Big Hollow OM - 25.7" scale Sinker Cedar/Koa

[newvintage]

This guitar has been in the works for a while but it is turning out so nice I want to show everyone!

My family and I were driving around Kona in Hawaii a couple years ago, when the sound of our one year old screaming became too much. At exactly the same moment I saw a sign advertising Koa wood.

The universe aligned! I was at Kimo's sawmill, and he hooked me up with two boards, one for backs and one for sides.
It was a stress curl, radiating rather than uniform, with strong dark and light stripes. Resawn it gave 5 bookmatched like this:

[newvintage]

Sides and back

[newvintage]

For this model I had a new form CNC cut from a drawing I made in sketchup. One thing I'd been trying to incorporate into my process is Positive Alignment, meaning the back and top can never be misplaced. This is achieved through bronze sleeve bearings and locator pins that go through them

[newvintage]

Sinker cedar top with advanced scalloped X bracing



The body after it comes out of the mold. The new CNC mold made this process more precise and easier. Double Win!!

[SJ VanSandt]

That is going to be so gorgeous - can't wait to see it!

[Zandit75]

Originally Posted by newvintage

For this model I had a new form CNC cut from a drawing I made in sketchup. One thing I'd been trying to incorporate into my process is Positive Alignment, meaning the back and top can never be misplaced. This is achieved through bronze sleeve bearings and locator pins that go through them

Can you please tell me what advantage you get from the thicker/wider back braces in the lower bout?
I see many variations on this theme, but the majority I see are thinner like you have in the upper bout.
I am looking at doing a guitar building course later this year, and all of the photos I have seen of his builds have the larger braces in the lower bout.
What does this do for the sound, and does it change when different bracing is used on the sound board?

[newvintage]

I see it as matching the stiffness of the brace to the span of the plate so you can get the best tone from a given area. The upper bout is narrow, thus vibrates at a higher frequency than the lower. A tall narrow brace will support this resonance range.
The job of the lower bout is to generate the long wave, so a bit of flexibility and more mass without the stiffness of height helps it to to that best.

[newvintage]

Cutting in the End graft

[newvintage]

This one gets Macassar Ebony binding.

[newvintage]

I'm using Prima Vera as a neck wood for the first time.

[newvintage]

The headstock is my variation on an old theme

[heyjames]

I like the banjo-style headstock, especially with the matching fingerboard.

[newvintage]

Final sanding the oil varnish. Trizact 3000
Nice and glossish!

[newvintage]

[newvintage]

After buffing