Another way to stiffen sides...

Got a new way of doing something? Or maybe an old method that needs some clarification.

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Rick Turner
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Another way to stiffen sides...

Post by Rick Turner » Sat Mar 14, 2009 6:24 am

Here's how I've been stiffening the sides on my acoustics. This concentrates the stiffness at the very top of the rim. My latest wrinkle for which I don't have photos is to laminate some CF on top of the reverse kerfing and then use CF as binding.

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Last edited by Rick Turner on Sat Mar 14, 2009 10:11 am, edited 1 time in total.
Rick Turner
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Rod True
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Post by Rod True » Sat Mar 14, 2009 8:52 am

That is nice clean work there Rick. That's a very cool idea adding a strip under your liners to really stiffen up the joint between the top and the rim.

Now here's a question for you Rick (and Dave White who also uses the flying buttress).

Is there any reason why one couldn't use wood to do the same thing? Something stiff like Ash or maybe ebony?

Now, I know that the wood will move with humidity, so maybe this is a worse idea vs not doing the flying buttress at all.

Just curious more than anything.

Thoughts?

Oh, one more question. How difficult is it to bend the CF binding at the compound radius locations (waist on the back, cutaway on the back). Forcing the CF into that binding channel would be difficult I would think. But, you've been there done that so I'm curious.

PS, I have more questions from looking at your picture. Like you're using a thinner head block. I assume that you can do that because of the FB rods. Do you use a bolt on neck joint? Very cool.
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Dave White
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Post by Dave White » Sat Mar 14, 2009 9:05 am

Rick,

Great stuff!!

Rod,

Rock is the trail-blazer and guru. I was just inspired by what he did and put my own take on it. As for wood fb's, I'm giving it a try on the multi-scale Taropatch harp ukulele (tenor size) that I'm currently building where the string tension isn't as great - the strings will be on it early next week:

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Dominic
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Post by Dominic » Sat Mar 14, 2009 10:02 am

Hey Rick, does this extra work on the linings allow you to build lighter better sounding tops? Or do you do it for added longevity?

The idea to stiffen the sides has always appealed to me since i read about Greg Smallman's approach.

On my first few guitars I only had standard kerfing so I glued another piece on top of it but upside down around the upper bout and past the waist. It formed a very light square box section that was very stiff. Not nice to look at so I only did it on the top.

But this is where this idea seems to be going. Use combinations of light stiff material to build a very stiff once glued but flexible easy to apply lining.

Anyway, I like checking out your work Rich. Makes me think.
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Rick Turner
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Post by Rick Turner » Sat Mar 14, 2009 10:03 am

You could certainly use wood for flying buttresses; they're in compression and so wouldn't move much. I just happen to like CF rods and tubes because they don't move at all, I like the look, they're not stupidly expensive, and frankly, I think they impress potential buyers...and that's not a bad reason to do things that work.

For the binding, I'm laminating three strips that are .250" (6.35mm) by .023" (0.5 mm) that are pre-cured; I get the stuff from "the Graphite Store" on-line. I tape them in place and flood with superglue after shellac sealing the wood so as not to get any staining from the CA. You really can't see the lamination lines and they're just flexible enough to make it around gentle compound curves. Not sure they'd work on a Sobell or Howe-Orme style cylindrical arch... But with the CF binding on the outside and the CF lined reverse kerfing over side doubling, and then the flying buttresses, the upper rim of the guitar is incredibly strong and stable. I'll post a picture of how I cap the back seam strip and back braces with CF, too. I've kind of gone overkill with this, and I'm going to back off of how stiff my guitar backs are to see how they sound if they're a bit more active. Right now I've got projection like mad, and that's good for some players, but it's not the only way to take a guitar design. I'd like to make some more intimate instruments, too, and really have control over the whole issue of directionality of the sound. Some clients will want one thing, some will want another. To me it's just another range of possibilities at my disposal as a designer.
Rick Turner
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www.renaissanceguitars.com
www.d-tar.com

Rick Turner
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Post by Rick Turner » Sat Mar 14, 2009 10:10 am

Re. the tops...yes, I take them pretty thin out at the edges...a little over .080" (2 mm). I have a shallow dished backer board on which I put the tops when running them through the wide belt sander. It leaves the tops at about .130 (3.25 mm) in the center under the bridge and takes them out to about .090" (2.25 mm) at the edge. I then figure I'll lose about .010" (.25 mm) in sanding and scraping the completed box. So these really get graduated tops. This is another way to get great projection in the midrange. My guitars in this series are flattops, but they have more than a hint of archtop and Selmer-Maccaferri cut to them.

Once again, it's not the only way I intend to build acoustic guitars, but it's been my journey of the past few years, and I feel as though I've really gained an understanding of this particular design direction.
Rick Turner
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