Phoenix Gold Phorum

Hi, i am in the middle of fibreglassing my first box, its for 2 12's one inverted. How thick would you reccomend i build up the fibreglass? I was aiming for about 6-7mm is this enough?

Thanks
Rob

At about 1/4" thick overall, I think that'll be enough..... . I'm no expert but it seems asthough that is what I've seen many times..... I'll go out on a limb and say that's roughly 8-10 layers you'll be doing...... Check out fiberglassforum.cizom and do some reading.....

It also depends on what type of fiberglass you are using and if there is any bracing of any type. If you have bracing, then you could get away with using less glass. If there won't be any bracing on the inside, then a thicker application would be needed.

make it thick enough to stand on it............

the rule of thumb i always used was when you can't see light coming through. of course that depends on the color of the resin too

I've seen glass built well over an inch which light still shined through. Im sure 1/4" or 6-7mm would be fine unless you plan on having a large amount of power.

like I said, if you can stand on it, its thick enough......

Thanks for the replies, looks like im not too far off, and Fuzzy thanks for the link =)

Rob

It also depends on the shape a bit Robbie.

Fiberglass is stronger on curved areas, so you can afford to go a bit thinner, but on flat areas it isn't quite as good so needs to be thicker, or have some bracing added.

I'll soon be starting my first FG box for ten years and have had some really good 'refresher' advice over on fibreglass forums

I use 1oz mat and usually put 5-6 layers, when dry it become strong as hell! After that, just try to push on every spots with you thumb, if it moves, put more. And when you think everything is ok, just try to stand on it as stated above. I weight 175lbs and if mine can hold me, it sure can hold enough power for my system

for best results (strength wise) use stitched mat vs. chop mat. it is much much stronger.

Yea but not really necessary unless you're throwing alot of power! But you can make like 2 layers of mat, 1 layer of stitched (weird name, in french it's fibre de verre tressé ) and then finish with 3-4 other layers of mat. Always finish with a mat, not with stitched, as it incorporate with the stitched mat and makes it more stronger... (At least that's what i was shown when i used to work in a fiberglassing shop, maybe someone else can confirm)

[rant]

Your fiber glass mat whether its 1 oz, 2 oz, 3oz etc...has very limited strength. The mat is more of a binder and helps with the adhesion of the glass material. You get your strength from the "stitched" or "woven" materials. However using your stitched or woven materials alone isn't a good idea either, unless they have a mat backing stitched in on one side such as a 2408 or 2415 which even so, it is still a good idea to add a few ounces of mat before the material. If you used stitched material without any mat backing on it, or without using a chop strand mat of some sort, you could eventually get shearing between layers of material. Now don't get me wrong, you could use mat only on many applications and it would work just fine. It all depends on what is being built. If you making something like a custom panel for a dash, mat only should be fine. If your making something that is going to have a lot of stress put on it, then some type of material should be used.

[/rant]

guys he is building a subwoofer enclosure, not a boats or airplane hull. Chopped mat will be find to build it up to the required thickness and strength.

yeah, i have never had any problems using just chop mat either.

ttocs wrote:make it thick enough to stand on it............

x2 - never had a problem with an enclosure strong enough to support me... and they are usually only like 1/4" thick... give or take.