Nomex for Upright

[powerbass]

I recently reread the thread about carbon fiber basses and it got me thinking about nontraditional/not wood materials for instrument making. So I stumbled across a few websites by acoustic guitar makers touting the acoustic benefits of Nomex honeycomb bonded to wood, "double tops" they are called. They claim that tone is enhanced and volume is increased. I'm wondering if there are any TB double bass luthiers who have experimented with composite materials like nomex?

[Jake deVilliers]

That technique may be fine for flat tops with relatively little graduation but I don't see it working on a carved top that goes from 3mm to 12mm!

[Matthew Tucker]

I agree but ... 3mm Jake?

Honeycomb might be a good lightweight idea for a flatback to reduce the weight and need for bracing. Who's going to try it?

[powerbass]

I have been researching building an AUB and several factors make it daunting - finding suitable solid wood material is pricey and then there is the labor to fabricate a solid wood instrument. The acoustic/classical guitar makers seem to love the "double top" design using Nomex sandwiched between solid wood veneers. Tone, clarity and volume seem to increase. From Wikipedia "Nomex reflects high-frequency sound, and increases mid- and low-level frequency sound" I am considering building a bass using Nomex. The appeal to me over carbon fiber is that you are still building a wooden instrument. Since the honeycomb design increases stiffness substantially the need for bracing is minimal - this is another reason why guitar makers love the material - tops resonate more because of less bracing. It would be built just like a plywood bass utilizing a vacuum bag for forming which again is much easier than CF. So far this is just an idea, material costs would be less than a solid wood instrument.

[George700DL]

Originally Posted by Matthew Tucker

I agree but ... 3mm Jake?

I was wondering the same thing - the lowest I've heard is 4mm around the edges. It really makes me think about taking the top off and regraduating...it's 6-12mm on my bass right now.

George

[powerbass]

The method is to laminate solid wood veneers to a core of honeycomb. I am imagining using 1/16" veneer (inside and outside faces) bonded to 1/8" honeycomb core which results in a 1/4" think panel. Honeycomb panels have excellent strength to weight ratios with good compressive strength in all directions just like plywood though the honeycomb reduces weight. What I am curious about is the possibility of building an acoustic upright bass using materials and fabrication techniques similar to the methods used by the best acoustic and classical guitar makers. Here is a quote from McNight Guitar website http://www.mcknightguitars.com/soundboards.html:

"Everyone who has played my Double Tops has been amazed at the sheer volume, power, projection and headroom the top has while still being extremely responsive to a light touch. These tops have the widest dynamic range that I have ever heard on any guitar. There is no discernable change to the overall tone of the guitar. There is a tremendous future for this top design..."

The other feature of Nomex is that it can come in a variety of thicknesses and weights - it is also a flexible material so ribs could be constructed in the same manner as the top and back plates - increased strength, decreased weight etc.

[Jake deVilliers]

Originally Posted by Matthew Tucker

I agree but ... 3mm Jake?

I've seen a bunch of graduation patterns and one had a section at 3mm.

3mm or 4mm, the point had to do with the unsuitability of a Nomex sandwich for carving.

Focus, Matthew, focus.

[George700DL]

Originally Posted by powerbass

The method is to laminate solid wood veneers to a core of honeycomb. I am imagining using 1/16" veneer (inside and outside faces) bonded to 1/8" honeycomb core which results in a 1/4" think panel. Honeycomb panels have excellent strength to weight ratios with good compressive strength in all directions just like plywood though the honeycomb reduces weight. What I am curious about is the possibility of building an acoustic upright bass using materials and fabrication techniques similar to the methods used by the best acoustic and classical guitar makers. Here is a quote from McNight Guitar website http://www.mcknightguitars.com/soundboards.html:

"Everyone who has played my Double Tops has been amazed at the sheer volume, power, projection and headroom the top has while still being extremely responsive to a light touch. These tops have the widest dynamic range that I have ever heard on any guitar. There is no discernable change to the overall tone of the guitar. There is a tremendous future for this top design..."

The other feature of Nomex is that it can come in a variety of thicknesses and weights - it is also a flexible material so ribs could be constructed in the same manner as the top and back plates - increased strength, decreased weight etc.

That sounds interesting. Before I made my bass (carved top, plywood back and ribs), I was going to make a plywood top - about 5mm thickness by gluing together 2 2.5mm sheets over a custom contoured form.

If you go forward with this, I'd like to see some pictures. One question: How does one prevent glue from filling up the chambers in the honeycomb material, when you're making that sandwich?

George

[powerbass]

The question of glue is a good one. From what I can see online the classical guitar makers have this process very dialed in. They use very little glue/epoxy, the goal is to not fill the voids. I believe they even have graduated tops and have done arch tops as well w/this process.
Type Nomex into wikipedia:
"Nomex has also been used for its acoustic qualities, the first time being used in Troy, NY, at Rensselaer Polytechnic Institute's Experimental Media and Performing Arts Center (EMPAC's) main concert hall. Nomex reflects high-frequency sound, and increases mid- and low-level frequency sound.[3] According to RPI President Shirley Ann Jackson, EMPAC is the first venue in the world to use Nomex for acoustic reasons. It is also used (like Kevlar) in the production of loudspeaker drivers".

[Matthew Tucker]

Originally Posted by Jake deVilliers

I've seen a bunch of graduation patterns and one had a section at 3mm.

3mm or 4mm, the point had to do with the unsuitability of a Nomex sandwich for carving.

Focus, Matthew, focus.

there's a plan of a "del gesu" bass somewhere with 3mm grads ... but i wonder if the bass is still around today?

This IS focus Jake, but not as we know it.

[robobass]

Sounds like a really cool idea. McKnight seems to only use spruce or other conifers for tops, but I wonder if some other woods might also work well on a bass. Imagine a flamed maple top? Also, wouldn't you have to make bindings like on guitars around the edges and in the F holes?

[gbaker]

Tops are graduated to provide strength where necessary, such as thick under the bridge area and flexibility where desired, such as thin close the rib joints.

So instead of graduation could you use a change in material to accomplish the same goals? For example use a strip of flexible filler in place of the Nomex, or maybe just stop the internal liner ply around the edges where thinness is normally used?

Where does one buy Nomex?

[powerbass]

I would need to research this idea a lot more but what interests me is the possibility of a "laminated" top and back that has enhanced tonal qualities as opposed to just plywood. I think this design eliminates graduating since it is a laminating process. I love solid wood basses but they are too expensive for me to either build or buy at this point. Also it seems that the solid wood basses can be problematic due to wood movement/repair/set up costs/issues. Here is a source for honeycomb http://www.acp-composites.com/home.php?cat=256. I have extensive experience with vacuum laminating and I have used other honeycomb materials, they are impressive for weight to strength issues

[JtheJazzMan]

How does thin wood veneer hold up to steaming and pressing into a moulded curved top or back?

Make 2 pieces then sandwich nomex within that, and presto, a top or back that only needs some minor finishing.

With a CNC you could cut 2 metal slabs into a positive and negative mould. Then youre ready to go into production.

[Matthew Tucker]

Off you go then!

[forester]

nomex...what to wear when the trees are afire.
timely when you consider the flaming going on in that other forum. instruments set ablaze etc,etc.

[fdeck]

Originally Posted by JtheJazzMan

How does thin wood veneer hold up to steaming and pressing into a moulded curved top or back?

Make 2 pieces then sandwich nomex within that, and presto, a top or back that only needs some minor finishing.

With a CNC you could cut 2 metal slabs into a positive and negative mould. Then youre ready to go into production.

Well, at least you're ready to find out if your design sounds good or not. I think that's one major barrier to the use of modern materials. I used to work with giant steam heated laminating presses. Making those molds is expensive, and the design work is non-trivial. And if you want to go through a few iterations of the design until it sounds good, it's going to be a substantial investment.

[powerbass]

With vaccum forming you would use a form and glue the veneer and nomex together over the form. I have not done compound curves but I think it could be worked out. I Like the CNC idea, instead of steel forms cheaper ones could be made from dense foam or wood products like MDF.

[powerbass]

The other option is to make a flat top and back just like an acoustic guitar. I am assuming the curved top and back is essential for sound production using solid wood, perhaps the curve also facilitates better bowing access. Has any seen or played a flat top/back bass?

[JtheJazzMan]

Originally Posted by powerbass

The other option is to make a flat top and back just like an acoustic guitar. I am assuming the curved top and back is essential for sound production using solid wood, perhaps the curve also facilitates better bowing access. Has any seen or played a flat top/back bass?

I would assume the top is curved, like a speaker cone, to properly disperse the vibrations from the bridge, creating maximum surface area for a sound driver.