Multi-laminate wood / graphite necks?

[TimBosby]

Hello-

I'm wondering if it would be possible to have a neck made out of various laminates of wood and graphite. The way 3, 5, 7, etc piece necks are made on boutique basses, but instead of all the pieces being wood, some of them being graphite. Would this even be possible? And if so, practical? I wouldn't be making it myself, but was thinking about contacting a few builders for a hair-brained neck project idea. Purely speculative, but I thought it might be a cool idea - I don't know if it would change anything tonally, though.

Thanks!

 

[pilotjones]

Hello-

I'm wondering if it would be possible to have a neck made out of various laminates of wood and graphite. The way 3, 5, 7, etc piece necks are made on boutique basses, but instead of all the pieces being wood, some of them being graphite. Would this even be possible? And if so, practical? I wouldn't be making it myself, but was thinking about contacting a few builders for a hair-brained neck project idea. Purely speculative, but I thought it might be a cool idea - I don't know if it would change anything tonally, though.

Thanks!

Matt Pulcinella makes necks with two CF composite layers clear through to the back. They are then five layer beams, wood-CF-w-CF-w.

He says it is a lot of work shaping the composite. mpguitars.com.

 

[Beej]

My only experience was a world away, but may be relevant. In the late 80's a skateboard manufacturer called Powell Peralta sold boards with laminated layers of "Boneite" between the wood layers. It was some kind of compressed tar paper or something that really stiffened the boards, but also weakened them in shear strength and caused them to delaminate if they were wet. A small Canadian company (I forget which) took the concept a step further and inserted graphite layers into their maple plywood decks. The boards had two layers of graphite, one layer in from the top and bottom on a seven layer board. What i recall clearly about those boards is that they were so stiff, they didn't flex enough to allow for the motion of the deck to which we were accustomed. Hence, our ollies suffered, and complicated big ramp or pool moves were compromised. They had great shear strength, but lacked the "snap" (bendability and reboundability) of the seven ply maple boards.

What I'm getting at is that introducing a full laminate of graphite that is perpendicular behind the fretboard, may introduce so much stiffness as to make the neck less adjustable. Of course, the type of graphite used will impact this, if its even doable.

mikeyswood will probably have succinct thoughts on the subject...

 

[TimBosby]

Thanks for the input guys! I will check with Matt Pulcinella.

 

[LuckeyLukey]

While laminating graphite and wood is possible, graphite is hard to work with... I think Alembic did something like that in the 80's

 

[Dan Knowlton]

Isn't that how they made some of the more expensive Steinberger upright basses?

Dan K.

 

[iamlowsound]

My only experience was a world away, but may be relevant. In the late 80's a skateboard manufacturer called Powell Peralta sold boards with laminated layers of "Boneite" between the wood layers. It was some kind of compressed tar paper or something that really stiffened the boards, but also weakened them in shear strength and caused them to delaminate if they were wet. A small Canadian company (I forget which) took the concept a step further and inserted graphite layers into their maple plywood decks. The boards had two layers of graphite, one layer in from the top and bottom on a seven layer board. What i recall clearly about those boards is that they were so stiff, they didn't flex enough to allow for the motion of the deck to which we were accustomed. Hence, our ollies suffered, and complicated big ramp or pool moves were compromised. They had great shear strength, but lacked the "snap" (bendability and reboundability) of the seven ply maple boards.

What I'm getting at is that introducing a full laminate of graphite that is perpendicular behind the fretboard, may introduce so much stiffness as to make the neck less adjustable. Of course, the type of graphite used will impact this, if its even doable.

mikeyswood will probably have succinct thoughts on the subject...

If they were delaminating, that would be a failure in axiel stress, not shear.

lowsound

 

[pilotjones]

If they were delaminating, that would be a failure in axiel stress, not shear.

lowsound

I disagree, friend. While a stress on the axis perpendicular to the bond plane would also cause delamination, in this application the far more likely cause is the shear on the glue plane when subjected to bending stress (stepping on the board).

 

[Swift713]

Isn't that how they made some of the more expensive Steinberger upright basses?

Dan K.

I thought those Steinbergers were layered front to back. Sort of like this (((((. The outside of the curve being the ebony fingerboard.

 

[iamlowsound]

I disagree, friend. While a stress on the axis perpendicular to the bond plane would also cause delamination, in this application the far more likely cause is the shear on the glue plane when subjected to bending stress (stepping on the board).

From my understanding of it, it doesn't matter what causes the failure (bending stress or otherwise) as long as it fails along the longer axes, it is an axial failure. I would argue that the glue is what is failing and it is failing in the axial plane. If the board cracked through the 7 laminates, then it would be failing in shear.

lowsound

 

[pilotjones]

I think we have a terminology disconnect here. The glue is certainly failing, but I don't know what you mean by an axial plane; you can have an axial direction, defined of course by an axis. There is, to the best of my knowledge, no such thing as an axial plane. Do you mean the transverse plane, which is normal to the longitudinal axis? Because it surely isn't that. Or maybe you mean one of the two planes of which one of their two axes is the longitudinal axis; this would be correct.


No, the failure is due to shear stress (which was caused by a bending moment), resulting in a shear strain, to failure. In my book (or any I learned from) that's called a shear failure.

Think about theory of stress in an I-beam (or actually any beam) under a bending moment. Tensile stress on the upper flange (if the moment is due to a downward force on the end of a horizontal cantilever); compressive on the lower flange; and shear in between, starting at a value of zero at one flange, increasing to a maximum at the neutral plane; and decreaseing back to zero at the opposite flange.

Top illustration is the tensile compressive stress distribution; bottom is the shear stress distribution.
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But I think more than likely we are both thinking the same thing, and just confusing terms.

 

[iamlowsound]

I think we have a terminology disconnect here. The glue is certainly failing, but I don't know what you mean by an axial plane; you can have an axial direction, defined of course by an axis. There is, to the best of my knowledge, no such thing as an axial plane. Do you mean the transverse plane, which is normal to the longitudinal axis? Because it surely isn't that. Or maybe you mean one of the two planes of which one of their two axes is the longitudinal axis; this would be correct.


No, the failure is due to shear stress (which was caused by a bending moment), resulting in a shear strain, to failure. In my book (or any I learned from) that's called a shear failure.

Think about theory of stress in an I-beam (or actually any beam) under a bending moment. Tensile stress on the upper flange (if the moment is due to a downward force on the end of a horizontal cantilever); compressive on the lower flange; and shear in between, starting at a value of zero at one flange, increasing to a maximum at the neutral plane; and decreaseing back to zero at the opposite flange.

Top illustration is the tensile compressive stress distribution; bottom is the shear stress distribution.
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But I think more than likely we are both thinking the same thing, and just confusing terms.

In its simplest form "Axial Stress: A tension or compression stress created in a structural member by the application of a lengthwise axial load." Then when something fails lengthwise (in our case a delamination of plywood), it fails axially. It doesn't matter if the force is applied perpendicularly or if the failure is caused by a bending moment.

lowsound

 

[Beej]

I'm no engineer, but also think you guys might be arguing the same point with different terminology: http://en.wikipedia.org/wiki/File:Axial_stress.svg

At any rate, the root of this I think is actually due to my own syntax disconnect:

but also weakened them in shear strength and caused them to delaminate if they were wet

I missed a comma there, but suffice it to say that I meant to communicate two ideas:
1. the "Boneite" caused the boards to be weaker in shear strength than a regular maple board.
2. the "Boneite" allowed water to wick into the layers if the board became submerged, or repeatedly wettened, and caused delamination.

My point is the delamination was not related to its ability to handle shear stress. Not having a comma there apparently led iamlowsound to believe I was connecting the two notions...

 

[iamlowsound]

I'm no engineer, but also think you guys might be arguing the same point with different terminology: http://en.wikipedia.org/wiki/File:Axial_stress.svg

At any rate, the root of this I think is actually due to my own syntax disconnect:


I missed a comma there, but suffice it to say that I meant to communicate two ideas:
1. the "Boneite" caused the boards to be weaker in shear strength than a regular maple board.
2. the "Boneite" allowed water to wick into the layers if the board became submerged, or repeatedly wettened, and caused delamination.

My point is the delamination was not related to its ability to handle shear stress. Not having a comma there apparently led iamlowsound to believe I was connecting the two notions...

That actually clears up a lot for me, I did miss that they were two separate things.

lowsound

 

[stevetx19]

wow

what course or progression of courses can you recommend to have any idea what is going on here?

thanks

 

[TimBosby]

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[iamlowsound]

wow

what course or progression of courses can you recommend to have any idea what is going on here?

thanks

Statics, Mechanics of Materials and Structural Theory are the courses that make up my bases. Those are just general courses, then I will be getting into stuff like steal design, reinforced concrete, masonry construction ect. PilotJones is a mechanical engineer, whereas I am a civil, so I have no idea what courses his knowledge come from, but I suspect that he has taken a course or two in statics and dynamics.

lowsound

 

[Musiclogic]

I was thinking Linear functions, practical physics, and applied statistics for engineering, but that was a long time ago. what they call them these days is not in my realm of curiosity. I walked away from that life 18 years ago.

Thanks for the flashback Pete...LMAO

 

[pilotjones]

In its simplest form "Axial Stress: A tension or compression stress created in a structural member by the application of a lengthwise axial load."

Right. But

Then when something fails lengthwise (in our case a delamination of plywood), it fails axially.

Well, kinda sorta. The sheared plane does progress along that longitudinal axis, but it would never be referred to an "axial failure" IME. Maybe that's a term in Civil, though. In ME, a failure caused by tensile or compressive stress exceeding Sy or Su, whether those stresses were caused by straight axial loading or some other loading condition, would be called tensile failure or compressive failure.

In the skateboard case there is no axial loading, there is side loading creating a bending moment. While this bending moment does create compressive stress on the top of the board and tensile on the bottom, neither of these causes the failure mode. The failure mode is due to shear stress on the defective glue planes. Hence it is a shear failure.


But I can see how, maybe especially in CE, you'd be just as concerned with the physical orientation of the failure, and therefore name it by that rather than by the causal stresses.

 

[pilotjones]

Statics, Mechanics of Materials and Structural Theory are the courses that make up my bases. Those are just general courses, then I will be getting into stuff like steal design, reinforced concrete, masonry construction ect. PilotJones is a mechanical engineer, whereas I am a civil, so I have no idea what courses his knowledge come from, but I suspect that he has taken a course or two in statics and dynamics.

lowsound

Same basic courses in ME (Statics, Mechanics of Materials) to get this grounding, followed by a bunch of further ones.