View Full Version : Sound Board Bracing

Moore Bettah Ukuleles
03-07-2011, 05:35 AM
Somewhere I recently read that "Most 'ukuleles are not made with fan bracing because it would make the soundboard too rigid." This is news to me but I tend to be a bit of a traditionalist when it comes to instrument construction. I was under the impression that most ukuleles were fan braced. So it got me to thinking and I'm just curious how you brace. I don't mean what you've tried; many of us have experimented with different bracing designs, but what you commonly use and what you are successful with. Personally, on my tenors I'll use between three and five fan braces depending upon what I'm trying to achieve. My sound boards tend to be pretty light and my bracing is extremely low in profile. What do you do?

Pete Howlett
03-07-2011, 06:21 AM
2 fan braces for concerts and 3 for tenors. All 1/4" thick by 5/16" high tapered to nothing from the transverse brace... 2mm bridge plate. Top is tapered from bridge area... Not scientific, probably totally wrong but folks comment on the volume and tone from my instruments.

Steve vanPelt
03-07-2011, 06:26 AM
Thanks Chuck, for starting a great thread. Would you mind sharing what you're going for between the 3 and 5 fan top?

Now, I don't have hundreds under my belt like some folks here, and the experimenting is likely to continue. The last half dozen or so have all been pretty close to this pic.


This is the top on 'Grandma's uke. We took it to the Sacramento kanikapila last week and of the three we brought, this one had the most popular sound and tone. The braces are pretty light and I still took them down a bit from here.

One thing I did a little different, inspired by Allen's lattice braced ukes, is add a little strip of CF TOW across the fans at the waist brace. The idea being to strengthen that connection so the light top doesn't fold up over time. This year i'll be giving a lot of attention to the way the fans couple, or don't at that point.

I just got back in the shop last week and am building 3 super sopranos as a part of my own little ukes for kids program. They going to the neighbor's daughters for their birthdays in a couple weeks. The tops on these have only 2 transverse braces and a bridge patch.


03-07-2011, 07:23 AM
Like Pete, I have two for concerts and three for tenors. Mine are about 1/4" x 1/4".


03-07-2011, 09:21 AM
I was using 2 on concerts but tried just going with a bridge patch on a batch of NSW Blackwood (Acacia orites) ukes we did in a class. 12 ukes in all. Tops were 1.8 mm thick and bridge patch at 2 mm thick. They all sounded great with lots of volume and sustain. Did the same with some Tasmanian Blackwood (acacia melanoxylon)in a class of 6. They also sound great. So I'm going to try this on some spec ukes of my own.

Tenors get 3 fan braces. 4 mm wide and 8 mm tall. They are tapered out to nothing from saddle position to each end. I build with so many different species of top that giving dimensions on them is a bit pointless. Western Red Cedar is a lot thicker than Red Spruce or Blackwood. I go by feel when I'm thicknessing them.

I've always used a 2 mm thick bridge patch, but just got in some CF as David Hurd uses (used) and am going to give it a go. I'm hoping that it's less susceptible to humidity swings in a conventionally braced instrument much like my lattice braced ones are.

03-07-2011, 11:01 AM
On the dozen sopranos I've made I've just used transverse braces per the Scott Antes drawing. On my two tenors, I've used three fan braces. I've recently been using a H bracing system on my Octave Mandolins with great success, so I am going to give it a try on a tenor that I'm working on now. I should have it done by the World Congress uke festival in Nashville, so maybe a couple people can give me their impressions of it there.

dave g
03-07-2011, 01:49 PM
I do a 1/16" x 1" x 4" bridge patch, then a single 3/16" x 3/8" longitudinal brace from the end block, over the bridge patch, to just a bit short of the sound hole. The end near the sound hole is cut at an angle and let into a matching notch in a cross brace running just south of the sound hole - the result is that the cross brace holds down the end of the long brace. The long brace also acts as a batten on the glue joint in the two-piece top.

03-07-2011, 04:49 PM
2 fan braces on my concert and 3 on my tenor. I was looking at my Pono concert and it has no fan brace at all . Just cross braces one just above the sound hole and one below and a bridge patch . It seems to be fairing pretty well I have had it for 5 years and the top still looks really good

03-07-2011, 09:50 PM
5 fan braces, peaked at the edges of the bridgepatch (same dimensions as Dave G, okay, its 3/4" wide), tapered to nothing. 1/8" by 1/4" high, very lightly braced.

Must be a Hawai`i thing with the 5 fan - if I'm not mistaken, two other guys on your island use them as well. My kumu used 5, then went to 3 when he teaches class (but keeps 5 on his own builds). I know a guy who had a request to install 5 braces on the top (by the player) - comparatively speaking, it changed the sound volume of the instrument (which is known for loudness and projection) a few notches down on the volume meter, but brought in so many other complex nuances that it was worth it. Of course, not every instrument gets this done. And if the player needs it louder, he just turns up the volume control. . .

I think most of the builders I know use 3 fans. I have no reason to change.

03-08-2011, 05:13 AM
Sopranos - bog standard two transverse braces and a bridge patch.
Concerts - As above but with a slightly thicker bridge patch and slightly taller transverse braces. My concerts are an unusual shape and are relatively narrow across the body at the point where the bridge sits. (Same width as a soprano at this point).
Tenors - I'll let you know when I've built one I'm happy with ;)

03-09-2011, 05:15 AM
Question for Pete: What changes do you make, if any, for one piece soundboards vs bookmatched structurally?

Pete Howlett
03-09-2011, 06:43 AM
None - sorry but I have no science or calculations. Disappointing I know but there it is...

03-09-2011, 06:51 AM
Sopranos- no fans
Concerts- 2 fans
Tenors -2 fans
Baritones and Tiples - 3 fans

My fans are a little beefier than the rest of yours and I usually end up with tops that are 1.6-1.9 mm thick, depending on the wood.

I also have messed with the angle of the cross brace beneath the sound hole to make a asymmetrical resonance area. No results that I could feel or hear!