Glue Holds Bbox Together, Not Screws?

[KTMrida4life 10+ year member]

If I used JUST glue I know my boxes will break.
Glue makes a good bond, yes, but it doesn't give it much tensile strength. I've easily hammered off baffles of boxes after backing the screws out. This is using titebond II on MDF with screws every 4-5".

Screws hold it much more securely, IMO.

This. On smaller installs it's not a big deal. But with high powered setups that layer of MDF that is glued at the joint will literally peel off and separate that pieces that way. The screws keep the joints from coming apart in that way. Fiberglass for extra strength.

Okay.. a question for both of you two ^^. Whats your opinion if I CANT get screws in? Im building a box in my trunk within the next month or 2 and I can use brad nails everywhere except to put the last piece of the box on.. which will probably be the top. I will not have space to get a brad nailer or any other tool in there.. what do I do then?

There was a video done by AMI Creations a while back and he tested this with just a glue bond, glue with brad nails, and glue with screws. The straight up glue bond failed first, the the brad nails, then the one with screws after a much more significant amount of weight was applied. I can't find the video.

I saw that video.. and at the time thought "Hmm, good thing my box is screwed and glued together"

But honestly.. think about it. IMO I doubt a box really sees ANY lateral force like the test he had setup. IMO a better test would be to make an airtight box with glue, glue + nails and glue + screws.. and then to somehow pressurize it with air. You would be making a bomb.. but just curious at what point something would fail.

 

[RAM_Designs 5,000+ posts]

It's a no-brainer, like boats and hoes.

I'm a pussy Pirate my name is Jack Sparrow, take off my pants so you can see my flesh arrow.

 

[ciaonzo 5,000+ posts]

lulz

 

[murph 10+ year member]

I'm a pussy Pirate my name is Jack Sparrow, take off my pants so you can see my flesh arrow.

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[keep_hope_alive Premium Member]

Screws themselves are failure points, you weaken the walls IMO with a screw into the end of a board. It will be the first place to split. If I want screws I will have corner/edge braces so the screws are inset and not into the edge of a board. But if you want strength, single layers aren't what I consider sufficient. Screws in MDF are less effective anyway, nothing for the threads to hold onto and MDF is well known to **** at holding screws.

I vote multiple layers of 3/4" or 1" MDF with overlapping and glassed seams - screws in that would only weaken it, IMO.

Or build forms, fill with concrete and rebar, coat with bed liner... //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif. Mythbusters made a CMU wall withstand a bomb with bed liner!

 

[keep_hope_alive Premium Member]

But take my comments with a grain of salt... Engineers are known for being conservative with structure. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[KTMrida4life 10+ year member]

But take my comments with a grain of salt... Engineers are known for being conservative with structure. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Did you see my post?

Okay.. a question for both of you two ^^. Whats your opinion if I CANT get screws in? Im building a box in my trunk within the next month or 2 and I can use brad nails everywhere except to put the last piece of the box on.. which will probably be the top. I will not have space to get a brad nailer or any other tool in there.. what do I do then?

Whats your opinion on that?

 

[RAM_Designs 5,000+ posts]

Screws themselves are failure points, you weaken the walls IMO with a screw into the end of a board. It will be the first place to split. If I want screws I will have corner/edge braces so the screws are inset and not into the edge of a board. But if you want strength, single layers aren't what I consider sufficient. Screws in MDF are less effective anyway, nothing for the threads to hold onto and MDF is well known to **** at holding screws.

When I use coarse thread drywall screws and pre-drill, I literally can't strip it without REALLY trying with an actual power drill and not my 24V one. Just an example.

 

[ciaonzo 5,000+ posts]

Did you see my post?


Whats your opinion on that?

Get to glassin', buddy.

 

[KTMrida4life 10+ year member]

Get to glassin', buddy.

There wont even be space to do that. lol

Besides, would putting glass on the outside of a box really do any good? I need like a right angle screwdriver or something.

 

[keep_hope_alive Premium Member]

When I use coarse thread drywall screws and pre-drill, I literally can't strip it without REALLY trying with an actual power drill and not my 24V one. Just an example.

Do you add glue in the screw hole also? I agree pre drill with the proper size hole for a proper screw and you can be successful... But you are a pro. Most people can't make a straight properly sized hole for anything... And use random screws.

 

[keep_hope_alive Premium Member]

There wont even be space to do that. lol
Besides, would putting glass on the outside of a box really do any good? I need like a right angle screwdriver or something.

Fiberlgass and Angle iron outside seams? srs answer

Add interior edge braces to substantially increase surface area for gluing.

 

[ciaonzo 5,000+ posts]

Straight hoes and random screws. I'm writin' this down.

 

[KTMrida4life 10+ year member]

Fiberlgass and Angle iron outside seams? srs answer
Add interior edge braces to substantially increase surface area for gluing.

Not sure on the fiberglass and angle iron.. lol

Will do on the braces. Im having RAM designs do the box.. still not sure what shape/design it will be, but Im trying to squeeze 4 SA 10s in my trunk. Powered off a SAZ 3k..

 

[AStovall 10+ year member]

The screws help with MDF becasue you are only guled to one layer than can peel off unless you are using miter joints or some other fancy technique. But IMO you dont need to go nuts with screws iv seen people go 1 every inch or so...way overkill. But in traditional wood working the Glue is the bond.