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View Full Version : new fiberglass box question



badboyzx2
12-29-2002, 11:31 PM
OK, now before anybody says anything, i searched the forums and other sites, but i didnt really find any answers to this question.

Im planning on getting a RE 12" XXX and a RE35.1d. First, i'm just going to build a ported MDF box about 2.25 cubes. I will use this box to get it broken in and everything, but not to look good. But later (i like to think ahead) i want a good looking fiberglass amp rack and enclosure. However, I never really have any long free periods of time with school and work and what not.

-So could i build a fiberglass enclosure over a long period of time. Like maybe get the base part done over a long weekend or whatever, and then take it out of the car and do the rest little by little? or will i have to lay all the fiberglass down at once, resin all at once, etc.

I have never worked with fiberglass before, but my dad will help me and he has minimal experience with it. Also, how can I port a fiberglass box? I read that its possible, but i never read how. thanks.

evo2k3
12-30-2002, 11:46 AM
i wouldn't try to make 3 or 4 different peices and then join them together, but you have to do it layer my layer anyways, so not having 36 straight hours to build it is fine. be aware that a fiberglass enclosure for an xxx is going to need to be at LEAST 5/8" thick, probably thicker, dependent on the matting you use, your looking at about 12-18 layers, which is going to get pretty costly, just dont be surprised by this. you port the enclosure the same way, cut holes, drop tubes in. the only problem i can see is if you have contours and curves its going to be difficult to calculate the volume for port length calculations. you may have to fill it with water or soemthing to get the volume.

Savant
12-30-2002, 02:08 PM
Some of the stuff I've read suggests you let each layer harden before the next layer.. so you should be able to piece it together over time.. Other info I have read said go ahead and build it all up at once... *shrug* I immagine that as long as you scuff the surface for each layer that the resin should bond fine to the previous layers.. If you can do 2 or 3 at a sitting, that would probably help too..

Porting I'd immagine is just like normal.. and you can probably just resin/glass the tube in place once you are done (from the inside)..

You will have to fill it with water to get the volume though.. At least, I've not heard any other ways to determine vol in odd shaped boxes (you can guesstimate by making it into rectangles/triangles.. might get kind of close).. Once you get the volume, if it's too much you can add stuff to the box.. in side.. like 2x4 pieces, etc.. someone even mentioned a foam ball for crafts (stiff foam balls/blocks/etc).. they also said that the air space in those would be problematic for specific volume calculations, but I was thinking that if you coat the outside with a layer or 2 of glass/resin that the interal air volume of the foam piece would no longer be an issue (you have a solid object in the box now).. Just make sure you secure it well ;)

I'm not sure about having to run to 5/8" though.. seems a bit thick for fiberglass.. Part of the idea of using glass is that it's stronger than wood.. Although, if you go thin, you will need to have bracing in a few places to prevent flexing...

Hope that helps ...

evo2k3
12-30-2002, 02:38 PM
i dont know how thick it NEEDS to be, but i would make it at least 1/2" for that xxx....probably bigger, thats a freaking massive sub....make sure you use a baffle for the "front" face. you dont even need to scuff the surfaces in between layers, its ment to bond to itself. although sanding every other layer helps keep a good looking surface.....normaly people bondo the surface to clean it up at the end.

Savant
12-30-2002, 02:44 PM
Originally posted by evo2k3
you dont even need to scuff the surfaces in between layers, its ment to bond to itself. although sanding every other layer helps keep a good looking surface.....normaly people bondo the surface to clean it up at the end.

There are different types of resin.. laminating and surfacing.. if he uses laminating then no, he wouldn't 'have' to scuff if (I'd still suggest it).. if it's surfacing resin, it forms a waxy layer as it dries that needs to be scuffed off so the next layer can properly bond to the lower layer..

At least, that's what I read from some of the How-To links posted here..