# Fiberglass sub box, how thick?



## Mile Zero (Oct 10, 2012)

I was just wondering how thick you guys make you fiberglass subwoofer boxes? Or what other means do you use to make them as strong as possible.


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## SREMotorsports100 (Aug 8, 2012)

the normal that I use for fiberglass boxes is 1.5oz cloth/mat (whichever you prefer) I like to work with mat sometimes better than cloth just depends on the box and size/shape. but you try to shoot for 1/4" thickness. This is well laid meaning little to no air bubbles. and for as strong as possible, I have one I did out of carbon fiber and it was a beauty it was still about 1/4" thick, thus it is expensive to buy, luckily for me I had the material given to me. you will be just fine with your cloth or mat long as it's near or above 1/4". sort of lengthy but hope this helps!


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## Mile Zero (Oct 10, 2012)

1/4 eh, I guess I'm miles ahead then lol

My box is up to 1" in spots. On average I'd say its about 1/2 to 3/4"









I was just wondering how thick everyone else made there's. Good to know that I'm not under building.


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## SREMotorsports100 (Aug 8, 2012)

well then you are ahead of the game, I have never built one up that high before. never really any need to. it should be alright though, I don't see why it would hurt. just don't want it to thin or the glass will flex and eventually start to crack and well you know what happens from there. 

this is one I did with a complete mdf box and a face of carbon fiber.


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## Mile Zero (Oct 10, 2012)

Thats pretty sexy, I love carbon fibre. Mine is pretty fugly right now, but still covered in Bondo.

I made one around 1/4" thick once before but the amount the box vibrated was really upseting. You couldnt hear it but you could feel it if you but you hand on the box, so from then on I make them at least 1/2".

I have a 10" Hertz Mille going in this so I want it to be strong.


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## SREMotorsports100 (Aug 8, 2012)

thank you sir! this was more for cosmetic reasons since the entire box was mdf with cut outs then just the face was fibered. still a lot of work to make it look like that lol. I did at one time do an entire box out of carbon fiber and it came out pretty nice. 

yeah I have never had a problem with anything thats been 1/4". going above though will not hurt if anything it will help to a certain extent. well with what you have it will definitely be strong enough. 

here is some other carbon fiber work we did when I raced go karts.


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## Mile Zero (Oct 10, 2012)

That looks amazing man! Nice job, I love carbon fiber so much.


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## SREMotorsports100 (Aug 8, 2012)

thanks! thats just a little bit of work we have done. I grew up in it all so it wasn't hard to access to learn. not bad for 20 years old eh? haha


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## Chaos (Oct 27, 2005)

It mostly depends on the size and shape of the finished product, but overall I'd say certainly no less than 1/4" in general and closer to 1/2" with bracing in any relatively large flat spots.


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## jon w. (Nov 14, 2008)

dear mile zero,

my part 5 article i wrote some time ago answers your question directly. the answer shown in Table 2 will surprise you!

http://www.whitledgedesigns.com/uploads/CAE_part5_oct08.pdf

best regards,
jon


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## Aaron'z 2.5RS/WRX (Oct 24, 2007)

Strong is a function of shape... 

I had a glas box with 2x10 in it, it was 1/8 to MAYBE 1/4" thick and didn't flex.. 

However, It was shaped like a bowl and fit to my spare tire well...(small vid, pre-deadening of the glass)



The "flatter" the glass, the thicker it's got to be, the larger the "flat" area, the thicker it's got to be... 

The more "convoluted" the shape or the closer to a "structural" shape, the less glass is needed... 

On flat surfaces, you can also ADD structural support in the form of ridges (think cardboard) 

This is the rear deck I built for my car (running IB, sealing rear deck) 

It's a layer of 1/2" carpet padding, soaked on the top side with resin (leaving the bottom "soft"), then layered with 3-4 layers of glass, and adding "ridges" 










Looks rough here, but in the end, did just what I wanted and you couldn't tell... lol..


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## cobraa (Dec 4, 2009)

Mine is a bit over 1/4 thick and it never cracked in 2 years


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## Offroader5 (Apr 8, 2011)

Wow, that's a good read!



jon w. said:


> dear mile zero,
> 
> my part 5 article i wrote some time ago answers your question directly. the answer shown in Table 2 will surprise you!
> 
> ...


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## Richv72 (May 11, 2012)

I made my fiberglass box by alternating woven roving (looks like super heavy duty fiberglass cloth) and fiberglass mat. Made it about 1/2-3/4 thick, braced the hell out of the insides also.
making the structure and shape.








Finished and painted.


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## dirtracer27x (Aug 11, 2009)

here is one i did for are ski centurion,was a little over 1/4" thick and very strong,no flex


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## SREMotorsports100 (Aug 8, 2012)

one I did for a buddy of mine 3 months or so ago. just over a 1/4" think and no problems what so ever.


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## the Butler (Feb 21, 2021)

SREMotorsports100 said:


> thank you sir! this was more for cosmetic reasons since the entire box was mdf with cut outs then just the face was fibered. still a lot of work to make it look like that lol. I did at one time do an entire box out of carbon fiber and it came out pretty nice.
> 
> yeah I have never had a problem with anything thats been 1/4". going above though will not hurt if anything it will help to a certain extent. well with what you have it will definitely be strong enough.
> 
> here is some other carbon fiber work we did when I raced go karts.


wow this is amazing work


Aaron'z 2.5RS/WRX said:


> Strong is a function of shape...
> 
> I had a glas box with 2x10 in it, it was 1/8 to MAYBE 1/4" thick and didn't flex..
> 
> ...


I just wodered if that was big enough box for 2 10"s looks to be just big enough for 1 10" just wondering, trying to do research for my upcoming project?


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## doeboy (May 2, 2012)

I have built mine up to .5" and 3/4" right behind the sub itself with the only wood involved being the subwoofer ring I mount the wub to. It thumps. I used chopped mat. While I haven't sanded it down and painted it up to look at it is really rigid. It sits in the corner of my vehicle trunk. It was a fun project to understand fiberglass as I had not worked with it before. THe idea being it would save space in the limited trunk.


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## LBaudio (Jan 9, 2009)

I would say at least 8-12mm thick (1/3 - 1/2 of an inch), but it all depends of the shape and size. If there is a lot of contours and complex shapes then it can be a bit less thick.
In any case, put a layer of damping mats on inner enclosure walls to prevent ringing of the enclosure which is common issue with fiberglass enclosures.

You can also use a rope trick to make braces on the enclosure walls


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