Build a Fiberglass Subwoofer, Start to Finish

    I'm a music enthusiast and have been interested in car audio for a while. I've seen many youtube videos on how to make a custom fiberglass body for a subwoofer. However, I needed to find many different videos to answer all of my questions. Hopefully this how-to will put them all in one place for you. I had acquired two 15 inch PYLE subs and needed to do something with them, so I started researching. I found a cool design from this site :

http://www.tccustomz.com/inc/sdetail/68/96

and went from there.

Here are the specs at a glace:
Specs
- Dual 15 inch Subwoofer Box
- Two PYLE 15 inch speakers
- 1000 watt peak each
- Dual voice coils/ 100 oz magnet
- Custom Fiberglass Front
- Dual port holes tuning box to ~34 herts
- Voice coils in parallel then speakers in series ( aka 4ohm)

Dimensions
- Height 21 inch (top speaker ring)
- Width 20 inch
- Length 37.5 inch

Step 1 Materials List and Project Outline

There's a few stages involved in this particular project:
1) Research and have planned exactly what you want to build. This involves selecting size of speakers, how many speakers, color, port hole location, box tuning frequency.
     - No materials, just time and graph paper

2) Make the wooden body
     - 0.75" Medium Density Fiber Board (MDF Board) 
     - Wood glue
     - Clamps
     - Table saw (gives you straighter cuts than hand held)
     - Drill and different sized bits
     - Screws
     - Caulking (I used Liquid Nails)
     - Jig Saw (Most people use a router with a bridge that lets you cut perfect circles, I found my own way)
     - Port Holes

3) Add the fiberglass
     - Fabric Cloth (like Tshirt material)
     - Staple Gun
     - Fiberglass Resin
     - Gloves
     - Paint Brushes
     - Acetone
     - Plastic Containers for mixing
     - WD-40 optional
     - Fiberglass mats
     - Mask for your mouth (fiberglass resin has lots of fumes)
     - Good weather and open area to work in!

4) Add bondo and Sand to make a smooth face
     - Bondo and Hardener
     - Plastic Putty knives
     - Range of sandpaper from about 80 to 400 or more. (An electric sander here helps a ton!)
     - Rounded wood file (looks like a cheese grading tube)

5) The Cosmetics: Paint and add speaker carpeting
     - Spray Paints
     - Speaker Terminal
     - Speaker Carpeting
     - Spray adhesive
     - Exacto knife/ carpenter's knife

6) Wire the speakers and connect to the speaker jack
     - Speakers
     - Mounting Screws
     - Appropriately Gauged Wire
    

Comments

[scripterz]

Hi , the box looks incredible and I'm gonna build the same one right away.
But there is one small problem. In our country theres nothing called bondo. So is there like an alternative putty I could use? What happens if I mix talc with resin and then add the catalyst as a hardner? Will that work?

[bsodergren]

Fleece is what you want to use. Don't use cotton/polyester materials like t-shirt material, they don't absorb enough resin to solidify properly. It won't last long (my all fiberglass box is almost 10 years old).

You can get Fleece from walmart for very cheap. old fleece pullover blankets, just make sure it's 100%. Fleece also soaks up WAY more resin than you think. at least twice what you would expect, then add another 50%.

Fleece (and t-shirt material) isn't strong enough on its own to support the pressure in a box. A pair of 12's such as JL W7's can blow apart a properly made 3/4" MDF box that's been glued and screwed, Fleece will be obliterated. Pile on the fiberglass matte until it's roughly 1/2" thick or more. My box is 3/4" thick completed.

I lightly sanded between each layer to knock down any peaks and you MUST get a fiberglass roller to get rid of air pockets. Air pockets will kill your box.

Take extra care putting on the last layer of fiberglass. the more care you take here the less "bondo" and the less sanding you have to do later. I did a rough sanding and put a smoothing layer of bondo over the box. I then put a thin padding material and pulled cloth over it.

Also, the mask for your mouth? don't be fooled. you CANNOT use one of those 99cent things that you see doctors use to keep germs out.

you have to use a full respirator, something like http://www.amazon.com/3M-R6211-Low-Maintenance-Half-Mask-Respirator/dp/B00004Z4EB/ref=sr_1_2?s=automotive&ie=UTF8&qid=1326478039&sr=1-2

[DrScott]

Oh, and I use auto carpet from Wally World. It stretches a bit and looks good. Comes in rolls and a variety of sizes. And it is inexpensive.

[DrScott]

Great job!! Cardboard, like from big boxes, can be cut out and used to figure out sizes and shapes. Then the cardboard can be a template to cut out the MDF parts. I find having a hunk of stuff in the space I am putting the speaker box helps me with the vision of the final product.

[blanchae]

I've heard that fleece is a very good choice of material. It can stretch and will hold the fiberglass. I've used stretchy material before with so so results and haven't tried fleece yet.

[agis68]

ooooooh!......iam speechless.....outstandind job

[MarcusAvery]

OUTSTANDING!

[iminthebathroom]

Fantastic, Its about time someone did a good instructable on this. I used to make ones just like these in the past - pre/instructable time period, but I've had others ask how, now I can point to yours, excellent 5 stars!

[pfred2]

Pretty cool looking project.

I guess I ought to clue you in on the #1 secret to working with fiberglass. Acetone takes it right off you. I don't go near fiberglass resin unless I have some acetone around to get it off me. Then I don't wear gloves, I just go with the fur factor. I don't think I'd want to contaminate glass I was working with with WD-40.

One of my more disturbing nightmares is in fact trying to work with fiberglass resin without acetone. I just wouldn't do it.

1 gallon LDPE jugs cut in half are great to mix in too. Milk jugs, water jugs, those sorts of bottles. You can even reuse them, once the resin hardens in them you can break it right out. Unless you really scratch the plastic up resin won't stick to it at all.

Oh, and for brushes use bristle brushes. I use what I call chip brushes, they're the China bristle brushes? They come in packs of 3 dozen for the 2" size. I don't even bother trying to clean them out after a session I toss the things.

[landonairey]

Hey thanks for the advice! You also clued me in on a mistake in the writing. I meant to say use acetone, NOT paint thinner. And yes I eventually just used up all of the brushes and didn't care about reusing them.

[pfred2]

heh yeah I don't even open a can of fiberglass resin unless I have a liberal supply of acetone. That is one of my immutable rules in life. Sometimes acetone is considered paint thinner, but usually when someone says paint thinner I think of either lacquer thinner or mineral spirits. I don't think either of those is nearly as effective removing fiberglass resin as acetone is. When I have werewolf hands I don't reach for anything but acetone so I don't really know. Other than on me, I usually don't try to clean fiberglass resin up ever.

[landonairey]

I had actually confused the two when I went to buy materials and was pretty upset when the thinner wasn't working at all haha. I hope to do this project again but incorporate LEDs which will be synced to the music!

[colorex]

Yep, was going to suggest that you use Led lighting on them!

[gregjd5000]

Very well done. The one recommendation that I have is to add a sound dampening material to the inside of the box. This wil reduce interference from the sounds sent back into the box from the speaker. I have put fiberglass, dense fabrics, or even some soft ceiling tiles on the inside walls. That would increase the quality a bit.

[landonairey]

Hey that's a good thought! I would put insulation in only when the box stops smelling like chemicals. Otherwise the insulation might absorb the smell. Just a thought. It certainly would add a quality factor to the trained ear!

[Diabloscope]

came out good , you could have done away with all the bondo , I've gone through so many different materials trial and error over the years nothing works better than plain old thick tshirts , dont fall for all that fish felt material yea its thick but you use so much resin and is a pain sanding ... Beefy T's WORK THE BEST !! The seam is minor when you stretch it good , you can also mix MEKP HARDENER to thin the bondo to lessen the peaks , and gives a smooth finish just like Evercoats METAL GLAZE , TRUST ME on this !! I hate to sand and hate doing more work than i have to ! another tip , do away with liquid nails ( Liquid Fails ) seal all your edges with chopped up fiberglass and resin apply to all corners ! much like a watery Kitty Hair ooooh Another Great Product ! Yea and what pfred2 said "Always have a liberal supply of acetone" and chemical resistant nitrile gloves !!! ALL IN ALL HAVE FUN !!!!!