Glue MDF: Is it really necessary

[drpeeb 10+ year member]

low powered system you might not hear a difference, but if there's even a 1/32" gap, you will lose output. if this is for 1,000w+, glue it.

Aaaahhhh .. now that is probably the answer.

Mine amp is 110W RMS/ 160W max with a 150W RMS/ 300W max 10" sub in a non-ported box.

Maybe this combination isn't capable of pounding the boxes screwed joints apart?

 

[drpeeb 10+ year member]

When you stated that you might take it apart and change it...what did you mean by that? Change it how?

I don't have much experience with car stereo subs, and I have very little space in my trucks extended cab, so I want to be able to re-cut/ re-shape/ re-configure the box until I'm happy with it. With this small space I think I need to maximize the sub enclosure as much as possible.

With it still not glued I can unscrew it, replace a panel or 2 or 3, or whatever, and re-screw it back together.

If it's glued I have to start over with new MDF every time I want to try a different configuration.

For instance right now I want to try it ported, so I will still be able to un-screw it to add a port (either PVC or an MDF slotted port) and then screw it all back together.

And, if I don't like the port, I can unscrew it, remove the port, replace any panel(s) I have cut, and screw it all back together again.

Once I have a final, I will probably go ahead and finally glue it. Until then it's a prototype.

I was just wondering if people were pounding their un-glued boxes apart, because I'm not seeing that on mine. It may just not have enough power to do that with screws every 4".

 

[amartin_72]

I use liquid nails and cannot get the boxes apart without the mdf breaking into pieces, not at the seams.

 

[ramos 5,000+ posts]

The thing is ... with no glue at all right now, only screws, my box is holding together great. I did pre-drill the screw holes. So, why do I need it to be glued if it's holding together great right now?
I could understand this if you only put screws in the corners, or like every foot, but mine are 4" apart.

Now, for the sealing issue ... I think I will just caulk the interior joints; Caulk can be removed later.

Main reason for glue is structural integrity down the road. While your screws, brads, staples, boogers, midgets holding it, or whatever seems tight now. They will loosen up their grip on the mdf over time due to vibration, and expansion and contraction of the mdf. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Buck 5,000+ posts]

Use glue, not screws //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

It seals the box as well as it will hold it together much better than screws will.

 

[drpeeb 10+ year member]

Use glue, not screws //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif
It seals the box as well as it will hold it together much better than screws will.

When I do settle on a final box configuration/ shape, then un-screw it, glue it, and re-screw it ... will I notice a difference in sound/ bass?

My seams are all very, very tight right now, although not sealed with anything (it is completely filled with polyfil). I've built homes & buildings, etc. (me not subs!), done lots and lots of shoe molding, crown molding, etc. I'm very proficient with a table saw! (and clamps, screw gun, counter-sinker, router, sander, etc.)

I will post a pic of the worst seam and see what you all think ... just for reference.

Maybe I should've titled this thread: "Glue MDF: Is it really necessary if you have lots of screws, tight seams that are caulked, and polyfil?"

 

[mcsoul 10+ year member]

IF you want to caulk it, then do that. At least it's something. I'm with italyn, how the heck would you reconfigure a box? You going to keep the sides and increase the width? What a waste of

time. Just cut some more wood you cheap lazy bastage.

 

[ramos 5,000+ posts]

When I do settle on a final box configuration/ shape, then un-screw it, glue it, and re-screw it ... will I notice a difference in sound/ bass?
My seams are all very, very tight right now, although not sealed with anything (it is completely filled with polyfil). I've built homes & buildings, etc. (me not subs!), done lots and lots of shoe molding, crown molding, etc. I'm very proficient with a table saw! (and clamps, screw gun, counter-sinker, router, sander, etc.)

I will post a pic of the worst seam and see what you all think ... just for reference.

Maybe I should've titled this thread: "Glue MDF: Is it really necessary if you have lots of screws, tight seams that are caulked, and polyfil?"

Then you should be familiar with the fact that mdf has crappy arse screw holding characteristics. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[thegreatestpenn 5,000+ posts]

the bigger issue at hand is re-using a box in a different "configuration." Even though the price of MDF is rising more and more, its still much easier to just build a new box instead of trying to configure one over and over. the more alteration you do to the current box, the less integrity it will have. It will get weaker and weaker. leak more air after every alteration. All this will lead to less output

 

[Buck 5,000+ posts]

The polyfil won't affect the actual box in terms of how well it's sealed. I've had the sides of boxes stick out a little where the screw went in. Be sure to pre-drill the screw holes and don't use to big of screws. If you have clamps and know how to use them, I wouldn't use screws at all.

 

[ItalynStylion 10+ year member]

Aaaahhhh .. now that is probably the answer.
Mine amp is 110W RMS/ 160W max with a 150W RMS/ 300W max 10" sub in a non-ported box.

Maybe this combination isn't capable of pounding the boxes screwed joints apart?

A ported box MIGHT get away with not being 100% sealed since it's vented anyways but a SEALED box will suffer considerably. I highly doubt you've got wood cutting skills that can provide joints true enough to get you any type of good seal. If you're going to use caulk or silicone to try and seal it up you will have trouble taking the panels apart and changing it like you mentioned.

I suggest that you take the time to plan your setup correctly before you start cutting anything. Heck, build a crappy cardboard mock up, sometimes that helps to visualize it in the car. After you're satisfied with the plan THEN cut everything and build the box the right way with wood glue. Don't try to cut corners because you skimped on the planning. Do it right, do it once.

 

[drpeeb 10+ year member]

IF you want to caulk it, then do that. At least it's something. I'm with italyn, how the heck would you reconfigure a box? You going to keep the sides and increase the width? What a waste oftime. Just cut some more wood you cheap lazy bastage.

Easy!! Simple example: Keep the bottom and top rectanglular pieces and replace the sides with taller or shorter ones.

Why?: My sub maker recommends a 1.0 cubic foot sealed box or a 1.25 cubic foot ported box, and I want to try both.

Nothing to do with being lazy. Everything to do with efficient use of time and materials (aka money) during the test-it-until-you-like-it phase.

 

[drpeeb 10+ year member]

A ported box MIGHT get away with not being 100% sealed since it's vented anyways but a SEALED box will suffer considerably. I highly doubt you've got wood cutting skills that can provide joints true enough to get you any type of good seal. If you're going to use caulk or silicone to try and seal it up you will have trouble taking the panels apart and changing it like you mentioned.

I suggest that you take the time to plan your setup correctly before you start cutting anything. Heck, build a crappy cardboard mock up, sometimes that helps to visualize it in the car. After you're satisfied with the plan THEN cut everything and build the box the right way with wood glue. Don't try to cut corners because you skimped on the planning. Do it right, do it once.

What I meant is ... my sub is currently mounted in a non-ported box. It has the same 150W RMS/ 300W power ratings in a 1.25 cubic foot ported sub, and I would also like to try ported.

 

[99grandprixGT 5,000+ posts]

id glue and screw, but do not go over board on the screws.

 

[bhsdriller 10+ year member]

use glue dumbass