Glue for stiffening braces

[donnyb]

Hello and thankyou for reading.

For several months I've been flattening a 6 string body using a combination of strap clamps and humidity. The guitar had serious dips and humps in the bridge area. Neck projection is now good, so I think its ready to glue in a couple of additional stiffening braces to the top.

2 questions that I have are :

What would you recommend as the strongest or most effective glue to use ? As I expect that the top will have a memory set and sooner or later will want to return to its previous condition, unless restrained.

And, should I glue the braces in while applying and keeping for a while some strap clamp flattening pressure to help hold the almost flat original 40' radius of the two extra soundboard braces to the top ?

I usually use Titebond Original for general repairs and a marine grade epoxy resin for something I (or someone else) wouldn't want to take off again.
Thanks in advance for any advice.

[Rudy4]

Originally Posted by donnyb

Hello and thankyou for reading.

For several months I've been flattening a 6 string body using a combination of strap clamps and humidity. The guitar had serious dips and humps in the bridge area. Neck projection is now good, so I think its ready to glue in a couple of additional stiffening braces to the top.

2 questions that I have are :

What would you recommend as the strongest or most effective glue to use ? As I expect that the top will have a memory set and sooner or later will want to return to its previous condition, unless restrained.

And, should I glue the braces in while applying and keeping for a while some strap clamp flattening pressure to help hold the almost flat original 40' radius of the two extra soundboard braces to the top ?

I usually use Titebond Original for general repairs and a marine grade epoxy resin for something I (or someone else) wouldn't want to take off again.
Thanks in advance for any advice.

Did you consider using a Bridge Doctor to avoid all that work?

[ProfChris]

Most builders use hot hide glue or Titebond original. I've used both, both work.

What keeps the top in shape is the brace itself - I shape mine to fit the contour I want for the top (usually a dome peaking at the bridge. The brace is straightened by the spring in the top, so you like some of the shaping - a ladder bridge shaped to rise 1/4 inch in the centre might end up with only 1/8 inch rise.

The most important thing is to get a perfect fit the full length and width of the brace; that produces the strongest joint whatever glue you use.

[JonWint]

Originally Posted by donnyb

...Neck projection is now good, so I think its ready to glue in a couple of additional stiffening braces to the top. ....

If you "flattened" the top why would want to add braces? Do you want to deaden the top and change the sound?

When I do a belly reduction, the procedure restores the top to near-original shape and it's good for another 20 to 50 years.

[printer2]

I need to flatten this top myself.



Hide glue is not suppose to creep.

[donnyb]

Originally Posted by Rudy4

Did you consider using a Bridge Doctor to avoid all that work?

Thanks for the reply Rudy.
I have used bridge doctors with good result for at least flattening and stabilising the top on mid price range guitars. The owners say there's been no effect on the sound or at least noticeablely so, but I have read that others have .

The reason I'm using 2 braces instead is that this ( after top flattening ) is the manufacturer's and professional luither's fix for the issue.

Also the guitar is top shelf and the owner ( a family member) wants to go that way .And wants me to do it .

Im confident I can do it well, but it is a task I've not done before. I have fixed loose braces though and always used Titebond Original for that task.

[donnyb]

Yikes Fred.
Coates Hire have "steam -rollers "and it looks like it needs both !

[Quickstep192]

I’ve used LMI’s yellow instrument glue and it seems that it has a bit more “grab” than regular yellow glue and sets up a little harder.

[donnyb]

Originally Posted by ProfChris

Most builders use hot hide glue or Titebond original. I've used both, both work.

What keeps the top in shape is the brace itself - I shape mine to fit the contour I want for the top (usually a dome peaking at the bridge. The brace is straightened by the spring in the top, so you like some of the shaping - a ladder bridge shaped to rise 1/4 inch in the centre might end up with only 1/8 inch rise.

The most important thing is to get a perfect fit the full length and width of the brace; that produces the strongest joint whatever glue you use.

Thanks Chris. I have shaped the brace to go behind the bridge to the original 40 foot radius of the top. I read that many steam the tops flat. I've not done so as in my experience with steam straightening wood, it doesn't last. Maybe I did it wrong.

[donnyb]

Originally Posted by JonWint

If you "flattened" the top why would want to add braces? Do you want to deaden the top and change the sound?

When I do a belly reduction, the procedure restores the top to near-original shape and it's good for another 20 to 50 years.

Thanks Jon,

What method do you use to flatten a top ?

[donnyb]

Originally Posted by Quickstep192

I’ve used LMI’s yellow instrument glue and it seems that it has a bit more “grab” than regular yellow glue and sets up a little harder.

Ahh, thanks for that Quickstep.
What's the work time with it ? The rear brace will be tricky.

[JonWint]

Originally Posted by donnyb

Thanks Jon,

What method do you use to flatten a top ?

I use the TJ Thompson belly reducer system. This one is a 1927 00-18. It didn't need much reduction but since bridge was off I treated it.

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Or steam it. Worked on an Ovation plywood top.

[IMG][/IMG]

[IMG][/IMG]

[John Arnold]

I would not radius a brace added below the bridge. The torque on the bridge will pull some belly in that area.

[donnyb]

Originally Posted by JonWint

I use the TJ Thompson belly reducer system. This one is a 1927 00-18. It didn't need much reduction but since bridge was off I treated it.

[IMG][/IMG]

Or steam it. Worked on an Ovation plywood top.

[IMG][/IMG]

[IMG][/IMG]

Thankyou for the photos Jon.

So heat used with the belly reducer . I have read these work well.

With the Ovation steaming, does it hold its position well because of the ply construction?

[donnyb]

Originally Posted by John Arnold

I would not radius a brace added below the bridge. The torque on the bridge will pull some belly in that area.

Thankyou John. I tossed and turned about that with the rear brace , thinking "why give the belly area a head start.?"
Glad you settled that one before gluing it.

Im starting the transverse brace in front of the bridge today and can see a benefit in radiusng that one. Would you concur ?

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