So I got my boxes built out of 3'4" MDF. They came out sweet. I glued all joints with gorilla glue and nailed with 18G finish nails. I then started screwing with S.S. screws. Are the screws needed? What a bitch. Drilling and countersinking. What are you guys doing? Going to carpet at the end.
I'm going to mount my subs through the fiberglass into the box. The box is completely enclosed. Should I glue the face of the box to the fiberglass? Or is bolting the sub through the glass to the box good enough? What knind of glue. Epoxy?
Thanks
Thanks, I just thought without screws the constant vibration would disinigrate the box. I plan on using the screws for the actual subwoofer to hold the box through the glass. Then use aluminum angle to bolt it in spots that would not be seen in the cockpit. For structural support.
Thanks SWB, I should send you a rack of beer for all your help!
I'm going to differ with Bob.
Air leaking will only sound bad if it whistles, but the performance of the sub will not be affected. I'd worry more about the box vibrating and rattling. MDF is easy to cut, and works well in a car, but doesn't like being in a boat.
I'd screw it and glue it (and hope you sell the boat before it comes apart).
Ok, first, you're freaking nuts if you think a sealed enclosure won't sound bad if it leaks. We're not talking about leaking in the back of the box, we're talking about leaking around the woofer, create cancellation.
Second, the box is already glued and built. Adding screws to it would be as useful as adding hearts and glitter, it would look good and that's about all.
Sorry, HH is wrong on this.
Hey Bob...it's OK to disagree.
Leaking air does not cause cancellation. Some guys have even drilled holes in boxes to prove no ill sound effect. The only ill effects could be air whistling...but that can happen with a noisy port, too. Of course, I'm talking about small leaks...not vented enclosures.
The glue will only bond the surface of the MDF- screws will add more bonded surface area, which is needed since MDF has very poor structural properties (but decent sound properties because it has consistant density).
Boats beat the hell out of boxes...not just the sub.
Screwing a box after it's glued does not make it stronger, period.
We'll have to disagree on the sealing. We install these exact boxes at least once a week in every Mastercraft we redo, I can tell you for a fact that you can tell immediately when one is not sealed properly.
Since MDF isn't as strong as say...marine grade plywood...then the glue holds, but the surface of the MDF cracks- then the box will rack itself apart. You will still have a nice bead of glue holding on the surface, but the box will be junk. Period.
Screws pull the box from inside the wood, which means that you don't have to rely on a thin area of bonding on the surface to hold the wood together. I guess it depends on whether you want the box to last many years, or just as long as it takes to leave a stereo shop.
In fact, I would never use MDF in a boat again...but I like my stuff to last longer than a couple years.
Small holes do not affect sound wave properties, but they can whistle. I'm not saying don't seal the sub, I'm just saying that air leaks do not affect sound waves.
If you don't believe me on the sealing, try this:
Take two identical boxes and subs...and hook them to an amp in stereo. Drill a couple holes in one box, and cover them up. Then, have a couple impartial people try to hear the difference- you will be amazed.
You can always plus the holes after you are done, so the box isn't ruined.
There's a big difference between drilling some small pinholes and not sealing the sub to the surface of it's enclosure. A big, huge difference. The latter will sound like shit.
Maybe what you are talking about is the sub vibrating against the box. Yes, that will create noise, but it is not from the accoustics changing because the box isn't sealed.
I've personally seen boxes come apart in boats. Nails and glue alone don't work well with MDF. In fact, screws don't work well in MDF, but it's better than just glue.
I think most professional woodworkers will tell you, glue is what holds what together, not screws. Screws provide an excellent clamping mechanism during curing, but then again, so do clamps. We obviously have different methods. Roundabout, my dad was a professional woodworker. It wasn't what he did, but his job required that he construct wood enclosures from particle board. He built guitar amplifiers for Fender and Mesa Boogie. I can remember amps coming back for repair, they had been dropped by roadies or smashed with a guitar. The entire thing was destroyed, except for the glue seam.
In any case, screwing AFTER the glue has dried will not do anything. You fail to address that point, even though I keep pointing it out. His box is built, putting screws in it now will only do one thing, make Havasu Hangin' feel better.
I think you are missing my point. MDF in a boat is not strong enough to be held together by glue alone. The glue (and the surface it mounted to) will remain intact, while the area adjacent to the glued area comes apart. If you have screws in there, it provides clamping force (from inside the wood) that will slow it.
How fast a box comes apart also depends on how the box and sub are mounted. If the sub is horizontal, or the box is bolted to a vertical surface without support on the bottom, every wake you hit makes that heavy magnet try to rack the box. That's why MDF works in cars, but not in boats.
Using MDF, and not putting screws in MDF will only make a stereo shop more money when they have to build another to replace the one that's coming apart (which makes Bob happy).
So I'm no expert but since these guys can't seem to agree... Here's what I did. I took the existing rear seat base that is built out of plywood, and reinforced and boxed in the subs with more 3/4" marine ply. I used a few screws to hold things in place while I epoxied the hell out of everything and made darn sure they were sealed and totally bomb-proof. MDF may sound better but in a boat I just didn't want to take a chance on the stuff disintegrating if it gets wet or beat up. Sounds great to me...
You do know that WFS does every Eliminator that leaves the compound? When we start having problems with the hundreds of boxes we've built, we'll go to a different construction method, until then, it's 1.5" air nails and glue.
I guess that would explain why I had to rebuild the boxes in my buddy's 28' Eagle...seriously.
MDF just sucks for boats. All the good builders use marine ply (but don't use that Kicker crap, either).
Are you just purposely being contrary? I never thought you'd stoop to insulting our shop without some proof that WFS actually did the work in question...seriously.
That's in really poor taste, especially for a "moderator."
I had to replace the boxes in an Eliminator, that is a fact. I would expect anyone who wants to make quality boat boxes will not use glued MDF...but that's my opinion.
Are you insulting my box-making ability? I think that is in poor taste.
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