Double top construction with Nomex

agilitydog

agilitydog

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I've heard some wonderful classical guitars made with a double top construction with nomex mesh sandwiched between the very thin top pieces. Has anyone had experience with this construction technique on ukuleles? The only place I know that even sells nomex is LMI. There are a few demo videos out there but none with ukuleles. Curious!
 
I've had a bit of a think about this. double top classicals are approx. 2 layers, each 1mm thick plus 1mm of nomex. The overall thickness is still around 3mm.

My cedar top tenor ukes are around 1.7mm thick. To delete the middle of the top and replace with nomex I'd need 0.6 cedar then 0.6 nomex then 0.6 cedar.

That's pretty thin, difficult to work with and easy to puncture. I hope someone has done it or plans to do it. It would certainly be interesting.

Liam.
 
There was a thread about this type of honeycomb construction on one of the ukulele forums last year...
Some info Here http://www.trentonscott.com/deerheadTop.shtml

Cos i remember it reminded me of the "WW2 Wellington Bomber"
Honecombe.jpg
 
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I wonder how you "shave" nomex down from 3mm to 1mm. It must be stiffer than it looks. Interesting bracing pattern.
 
Robbie Obrien has a good video series on youtube about using Nomex for guitars. Definitely worth checking out.
I wonder if you could use alot less wood for a uke. Maybe use some pretty veneer for the outer layer and a spruce or mahogany inner layer. You could get some pretty wild veneer and not worry about stability.
I'd like to try it someday...but I don't build enough of one model uke to really evaluate the results. Seems like too much equipment and set up for a one-off
 
ksquine said:
Robbie Obrien has a good video series on youtube about using Nomex for guitars. Definitely worth checking out.
I wonder if you could use alot less wood for a uke. Maybe use some pretty veneer for the outer layer and a spruce or mahogany inner layer. You could get some pretty wild veneer and not worry about stability.
I'd like to try it someday...but I don't build enough of one model uke to really evaluate the results. Seems like too much equipment and set up for a one-off
Click to expand...

I'd worry a bit about the weave of the Nomex telegraphing through the veneer (ie 1/20" thick stuff). Maybe if the veneer was on the thick side.
 
I believe there are some super strength materials being created with the help of nanotechnology. I was kinda brainstorming one day (with my head in the clouds), wondering about what materials found in nature are strong and light and the idea of a honeycomb or wasp's nest came to mind. I looked it up and found luthiers already using it in the form of Nomex. I think Nomex combined with new materials surfacing and stuff like carbon fiber, all of these things are going to make for some interesting instruments in the future.
An ultra thin carbon fiber and Nomex uke might be interesting...
 
Vic D said:
I believe there are some super strength materials being created with the help of nanotechnology. I was kinda brainstorming one day (with my head in the clouds), wondering about what materials found in nature are strong and light and the idea of a honeycomb or wasp's nest came to mind. I looked it up and found luthiers already using it in the form of Nomex. I think Nomex combined with new materials surfacing and stuff like carbon fiber, all of these things are going to make for some interesting instruments in the future.
An ultra thin carbon fiber and Nomex uke might be interesting...
Click to expand...

I know a guy Brook Adams he had a cabon fiber uke. It was very cool and super loud

it was a DaSilva Ukulele
 
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I can for-see a few construction problems to negotiate here.:(

Nomex at 1mm "I imagine", would be a difficult thing to sandwich, and not fill the voids with adhesive..and what adhesive is best..... and what do you do when gluing on a bridge ??? will it need a bridge plate ? co's a 1mm thin top skin will easily rip off (I imagine :confused:) maybe bridge pins would work ?... it will need edge bindings too, to hide the Nomex, including the soundhole.
 
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Vic D said:
I believe there are some super strength materials being created with the help of nanotechnology. I was kinda brainstorming one day (with my head in the clouds), wondering about what materials found in nature are strong and light and the idea of a honeycomb or wasp's nest came to mind. I looked it up and found luthiers already using it in the form of Nomex. I think Nomex combined with new materials surfacing and stuff like carbon fiber, all of these things are going to make for some interesting instruments in the future.
An ultra thin carbon fiber and Nomex uke might be interesting...
Click to expand...

Funny you should mention that. There was just a thing on NPR about two russians winning a nobel prize for creating a carbon sheet that is one atom thick. It is supposed to be transparent and super strong. They are already making it but don't know what to do with it.. Maybe the uke could be the first real world application!! :cool:
http://www.npr.org/templates/story/story.php?storyId=130344614
 
Timbuck said:
I can for-see a few construction problems to negotiate here.:(

Nomex at 1mm "I imagine", would be a dificult thing to sandwich, and not fill the voids with adhesive..and what adhesive is best..... and what do you do when gluing on a bridge ??? will it need a bridge plate ? co's a 1mm thin top skin will easily rip off (I imagine :confused:) maybe bridge pins would work ?... it will need edge bindings too, to hide the Nomex, including the soundhole.
Click to expand...

There is no problem at all with a top that is 1.0 mm thick and even less in regards to a bridge ripping off. My lattice braced ukes are all at 0.8 - 0.9 mm thick from the waist south. Braced with Carbon Fiber TOW and Balsa. Makes for a very stiff top that weights just a fraction of a conventional braced top.

Bridge goes on with a vacuum clamp. Very easy.

The problem with using Nomex at such thin dimensions is that the epoxy used to glue it up with is going to fill up any space left between the two plates. Thus negating any weight savings, and with that much epoxy, there is going to be a fair bit of damping. I can't see it being a viable option on something as small as a ukulele. A guitar top is an entirely different matter, though it's still a very fiddly and costly exercise.
 

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    lattice bracing.jpg
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Allen said:
There is no problem at all with a top that is 1.0 mm thick and even less in regards to a bridge ripping off. My lattice braced ukes are all at 0.8 - 0.9 mm thick from the waist south. Braced with Carbon Fiber TOW and Balsa. Makes for a very stiff top that weights just a fraction of a conventional braced top.

Bridge goes on with a vacuum clamp. Very easy.

The problem with using Nomex at such thin dimensions is that the epoxy used to glue it up with is going to fill up any space left between the two plates. Thus negating any weight savings, and with that much epoxy, there is going to be a fair bit of damping. I can't see it being a viable option on something as small as a ukulele. A guitar top is an entirely different matter, though it's still a very fiddly and costly exercise.
Click to expand...

The difference in translucense between the upper and lower bouts is very apparent. Do you do all of that by hand after the lattice is glued on? And no bridge patch. Interesting.
 
Timbuck said:
I can for-see a few construction problems to negotiate here.:(

Nomex at 1mm "I imagine", would be a difficult thing to sandwich, and not fill the voids with adhesive..and what adhesive is best..... and what do you do when gluing on a bridge ??? will it need a bridge plate ? co's a 1mm thin top skin will easily rip off (I imagine :confused:) maybe bridge pins would work ?... it will need edge bindings too, to hide the Nomex, including the soundhole.
Click to expand...

If you're going to go with 1mm spruce/1mm nomex/1mm spruce you'll have a 3mm thick top, 2mm of which is timber. We already know a uke top can be 1.7mm with fan bracing and 1mm with lattice. This sandwich formula will be heavier than a standard top. I believe the whole point of the nomex is to reduce weight but not stiffness.
 
The lower bout is thicknessed prior to the lattice being installed. The lattice is installed in 2 steps. Step one has the CF Tow and Balsa glued on in a vacuum press. Once dry the Balsa is shaped and then another layer of CF Tow is added to the top of the lattice. Essentially it makes an I-Beam structure of CF on the outside with a Balsa web.

You would not use this method if you were wanting to use a pinned bridge. These are always a tie bridge.

lattice bracing profile.jpg
 
Allen said:
The lower bout is thicknessed prior to the lattice being installed. The lattice is installed in 2 steps. Step one has the CF Tow and Balsa glued on in a vacuum press. Once dry the Balsa is shaped and then another layer of CF Tow is added to the top of the lattice. Essentially it makes an I-Beam structure of CF on the outside with a Balsa web.

You would not use this method if you were wanting to use a pinned bridge. These are always a tie bridge.

View attachment 16543
Click to expand...

Fascinating stuff, Allen--thanks for sharing.
 
Couple more pictures

DSC_0814.jpg

This is the initial vacuum pressing of the CF and Balsa. The top is supported by a workboard that has the lower bout dished out to press a dome in the lower bout.

After it has dried over night I shape the lattice much like a mountain. Full height in the area directly below the bridge and tapering out to nothing at the perimeter. Then another layer of CF is vacuum pressed on top of the Balsa. The CF extends out under the linings and the lower soundhole transverse brace. It makes an incredibly stiff top. The hardest thing about building like this is to get the stiffness right. It's all a bit of a guess until that last layer of CF is laminated on. Done enough of them now that I've got a pretty good idea.

DSC_0803.jpg

Anyway, it's my take on making the top as light as I can while keeping the structural integrity. It came about after attending a luthiers gathering in Western Australia a few years ago and got to sit in on a session with Greg Smallman who pioneered lattice bracing on Spanish Style guitars.
 
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