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Should I try to build a plastic bass?

S

SpankBass

Jan 2, 2001
2,907
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Orange County, CA.
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#1
Here's my idea: a completely see through acrylic bass body AND neck.

The body i think is going to be childsplay, it's the neck that scares me. I don't know much about scale lengths, and nut sizes, and truss rods, oh my. And I don't know how much the width of the neck should increase as it goes down. So I plan on making it a bolt on that I can easily through on a warmoth if my neck doesn't work. I also don't know if the acrylic can handle the stress.

Despite all the "don't knows" I think I can pull it off. Who here thinks it would be cool to have a completely see through bass from top to bottom (I just think it would be the coolest thing in the world to be able to see the truss rod.)?

Any tips or useful sites you all can refer me to?
 
#2
Sounds like a cool idea! I've seen a few acrylic bodies, but never an acrylic neck. I have no idea if the acrylic would be strong enough for the tension, but having never worked with it, I don't know.

Are you planning to use wood for the fretboard, or acrylic? Fretted or fretless?

If you're worried about neck demensions, you can find info all over the net, or just bust out the old tape measure! :D
 
#3
Originally posted by ChaosGwar
Sounds like a cool idea! I've seen a few acrylic bodies, but never an acrylic neck. I have no idea if the acrylic would be strong enough for the tension, but having never worked with it, I don't know.

Are you planning to use wood for the fretboard, or acrylic? Fretted or fretless?

If you're worried about neck demensions, you can find info all over the net, or just bust out the old tape measure! :D
Click to expand...

Acrylic fretboard too. I'm thinking fretless because its just more work to put the frets in :p. And If I do decide I want it to be fretted, I can just put them in later, whereas it would be a lot more difficult vice-versa. The only problem with a see through fretboard is that you can see the glue, which is actually more of a solvent than a glue. So I plan on mixing the glue with dye and applying it in some sort of loose pattern.

I'm not sure when I'm going to start this, I need to talk with my ROP teacher about getting a big enough hunk of acrylic.
 
#10
A friend of mine makes all sorts of things out of acryllic. It's heavy and not very strong. To make a neck, I guess you'd have to make it out of many pieces to increase the strength. If you have the right kind of acryllic glue, joints will not be visible at all (you can't see the glue after it cures).

Acryllic scratches easily, so I don't think it would work for a fingerboard, unless you can cover it with something transparent and strong, such as the coating used by Pedulla. No idea if that would stick to acryllic though.

All in all.. a lot of effort against a questionable final result
 
#11
-as mentioned, acrylic is not very strong. You would need somrthing for reinforcement, to act as the structural member.

-Gluing many pieces would not increase the strength. Glueing several pieces of wood in different orientations balances out the way wood has different properties in different directions. resulting in a more stable structure. Acrylic is a homogeneous material, so lamination of multiple acrylic layers would yield no improvement.

-How about strips of acrylic separated but thin sheets of carbon-fiber composite (AKA "graphite")? This could look like venetian blinds, clear in the "good" direction, opaque grey-black in other directions- cool effect! Don't know what glue would be good for this, you would have to research it.

-some #s to think about:
--weights:
---hard maple, airdry: 44 lb/cu. ft.
---acrylic: 75 lb/cu.ft.
--strengths, tensile modulus of elasticity (describes how much a material will bend when a load is applied- higher # equals stiffer):
---acrylic: 0.4 Mpsi
---hard maple, airdry: 1.83 Mpsi
 
#13
Originally posted by pilotjones

-Gluing many pieces would not increase the strength. Glueing several pieces of wood in different orientations balances out the way wood has different properties in different directions. resulting in a more stable structure. Acrylic is a homogeneous material, so lamination of multiple acrylic layers would yield no improvement.
...
Click to expand...
Actually, when laminating, you add that inhomogenity that increases stiffness. Though you have to consider directions! If you make a "vertical laminate", that is with the joints vertical when the bass is laying on a table (ordinary on most basses), the thin layers of glue will make a rudimentary difference.
If you, OTOH, make a "horisontal laminate", the glue properties will make a difference.

But: not enough to make an acrylic neck work.

Though, come to think of it, I saw a picture of a homebrew guitar in the mid '80s, all acrylic in one piece, except fretboard. A thin stringed guitar, mind you, and almost 10 kgs of it ¤puke¤
 
#14
Originally posted by Suburban
Actually, when laminating, you add that inhomogenity that increases stiffness. Though you have to consider directions! If you make a "vertical laminate", that is with the joints vertical when the bass is laying on a table (ordinary on most basses), the thin layers of glue will make a rudimentary difference.
If you, OTOH, make a "horisontal laminate", the glue properties will make a difference.
Click to expand...
OK, I accidentally used the wrong terms. Wood is anisotropic, meaning it has different properties when measured in different directions. By combining layers of wood with the grain oriented in different directions, you even out the properties of the composite glued piece, making it act more isotropically (same properties regardless of direction). The acrylic, on the other hand, is both homogeneous and isotropic, so lamination has no positive effect, unless the glue is actually stronger (stiffer) than the acrylic. This is why I suggested carbon fiber sheets between layers of acrylic, to provide the increased stiffness that I think you are assuming the glue will provide by possibly being stiffer than the acrylic itself.
 
#15
Pilotjones is correct. If the glue has a lower elastic modulus than the acrylic then the neck should actually be weaker when laminated. This is the rule of mixtures, as engineers call it (I am not an engineer :D). The force of the strings will also be perpendicular to the long acrylic pieces, and the neck will be weaker in this direction. I personally have no experience with acrylic, so I don't know if it would work.

Geoff
 
#16
Looking at the material properties, a neck made of pure acrylic would have have only 22% of the resistance to bending as the same neck made of hard maple. While the trussrod could be used to provide additional bending moment to counter the bending moment produced by the strings (in a conventional neck, the neck provides most of the reactive force by its stiffness and the truss rod "helps"; in the acrylic neck, the truss rod would have to produce most the the moment by itself), the neck would still be extremely flexible, so much so that I would guess that your left hand fretting pressure alone might be enough to make it go out of tune.
 
#18
I've seen acrylic guitars too, but it's a little different. You've got three things working against you on a bass:
1. The "unsupported beam" length of the neck on a guitar is much shorter. The amount of deflection with respect to the beam length is second- or third-order (sorry, my references are at work); this means that, for example, doubling the beam length either quadruples or octuples the deflection.
2. Also, the tension on guitar strings is 10-20 pounds each, for a total of about 100 pounds; for bass strings it is generally about 35-45 pounds each, for at least around 150 pounds total for a 4 string.
3. Also since the action is generally higher on bass than on guitar, the bending affect is intensified. Doubling the action height approximately doubles the bending torque on the neck.
 
#20
Originally posted by moparpunk281
you can always use a double truss rod
Click to expand...
Using a double truss rod will help counter the bending, possibly giving you a straight neck. Unfortunately, it will not add significant stiffness to the neck (especially since it lies approximately on the neutral axis), so you would end up with a neck which may be straight until you put any kind of outside force on it, which will make it flex.
 

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