Fiberglass vs. mdf

[04murdalanche]

Wondering myself because plan on doing a mostly MDF box, but glass the mounting rings on top so I can push the subs towards the back of the enclosure if that makes sense, using the 4 sa-8s in my sig. i want room at the front of my center console for cup holders and stuff.. Should I just brace from the mounting rings to the bottom of the enclosure?

 

[fasfocus00 5,000+ posts]

if you are a person that is so concerned about your enclosure flexing, fiberglass is not the route you want to take. bracing fiberglass? you can't really brace fiberglass you can reinforce it with more layers b/c your "bracing" is actually more dependent on the shape of the enclosure. the main reason for it is that the bracing is the skeleton of your enclosure or shape. if your skeleton is poorly constructed than the strength of your enclosure will suffer. as said earlier, fiberglass is strongest in a curved shape and you'll want to use mdf or another wood in any flat areas. i can give numerous examples of how to brace/reinforce a fiberglass enclosure if needed.

 

[Falcons 5,000+ posts]

if you are a person that is so concerned about your enclosure flexing, fiberglass is not the route you want to take. bracing fiberglass? you can't really brace fiberglass you can reinforce it with more layers b/c your "bracing" is actually more dependent on the shape of the enclosure. the main reason for it is that the bracing is the skeleton of your enclosure or shape. if your skeleton is poorly constructed than the strength of your enclosure will suffer. as said earlier, fiberglass is strongest in a curved shape and you'll want to use mdf or another wood in any flat areas. i can give numerous examples of how to brace/reinforce a fiberglass enclosure if needed.

Five as many examples as possible. I'm glad I made this thread. Obviously a lot of people need to be educated on this.

 

[butterMilk 10+ year member]

Wondering myself because plan on doing a mostly MDF box, but glass the mounting rings on top so I can push the subs towards the back of the enclosure if that makes sense, using the 4 sa-8s in my sig. i want room at the front of my center console for cup holders and stuff.. Should I just brace from the mounting rings to the bottom of the enclosure?

Yeah bracing to the bottom of the box is good. 4 pieces should do the trick.

Goingdef where are you going to have flat areas? the bottom, or like in one spot at the back of the box? Other than that it should have enough curves to be strong.

For me all my wood dowels went from the front baffle to some point on the box, that was enough to make the box very strong. If you have a large flat area( 10''x10'') just make it a little bit extra thick. For me, i had a large flat area behind the sub, by the magnet, i went a lil thicker than 1/4 in that spot.

 

[fasfocus00 5,000+ posts]

Five as many examples as possible. I'm glad I made this thread. Obviously a lot of people need to be educated on this.

this guy did a good job of minimal flat area of fiberglass work. the enclosure's skeleton is well constructed and has very smooth transitions. I especially like this build b/c it's one of the rare fiberglass enclosures that is ported.

 

[butterMilk 10+ year member]

When positioning the wooden dowel use a hot glue gun to get it where you want it. Once your front baffle is on, pre drill and put a screw into all the dowels. Also pre drill through the fibreglass box and put screws into the other side of the dowel. Then glass them in, i would also pick up some kitty hair and do that to.

 

[Falcons 5,000+ posts]

How do you get the enclosure to stay once you are all completed with it? I don't want mine falling over

 

[04silverz 10+ year member]

I've never done this but supposedly adding thin pieces of rope into the layers helps with adding strength to large flat pieces of glass.

Read as much as you can on it, diyma is probably a good site to search. Also watch a bunch of tutorials.

For resin I'd buy from US composites, not the bondo crap. I've used both and bondo is messier and harder to work with.

Be sure to have a clean, organized work station set up before hand and take your time. also remember its way easier to cut any shapes while semi cured and do your best to keep it smooth through out as sanding the final product is a huge pain

 

[Falcons 5,000+ posts]

should i use epoxy or polyester resin?

 

[galacticmonkey 5,000+ posts]

A 1/4" thick is plenty in curvy areas.

 

[butterMilk 10+ year member]

How do you get the enclosure to stay once you are all completed with it? I don't want mine falling over

I bolted the bottom piece of my box to the car(mdf) and then went on fibreglassing in the car and to the mdf. so it was a perfect fit. I had to cut the mdf to the shape of the trunk. So when i was all finished i had to install the box, 2 bolts hold it down, and then install the sub in the box. It was a lil difficult to do, considering the sub weighs about 50lbs. But its a nice clean look you cant see any mounting hardware, and its very solid and not moving around. Lucky for me there was already 2 holes in the trunk where the stock sub was.

 

[hispls 5,000+ posts]

google "us composites" and order from them. They're a good source and will help you decide which types of materials are best for your application.

 

[04silverz 10+ year member]

should i use epoxy or polyester resin?

im no expert but i think for our purposes it doesnt matter. for example, i had to do some fiberglassin on my jet ski (actually i used CF but same rules apply) and due to the type of composite used on yamaha ski's polyester doesnt work so i had to use epoxy resin

also us composites doesnt use wax in their resin

 

[martiandancer31 10+ year member]

falcons, I used stuff from US composites until it ran out, then I finished off with the home depot stuff and regretted it. And FYI what they say about the curves is quite right - and in several areas of my build I laid thin pieces of rope down to induce curves. Made a huge difference.

If you want some really heavy duty mat, i'll send it to you for the price of shipping! Just want to get it out of my garage. Should be cheap since you're not far.

 

[04murdalanche]

falcons, I used stuff from US composites until it ran out, then I finished off with the home depot stuff and regretted it. And FYI what they say about the curves is quite right - and in several areas of my build I laid thin pieces of rope down to induce curves. Made a huge difference.
If you want some really heavy duty mat, i'll send it to you for the price of shipping! Just want to get it out of my garage. Should be cheap since you're not far.

If he doesn't want it ill take it. I'll gladly pay shipping