So what will a CT scan of a guitar show?

[62burst]

Looks like JT has his hands full on the "Why does a vintage guitar sound so good" thread, so I thought I'd break it away a bit with a follow up question that TM had asked when I was wondering if the CT scan would be a non-invasive way to see if a guitar was of laminate construction.

 

During "the war", the limited nature of spruce saw Gibson using a variety of methods to keep producing guitars. Of course, the use of the Sunburst finish itself is a legendary feature, allowing for the use of many topwood variations, from 4 pc. tops, 2 pc, non-bookmatched tops, mahogany tops, 'skunk-stripe' tops, and... laminated maple back/sides with a mahogany stain.

 

JT had mentioned that specific wood varieties were pretty easily determined thru the CT scan. 'Makes one wonder what the laminates would look like revealed in all their "glory"(?).

[Murph]

I know for a FACT that a CT scan will show if it has a herniated disc, L4/L5.......

 

[jt]

62,

 

A CT-scan will reveal laminated sides (as will an X-ray). The CT-scan presents mind boggling possibilities. Our new state-of-the-art machine takes an X-ray slice every 1/2 cm, both horizontally and vertically. Then, the machine assembles 3-d images from the data. The machine can make very precise measurements of density. so, run a human being through the thing, pull up the 3-d images, press the skin, skeleton, muscle, heart, kidney, vascualr system, etc. preset adn you see only that organ in s-d.

 

For guitars, we can produce absolutely accurate, 3-d images of the inside of the box. Toshiba, the manufacturer, is so intrigued that it's gonna write presets for bracing, internal surface, external surface, etc. We'll be able to model any aspect of a guitar. plus, you can slice it any where in any direction, to see a cross section. It's really amazing.

 

My initial problem is that the images are huge -- about a terrabyte, savable only to a double sided DVD - and can only be seen courtesy of the machine's proprietary 180,000 software package. But, Toshiba has promised to write me a jpeg write-down feature.

 

To give you an idea, here's a screen shot. That image in the upper right is a cross section of the neck. The large image is a lateral view. Those little windows at the bottom show various other 3-d depictions of aspects of the guitar (a 1943 Banner L-50):

 

[62burst]

That is amazing. Love that cross sectional view of the neck. Is that a truss rod in the center?

 

Can't wait to see some more 2-d images. Hope there's bunches of them in your book!

[larryp58]

Kidney stones

[jt]

That is amazing. Love that cross sectional view of the neck. Is that a truss rod in the center?

 

Can't wait to see some more 2-d images. Hope there's bunches of them in your book!

 

Yes, that's the truss rod. Our book will have detailed X-rays and CT-scans of all the Banner models and Gibsons pre- and post- Banner (the transition in bracing, etc, from an early J-35 to a late J-35 to a J-45 is particularly interesting to see).

 

Thanks for the kind words.

[BigKahune]

All kidding aside,

 

I find this stuff very interesting.

 

OWF's thread on vintage sounds was great reading.

 

...the images are huge -- about a terrabyte' date=' savable only to a double sided DVD - and can only be seen courtesy of the machine's proprietary 180,000 software package. But, Toshiba has promised to write me a jpeg write-down feature.[/quote']

 

JT - Cool tech. If you do get images down to jpegs, will you be able to share them outside of your study? I'd love to see a couple.

[jt]

Cool tech. If you do get images down to jpegs' date=' will you be able to share them outside of your study? I'd love to see a couple.[/quote']

 

Sure!

[onewilyfool]

That truss rod does look pretty low into the neck meat. You would think that being just under the fret board would be better for adjustments. I don't know but I think some guitar manufacturers just put in the rod for reinforcement and they were not adjustable. Is this the case here?

 

 

[jt]

That truss rod does look pretty low into the neck meat. You would think that being just under the fret board would be better for adjustments. I don't know but I think some guitar manufacturers just put in the rod for reinforcement and they were not adjustable. Is this the case here?

 

One' date='

 

That's the adjustable rod in a 1943 Banner L-50. It's low there because that "slice" is down near the heel, where the rod bends down. Here's an X-ray of the heel area of a 1942 J-45:

 

[img']http://inlinethumb64.webshots.com/44991/2361299050033810361S600x600Q85.jpg[/img]

[onewilyfool]

that is sooo cool.....thanks JT

[jt]

that is sooo cool.....thanks JT

 

You're welcome! I've learned a ton peering through 60 or 70 guitars. For example, I can tell you that the dove tail in the L-50 was cut by band saw before Gibson acquired a big routing machine mid-1944.