Tenor Bracing dimensions for an experimental model

mayrluthier

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Hi!

I'm rather new to the trade, building a Uke for the first time, after having built a couple of guitars.
I'm currently working on a tenor build with a large body (baritone-like).

Tenor scale length, low-G tuning (a wound guitar 4th string will be used), cedar top, dark walnut back & sides. Di Mauro chorus-style F-holes. A beaut.
1702.jpg

I recently finished the form for this build.
Body is 13" long, waist is a tad over 6" wide, lower bout goes around 10" wide.

I'm currently thinking of 1/2" tall and 1/4" wide for the braces to start with, plus 1/4" (tall & wide) for 3 struts in a fan array on the lower bout.

In your experience, and considering a 0.12"-thick cedar top, would these dimensions be too weak for the additional low-G force?
 
Are you building the top flat or carved arch? The rest depends on the neck angle to the body, the height of the bridge, the type of strings used, and the string downward pressure on the top. Too many unknown variables to say which strut size is needed.
 
I think it might be overbuilt but then again I do not have the wood in front of me. As an archtop you only have the downward pressure of the strings to contend with while a fixed bridge is battling the string tension.
 
Hi! In your experience, and considering a 0.12"-thick cedar top, would these dimensions be too weak for the additional low-G force?

I tend to agree with Printer2 that the dimensions seem to be a tad overbuilt. 0.12 (3.2mm) seems a tad thick for a top to my thinking... Remember that the wound low-G is tuned an octave lower than an unwound G string and does not exert undue force on your bridge/top although I do not have the lbs per square inch forces differences off the top of my head, but it certainly isn't excessive.
 
You're all right guys, I missed some parameters that deserve more attention.

I'm thinking of a flat-top build (perhaps *very mildly* radiused), flat neck-body angle (0°), D'Addario tenor strings for the first 3 strings, 4th string is a low-G so a wound guitar D string will be used.
I'm considering Pro-Arté classic student, about 15 lbs of maximum tension, should be about 13 lbs tuned down to G.

String tension would be:
- 1st string: 13.3 lbs
- 2nd string: 10.6 lbs
- 3rd string: 11.9 lbs
- 4th string: 13 lbs
- Total string tension: 48.8 lbs

Bridge height (to saddle top edge) should be about 1/2" (12.7 - 13 mm, considering mid-low action).

The top is some seasoned red cedar that rings nicely to tapping, but may not be too structurally rigid when compared to spruce or Koa; that's why I've planed it down to 0.12", just to make sure before thicknessing it down a notch. Could dare to go down to 0.11" - 0.10" with some careful sanding.

Since my other current build is a heat-bent-top Selmer guitar, I also thought about treating the top with the same 'pliage' bend, but I imagine it could sacrifice sustain for structure.
What do you think?
 
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Sounds like a plan even though I think 0.1 is still probably too thick... Also radiusing *very mildly* brings up the same issues as radiusing no matter how mild it is. These issues can be overcome of coarse as luthiers do it all the time (I do not). It just adds an extra layer of complexity. Since you sound comfortable with these issues, go for it... Good luck and send pictures!
 
Are 1/2" braces too tall, or perhaps 10mm could do?

1/2" tall ok for transverse, but fans about half that. I would give you my dimensions but I'm not near the shop now. I will attach pictures of a tenor braced which might give you some idea on relative size. But this is just my system and others may feel differently. It depends on the wood and how it feels and sounds. Good luck.

DSCN8051.jpg DSCN7955.jpg
 
Thanks @sequoia!

I’ll post pictures of the build in a few days, I’m currently ripping some material for a stiff laminated neck plus a Selmer-style headstock joint, because it’s a waste of time but a work of art in itself and structurally stiff.
These figures are all I needed, the rest I can tap-tune without too much trouble.
 
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