fiberglassing inside of boxes

[snb778 5,000+ posts]

yea... are you using actuall fiberglass mat, or sheet, or just pouring resin on the box...

again.. glass needs to have curves and twists and turns to gain full strength... unless you add like 3+ layers on a square box.. its not worth the time/cost vs just using proper bracing

 

[Jeremy M 10+ year member]

it won't help brace it...only make it air tight. u need to add mat and some other forms of bracing.

 

[phemps 10+ year member]

A... air will pass through it cause its not solid?? WTF you talkin about??
B. Resin will not add any kind of bracing to the box.. might act as a filler like caulk or glue or bondo

C. MDF is not solid?? wtf you talkin about

D. FIBERGLASSING the entire inside might help a little bit... but thats dam expensive for the POSSIBLE result.

E. Fiberglass gains its strength with curves and turns... you've never seen a whole SQAURE or RECTANGLE box made outta fiberglass... Most boxes with fiberglass have the base of the box made with MDF, and then just the top (which is usually curved or rounded somewhat for the cosmetic appeal) is made with fiberglass

F... so, did you fiberglass the whole inside, or just cover it in resin

G.. MDF is not solid and air will pass through it... WTF??

ahhhahaha this is exactly what i was thinking. maybe he has mistaken mdf with swiss cheese? its a common mistake:fyi:

 

[phemps 10+ year member]

yea... are you using actuall fiberglass mat, or sheet, or just pouring resin on the box...
again.. glass needs to have curves and twists and turns to gain full strength... unless you add like 3+ layers on a square box.. its not worth the time/cost vs just using proper bracing

i have alot of mat laying around. i was just gonna say fucck it and try it just for the hell of it. i can see what you mean with the curves of the boxes added the strength but at least if i can do 2 layers it should be a nice seal. unnescesary but oh well

 

[snb778 5,000+ posts]

seriously.. if you're just doin it for the deal... good cuts+glue+caulk should be PLENTY.. .you can use some resin w/o the mat for the edges and corners to be EXTRA safe... but covering the whole inside of the box is completely un-necessary... if it worked.. people would be doin that in comps all the time... and I don't think anyone even does that.... 2 threaded rods in each direction (up and across) would work MUCH better IMO

 

[thegreatestpenn 5,000+ posts]

from my understanding glass as stated before only helps seal better. it only works on curves so a square/rectangular box using resin for strength is senseless. threaded rod or 2x4's is the way to go.

also double baffle doesn't help much either, but it will keep a heavy heavy sub from bending screws out of the baffle.

also if you do a slot port, the port itself as some measure of bracing.

 

[Walled_Taurus 10+ year member]

What he is saying is MDF is porous. But resin is not. Build the box with double baffle and put 45s in the corners of it. Listen to it, meter it if you can, then take the sub back out and resin the inside and listen to it then. Better role off and should actually gain a little spl cus all that pressure is being maximized and not getting lost due to the fact of it it going through the pores of the mdf. It may not be audibly louder but on a meter you might gain a couple 10ths. And resin does add reinforcement. Not a shit ton but some.

 

[BassMechkanic 10+ year member]

MDF porous,-----i did not beleive it myself until i saw the vacuum test, with shop vac and a piece of 3/4 mdf 12" square, **** the mdf and pick it up, then place another piece under it again, picks both up, and tried a third it started to pick up then fell!. There use to be a utube video of this.. And i have seem many high spl boxes coated with resin - inside and out!

 

[snb778 5,000+ posts]

that test is interesting.. im going to have to try it myself though to believe it... something tells me im going to prove you wrong, but we'll seeeeeeee.

i don't think i've seen one SPL setup on here or wall that was covered in resin for that reason.. nor have i even seen or heard of a setup where doing that increased numbers... but I guess its possible.. I see its possibility, just not probable

 

[hatedonmostly 5,000+ posts]

it won't help brace it...only make it air tight. u need to add mat and some other forms of bracing.

This. And it'll strengthen, but not brace it. Those are two different things.

 

[JimJ 5,000+ posts]

Can someone explain to me how fiberglass mat only has strength as a curve? Can someone explain how a perpendicular layering of material isn't going to have structural integrity no matter what the shape of it is?

Not talking about what's economical, just...//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[nineball 10+ year member]

mat does have strength on a flat surface, just no where near what can be achieved on a curved surface. as stated most quality fg enclosures use as much mdf as possible because it is stronger than fg on flat surfaces (relative to cost), cheaper and much easier to work with. in most cases if you have to use fg alone on a large flat surface it is best to incorporate some form of bracing like pieces of nylon rope.

think of an arch. if the top was straight it would not have the same strength as a curved arch. check out the roman aquaducts.

 

[basshedz06 10+ year member]

as stated a few times fiberglass adds strength to the box not bracing. it does cut down on box flex but if an i man if your gonna do the inside an your doing for spl reasons i would say get a foam roller an do the inside you want that inside as smooth as possiable,

i have put my hand inside some fiberglassed boxes(without fiberglass in this sentence that would totally be funny lol) an felt the insides an it be like glass. a buddy of mind did it once an it was really smooth it was like touching a clean window.

 

[snb778 5,000+ posts]

Can someone explain to me how fiberglass mat only has strength as a curve? Can someone explain how a perpendicular layering of material isn't going to have structural integrity no matter what the shape of it is?
Not talking about what's economical, just...//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

kinda of the same concept as building a bridge... I remember back in middle school we had a project to build a bridge with tiny little sticks, then they would apply pressure to it and see whos was the strongest... we were all taught that the more curves (instead of a straight line) and criss crosses for the supports, the stronger it would be

 

[phemps 10+ year member]

MDF porous,-----i did not beleive it myself until i saw the vacuum test, with shop vac and a piece of 3/4 mdf 12" square, **** the mdf and pick it up, then place another piece under it again, picks both up, and tried a third it started to pick up then fell!. There use to be a utube video of this.. And i have seem many high spl boxes coated with resin - inside and out!

ill have to try this too... never would have thought it could be that pourous. in theory if suction through one mdf board can pick up another, then you shouldbe able to feel slight air movement on the outside faces of the box? or maybe its unnoticable due to the vibrations of the walls anyway it feels like it moves a little air. either way im def gonna resin the innerr surface of my box after hearing this