12" Fiberglass Sub enclosure build thread
 

I just started work on my sub enclosure. It will be a 12" sub enclosure and I'm making it out of fiberglass. I just finished the first step last weekend so I'm posting my progress so far.

First I started with a rough tape outline like a crime scene lol. It should fit nicely in the corner and not take up too much of the trunk. Hopefully I will still have enough usable trunk space...
http://i.imgur.com/GogWGqM.jpg

I cut out a piece of cardboard to get an idea what the front of the enclosure will look like. I am going for sort of a simplified version of the one from this link http://www.official-automotive.com/i...catch%C2%A0up/
http://i.imgur.com/JXkwhxb.jpg

I masked off the area with layers and layers of masking tape and tin foil. I went a little crazy here because I didn't want anything ruining my trunk.
http://i.imgur.com/QiGgiQI.jpg

This is after one layer of fiberglass. I used a lamp to help it cure faster. It's not really a heat lamp but it gets pretty hot.
http://i.imgur.com/Kq146p3.jpg

more layers... I think I did 2 to 3 layers before removing it from the trunk.
http://i.imgur.com/jYCvAAA.jpg

I did a few more layers outside of the trunk.
http://i.imgur.com/KDaCzFp.jpg

more layers... It took a lot more resin than I thought. I had to make a trip to the store to pick up more because I ran out.
http://i.imgur.com/S3eaGKw.jpg

after letting it cure for a day I cut out a rough shape.
http://i.imgur.com/riQPsci.jpg
http://i.imgur.com/JoAl6KK.jpg


plan to work on it again some time next week. I will post my progress if anyone is interested.

Looks fun. Subscribed.

What ft^3 do you expect to have for this 12" sub?

I'm really not sure... I think ideally it should be something like 2 - 3. I'll see if i can get some packing peanuts and measure out what I have so far.

Any plans for bracing or do you expect the fiberglass to be rigid enough? I really like the OEM look of this type of enclosure, but the others I've seen either take up too much space or don't allow for much room for a decent subwoofer. Yours looks really good, and with 2-3 ft^3 you could have a lot of options.

I'm not planning on doing any bracing but we'll see how it goes. The plan was just lots of layers of fiberglass.

I've always wanted to do something like that. Looks great! Definitely keep up the progress pictures!

Looks good so far! Here's some quick tips, if you're already familiar then disregard.

If you can get the fiberglass roughly 1/4" thick in the thinnest areas, you should be OK if there's no large flat areas. If you're going for huge sound then you'll want it even thicker. 1/4" is already too thin for some, even with a smaller sub. Curvature also adds a lot of rigidity, flat areas will likely be too flexible. It might feel rigid to the touch, but it will be far more prone to resonating at certain frequencies. If you have a local composites supplier who can supply some really heavy weight glass fabric (more than 10 oz/sq yd), it can go a long way toward ease of fabrication (fabric drapes a million times better than mat) and is a helluva lot stronger. Alternating is the best balance between bulk and strength.

If its a large enough shape, you might need to add a wood arch or rib or something to help hold the fabric outward for the outer shell, it can add some rigidity as well as help determine inner volume.

If you stretch fabric around it all to make the outer shell, it will first let you see roughly what the final shape will be, but also a great backing to hold the first layer of glass. Also, you can fill it with packing peanuts before you begin lamination,(roughly dig out the sub shape since it'll take up space) and dump the peanuts into a box and measure LxWxH to get actual volume. 144³ in. = 1³ ft. If you need to adjust it, tear off the fabric and adjust the rib(s) or cut some edges. (Id also recommend only laying up one layer of glass and letting it cure to prevent too much heavy glass from making the stretch fabric droop).

thanks for the advice wheelhaus. I was thinking of making the front out of MDF sort of in the shape of the piece of cardboard in the second image I posted then using fabric and fiberglass to finish it up. I had been using a mixture of fiberglass fabric and mat. One mistake I made was using the mat for the first layer. it left some weird gaps in the corners. I will probably fill those in with bondo later.
I'll look into getting heavier weight fiberglass fabric for the front.

Yeah mat is pretty unforgiving in tight radii. Some fabrics are as well if the weave is stiff.

For some reason the pic with the cardboard template didn't load earlier. That should make a really clean shape, I think it will look great!

It's hard to judge from the pic, but would you have enough room to flush mount the sub? Use like 1/2" MDF for the face, and mount a thicker 3/4" plywood or MDF ring behind it, to create a step that the sub chassis mounts to. Also, if it helps, check out ebay for some MDF subwoofer rings in an ideal diameter to make a perfectly trimmed circle/mount. This is what I did for my two 8" subs, I used ribs as struts to support the rings where I wanted them and just draped fabric over them, then trimmed the fiberglass at the opening.

Sorry if I'm making too many suggestions, I just love watching things like this come together and want to offer any ideas that may help. I've watched several projects get started and abandoned from frustration.

Looks good so far! Keep it up, love seeing people create their own stuff. 👍

Build Update:
 

I didn't get that much time to work on this this weekend but I did make some progress. I started working on the speaker ring and front face of the enclosure. I made this out of 3/4 inch MDF.
http://i.imgur.com/SrK5OUK.jpg

This is roughtly where I think it will be positioned
http://i.imgur.com/cvMxWdL.jpg

from this angle you can see how much volume there will be inside when this is finished. I can adjust it a little bit by changing where the front is positioned and how I finish it.
http://i.imgur.com/ayMHhqB.jpg
http://i.imgur.com/ENCk6TB.jpg

I think I will be busy next weekend so I don't think I'll be posting any updated for a couple weeks but I'll post again when I get a chance to work on it again.

I always welcome comments and suggestions so let me know what you think!

Build Update:
 

I have another build update and I did run in to some issues this time... you'll see what I'm talking about when you see the pictures, especially the last one.


as you can see I rounded off the corners of the front face of the enclosure. I think it gives it a cleaner look. I used some scrap wood and a hot glue gun to keep it in place while I covered it.
http://i.imgur.com/WWbyrfx.jpg

I used some kind of fleece material that was on sale at walmart to cover it and used spray adhesive to keep it in place. Maybe fleece may not have been the best idea for this. again you'll see why later...
http://i.imgur.com/KPjGA5P.jpg

http://i.imgur.com/MUXYxi5.jpg

http://i.imgur.com/BqDL1E9.jpg

so this is where everything started to go horribly wrong... as soon as I started to put fiberglass resin on the fleece material all of the spray adhesive started to let loose and the material started coming off.
http://i.imgur.com/AbYjD1n.jpg
http://i.imgur.com/016Vqz8.jpg
http://i.imgur.com/7dAblBR.jpg

This is where you can really see what happened... the material completely came off and there was a huge gap here as well as tons of wrinkles. the only thing I could think to do was try to close the gap quickly before the resin set. I used some quick thinking and whatever I could grab from the junk drawer to try to pull the cloth tight and close the gap as much as possible.
http://i.imgur.com/EtUvG29.jpg


OK so now I don't really know what to do.... do you think I should just fiberglass over everything and try to work some magic with a butt load of body filler or does anyone else have a better solution?

I could use suggestions and comments.

If the fiberglass fleece cured already and have already added a good amount of fiberglass layers underneath the fleece, you can use an orbital sander and try to sand it flat as you can, then use body filler to fill in any pores and imperfections. Once done shoot some primer, sand at 800 to have as flat finish for paint. Shoot paint coats and then cleat coat and should be ready to go.

the fleece is cured already but I don't have any actual fiberglass on it yet. just one layer of resin to keep the fleece in place. Did you put fiberglass on the inside of the enclosure? did you have to work through the speaker hole? That couldn't have been easy...

If you think about it, the first layer is only there to hold a shape. So, you can grind and shape it however you like before/while you add thickness. If you burn through some small areas trying to smooth it out, you can lay some glass to patch over it. If its a larger area, you might need to stretch another piece of fleece. Once you're happy with the shape you can sand down any rough/sharp protrusions. Later in the process once it's built up thicker with glass, you can smooth it out even more, just be cautious to not get too crazy with material removal. You'll be able to see each layer as you grind it away as an indicator of how deep you're going.

If the wrinkles are in an area where it already overlaps the main shell, just sand/grind it away. The fleece doesn't need much overlap on the shell, even 1/2" is plenty to hold the shape until more glass is wrapped around it.

Instead of bondo, you can make a paste with resin and microballoons as a thickener. Using this instead of bondo to smooth the outer wrinkles will create a stronger bond than having a layer of brittle bondo in between layers of glass. Mix it quickly (so it doesn't kick too early) until it has a consistency like frosting.

If you want to add strength inside the enclosure, you can use this thickened resin like caulk around the inside corners where the fleece meets the shell. This isn't quite as strong as fabric, but the microballoons add structure to the resin, and you can smear it around blindly into the corners without having to see everything. Use a mirror on a stick to see what's going on in there. I recommend starting at the farthest, hardest to reach area first, and working toward your opening. (Again this isn't necessary but can help add some strength).

Build Update:
 

I finished fiberglassing and did a test fit in the car. It fits like a glove and I think it looks pretty good. Next step is body filler and sanding, then more body filler and more sanding and so on and so on...

Let me know what you think!

http://i.imgur.com/w3LrzNq.jpg
http://i.imgur.com/hC82gi2.jpg
http://i.imgur.com/JzLZoFB.jpg
http://i.imgur.com/RKKJwjG.jpg
http://i.imgur.com/4anIqxk.jpg

Looks great! When can you build mine? Lol

poor Woofer ... with some holes in it. You need a Grill

they're not holes. Just dents. and it was free lol can't argue with free. :thumbsup:

Looks good! I've been wanting to do this in my audi for years.

Looks great so far!

Build Update:
 

I went a little crazy with the bondo but it looks really smooth now. I'm pretty happy with this for now. The fit is perfect. I was worried layers of fiberglass and bondo might make it not fit quite as well but it still fits.

Here are a couple pictures of the build so far. This is mostly stuff I finished over the weekend but haven't gotten a chance to upload the progress yet. I just ordered some carpeting to cover it but I have to wait for that in the mail so I am sort of stuck for now. My plan is to start working on some wiring and maybe look into plans for an amp.

http://i.imgur.com/eBjpE7S.jpg
http://i.imgur.com/pjyWSr3.jpg
http://i.imgur.com/LjcbaKv.jpg
http://i.imgur.com/365mcVi.jpg
http://i.imgur.com/EfA457i.jpg

as you can see from this picture I left the back a bit unfinished but hopefully none of that will show so it won't be a problem. I still put a layer of bondoglass in some of the weak looking areas on the back, that's why its a different color. I also knocked down some of the high spots so at least it slides smoothly.

http://i.imgur.com/nRmkVgg.jpg

I do also need to think about a terminal cup. I might have shot myself in the foot by not taking it into consideration earlier but I hope there is a flat enough spot to put one that won't require too much fabrication. I'm thinking I will probably put it on the back in that flat spot towards the right hand side.

Let me know what you think!

Great work! Fitting a 12 in our trunk is a challenge, and everything is coming out looking professional.

There's no shame in Bondo. You could paint or vinyl it with that smooth of a finish.

Thanks for taking the time to post it up.

Build Update:
 

I'm almost done!!!
here are a couple of pictures of my progress so far. I am working on wiring and installing an amp now and hopefully I'll be able to post the final build after the weekend.

http://i.imgur.com/v7seKOV.jpg
http://i.imgur.com/MWk8j2v.jpg

Nice!!! Came out pretty clean. Props to ya!