I’m in the process of building a cardboard mock up of my speaker box. I’m planning on 4 10’s in a box that curves around the rear hatch section. I plan to use carbon fiber to construct the box by laying it over the cardboard. The box will be vented bandpass with four separate chambers
Any one have ideas of how many layers will be necessary or what thickness I should have??
Are you going with carbon fiber for the looks, or some other reason? If you just want the look, I’d build the box primarily out of fiberglass then put a layer of carbon over it for decoration. Building something like a speaker box out of carbon entirely would be pretty expensive (depending on size, I’d imagine around $500 or more, unless you don’t mind the box flexing.) Carbon is stiffer than fiberglass, but in relatively thin, uncored layers, it’s not much stiffer, and a whole lot more expensive. Stiffness will also have to do with what resin you use, primarily polyester/vinylester or epoxy. It’s hard to say exactly how thick the box should be without seeing it or know what kind of stress it’ll be under, but I’d imagine you’d probably want it at least an 1/8" thick. Also keep in mind that a higher glass/resin ratio will yield a stiffer box, so if you really pack the cloth down and try to squeeze as much resin as possible out, you should be able to make a stiffer box. Good luck!
I’m going for wieght reduction. I was thinking about just going with 'glass but I’ve done that before and it turns out a lot heavier than you’d think(by the time you get it thick enough to stop ringing). The time investment makes CF a consideration. I’ve looked around on the net and found some pretty good deals on CF mat if you buy closeouts, constuction grade, (not finish quality mat) or end of rolls.
I like your idea on the hybrid box though. A CF core with a glass shell will cut the wieght down while incresing strength (rigidity) over just glass and also keep the price a little more reasonable.
Thanks
Oh, well if you’re going for weight savings, scratch most of what I said. When I said core, I was referring to composite core construction, where you would use something like foam or honeycomb or balsa sandwiched between two layers of glass or carbon. Core construction makes MUCH lighter and stiffer structures, although if what you’re trying to make has a lot of curves, it can be pretty time consuming to get it to turn out right. If you’re using epoxy resin, you can get away with using just basic insulating styrofoam (blue or pink stuff, not the white “ball” stuff) as a decent core for what you’re doing. If you’re using polyester/vinylester resin, you can use polyurethane foam in some cases, but polyurethane tends to be a bit too soft and shear/delaminate too easily. Sites like www.aircraftspruce.com and www.wicksaircraftsupply.com sell small quantities of other foam cores as well. Divinycell or Lastafoam will both work very well with either polyester/vinylester or epoxy resin, but tend to be a bit more expensive, but if you’re looking at carbon fiber, these aren’t that much in comparison. I’d just do a box out of a foam core and fiberglass skins, it’d end up being much stiffer than just a single skin carbon fiber core, and probably cost less and might be comparable in weight assuming the same stiffness. I’m actually working on building a fiberglass/divinycell interior for my car currently (don’t have much done though, busy with other things), and am planning on doing a very small sub box out of divinycell/fiberglass. I’m trying to keep a nice interior/decent sound system and still have a relatively light car.
Let me know if you need more info on how to lay up foam cores or anything. Good luck!
I never would have thought of using the foam core for a speaker box(I’ve built a few model planes). I think I’ll build a foam core & ‘glass enclosure for a single 10’’ to get a feel for actual specs and finished weight.
thanks
carbon fiber
Does anyone know a internet site that sells real carbon fiber for a decent price, on the other hand does anyone know anywhere on the internet to order carbon fiber, and resin, and harner? Thanks
John
Why would you want weight reduction if installed 4 10’'s?! Makes no sense to me but to each his or her own…anyhow, do your question…
Your layers are quite simple. It’s going to be one layer of mdf wood but it’s the chambers that will be kind of difficult. You want them to be the same size and the same kind of volume so you can get equal volumes of sound. Making it a bandpass will be kind of tough too because then you have to cut the plexiglass the same and plexiglass ain’t all that easy to cut either…