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-   -   Neck stiffness question. (https://www.acousticguitarforum.com/forums/showthread.php?t=603182)

Steenamaroo 01-06-2021 06:03 PM

Neck stiffness question.
 
Hi all,
I'm hoping some kind soul can offer me some advice.
I'm taking on my first acoustic build but don't get too excited...
It's a 1/4 size and I'm trying to use some wood from old family furniture.

There's no pressure on it and if it doesn't work out it doesn't work out,
but it would be nice to make something that an infant could learn on, at least.

Anyway...To get to the question.
I have some pieces here which I believe are mahogany and have taken a scrap piece to use as a test for doing a scarf joint.
That went well but I have the piece with the body joint end in a vice and it seems that it takes very little pressure at the headstock end to put a substantial bend in this thing.

I do intend to install a truss in the real deal but, as much as there's the sentimental thing, I don't want to start in with materials which are doomed to fail,

I know it's a hard thing to gauge or describe but can anyone give me an idea of how stuff a bare neck should be and, of course, if this is even mahogany. :lol:

Many thanks in advance.

http://steenaudio.com/shared/acousticbuild/1.jpg
http://steenaudio.com/shared/acousticbuild/2.jpg

mirwa 01-06-2021 06:56 PM

You wont know until you try.

Only experience can tell when a piece of wood is satisfactory or not for its purpose, how thin you make the neck, how wide, how much string tension are all components that affect the decision on wood choice

You can always stiffen a piece of wood up afterwards with carbon fibre rods or ebony inserts etc

Steve

Simon Fay 01-07-2021 12:59 AM

I could snap a carbon fiber reinforced neck with very stiff mahogany over my knee without any problems. And I'm fairly certain I could easily break it off the headstock with just my hands but I've never tried that . Most of the string tension is pulling/compressing the neck together -- very little of the force is pushing the headstock "forward".

I strongly advise using a structural timber like Mahogany for the neck of steel string guitar. IF you are concerned about your neck, then I'd try adding some carbon fiber beams to help it out.

Steenamaroo 01-07-2021 06:48 AM

Thank you for the replies, folks.
That's very encouraging to hear. It may be I'm worrying about nothing.

Any thoughts on whether this is actually mahogany?

charles Tauber 01-07-2021 08:54 AM

I awake most mornings with neck stiffness.

Sorry, I just couldn’t resist.


It looks mahogany-like, I.e. one of the woods often labelled as mahogany these days. From old furniture, probably is mahogany.

Alan Carruth 01-07-2021 11:30 AM

Simon Fay wrote:
"I could snap a carbon fiber reinforced neck with very stiff mahogany over my knee without any problems. "

I doubt it, but I've never tried. Still, you're right; any neck that's stiff enough should be strong enough.

Who was it that first used that 'backward' scarf joint? I first saw that on the cheap import solid bodies that I used to work on for the local music store. They tended to have a hump in the fingerboard around the fourth fret where the joint ended. Also, the nut end of the joint is seeing peeling stress on the glue line, which is not good. :confused:

redir 01-07-2021 01:42 PM

That looks a lot like Walnut to me.

Doesn't a traditional scarf joint have similar peeling forces at the tip of the joint?

The first time I saw a joint like that was on a Kramer guitar in the early 90's.

printer2 01-07-2021 02:39 PM

I built a 22" scale guitar with a fir neck and truss rod. It has not complained in seven years about not being stiff enough.


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