ears) and bottom (backstrap). Probably the strongest part of the guitar, yes?
Anyway, I probably worry needlessly.... Thanks for the reply.

Steve

[whitespruce]

Yes, in theory I do agree. In practice I enjoy fretting. (Good enough place to use that term.) So, when I do a scarf joint, I cover it top, side (ears) and bottom (backstrap). Probably the strongest part of the guitar, yes?
Anyway, I probably worry needlessly.... Thanks for the reply.

Steve

Steve, no hurt in being concerned...keeps us thinking. Overall though,I guess we gotta trust the glue (providing we use it correctly)...it IS all that holds the whole shebang together

g

[Steve Kinnaird]

Steve, no hurt in being concerned...keeps us thinking. Overall though,I guess we gotta trust the glue (providing we use it correctly)...it IS all that holds the whole shebang together

g

Fair enough. Although my Gallagher, like some Gibsons, uses wee bolts to help hold on the bridge. I never could bring myself to go that far. Just glue--and think of all the tension on that joint!

Steve