FirebirdNYC

okay so i am attempting to buld my own box , I have the mdf wood, what kind of screws should i use for it. Any sort of glue also? silicone. I have searched and found only mdf related questions but not on what to use to actually build it

Justins86bird

Use wood glue like tite bond or elmers yellow. I use #8 wood screws. Make sure to counterskin them. After the box is screwed together, I also run a fillet of wood glue at all the seems. After a few days drying, seal with caulk.

FirebirdNYC

would i have to distance the screws. I would hate to put to little. Is it bad if you put too much?

PhLaXuS

I would recommend pre-drilling your screw holes because some (but not all) types of MDF like to split. I built a box for an 18" sub when I was in high school shop class just to kill time. I placed the screws about every 3"-4" or so. The only danger I can see of using too many is it will weaken the MDF and make it prone to splitting. If you pre-drill, you greatly reduce that risk.

Also, if you want, try to place some bracing in @ a strange angle to help disperse any standing waves.

Jim85IROC

iTrader: (2)

Keep in mind that the only purpose of the screws is to keep the wood tight while the glue dries. It's the wood glue that gives the box it's strength.

I pre-drill my holes with a 7/64 drill bit. I don't countersink. With a #8 screw, it's got enough grip that it'll pull the screw into the wood, and it'll pull it tighter than if you countersink. If you use #6 screws, then you need to countersink because you'll strip the hole instead of pulling the screw in. With 3/4" wood, as long as you drill the hole in the right spot (i.e. not an 1/8" away from the edge), you won't split or pucker the MDF when you drive the screw in.

The most important part is making sure that your cuts are square and properly sized. If the wood is too long or too short, the wood surfaces won't mate properly, which means the glue won't have enough surface to hold properly, and your box won't be as strong.

Once the box is constructed, use silicone to seal up the seams. Other caulks will probably work fine, but I've found that clear silicone is most effective. Run a bead around all the seams, then use your finger to smooth it into the seam.

Don't install your subs for 24 hours after using the silicone. The chemicals in the silicone can rot foam surrounds.

FirebirdNYC

okay so i got all that down the box is coming along pretty well. Id take pictures but i want to take pics of when the box is done completely. Where can i find the thing that the speaker cables plug into from the amp..any suggestions on where to make the hole for that?

what do you mean by bracing? i have heard of this term before. Do you mean adding angles in the inside of the box? thats what i would think bracing would mean....

PhLaXuS

You can buy terminal cups all over the place, but it's probably least expensive online. My box came without them -- I drilled two holes in the back of each sub chamber, run 10 gauge through and then sealed the holes with JB Weld.

As for bracing, you can use small pieces of MDF maybe 4" x 7" mounted to two of the inner walls of the box for a standard 1 cu ft chamber. The point of it is either: 1.) Structural, 2.) Reflective, 3.) Both. The structural is just for reinforcement mechanically to help make a stronger box and to prevent longer wall runs from flexing outward on hard bass hits. The reflective doesn't do much structurally, but does help acoustically by helping to disperse the types of waves which can build up in a cubic-shaped chamber.

This pic isn't so big, but it should give you an idea of reflective bracing:



And don't make my mistake and purchase stainless screws to mount the subs with: stainless is typically (if not always) softer than steel and I stripped the philips head off in a really bad spot.

Jim85IROC

iTrader: (2)

I prefer to just drill the smallest hole possible, push the speaker wire through that hole, then silicone it up. Terminal cups just provide another location for air leaks and vibrations. The only time I put terminal cups on a box is when the customer insists on it.

Just to clarify on the bracing issue, all you basically need for a sub is some scrap MDF that extends across the enclosure to opposing walls. I like to cut the piece just a hair too big (maybe 1/16" or so) in order to make sure that it provides positive pressure at all times to the opposing walls. The positive pressure on those walls will significantly strengthen the box and reduce vibrations.

FirebirdNYC

okay so basically bracing is making angles in the box so the air wont get trapped in one area. I have alot of rectangle and square areas in the inside of my box, i'll add bracing so the air can flow throughout the whole box...?.


so i really dont need terminals, i never thought of that

Justins86bird

That's what I do too. Cheaper that way

Jim85IROC

iTrader: (2)

No, forget about the angled cuts. Nobody's trapping any air, especially in a sealed box. You're making this way too complicated. Just take a piece of scrap MDF and stick it between 2 opposing walls. Period. That's all you need to do to brace the enclosure.

Let's say that you build a rectangular box that's 10x12x30". That 30" side is long enough that the MDF is going to flex. You need to take a scrap piece of wood and stick it between the two 30" pieces to make the enclosure more rigid.

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If I drew this right, the bold part should be the center brace. Is this starting to make sense yet?

FirebirdNYC

understood.

AJ_92RS

Liquid Nails

Liquid Nails Construction Adhesive is the bomb. Use it for all your joints and your sealer. You won't build a stronger box without it.

http://www.liquidnails.com/adhesives/ln-903.html

Can easily be found at Lowe's, Menard's, Home Depot, etc.

1meanGTA

x3 same thing i did. i didnt use any bracing in my box, but it doesnt flex or anything, and that box is sturdy as hell so i think im ok. i used silicone for the seals and i used some high grade wood glue i got at lowes, can't remember the name. it has a fancy little cap, and comes in a clear and green bottle, glue is a real light brown. very good stuff, i'll see if i still have the bottle. had only one place where i could see light through the other side and i used some elmers wood filler on that. packed it in there so it went all the way through.

have you gotten your rl-ps yet or are they still on backorder?

FirebirdNYC

still on backorder unfortunately. He has 1. I'll just wait for a fresh batch the end of this week