Proper Fiberglass thicknees
Printed From: the12volt.com
Forum Name: Fiberglass, Fabrication, and Interiors
Forum Discription: Fiberglass Kick Panels, Subwoofer Enclosures, Plexiglas, Fabrics, Materials, Finishes, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=41115
Printed Date: April 24, 2024 at 9:22 PM
Topic: Proper Fiberglass thicknees
Posted By: drsnoze
Subject: Proper Fiberglass thicknees
Date Posted: October 18, 2004 at 10:59 AM
What is the proper thickness in order to handle 4 JL 10 W0s. Is 2 layers of fleece enough or should i add more?
Replies:
Posted By: ice4life8269
Date Posted: October 18, 2004 at 1:31 PM
you are only supposed to use the fleece for the initial "shape".... so you only use one layer of that. the rest of the layers are fiberglass and resin..... i always used at least 8 layers of 'glass, but somone in this forum said to make your 'glass as thick as your MDF, and i thought about it, and that deffiately makes sense, and you won't have to worry about flexing at all.... and i don't know what your plans are for you enclosure, but i'd make 4 seperate chambers, just a thought.. good luck dj -------------
Posted By: boxmaker85
Date Posted: October 18, 2004 at 1:39 PM
The thickness depends upon what weight of fg you are using and how much pressure the subs are pushing. If you're using the standard 1.5 oz mat then yeah bout 8 layers for a good strong enclosure. If you're using a thick 4 oz cloth then only 2 layers are actually needed. If you've got a low power system then a sandwich of fleece, a layer of 4 oz cloth and another fleece would probably do. But I wouldn't recomend that for anything that pushes more than like 150 watts. It's strong but could flex.
Posted By: ice4life8269
Date Posted: October 18, 2004 at 1:45 PM
fleece is difficult to finnish, that's why your final layer should be 'glass, not fleece. when you get good at it, you won't need much bondo or any other kind of filler to make it smooth
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Posted By: dpaton
Date Posted: October 18, 2004 at 2:08 PM
4 10W0s will need a well braced box of ~ 1/4" thickness, or a less well braced box that is thicker. The enemy of good bas is a flexible box. When the box flexes, that's energy not being turned into sound in the car. I've been around and around with the stealthbox like enclosure for the second 10W6 in my Civic. After 5 tries, I finally have one that won't wiggle when I pump the low end. 1/4" thick (1 layer fleece, 6 layers 4oz mat, vacuum bagged), 1/4" baltic birch (1 layer of 1.5oz mat) braces every 8", and a 1/2" baltic birch baseplate was the recipe that finally worked. 4 10W0s will need something similar if they share an airspace.
-dave
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This is not a sig. This is a duck. Quack.
Posted By: drsnoze
Date Posted: October 18, 2004 at 3:28 PM
thanks guys. you guys are so help full. I was alittle afraid to ask that question because i was afriad you was going to get bashed for being a noob ect. When u guys say use fleece to get the shape and then glass over it, should i be using mat or cloth(weave look)? So in theroy you cant add to many layers of glass but it seems 8 layers after fleece is minimum.
Posted By: audiomechanic
Date Posted: October 18, 2004 at 5:53 PM
resin hardened fleece and speaker box carpet are the easiest thing to finish if you are using polyester primer and the enclosure is filled from the inside.
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Posted By: boxmaker85
Date Posted: October 18, 2004 at 8:44 PM
dpaton you've got how much crap in that thing? For just one 10w6? Curves are fiberglass's favorite thing and in a tire well you've got more curves than a river. You can use as much fg as you want just make sure it doesn't flex. You can use mat but you'll probably be using more of it. Cloth tends to be thicker in weight and is normally stronger than the mat. I would do the cloth and have about 2 or three layers (which ever you're comfortable with) of the 4 oz stuff (or 6 oz if you think you'll need it). But for four speakers in seperate chambers 3 layers of 4oz should be plenty. Good luck.
Posted By: dpaton
Date Posted: October 18, 2004 at 9:22 PM
boxmaker85 wrote:
dpaton you've got how much crap in that thing? For just one 10w6? Curves are fiberglass's favorite thing and in a tire well you've got more curves than a river.
Yup, you read that right. JL's box is rougly the same, only with a different kind of resin and chop instead of bagged mat, and 1 fewer brace.
Put your hand on my box when it's really going, and there is no flex. The JL wiggles a little bit. The weak MDF box I used originally cracked in a few places. My woofers don't exercise much, but when they do they work hard. As for the shape, it's on the side of the trunk, not in the well. It's not as curvy as I like, but it'll do.
-dave
And yes, I'm a little nuts about bass. Ask me about the Contras some time. ------------- This is not a sig. This is a duck. Quack.
Posted By: boxmaker85
Date Posted: October 18, 2004 at 9:54 PM
oh ok. Yeah now that I think of it the w6 has some power behind it. Makes sense.
Posted By: ice4life8269
Date Posted: October 19, 2004 at 5:42 AM
the woven cloth is ONLY strong in 2 directions. the chop mat is stronger because the fibers go in all directions, not just 2 ways.... the woven mat is easier to finnish, way easier the trying to finnish a layer of fleece... 1/4 might be too thin if the box is going to hold 4 subs, even if they are 0's.
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Posted By: audiomechanic
Date Posted: October 19, 2004 at 6:59 AM
i am having a difficult time trying to figure out why everyone has a hard time finishing fleece?
what are the problems that you guys are running in to?
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Posted By: dpaton
Date Posted: October 20, 2004 at 6:51 PM
ice4life8269 wrote:
the woven cloth is ONLY strong in 2 directions. the chop mat is stronger because the fibers go in all directions, not just 2 ways....
Unfortuately that's the furthest thing from the truth. Woven mat is inherantly stronger, once it's in the resin, because of it's weave. Chop mat has no overall structure, and there is little to keep asymmetrical stresses from compromising it's structure.
Ask anyone who makes composite aircraft. Chop mat is only used as nonstructural filler. Vacuum bagged woven mat is where it's at.
-dave ------------- This is not a sig. This is a duck. Quack.
Posted By: boxmaker85
Date Posted: October 20, 2004 at 11:29 PM
I was thinking about that dpaton... Look at good old physics class. If you have a force in the x direction and a force in the y direction you get a resultant force in the x-y direction. Now reverse that and apply it to woven fiberglass. You have a force (pressure) acting in a direction (lets say for crap's sake) 30 degrees above the x axis. It has a component in the x and y direction right? Those directions are the directions the fiberglass cloth is woven. Sorry bout the explination but I get into a lecture mode when people talk about stuff like this. Can you tell I'm an engineer? 
Posted By: Carbonb
Date Posted: October 20, 2004 at 11:56 PM
Wouldn't the cloth be flat? It is going in both direction while it is woven, I don't think I would explain it in terms of X and Y and a graph. I would say that since the tight weave it would bind together and make the overall structure stronger, due to the simple idea of it being bonded completely do each other instead of being in little pieces.
Posted By: realitycheck
Date Posted: October 21, 2004 at 8:13 AM
So the fiberglass cloth is stronger then the mat. So why do you have to put like 10 layers of cloth down compared to like 6 of the mat?
Posted By: boxmaker85
Date Posted: October 21, 2004 at 9:29 AM
Yes the cloth is flat. Looking at the fg cloth when it's flat up being the y direction x going across and an imaginary z axis coming up toward you. You have an x and y direction. But it's not in terms of a graph necicarily but as the cloth's components of x and y. And some woven cloth is not very tightly woven. Take carbon fiber for example. Extremely strong right? But you normally tape the cut edges to prevent it from coming undone so easily. Now not it's not falling appart loose but you get what I'm saying. The moral of the story: Fiberglass cloth is stronger then mat. To answer realitycheck: It's the other way around and normally a bigger ratio. You usually only have to put like 2 layers of cloth down to get like 7 or 8 layer's of mat. Cloth is normally a heavier weight (4 or more oz.) while cloth is either 3/4 or 1.5 oz. You could put down about 2 layers of 4 oz cloth and it would be about equal to 6-8 layers of 1.5 oz mat. A 10 layer clothed enclosure would support like 10 13w7 subs running 1000 watts each. Enough to park your whole car on (well, maybe depends on what car).
Posted By: realitycheck
Date Posted: October 21, 2004 at 10:26 AM
So how many layers of the cloth would it take to handle two 12" rockford subs like 250 watts each, I am using the cloth you get at wal mart, so im assuming its 1.5 oz. Can someone please help with this question.
Posted By: boxmaker85
Date Posted: October 21, 2004 at 2:51 PM
1.5 oz cloth or mat? Is it tiny strands of fg going in every direction or does it look like white fiberglass? If it's cloth then it's probably 3 or 4 oz. Use about 2 layers in addition to you're resined fleece/cloth material. DO NOT tear this up. It's woven design is where it's strength comes from. If it's mat then it's probably 1.5 oz., use about 8 layers of this. When using the mat then take and tear it up into 2" x 2" pieces (tear don't cut, tearing allows the edges to blend better) and resin those on. Sand and finish to you're liking.
Posted By: realitycheck
Date Posted: October 21, 2004 at 3:01 PM
Well my first layer was mat the stuff that youre talking about that goes in every direction. But, I think I will take that back and get the cloth since I hear its easier to get bubbles and also easier to lay down. But I still need to know how many layers of the cloth I need to lay down? and by cloth I mean the stuff thats checkered like. This that im referring is the same stuff they sell at home depot or lowes. How many do you guys say?
Posted By: ndm
Date Posted: October 21, 2004 at 4:04 PM
boxmaker85 wrote:
Yes the cloth is flat. Looking at the fg cloth when it's flat up being the y direction x going across and an imaginary z axis coming up toward you. You have an x and y direction. But it's not in terms of a graph necicarily but as the cloth's components of x and y. And some woven cloth is not very tightly woven. Take carbon fiber for example. Extremely strong right? But you normally tape the cut edges to prevent it from coming undone so easily. Now not it's not falling appart loose but you get what I'm saying. The moral of the story: Fiberglass cloth is stronger then mat. To answer realitycheck: It's the other way around and normally a bigger ratio. You usually only have to put like 2 layers of cloth down to get like 7 or 8 layer's of mat. Cloth is normally a heavier weight (4 or more oz.) while cloth is either 3/4 or 1.5 oz. You could put down about 2 layers of 4 oz cloth and it would be about equal to 6-8 layers of 1.5 oz mat. A 10 layer clothed enclosure would support like 10 13w7 subs running 1000 watts each. Enough to park your whole car on (well, maybe depends on what car).
this is true to a certain extent....but did you know that the cloth is measureed most times in yards squared and the mat is measured in ft squared? which means that 1.5 oz mat measured the same way cloth is measured is actually 4.5 oz. now if you take 1 pound of cloth and 1 pound of mat then yes the cloth is stronger...but the way i feel is that to me the mat builds up alot quicker. im not super worried about weight so i would rather use mat.... just sharing some knowledge.... i just registered...this is a nice forum...im more active on the truck forums....okay im rambling on see ya ------------- do it right the first time ....or do it again and again and again...
Posted By: boxmaker85
Date Posted: October 21, 2004 at 5:50 PM
I stand corrected ndm. Totally forgot about that. But I still prefer the cloth. If you have already taken the mat back then get the cloth and put two layers of that down. For two 12" then that should be good. If you still have the mat, ndm's right w/ mat building up faster. It's up to you. Good luck and keep the questions comming.
Posted By: boxmaker85
Date Posted: October 21, 2004 at 5:55 PM
I've been thinking which is better... laying the fg on the outside of the box or the inside behind the fleece? or does it really matter? I've mostly seen the laying on the outside but sometimes I see it on the inside if it can be done.
Posted By: drsnoze
Date Posted: October 21, 2004 at 8:24 PM
i kinda feel as if i am a bee keeper and i have acidentally knocked over the bee hive. But i like reading the post, to get everyones point of view and make a mix of ideas. So you think a layer of fleece and then 2 layers of mat then 4 layers of cloth would but more than enough to handle 4 WO's?
Posted By: realitycheck
Date Posted: October 22, 2004 at 7:19 AM
Well I took the mat back and got me some cloth I layed down one layer of it last night, and it is so much better than mat. It lays down a 1000 times easier and conforms to the curves way easier. I think that from now on I will use cloth, but I think im still going to put down like 6 layers of cloth because its just so thin.
Posted By: boxmaker85
Date Posted: October 22, 2004 at 8:08 AM
drsnoze: Yeah that should definately be good. Are you seperating the chambers? And remember whenever possible use mdf for those flat sides (mdf can be stronger on flat areas. unless you use like 1/2 inch of fiberglass.
Posted By: ndm
Date Posted: October 22, 2004 at 9:48 AM
boxmaker85 wrote:
I've been thinking which is better... laying the fg on the outside of the box or the inside behind the fleece? or does it really matter? I've mostly seen the laying on the outside but sometimes I see it on the inside if it can be done.
im doing it on both the outside and the inside....i just like to do it that way when i can.... im also going for like 1/2 in thick walls....im most concerned about the large les curvasious portions of the enclosure. so actually it will be like around 1/4 in in the corners but 1/2in on the flat portions. ------------- do it right the first time ....or do it again and again and again...
Posted By: drsnoze
Date Posted: October 22, 2004 at 10:42 AM
Shoud i separate the chambers?
Posted By: realitycheck
Date Posted: October 22, 2004 at 12:47 PM
I would seperate them! Just usually sound better seperated.
Posted By: boxmaker85
Date Posted: October 22, 2004 at 1:33 PM
If you can then yes seperate them. It gives the sub better airspace to react against and if one happens to blow then the other(s) doesn't have to push all that extra air in the box. More of a safety measure but sometimes adds to the sound quality.
Posted By: drsnoze
Date Posted: October 22, 2004 at 5:19 PM
you guys are awsome
Posted By: boxmaker85
Date Posted: October 22, 2004 at 11:01 PM
no just some loosers that sit around and read about speakers and help the people like you that actually have a life.... or maybe that's just me....
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