Fibrglass Enclosure building Tutorial
Well guys, here's the situation. We need to build a sub box for the beast with these 5 main concerns:
b) Stealth character
d) SQ virtues
So here it goes:
- One car (well doh)
- Masking tape, 3 rolls will do, preferably of the wide variety.
- 6-8 cheap brushes (the cheaper the better, they're expendable)
- 3-4 Garbage bags, large ones
- Polyester mix and catalyst
- Fibreglass wool, 2mm and 5mm
- 16mm MDF (or whatever there is available near that dimension, the bigger the better for rigidity, but also more weighty)
- 1-2 kg of sawdust (you'll see why later)
- polyester stucco / mastic / putty / whatever you guys call it.
- Car Carpet to match your boot carpet. (or slightly not)
- Screwdrivers (for step 1)
- 5-6 pairs of surgical gloves
- Pair of old trousers, t-shirt and old shoes
- Silicone bars and heat gun
Remove all unnecessary objects from the space around the location of the sub box and clean carpets etc (remove all nuts and bolts and holders as well.)
Cover the space with masking tape.
(Tip: start from the bottom and continue upwards, that way there won't be a leak through the tape layers)
Use garbage bags to keep the rest of the boot space clean and fg-free.
Cut the FG wool in small pieces of around 20*20cm, or 20*10 if you prefer (sorry, forgot to get pic, although they can be seen in the bottom right corner of the next pic)
Get a brush and mix some polyester with the catalyst, then place the 2mm fg wool (piece by piece) on the masking tape and start brushing it with the polyester mix to stay in place. The polyester works like a glue due to the moisture.
After you've covered the whole space with one layer of FG, wait for an hour or 10 (depending on how long the polyster mix you have takes to get stiff), then repeat procedure with another 2mm layer, and then another (well, it's not doing any harm)
Wait until the FG is totally set, then carefully prise the thing off the car and out onto a bench or something. It should now be totally rigid and not warp at all.
Take a break for a snack or beer. (no pic of that either)
Remove all the remaining tape and bags from the car, and test fit the FG construct again. Measure the front side (the one against the rear seat's back) so you can cut the MDF side piece.
Using another layer (or 2) of 2mm FG wool, glue the MDF side piece in place. Make sure it's parallel to the rear seat and doesn't leave any gaps.
Then, cut the extra FG by using the jigsaw. Make sure you don't cut it too much though. (You can see it cut at the side near the bumper)
Wait until the last layer of FG is set, and then lay the box down and fill it with material of your own choice (I used water) to measure the internal space. For this box we only needed 17 litres. Make sure you keep the box horizontal. Draw marks with a waterproof marker around the box (internal side) where the water surface is, that's where the baffle will go.
Also, keep in mind that if you glue more FG layers in there, then you'll probably need to leave some more depth to keep the internal space at required volume. In that case, depending on your build, just add a cm to that mark you just made.
Put some more FG layers in there, just to make sure it becomes as rigid as it can. I put 5 layers in total, 2 layers of 2mm wool and 3 layers of 5mm wool. Of course when dipped into polyester the wool becomes smaller in total height.
Measure the front baffle (three times) and cut it from 16-18mm MDF. It would be wise to cut it a little bigger, because that mistake is easily fixed, the opposite isn't.
Swear lots for making the baffle too large and cut it again and again until it does fit.
Measure the sub diameter and cut a hole in the baffle. In this box I wanted the sub to be flush-mounted, so I measured the external diameter and cut a hole using that measurement. (pic in next step)
File the baffle so it fits snuggly in the box, then secure it with masking tape all around.
Mix some sawdust with polyster and create a brown, slimy mixture which will glue the baffle to the box and seal all holes. Then use your hands to spread it round the baffle (using the sub hole to get through). You might have some difficulty reaching deep spots (as in my box, where one end is very shallow and I couldn't get my fat hand all the way). You just roll the box over and let the mix spread evenly on the edge.
The final result, after taking the masking tape off, should be something like this (another test fit):
I think I need another break, don't you?
Clean the boot area once again and get some masking tape around the edges of where the box will be placed.
Use something to keep the box steady in place (in my case, I used a roll of carton). Then get the polyester stucco to cover all holes, gaps and slots between the MDF baffle and the FG edge, as well as give the box its final shape.
We need to secure the sub somehow... We cut a rather wide ring piece of MDF, cut it in half, got the two pieces through the baffle hole and then glued them together on the baffle with some woodglue and woodscrews. We then added another layer of 2mm FG around the edges (from inside) to strengthen it and make sure there are no leaks.
Get the sub in there! A little more cutting in the inner baffle will probably be needed.
Spread the carpet on a table and make sure it's not wrinkled, then glue it on the box. We used an air spray gun to spray the glue from distance (to make sure it spreads evenly on the whole surface) and it glued on the box really well.
Make a hole in the rear side for the cable to run through. I don't have much confidence to those plastic connectors, so I preferred to just run the cable through and seal the hole with silicone. We also put some wadding in the box.
Here she is, at last. The final result.
Unfortunately there wasn't a carpet available that matched the colour 100%, so I prefered the slightly darker one, hoping to dress the whole boot with it at some point, so there's no difference. Mind you, in real life you can hardly see the difference, it's in the pic that it shows so much.
Don't forget to fix the box in place. I put 3 stripes of velcro in the plastics behind the box and strapped it on the front side to a metal welded to the chassis (it was already there, where the rear seat locks). It doesn't move at all (tested in a track).
Well, that's all, I hope you find it useful.