Top and Back warping after bracing

dm4026 · #1 02-19-2020, 05:00 AM

Hello everyone

I am just a hobby-builder. Im currently building a 000-Style guitar with cutaway. I was gluing the braces to top and back and had them lying around a few weeks, as I had no time to further work on the guitar.
By now both top and back had warped back and agains the original radius of the braces...
pics: https://ibb.co/3y86h3H
https://ibb.co/B6WBwQV
What did I do wrong? How can I possibly fix that?
I am currently "re-bending" them in a fixture with a lot of pressure on it. Hope that helps...
I would be happy for any advice.

Thank you.

Skarsaune · #2 02-19-2020, 05:04 AM

Check the humidity in your work area.
A swing in humidity can do exactly what you describe.
40-45% RH is what’s usually recommended for guitar work.

charles Tauber · #3 02-19-2020, 05:40 AM

Humidity change.

dm4026 · #4 02-19-2020, 06:54 AM

Thank you so much.
Do you think that I have a chance bending both pieces back with steam and then it can keep the shape?

Neil K Walk · #5 02-19-2020, 07:02 AM

As a fellow hobby builder, humidity has been my biggest bane. This is pretty much the time of year I have to stop building because if you leave your unfinished work out it will curl like this because my furnace is running more. The addition of a whole house humidifier has only made a dent in the dryness but I also made it a point to purchase a hard shell case for my guitar build to live in during these times.

JonWint · #6 02-19-2020, 07:42 AM

Quote:

Originally Posted by dm4026

Thank you so much.
Do you think that I have a chance bending both pieces back with steam and then it can keep the shape?

I once removed bracing and re-attached after humidity stabilization. I don't know of any shortcuts.

redir · #7 02-19-2020, 07:54 AM

I would heed JonWints advice and re-brace it while you can. I made the mistake on my first guitar building it in my dads basement workshop and the guitar had all kinds of problems. You can nip this one in the bud now before it's too late.

Using heat and a spatula you should be able to remove those braces pretty easily. Or you can just plane them off. Then set the top and brace wood in a lower RH environment of 40-45% or even a bit lower for at least a week.

Then rebrace it and you will not have that problem. Even now that I have a controlled shop I like to mount the top and back a day after it's been braced.

One other point is you need to measure RH reasonably accurately so you might want to research ways of doing that. Building dryer is always better.

dm4026 · #8 02-19-2020, 08:02 AM

Thank you so much all of you.

charles Tauber · #9 02-19-2020, 09:06 AM

Keep in mind that one doesn't necessarily have to control the humidity of one's entire work area. The materials/components can be stored in a controlled area and taken out to work on, then put back. The controlled area can be a small closet or even a large container.

packocrayons · #10 02-19-2020, 10:40 AM

Quote:

Originally Posted by redir

Building dryer is always better.

Is that always the case? I'm a little worried about bracing right now as house humidity is <30%

Neil K Walk · #11 02-19-2020, 11:01 AM

Quote:

Originally Posted by charles Tauber

Keep in mind that one doesn't necessarily have to control the humidity of one's entire work area. The materials/components can be stored in a controlled area and taken out to work on, then put back. The controlled area can be a small closet or even a large container.

Exactly. It's really hard to maintain a consistent RH in a large space or whole house. Keeping boards or plates stickered (suspended/divided from other plates by placing them on dowels or sticks) on a shelf in a small-medium room with a humidifier should probably do.

With regards to my "casing" tonewoods, I essentially take the same measures I do with my finished guitar: I keep a case humidifier (which is either just a slightly damp sponge in either an agape sandwich bag or a soap dish with holes punched in the top) in the headstock area of the case and another in the body area, with a small hygrometer between in the neck area.

redir · #12 02-19-2020, 11:14 AM

Quote:

Originally Posted by packocrayons

Is that always the case? I'm a little worried about bracing right now as house humidity is <30%

Well there are extremes on both ends too. Less then 30% is pretty low but if you live in a desert and plan on keeping the guitar there then you are fine. But in general it's shrinking that causes cracks and other problems in guitars and that is because a panel was made into a guitar when it was too wet. It gets braced and glued in it's expanded position and then sort of frozen or locked into place. Then when it is subjected to a dry climate the wood shrinks and the bracing and rims is trying to keep it where it was and it cracks.

While one might think the opposite would be true if built dry well to explain that what typically happens when a dry guitar gets wet is that the radius increase and the wood bulges out and that is less stressful then being pulled apart at the seams.

I would try to get your environment at least up to 30%.

Charles made a fine point in that you can make a little cabinet or use a closet or something like that as an RH controlled room. Brace the back and top and put it in there every night when you are done for the next day till the box is built up. And even then you would want to keep the box in there so as not to mess with your neck angle.

runamuck · #13 02-19-2020, 04:00 PM

For keeping instruments I'm working on properly humidified, I store guitars in a large Tupperware-like container with an insulated, snap-on lid ( water tight), and drop in one of these every couple months.

https://bovedainc.com/store/music-wood-instruments/

dm4026 · #14 02-20-2020, 10:53 AM

Update:
Removing the braces with a heatgun and spatula worked perfektly fine.
Now I wait for everything to set and will prepare new braces.
I will only glue them in my living room. I bought a device to measure the humidity. It has around 33% in my living room, which i hope will be fine.

Thank you again for all your helpful tips

printer2 · #15 02-20-2020, 11:02 AM

I really need to get my humidifier put in, but there always is a more pressing need. I have made a humidity chamber of sorts. Effectively a big plastic bag, not sealed on the bottom though, just weighed down on the carpet. There is a pan of water in the bottom with a fan blowing on it. Sub-20% RH in the house, holds around 45% in the bag. I kick start it by putting hot water in the pan, it settles down after everything gets into equilibrium. Today I am putting vapor barrier around a humidity grow-tent/humidity-chamber to start off plants and keep my working wood humidified. I have used the fan and pan of water before and found that it gets in the magical range of 40-50% for me so I doubt I will need to control it better.