Pain in the back

[pavliku]

Hi everyone,

I have a little problem. So I glued the braces on the rosewood back I am using for my first build - this was done a couple of months back, everything went well and it has just been sitting on the shelf ready for when I needed it. Well, I came to use it yesterday to shape the braces ready for assembly and found that the braces have changed from 15" radius to something like 14 1/2 " - I guess this has happened because I quite lazily didn't prepare them on the quater - the grain is at about 60 degrees to the face of the back instead of the 90 they should be. Every other part that I have made has been quater saw, I don't know why I neglected this part.

Anyway, the tighter radius doesn't bother me asthetically or otherwise, but will it cause problems latter on? ie, is it liable to move more? will it rise and fall extremely with the fluctuations of the RH? Should I remove them and start again? Could it be caused just as a consequence of the shrinkage of the glue (Titebond) as it dried?

Thanks,
Paul.

[Puff]

For starters do you really mean 15 inch radius? That's fingerboard/bowlback stuff. For that you will need to carve or laminate. It ain't the glue.

[DarwinStrings]

Hi Paul, It just sounds like your back has taken on a little moisture and swollen a tad to decrease the radius, you could get it back to your 15' by drying it a little or you could get it to 16' by drying it even more. It doesn't sound like a problem to me to glue it a 14.5' but you could change it back if you want. Also, yes it will rise and fall with humidity fluctuations.

Jim

[kiwigeo]

Hi Paul,

My shop is climate controlled so not a big issue for me leaving braced tops and backs lying around but if youre at the mercy of the climate then try and brace up and get the top or back onto the sides as asap. If you need to store the top/back for a while then a drying box is a good place to keep same.

Cheers Martin

[pavliku]

Thanks,
I guess I was a little supprised by how much it had risen. I have moved into a new humidity controlled room last week - I had the back in the old workshop, and as it has been raining quite heavily the past few weeks it is like a duck pond in there. So the non quater cut braces will serve?
Quack, quack,
Paul.

[DarwinStrings]

Should be fine Paul as it is not the skew sawn wood that caused the radius change, 1/4 sawn is preferable for dimensional stability of the brace and it may also be argued that the skew sawn brace may not be quite as strong as the 1/4 sawn one in the direction it is needed but I reckon your guitar will be fine as long as the braces are of a reasonable dimension.

Jim

[pavliku]

Thanks Jim and Martin for putting my mind at rest.
Paul.