Question on fiberglass

I have just started getting interest in fiberglass, I found these forums and have read a lot of posts and sites about fiberglassing.

I have a general idea and I think I am going to start trying to fiberglass a new box for my subs next weekend. The question I have is, I have 2 12", I want to make 2 seperate boxes and have the amp sit in the middle of them. The question is, how do I go about doing this?

Should I build 2 seperate sealed 12" boxes and then cover them in fiberglass? How do I determine how big to make the fiberglass enclosure fitting to the specs for the subs? I also want to know how to wire the subs?

Right now they are sitting in a single sealed box I guessed wired too each other? I don't know a lot about car audio so I don't know what that is called. I would like to use a cup thing? to hook to the fiberglass box so I don't have to drill a hole in it.

I think the first project I am going to do is with my sisters 2 8" subs in her Jeep wrangler because I want to practice before tackling mine.

I would appreciate any help :)

I have a 2003 Toyota Corolla, I don't mind how hard it is. I don't mind sanding by hand, and I think I am a decent woodworker.

Any advice on how to go about doing this would be great :) I am undecided if I want to make the subs flush against the side of the trunk, so have them close the gaps behind the tails or to have a box sitting against the back seats.

The question is, how is the sound quality going to be if they are on either side of the trunk, versus against the back sit, and I wouldn't be real sure how to point the subs to get the best sound quality.

Also the box I described above would be really bulky and I am looking for a more cleaner install, so I am leaning towards having it sit on the sides of the trunk. I don't know what to do with the amp then, it is mounted to the back of the seat, I could have a seperate FB stand made for it that sits up against the seats and have it match the subs on the side of the car door.

The posibilities are endless.  I would put the two 12" in a sealed box.  One for each.  And put the amp in the middle.  Place the subs facing the back of the trunk (one in each corner).  And the back of the box to be next to your back seat.  I wouldn't recomend putting the subs directly against the seat b/c it will lead to a cancelation of the sub's sound waves from bouncing around in the trunk.

Read up some more on using fg and even do a trial w/ a small spare speaker you have around to make sure that you're comfortable w/ using it.  A HUGE thing is to make sure you have EVERYTHING planed out BEFORE you start.  You don't want to get caught in the middle of fiberglassing and realize you should have done this other thing first.

Build as much of the box out of mdf (0.75") then leave all the curves to the fg.  Build a frame and cover that w/ fleece.  Resin that and start fging.  Place enough to your comfort (probably like 2 layers of 4 oz cloth should be plenty).  Then the funnest part.... sanding.  So sand and sand and sand and sand and........  Then bondo and sand and bondo and sand and bondo and sand.... until you get the smooth surface you want.  Then if painting: primer and sand and primer then paint and sand and paint and sand and paint and sand.  Then finish to your liking.  If you're doing carpet or something else then just make it good and smooth (don't primer). 

Good luck.

If I am building the boxes to face the back of the car, have them on the sides of the trunk, I have to use MDF? I thought that the complete enclosure was all fibgerglass except the rings and ring mounts.

I want it to sit nicely against the wall in the trunk, well I will get started. I am going to do my sisters 8" subs first, to make them sit flush in her Jeep wrangler.

You can use fg but most people will tell you to use mdf for a flat surface (ie a side of the trunk) if it's possible.  Also molding fg takes some experience and patience.  If you think you're up to it go for it.  But if I have (which i do) flat sides and a back then I make that out of mdf and then build my enclosure's top/side/front out of fg. 

https://https://web.njit.edu/~cas1383/proj/Glassing1/index.htm

Here is where a guy just does a demo of fging but shows him using the mdf.  No it's not a sub box but it's the same concept except a bigger speaker and box.

Well I am never going to get the experience unless I try :)

I am also confused about the process of laying down the mating, I first mix up the resing, lay it down, then I shred up the matting and lay it down piece by piece until I have covered everything? Let the resin soak in, then wait for it to try, then put more resin down and then put more matting down?

I have looked at that site numerous times ;) This is the only question that plagues me.

For a sub box I would use fg cloth.  It's like a woven fg.  Looks like white carbon fiber.  It comes in different strengths.  Probably look at maybe 2 layers of 4 oz cloth.  For this DO NOT tear it up like some do for the mat.  This cloth is very strong.  If you want to use the mat then yeah most people tear it up to help the edges blend better.

Use the fleece and resin that.  Let it dry and put some more resin down then use some fg mat/cloth and lay it on.  Glob on some more resin to let the fg absorb it and do this another two resin fg processes at most.  Let this dry for a couple of hours (if not then the resin will take forever to cure).  Then if using mat put down somemore resin and do the 2-3 layering again.  Make a sandwich with the resin and fg.  Resin fg resin fg resin fg resin.  Finish with the resin so that you can sand it down w/out sanding the fg.

Oh and make sure you don't mix up to much resin at once or you will be left w/ geled resin.  Don't use this stuff as it gives your box uneven layers.  Makes it a PITA to sand.  Mix up enough resin that you will use in about 10 minutes (use less hardner on a hotter day and more on a really cold day).  If it's a hot day try placing your container of resin and hardner in a large pan of cool water (maybe with some melted ice cubes in it).  This helps keep the resin useable longer.

Alright good deal, I am wondering, how do I calculate for the volume of the sub?

I am going to put the 2 8" in a seal'd box which should be abotu 1 cubic foot of airspace plus the volume of the subs. and then mount the amp in the middle, actually I am going to seperate the subs lol. :P

Should I use terminal cups to hook the subs up to the amp or should I just drill a hole?