Arch top structural challenge

[Chalks]

Hi boys and girls.
I know it has been a very long time since I was here last, but I visit for inspiration and education when I can. I have a problem you may be able to help me with.
I am at the tail end of building a carved top, f hole type jazz guitar. When stringing up and fitting the nut string slots I noticed the neck was pulling back. Not happy.
I am figuring I will need to remove the back and reinforce the neck block by strutting back to the top and back plates.
Does anybody have any ideas?

Thanks for any help that can be given.

Chalks

PS: Hope everybody has a safe and happy 2016

[jeffhigh]

What do you mean by "the neck was pulling back" ?

[kiwigeo]

What do you mean by "the neck was pulling back" ?

I'm thinking the same. If neck is under string tension it should be pulling up.

[Chalks]

Sorry guys not a good description.

The neck is tilting back toward the top. It seems to be hinging back. Mmmmmm. The neck remains dead straight but the peg head is lifting such that the action at the joint gets higher and the fingerboard extension touches the top.

Does that explain it better? I am a visual guy and could draw it but articulating is maybe not so good.

Chalks

[rocket]

What sort of joint did you use, dovetail, mortice, bolt?

[rocket]

Sounds to me like the neck is ready to come out! Take the strings off and see of you can remove the neck and re fit.

[Chalks]

Thanks Rocket. It's a bolt on neck. The joint is not coming apart. It looks like the whole neck block is tilting.

It's a worry.

Gec

[rocket]

Hhg. Titebond? remove neck and see if you can gain access to the neck block/front and back plate joints and see if you can get some glue in there?

[Nick]

Hey Chalks, long time no hear! Which way have you got your neck block grain orientation? if you've got it orientated so that the end grain is facing the back and front plates then it could possibly be a faulty glue joint with the back plate.

[Chalks]

Hi guys. Really sorry. I have been away.

Rocket I use Titebond pretty much throughout. I do not however glue my neck joints. The fit is always such that I can almost hang the body if I pick it up by the neck. The bolts hold the finished article of course.

Nick the grain is vertical, top to back plate.

I think I will be removing the back and working some kind of bracing. First I will measure the top and back deflection as string tension is applied. I suspect I will cry.

Thanks guys. Not a big contributor, but I am a lurker. I dig the site. Thanks again.