This will be my first major project with fiberglass (if covering a shirt with some cheap Wal-Mart resin counts).

I've read the sticky along with the two tutorials linked to in it. I’m probably going to end up following this example because it’s closer to the scale that I want to build on. I will differ on how I top my box off: instead of glassing in a piece of MDF I will be using fleece/rings.

I'm looking to create a 3ish cube box that will fit in the well and not take up any additional space (ie not spill over onto the top of the hump). I have a fairly clear cut idea of what I want it to look like when I'm done, so I'm not that worried about my approach/plan.

As of right now my only questions lie in materials: what resin should I get? What weight mat/cloth should I get? Should I invest in some Kevlar so I can do a layer or two of it to finish the box off?

I'm going to be ordering everything through US Composites, so I would appreciate it if people would only reference products they sell (they have a pretty good selection).

Resin: defiantly going with a polyester due to ease of use. I'm currently considering a 5 gallon jug of B-440 because it has a nice long work window.

Mat: I'm going to be starting the box off with 3-4 layers of mat because that will probably be the easiest way to get the ball rolling. Weight choices are: 3/4 oz chopped strand, 1.5 oz chopped strand, 1.5 oz mat tape, and 2 oz chopped strand. What would you guys consider good for a base layer? Obviously, following layers could be done with heavier mat since I would need less workability. Should I stick with the same weight mat or should I step up some once the base is established?

Cloth: After I have my base established I will put down alternating layers of cloth/matt until I get to a comfortable thickness level. Available weights here range from 3 oz to 40 oz. I really have no idea what's easily workable and what's not (guessing that 18 and 40 oz are cutting it but anything 10 or under should be fine). Obviously, the heavier I buy the better my bang/buck ratio will be but that's not the most important thing here. I defiantly need input on this.

Kevlar: How worthwhile would a layer or two of kevlar be? Would it greatly increase the strength of the box or should I spend my time/money building more layers of cloth/mat onto it?

Thanks in advance. Hopefully this will turn into a build thread

 

I use the 435 polyester resin in my kick panels, and I've found that it gives more than enough working time before it hardens. Sometimes it takes up to an hour to start to harden in the cup, and I ALWAYS use more catalyst than it calls for.

I would do the first layer in 3/4 ounce mat. You can probably get away with a thicker mat, but the thinner it is the easier it will be to work with, especially in the corners. When you use the thicker crap, it's tough to tuck it into tight areas. Toss a couple layers of that stuff down as long as you've got a cup full of resin anyway, and after it hardens you can pull the piece from the car and start adding the additional layers. You can alternate between mat and cloth if you want, but I've found that the mat is generally more rigid and builds up much faster. For a sub enclosure, I'd probably just pile on the mat, and maybe just finish off with a coat of cloth because it leaves a smoother finish that you're less likely to get cuts or slivers from while you're working on things.

 

So you guys are using actual mat? The guys at the local shop told me to use fleece, the medium furry stuff. Is it better to use the mat?

 

Fleece is used when you want to stretch fabric over a framework to make the overall shape of the piece, such as in my kick panels, or if you want to have a fancy sub enclosure with the woofer mount sticking up. Once you fleece it, you still use fiberglass mat to build it up.

But... I'm assuming that in Gummie's case, he's going to tape off the area, and fiberglass it in order to get a box that fits the exact shape. In that situation, fleece absolutely will not work.


Here's an example of where you'd use fleece:

Here's my picture of the framework I used when designing my kick panels:


Now here's the same piece after I stretched the fleece and brushed the resin on:


If these were my final product, I would apply a couple layers of fleece to it in order to build up rigidity and strength. In my case, I only used those as plugs to build molds from, so I just went right to the bondo to smooth it out.

In an example like I think Gummie is doing, the procedure is very different.

First you tape off the area to be glassed:
Most people will also put down all sorts of stuff around there to make sure that resin doesn't accidently get in places it shouldn't. Most people will also use a layer of aluminum foil over the tape to make removal of the fiberglass piece much, much easier.

So anyway... after you get all of your foil in, you can put down the first layer of fiberglass:


Then you can remove the piece (or leave it there if you'd like) and build it up as thick as you desire.

For a step-by-step set of instructions from the site I stole those last 2 pics from, go here:
http://web.njit.edu/~cas1383/proj/Glassing2/index.htm

Also, in his basic tutorial, he shows how to build a raised setup with a procedure similar to my kick panels, that you can adapt for subwoofer usage.

 

Just like Jim said. You can even go one step further and use some Turtle Car Wax on the foil so it peels off even easier in the end.

I like to start out with a thin OZ quality mat. I think I used 0.75 OZ or so. Once I got comfortable with it, I moved up to heavier mat. I didn't actually use a lot of cloth until I could pull the shell outside the car to work with. I used the most OZ cloth on the straight parts of the box.

As for kevlar that's overkill, I've read a little about it in the past. If I recall right you need special heavy duty scissors just to cut it.

The most difficult part in the project is building the MDF rings, that's the point most people just put a regular MDF faceplate on it.

 

I will be using foil and wax. I want removal to be as painless as possible, besides what's $5 extra for the wax when I might save hours?

I'm going to take both yours and Jim’s suggestion and start off with 3/4 oz. As of right now I'm debating buying resin now or just waiting for spring. I’ve got about 65 lbs worth of mat/cloth coming from some guy on e-bay. $55 including shipping :eak: The main reason I’m thinking about holding off on the resin is that it's freaking cold now and I don't think I will have a warm day to get the shell done. Once the shell is done I can pull it out of the car and bring it someplace warm but I have to do the initial layer outside in the cold car.

As for the rings, I'm thinking about buying my subs from elemental designs. They sell rings for something like $5 a pop so I will just buy the rings from them. I can't cut a circle to save my life.

 

Most of the rings that are available are pretty generic. I always prefer to rabbet the rings so that the driver sits flush. You can see what I mean in my pic above. However, if you don't have a router, that's a pain in the *** to do because you've got to use 2 separate pieces of wood.

 

Is there really that much flex in multiple layers of fleece vs fiberglass mat? From what i gather the guys at the local shop dont use mat at all. I get the whole tape/wax/foil thing...just still a lil confused on the mat vs fleece

 

Fleece is very brittle once you get resin on it. If you're not careful you can even crack/shatter it. I actually did manage to crack mine when trying to remove my wooden rods from it. Looking back I probably should have foiled and waxed the rods before I glued the fleece around them.

The idea behind using the fleece again is just to get your base shape. This could also be done with chicken wire or something similar to that. I only did 1 layer of fleece to get my shape, but it was probably only around 1 mm thick. You could literally put your finger in one spot and push and make the whole area concave.

If you're building something really small acouple layers of fleece should work. But if you have any kind of surface area then it's going to need some support. Don't forget depending on how you mount your MDF rings your lid might also be holding the weight of the subs too.

Your main structural support comes from the fiberglass you lay on top of the fleece. If possible lay the fiberglass on the inside, that should make paint prep a lot easier. In most cases this can not be done.

Doing multiple layers of fleece without doing any of fiberglass doesn't seem that good. Once you consider how much the fleece costs and it literally soaks up tons of resin. I imagine the cost would be the same if you used a good mat or cloth type instead.

Buying bulk off eBay is a good way to get mat/cloth. I bought a large supply of biaxial 15+ OZ cloth/mat off there. It came in a 35 lb box, from the looks of it it's the spare scrap pieces left from a fiberglass boat hull shapes. The pieces are still extremely long so I have to cut them down even more. I'm still using it for projects. Oh that brings me to another subject. Biaxial weave is much easier to work in the corners than a regular cloth. So you might want to look into that if you're buying bulk.

 

That's the problem - I don't have a router. The rings ED sells for $5 are rabbet rings. I can't stand it when I see a fiberglass with anything other than flush mounted subs. Like scrap once said, I was born to cut a square hole.

No need for paint prep because I plan on carpeting the box to match the kicks along with the rest of the interior

As for weave, everything I have bought thus far is plain (0-90). I’m going to play around with it some tomorrow to see if I think I would be better of with some biaxail for the corners. The way I'm currently thinking I shouldn’t have much of a problem starting with the 3/4 oz base and then jumping up to heavier stuff after the base is done. I’ll defiantly play around some before hand. Like I said, I still haven’t bought any resin. I also haven’t bought any 3/4 oz. I will just buy both from US Composites because lighter weight mats are harder to find on e-bay. It's not like I need a lot of it anyway.