Xtreme box building techniques

[shizzzon 10+ year member]

I want you guys to post things here such as materials and bracing methods used to create the stiffest, non-flex box out there and how it's done.

I'm tryin to find some materials so when i go to tear down my wall that i have something to fall back on.

I've came across this but the comments are up in the air... Some competitors say it's good... others who haven't used it say it won't hold up...

Durock...

I had visioned on using 5 layers of 5\16" thick in between 2 layers of 0.75" MDF = approximately 3" thick total material. Then cross brace it with - 0.75" all-thread.

Now, i'm looking for the stiffest out there...

I had read to pour resin in, on and around each Durock layer wedged in between the MDF to prevent air pockets between each Durock layer.

Do you guys have other suggestions for making a very stiff box?

I prefer not to use just concrete but rather material ready products.

Click to read more...

 

[basscort2009 5,000+ posts]

what i have found thats indestructable. is glue the joints. then screw together the box with 1 5/8 screws unless double walling then use over 2 inches. than resin the entire box inside and out at least 2 layers. then use automotive GOOP for all the seals and seams so no air leaks. then use 1.25 inch dowel rod or .75 all thread every way! up and down, left to right and front to back. then u should have a tank of a box

 

[shizzzon 10+ year member]

while i do use allthread currently.. it's not enough.

Allthread needs some sort of grab besides just large washers..

I need like a large steel plate for the allthread to grab with so the all-thread's strength's dispersion radius is a lot wider than a few inches.

Allthread keeps the walls intact, sure, but it still doesn't help prevent flex completely.

I've got 5 runs of it in my wall and it's not that i need more, i need a stronger material as well.

I'll keep the Goop in mind tough

 

[schackel 10+ year member]

good thred idea. i will be creeping the whole time

 

[basscort2009 5,000+ posts]

while i do use allthread currently.. it's not enough.
Allthread needs some sort of grab besides just large washers..

I need like a large steel plate for the allthread to grab with so the all-thread's strength's dispersion radius is a lot wider than a few inches.

Allthread keeps the walls intact, sure, but it still doesn't help prevent flex completely.

I've got 5 runs of it in my wall and it's not that i need more, i need a stronger material as well.

I'll keep the Goop in mind tough

bolts and lock washers on the inside and outside of the box. so 2 bolts and 2 lockwashers PER side of all thread.

 

[shizzzon 10+ year member]

yes, that would be to secure it.. but the thing i'm sayin is... where to get it at?

The only steel i ever see at Lowes are steel runs, steel bars... i need a plate, a steel square. I don't know where to find one..

I'm assuming 1\4" thick is thick enough. Just get 2 plates for every exiting all-thread and bolt them together.

 

[JimJ 5,000+ posts]

Concrete.

 

[basscort2009 5,000+ posts]

Concrete.

reading > you.

anyways OP just go to a hardware store and look. like ace or somthing. not lowes and home depot

 

[shizzzon 10+ year member]

Durock is already made concrete and fiberglass... has nobody any experienced knowledge about this stuff for SPL?

 

[mlstrass 5,000+ posts]

either buy some plate steel and cut/drill it yourself or get fender washers at ACE or wherever since they're oversized.

I don't see how resin alone would add any strength to a box....

Window bracing that ties all the sides together is VERY strong.

 

[mlstrass 5,000+ posts]

11ply baltic birch is a LOT stronger then MDF. My wall is 1.5" thick using BB and triple baffled plus a 2x2 between the subs.

How big is the wall you plan to build?

 

[shizzzon 10+ year member]

it may not be a wall... i currently have a wall that flexes like crazy in the rear.

Small car, not lots of room.

It's single sheet 0.75" mdf in the back. I got a single 3\4" allthread ran from it to the baffle. i got 3 runs of flat steel inside that wall that is bolted through to the other side but it seems like that doesnt help at all...

It's like the steel doesnt flex.. just the whole wall is still moving and the steel is just along for the ride..

I need to figure out a way to add additional bracing to this back area before i tear it down next year...

I'm thinkin about using some LARGE Steel L brackets and wrappin them around this back wall section. the back part is 29" high so i figured i get 4 12 x 12" steel l brackets bout 1\4" thick and secure them to the outside AND get 4 more for the inside and bolt them together. That should hold lot better than what i got now.

I'm doin 153s at the head now and 156s in the kick.

Once i decide to tear this down, i want to form a shell from the b pillar back throughout the car made out of mdf.. but i guess BB now and Durock behind it or just 13ply BB and 1" square steel tubing behind the BB to form the shell to make it stiff as hell.

that way whatever design i build will be built inside this shell.

I got plenty of more power to add to my existing setup anyway before i do another design.

I'm runnin 4 dc level4 15s off of only 7,000w right now.

I'm gonna try to tweak the design until nothin else works then i'll drop my amps and go with 24,000w and see if that does it.

I'm only 3.5db down from the world record in the division i'll be runnin in that was set last year in MECA..

This is my first year running in MECA so i'll see how i do.

 

[shizzzon 10+ year member]

ok, i found some Steel L brackets.. they pretty expensive too!

1\2" thick, cold Rolled Steel - 18" long x 14" long.

$36.99 per bracket.

I'll need 12 of them to try and keep this flex to a minimum.... looking for a cheaper version...

 

[pr-festiva 10+ year member]

it took alot of work to get the flex out of my wall, wound up taking many layers of wood and i was only running 3k.im going to be trying 3/4 inch cast aluminium plate some time next season on a small box and see how it holds up.

 

[spltuscon 10+ year member]

Lowe's sells 1/4" thick steel plate, its right next to the allthread, mixed in with the sheet metal.

Window bracing is the most effective thing I've seen, but might cause some turbulence. If you have any room behind the wall, you could use 2x4's externally, going vertically from top to bottom.