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FVGuitars
10-24-2013, 05:45 AM
hello to all,
I would submit a question to you.
I'm building a new ukulele. After gluing the braces in the standard way I saw that the table (Italian spurce Val di Fiemme, thickness 1.8), was taking a convex shape, accentuated in the zone on either side of the bridge.
then I added a brace, as you can see from the picture, so as to have a slight curvature, in my opinion always provides more sound.
Now, hitting the top in the bridge area I realize that it has good vibrations and good sound. it's more rigid.
Hitting the sides of the table, where the brace is touching the top, the vibrations are reduced.
60144
This was a instinctive modification and I have no idea what will be the result.
What do you think?

Thanks so much!
p.s. sorry for my english :o

ksquine
10-24-2013, 07:36 AM
I'm not sure what problem you were seeing. You mean the top had sunk on each side of the bridge? Or was it pulling up on each side of the bridge?
The new brace doesn't look good to my eye. Its too heavy and it runs in the wrong direction to prevent the pulling up or sinking in. I also don't like the arched areas and short glue segments....just more weight without adding stiffness from the glue joint
But...if it solves your problem and you like the tone of the finished instrument then its a success.

Moore Bettah Ukuleles
10-24-2013, 07:56 AM
It looks pretty but I don't see the point. It seems like a classic problem of over thinking the situation. If you are worried about maintaining the radius of the top, then proper sanding of the top of the ribs will give you the arch you want, even without any bracing. You walk a very fine line in bracing uke tops. Often times the less you do will provide the best results. I applaud your creative thinking though.

Beau Hannam Ukuleles
10-24-2013, 09:11 AM
What you have done is basically what is known is classical guitar making as a Bouchet bar-

https://sites.google.com/site/classicalguitardesign/therobertbouchetbar

I braced a few ukes with the lower transverse bar having those "bridges" with the two outer fan braces running under them full length to become sound hole reinforcements.

I found the top kinked slightly where the 'bridges' were. As Chuck said, it looks pretty but it isn't needed. I dont think it effects sound (better/worse) but it is a great way to get nice pics (hey, ive done it).

Personally, I hate pics of braces that resemble LA freeway overpasses (i may have the wrong city)

Brace bridges actually ADD weight. Think about it- More material is needed to get from A-B using a curve then a straight line. PLUS the material running directly under the bridge which would otherwise be butted up against the transverse brace (perhaps 4mm x 4mm x 4mm)- Yes, i'm taking a very small amount but it debunks the weight argument.

Weight is a good thing if it is in the right place and orientation.

http://www.scribd.com/doc/38533521/Making-Master-Guitars

PS- say 'top', not 'table', nor 'deck' nor any other word which is not 'top'.
Also, never says 'ribs' when you mean 'sides' or I will scream ;)

Moore Bettah Ukuleles
10-24-2013, 09:18 AM
Yes, we've all been through periods where we've done things like that. I've built enough of these things now to know my best result will come from coaxing the best sound I can out of the fewest pieces. From what I've observed in the ukulele world, simple almost always means better when it comes to sound. But I still like to see people trying new things, if for no other reason than to make shop life a little more interesting. (When you've braced a thousand plates you'll know what I mean.)

Beau Hannam Ukuleles
10-24-2013, 09:37 AM
(When you've braced a thousand plates you'll know what I mean.)

'Plates'!
AAARRRRRGGGGGHHHHHHHHH .

:stop: :biglaugh:

hawaii 50
10-24-2013, 10:13 AM
if I were buiding a Ukulele I would for sure use Chuck's advice too...
I have Moore Bettah and it sounds so good...I am sure the bracing and domed top has a lot to do with it....

yes the brace looks nice but sound is the most important...IMO

BlackBearUkes
10-24-2013, 04:07 PM
hello to all,
I would submit a question to you.
I'm building a new ukulele. After gluing the braces in the standard way I saw that the table (Italian spurce Val di Fiemme, thickness 1.8), was taking a convex shape, accentuated in the zone on either side of the bridge.
then I added a brace, as you can see from the picture, so as to have a slight curvature, in my opinion always provides more sound.
Now, hitting the top in the bridge area I realize that it has good vibrations and good sound. it's more rigid.
Hitting the sides of the table, where the brace is touching the top, the vibrations are reduced.
60144
This was a instinctive modification and I have no idea what will be the result.
What do you think?

Thanks so much!
p.s. sorry for my english :o

I don't think that brace is going to work at all the way you want it to, as others have suggested. Its more voodoo than science. If you simply want to stiffen the center of the plate near the bridge patch, you could add some addition spruce patches. Glue the spruce with the same grain direction and about as thick as your top in that area. You will add very little weight but double the strength.

Chih-Wei Liu
10-24-2013, 09:40 PM
I don't think this transverse bar will hurt the sound much. It might still sound really good at least to some people.

FVGuitars
10-25-2013, 04:51 AM
thank to all for the answers.

Your advices are very helpful for me. Even for the terms, sorry for "table" :D
Thanks for the links! are very interesting!

to explain better I show you the problem I have found
60169

in the drawing you can see why I wanted to insert the new brace.

I realized that if I want to keep the horizontal brace I'll have to as much as possible lighten it.

Thanks again
Francesco

aaronckeim
10-25-2013, 05:16 AM
Francesco- Keep in mind that when you glue the plate on the ribs, it will take whatever shape you prepared the ribs to present and whatever shape your caul is. Our tops are flat, but occasionally I have a plate that is a little warpy at this stage. After prepping the ribs and linings flat and using a flat caul, it always goes flat and behaves after that. I am not talking about a major warp, if I had a plate that was way off I would throw it out and try again.

I agree with Duane that some spruce patches to increase mass in this area would do the same job.

I agree with Chuck that it will take a lifetime to master the slight variations in even a simple design. But that is the plan, right!!!??!

Moore Bettah Ukuleles
10-25-2013, 06:51 AM
As Aaron mentioned, the radius of your top is largely determined by the shape of your bent and assembled ribs. That reverse radius we see in your drawing can easily be corrected with the proper sanding of your sides.
If your tops are moving a lot after gluing the braces on I would look at inconsistencies in your building environment.

ksquine
10-25-2013, 07:43 AM
I see what you mean now FV
I think your warping is caused by how you clamp the braces or maybe even some swelling from the water in the glue. I'd suggest what Aaron said....clamping in a radiused dish or use a radiused clamping caul on the top to set the shape you want while gluing the bridge patch and braces.

David Newton
10-25-2013, 07:49 AM
What is going on here, it isn't even close to the 1st of April?

FVGuitars
10-26-2013, 06:55 AM
As Aaron mentioned, the radius of your top is largely determined by the shape of your bent and assembled ribs. That reverse radius we see in your drawing can easily be corrected with the proper sanding of your sides.
If your tops are moving a lot after gluing the braces on I would look at inconsistencies in your building environment.

Thanks, I understood.

FVGuitars
10-26-2013, 06:58 AM
What is going on here, it isn't even close to the 1st of April?

"have courage!"
courage is also demonstrated by expressing my own shortcomings :rolleyes:

David Newton
10-26-2013, 08:27 AM
Francesco, no insult intended, though I suppose it did come off that way.
I once did a bracing job like yours as a April fools trick. I was remembering it.

Unusual bracing is often an experiment. I am a proponent of learning first what has worked reliably in the past, before thinking that I can make progress with something new.

Yes, "have courage" to move, build, make something, even if unsure of your way forward. Your reply tells me that you are in the right mind. Friend.

FVGuitars
10-26-2013, 12:56 PM
Francesco, no insult intended, though I suppose it did come off that way.
I once did a bracing job like yours as a April fools trick. I was remembering it.

Unusual bracing is often an experiment. I am a proponent of learning first what has worked reliably in the past, before thinking that I can make progress with something new.

Yes, "have courage" to move, build, make something, even if unsure of your way forward. Your reply tells me that you are in the right mind. Friend.

:D
I agree with you.

I can only learn from you.
Friend.

Garry Petrisic
10-27-2013, 05:12 PM
I have been using this style of brace on my ukes since I started building them. I use an A frame brace and a similar cross brace. My ukes do not have a sound hole on the middle of the top. Works well and allows top to move more freely6034860349

Sven
10-28-2013, 12:48 AM
That looks quite cool but how does it move more freely? There's such a small distance between the long bars and the transverse ones, so the difference from a badly fitted lap joint must be minute. If anything, the resulting joint of your braces ought to be stronger since both have their full height intact. Or am I thinking too much like a structural engineer, I do hang out with those too often.

Garry Petrisic
10-28-2013, 09:16 AM
It is strong. the result is that the braces can be adjusted down to get the right frequency happening. The pics of the braces are before adjustment. I have a side port in the lower bout and further tuning is possible through that port with special files I have made to get the final voice of the uke. You are thinking like a structural engineer and that is not a bad thing. You just have to apply the same principles and then reduce the factor of failure mode down to the absolute minimum. A fine line between the instrument caving in and a responsive and clear tone. The difference is also that the ukes I make are not clones of the millions of ukes out there. All have been experimental. I have made some good ones, brilliant ones and some absolute bad ones which I have had to revisit and adjust after full assembly.
Garry