Yet another bracing issue...

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limehills
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Yet another bracing issue...

Post by limehills » Fri Jan 08, 2021 8:41 pm

Ok so just finished this beast, super stoked with the sound!
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I have nearly perfected all of my bracing weak spots. Nearly... There is still one which I hope to fix on future guitars. It is just between the X brace and the structural brace under the fretboard, as you can see from the markings in the picture below it has dipped in about 0.5mm after about 2 weeks with strings on it,
C3AB6081-FA3A-434D-A865-54F782D54999.jpeg
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should I be worried about this? Or is it survivable. Anyway please let me know what you think!
Laurence.

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kiwigeo
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Re: Yet another bracing issue...

Post by kiwigeo » Fri Jan 08, 2021 8:49 pm

What's bracing the area around the soundhole? Is there a sound hole patch/bracing...or both? A picture of the underside of the soundboard with all bracing would be handy.
Martin

limehills
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Re: Yet another bracing issue...

Post by limehills » Sat Jan 09, 2021 4:17 pm

Here are some photos of the top, it’s Adirondack spruce if that’s helpful.
F087E820-A5AA-4126-AFBE-DA6087C772D4.png
E34B5A9D-6D3B-44DC-A105-D4DB4E25EB54.png
w
Laurence.

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kiwigeo
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Re: Yet another bracing issue...

Post by kiwigeo » Sat Jan 09, 2021 6:15 pm

Upper transverse brace looks robust. I assume there's no sound hole patch and you've just got those two braces either side of same. I generally install both a soundhole patch as well as much higher braces either side of the soundhole. Im not sure if this is the problem though.

How thin is the top?

Is that a patch I see behind the UTB?
Martin

johnparchem
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Re: Yet another bracing issue...

Post by johnparchem » Sun Jan 10, 2021 1:26 am

The bracing looks fine to me. Under tension the neck is going to pull forward a bit. I even allow a millimeter at the saddle when I do calculation for string height from the top at the saddle when setting the neck angle. That normal movement under tension will reflect itself in the top as the neck block rotates a bit. I am curious if the top has a radius? Having a radius on the top will not prevent it but will make it less visible than a flat top. I am not sure how visible it is on your guitar if you are not looking with a straight edge.

blackalex1952
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Re: Yet another bracing issue...

Post by blackalex1952 » Sun Jan 10, 2021 12:46 pm

Check your bridge rotation. 2degrees is ideal. Cap the X join if you haven't. I would be inclined to think about the X braces between the bridge and the soundhole, and if the top is too thin..... do you deflection test? The assembled, braced soundboard is the measurement to take. The calcs are out there or buy the Gore/Gilet books. There may be something in an ANZLF thread re the books that you could fish around for.
-Ross
"Everything I say on the topic is based solely upon inexperience and assumption!"

limehills
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Re: Yet another bracing issue...

Post by limehills » Mon Feb 22, 2021 11:02 am

Hi been a while since I logged on sorry!

No sound hole patch, just those two small braces. And yeah I should've used more robust braces either side of the soundhole. The top is just under 3mm.

yes there is some radius! not sure how much though considering I mostly eyeballed the radius dish... I guess I should expect some movement, no belly no tone right? :)

Ok yes I haven't been capping the X I probably should. I didn't do a deflection test but the guitar hasn't moved much since so I'm reasonably confident that it is structurally sound. Goes to show I shouldn't stress until I have let the guitar settle for a month.

Thanks for the advice!
Laurence.

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