Starting Fiberglass sub box!

**pcmofo** · 05-16-2006, 05:07 PM

ok thanks. I should have enough supplys to do another 2-3 layers making a matching 7 layers all around. Its harder to tell the thickness because I cant see how thick it is getting like I could when It was just half. 30 more minutes and it will be ready for another round.

**Slightly_Stoopi** · 05-16-2006, 06:28 PM

don't forget to add in the extra volume of your sub itself. otherwise your box will effectivly be smaller than 1cuft. you also need to add in any possible volume of any bracing or MDF that you use. It's not terribly important to be dead on though, make sure you add polyfill to the inside of the box and you can fool the sub into thinking it's ina 20% bigger box.

-Mike

**Slightly_Stoopi** · 05-16-2006, 07:22 PM

also if you can use MDF for the front face go ahead and do so, it will cut your fabrication time in half or more. The MDF will soak up resin too so you don't need to glue the FG onto it. It's a good idea to use fleece, like was mentioned in another post, to staple and pull taught to get the shape that you want. you then lay your FG over top of that. You really don't need 7 layers, you can get away with 4 sometimes, it depends on the sub that you are using, and also on how much resin you use and how many air bubbles you have in your layup. Best way to think of fiberglassing is that the resin is like a glue, the resin is actually weaker if you lay it up super thick, you just need to play around with different kinds of layups to find the right ammount for different applications. This is my general layup for sub boxes

5-7 layers for the back plate (the first part you make)
I then use as much MDF as I can to cut down on materials used and for bracing as well as a dual thickness MDF ring.
Stretch fleece over the front of the sub box and get the shape you want (get it as smooth and taught as possible) then another 5 layers over top of that.

I only use the FG Matte like you have, fiberous weave. I use the cloth for applications like headlight eyelids, or to cut down on the thickness of different projects, and also it a high ammount of curves are in the project. Also are you planning on painting or carpeting your box? If you paint you're going to have a LOT of sanding and bondo work to get everything smooth and ready for paint.

When you paint sub boxes you're increasing the ammount of prep work needed and you need to take more care when laying up your project so as not to have to do any extra prep/sanding later. Paint doesn't hide mistakes, it makes them stick out like a sore thumb. I usually use two different colored bondo's to determine how much I'm taking off (you'd be surprised how much you take off sometimes), and when assessing if it's ready for primer your eyes can decieve you, touch is needed to really assess if you're ready for paint.

-Mike

**pcmofo** · 05-16-2006, 09:48 PM

thanks for all the help guys. I ended up putting on 6 layers total on the front and its solid. I trimmed up the whole thing with my <3 Dremmel <3 and it looks great. It also fits perfect in the car and the trunk can close etc. I wired it all up just now in the dark and screwed the sub in place. It kicks great but is leaking like crazy around the uneven surface the sub is mounted to. I dont know what to do?!? maybe when I carpet it the effect will be SLIGHTLY reduced but I am thinking I need some sort of gasget or seal to stop the leaking. I am fairly sure I have the volume correct bc it is hitting hard. It is just leaking and not doing as well as it could. Please help!

**scott_fx** · 05-16-2006, 11:42 PM

easy solution. get fiberglass reinforced bondo (aka kittyhair) mix it up and patch all the gaps and corners. if you still have little leaks then all you have to do is get some resin, mix it up pour it in there and coat the inside of the box. it'll fill up any small gaps

**scott_fx** · 05-16-2006, 11:43 PM

oh...apply it to the inside not the outside

**pcmofo** · 05-17-2006, 01:38 AM

to clarify. My box is leaking around where the sub meets the fiberglass. I dont think it is leaking anywhere else. I am going to take it to a car audio place and see what they think. I am also going to try and find some matching gray carpet. I will take pics of the box in the car etc and post them along with the rest of the pics of the project in progress tomorrow when I am more awake. It sounds sweet even with the leaks and I think it will really be thumping when I fix it. Thanks for all the help guys!

**scott_fx** · 05-17-2006, 01:51 AM

hmmm... did you use the gasket/cork material that is provided with the sub?

**pcmofo** · 05-17-2006, 03:17 AM

no.... I dont have anything like that... thats why I am going to go to a car audio place to see what they can do for me.

**Slightly_Stoopi** · 05-18-2006, 05:51 PM

easy solution, and will only cost you like $5 is to use the stuff that they use to seal windows (it's a white calk). I know lots of people who use that stuff to seal their subs on in addition to the gaskets. DON'T USE SILICON ADHESIVE, not only will it destroy your sub from the fumes, but it will make it impossible to remove the sub later.

-Mike