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I have been using a soundhole patch of spruce.  I notice that their is some flex in the sounboard in the vicinity of the sound hole.  Should I use bracing instead on each side of the soundhole.  I am not sure if the flexing is actually good for sound generation or should it be more rigid?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

When do you notice the flexing?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

If I take the top in both hands - one hand at the top end and one on the bottom and bend the sound board, it flexes most in the area of the soundhole and patch.  I think this is to be expected, so I was thinking that the soundhole area would be more rigid with soundhole braces rather than a 1/8" thick soundhole patch.

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

It would be. Stiffness is all about the height of the support or brace. Adding those braces would add height.
Are you following a proven plan, or is this your design?
If is is a proven plan, I wouldn't worry about it.
Flex isn't a bad thing. If the top is too stiff, all you'll get is highs with very long sustain. You want the top to move some.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Its a proven plan from Hanalima.

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

If you are following a proven plan and you are new to building, I suggest that you follow the plan and write down you observations so you can reference them in the future.
Are you following the plan?

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

I'm assuming from what you're saying that this is a classical guitar? A steel string would normally have X bracing running up the top on either side of the hole, and that would stiffen it up. On a classical the only thing between the shoulder and waist braces is whatever bracing you have around the hole. As has been pointed out, a low patch doesn't add much stiffness, but then, you don't need much of that sort of stiffness in that area since the down forces of the neck and bridge are pretty well taken up by the shoulder and waist braces.

Many people do worry about the edges of the soundhole 'flapping' at high frequencies as the top vibrates, and somehow effecting the tone. It would be interesting to see if some sort of study could be mounted to look for this; I'm pretty skeptical myself, but you never know. I think there are more important fish to fry.

Its a tenor uke.

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

Does it have fan or X bracing: that's the opperative factor.

It has fan bracing.  This uke also has a deeper body than most:  3" at highest and 2 3/4" at tail and head.  I asked Hanalima why their plan is deeper than most and they referred me to http://hyperphysics.phy-astr.gsu.edu/hbase/waves/cavity.html
This site has a formula which shows the relationship among body depth, sound hole diameter and neck length.
They stated that ukes tend not to have good low tone so the deeper body compensates for that.
I am curious what goes into a design and like to fiddle with parameters, but I don't want to reinvent the wheel if a plan has been well thought out. 

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

Likeke,

I am interested in your progress and finished instrument as I have bought a tenor kit from Hanalima and so far have just studied their manual which is great for a new guy like me.

Aloha,

ckp 

CKP, you can see my first Hanalima uke at likekestrings.com and click on Likeke journal.  I ordered Koa from hanalima and am part way through my second uke. Aloha

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA