carbon fiber as a building material?

[stuman]

most people on here have probably seen wilson benesch speakers in the carbon fiber. are there any drawbacks to this material? does it perform as well as mdf or ply?

my idea is to rebuild the cabinets of my monitor audio radius with a couple of improvements. as well as try to reduce the size some more, improve sound and look better.

how does one bond carbon-fiber? epoxy? plasti-weld stuff?

[gedlee]

I've made speakers with Carbon fiber. It is excellent, but very expensive. It's usually made with an epoxy binder, so it bonds well with epoxy.

[trusound]

have you ever fiberglassed before?

[gedlee]

Yes.

[thermal runaway]

Carbon fiber has a hugely higher modulus of stiffness than ANY wood , let alone MDF !!

There are 2 basic types of material , wet lay and pre-preg.
Wet lay is just like working with fiberglass except the strand is woven carbon fiber. Pre-preg is the type used by F1 teams and aerospace. The woven CF matt is pre-impregnated with epoxy resin and has to be kept refridgerated to prevent it going off. Then after it is worked into the required mold it has to be cured in an Autoclave , which is a pressurised oven.

Pre-preg gives the ultimate structure and appearance , wet lay requires a great deal of skill to achieve consistant results and a good appearance.

Anything that needs to be bonded to it or CF parts that need to be bonded together can be done with special epoxy adhesives.

To attach anything by screws , threaded bushes would need to be bonded in.

[trusound]

this is what I was getting at.... wet lay is very labor instensive if you want it to look right... keeping the weaving perfect and making sure that the epoy resin is sanded to perfection between each time you apply it...

so if fiberglassing is difficult for you... carbon fiber will be a ton more difficult

[stuman]

yeah, a few years ago now tho.

so there are no downsides? how do you go about calculating resonant frequencies of a material is you have the specs and cabinet sizes?

i would be buying sheets from dragonplate and using an epoxy to join the sheets maybe using 90 degree edges?

they offer a custom cut service so i would just run a design in CAD and stick.

also, would 2mm carbon fiber be thick enough? or should i use one of their sandwich materials?



also without driver specs how would i reverse engineer the port so that i can increase width to reduce chuffing at higher volumes?

[thermal runaway]

My experience with CF is thru performance car parts and quality is a massive problem. Lots of small companies making all types of body and engine parts have sprung up all over the globe but VERY few of them can produce good quality in the first place let alone consistantly. The ones that use pre-preg and have all the proper equipment are best but also the most expensive.

Making speaker cabs is something I wouldn't like to try !!

[thermal runaway]

Originally posted by stuman
yeah, a few years ago now tho.

so there are no downsides? how do you go about calculating resonant frequencies of a material is you have the specs and cabinet sizes?

i would be buying sheets from dragonplate and using an epoxy to join the sheets maybe using 90 degree edges?

they offer a custom cut service so i would just run a design in CAD and stick.

also, would 2mm carbon fiber be thick enough? or should i use one of their sandwich materials?



also without driver specs how would i reverse engineer the port so that i can increase width to reduce chuffing at higher volumes?

Fabricating would be much easier. 2mm wouldn't be thick enough , it would need to be sandwiched. Resonant frequency calculation would need all the data for the material used and a mathmetician !!!

[stuman]

ok, looking at the pages a little more in depth it seems that this product

http://dragonplate.com/docs/DPSpecPP-Honeycomb.pdf

would work best? maybe just front and rear baffles?

double thickness on the front baffle for countersink of the driver?

how would one bond it to say mdf?

or would acrylic work for side panels?