Guitar back plate. Problem 324.

[ClaptonWannabe2]

Originally Posted by Neil K Walk

I’d listen to Charles.

I've yet to find a reason not to.

Current situation is the back is outside in garage. Just a muggy humid night. Just have the back between two flat surfaces and weight. Goal is just to flatten at this point and not do further damage.

[redir]

If the back was in it's maximal expansion state and then braced then when the RH returns to normal and the back shrinks then you will have warpage again. So I would think that removing the braces, then getting the back to it's minimal expansion rate and bracing again would be the proper fix.

IOW you can increase the RH and that back will go back to 'normal' but once it drops again in the winter time it will shrink again.

Maybe once the box is closed that will help it structurally too. But it seems to me that removing the braces is the right fix. It's not at all hard to do either.

[Bass.swimmer]

I built a black walnut parlor, with flatsawn wood for the back. It ended up sinking in about a 1/4 of an inch. It's been stable for about 2 years now.

[ClaptonWannabe2]

Originally Posted by redir

If the back was in it's maximal expansion state and then braced then when the RH returns to normal and the back shrinks then you will have warpage again. So I would think that removing the braces, then getting the back to it's minimal expansion rate and bracing again would be the proper fix.

IOW you can increase the RH and that back will go back to 'normal' but once it drops again in the winter time it will shrink again.

Maybe once the box is closed that will help it structurally too. But it seems to me that removing the braces is the right fix. It's not at all hard to do either.

Thank you. And thank everybody for the input. Its nice to get input from real guys, some with websites who support themselves to some extent or totally with this hobby to craft (depending on who you are).

The problem I have is that I glued and left it outside during a volatile month. March is nuts here in Texas. We usually get our last cold snap and then in 3-4 days we are at highs in the 80's to 90's with 70+ RH. I just for the life of me don't recall which mistake I made. Left outside muggy and dried as temps cooled or vice versa.

At this point I am flat. The back even slightly rocks longitudinally as it should, but it was the edge bends that was the worst anyway. I have it now in my 30' radius dish "cooking". Tomorrow I will put it in the 15' dish if able and take whatever result I get and glue up. I can remove the braces but do not want to, what way can I move forward without brace removal. Is there a way to slowly return it to the in home environment it will live in?

[ClaptonWannabe2]

A little update and a "what now"?

The guitar back is ready. It is curved back as well as I can expect, actually a little better. It is in my garage. We are currently Houston muggy with a flash flood warning. When the rain stops, how do I get the piece back inside and keep most of the curvature?

This has been just another learning experience. I need to remember I have nothing but time and this is just a hobby.

[Alan Carruth]

I'd have the rim in the garage too, so that they're both at the same humidity level before you glue. The rim won't move as much, of course, but you still want them moving in the same direction.

Make sure you've got everything ready to glue up before you bring the parts in, to minimize the exposure to shop humidity so things don't move too much.

Personally, I'd have removed the back braces and re-done them with the humidity at a more 'normal' level. As it is you're going to end up with a box that's happiest in the shower. That's OK if that's where you plan on keeping and playing it, but....

[MC5C]

I have one back I glued up, book-matched maple, one side is a potato chip, the other is dead flat regardless of humidity. I can make the potato chip flatten out, or even reverse, with moisture but leave it for a day in any humidity a human can enjoy, it's back to being a potato chip. I have no idea what I will do with it, but it's not going to be a guitar back (actually, a dobro back).

In this case I would start by taking the braces off, just plane them off, and re-evaluate. Maybe the inside wants to be the outside? In any event I would remediate it to want to be flat and re-brace, maybe with taller braces. I have decided that some wood just doesn't want to be a guitar.

[John Arnold]

how do I get the piece back inside and keep most of the curvature?

You have no choice but to rebrace. This time, make sure the back is dry.