What adhesive to connect lexan to MDF?

[DrewKaree]

I M-U-S-T glue lexan/plexi to MDF.  It's a "sandwich" I am making.  MDF-Lexan-MDF.  In that order.  I need to glue the three pieces together for a project.  

Does anyone know of an adhesive that will join the two materials, or can recommend one?  I've already tried a mock-up with Gorilla glue, but it expands as it dries, and it pressed the materials apart.  White glue or woodworking glue isn't strong enough.  Liquid nails is too thick no matter how thin I am able spread it.  I need the three pieces to be in contact with each other across the entire setup.

The problem is that on everything I've tried, the friggen MDF soaks up anything thin enough to work, and anything thick enough not to soak into the MDF is too thick to be able to press the "sandwich" together.  

[crashwg]

Only thing that comes to mind would be some sort of construction adhesive.  Not too sure on the thicknesses of the different kinds, but you may be able to get away with using one of those slotted or jagged putty knives like for tile work.  That's what I did to affix sheet metal to the solid panels of my ddr hardpad.

BTW, what's this for?  I can't think of anything that would require a sandwich like that...

[Tilzs]

I don't know if it'll work or not but you might want to look at some contact adhesive like what is used to glue down laminate.

[Witchboard]

I don't know if it will stick to the lexan, but you could try liquid nails?

[DeathDealer]

have you tryed contact cement??
When I use it, it seems to stick to everything.  You just put a coat on the wood and a coat on the plexi, let it dry a little and it should stick

[Doc-]

I would go with laminating epoxy.  If you get the thin stuff (used for laminating) you can apply it with a paint roller.

[Safron]

There are cheaper ways to make a bullet resistant cab

[Witchboard]

He says he's sandwiching it.  I'm presuming he's going to put a light on one side so the lexan will glow like a line from the side.  I think contact cement would probably work well, unless it melts your lexan.  Haven't really tried to go lexan to anything before.  Good luck and let us know your results.

[SirPeale]

The Gorilla Glue might work better, if it were compressed itself.  You'd need clamps, and use the glue *sparingly* and spread very, very thinly.

[jcoleman]

You might try priming the MDF before gluing it all together.  Seems like if the MDF is primed, it won't soak up the glue.  Check with the guys at Home Depot on priming the MDF.  They should have something suitable.

Coleman

[rchadd]

maybe use epoxy - the stuff you have to mix together to activate it, spread it thinly on both sides and leave til goes tacky and then put pieces together.

[hyiu]

can you tell us how thick is each layer ??

[fredster]

How about spray adhesive in cans?

[hulkster]

How about spray adhesive in cans?

like that stuff off the blues brothers

[Buddabing]

This guy did something like that. He used bolts for fastening the layers together.

[_Iz-]

use silicone.

[Sylentwulf]

Liquid Nails.

[Witchboard]

This guy did something like that. He used bolts for fastening the layers together.

Damn.. that's a smooth case.  You have to give props for somebody who makes a case from scratch like that instead of just modding a pre-built one.  I'm not sure if this is what Drew is looking for though.  When I was talking about that, I was just presuming that's what he was going to do.  He hasn't come out and said exactly what the project was.  I just don't want to inadvertently take this thread in a different direction than what Drew was wanting.

[Lance]

why not route out a rabbet in each piece of mdf for the lexan to float in and then you are just gluing MDF to MDF..  normal yellow glue and clamps would work fine then.

[DrewKaree]

CRIPES!

I didn't expect this many replies!  I posted and went to bed and BLAMMO!  OK.  

To reply...firstly, what I'm doing with it:  Like witchboard said, it's a sandwich to light it, and the lexan will let the light through as a thin line around my CP.  Each layer will be 1/4" thick (or it's close equivalent) but the botton layer will be more for thickness.  It will be routed to be almost an "outline" to the rest of the CP, mainly to give some "body" to it.  

I'll be using a convex edge bit (I found out today it'll work on the lexan.  I asked about this in another thread) to shape the edge of the CP because T-molding will not work in this case.  Because of this, I need to attach the MDF & Lexan in this "sandwich" so the three pieces aren't flapping in the breeze at the edges where (my kids, most likely) some fidgety person will be constantly picking at it.  I want my CP to have a smooth top with no bolts showing, just a nice clean look, AND I want the light to shine through with no obstructions, therefore, I have ruled out bolting it together.  

I'll try the primer route and the contact cement on Monday.  I'll let you know how that works out.  I can't find a spray adhesive stronger than the stuff I have (3M something-77) around by me.  Liquid nails was addressed in the original post.  Silicone has the same problem as the liquid nails.  I did a mock-up using epoxy.  It heats up as it cures and melts the lexan a bit and screws up the light transmission.  Does someone use an epoxy that cold-cures?  Thanks for all the replies and possible solutions so far.  I've got a full plate this weekend, but if I have any spare time, I'll be giving these a shot sooner than Monday and let you know how it works out.  


As an aside, here's a tip for anyone looking to spread glue evenly and thin....pick up one of those cheap crappy foam paint brushes.  Tear off all the foam.  Take a nibbler and notch it so it looks like a tile trowel (go to HD and look for a "notched trowel" to see what I mean) or some other implement to cut evenly spaced notched in it.  Viola!  A notched, handled glue spreader.  It will evenly spread and remove excess glue from whatever you need.  

Ya know, all your replies and the posts around here made me realize....Bob Vila ain't got $#!7 on us!  We could show HIM a thing or two, ain'a?!

[OSCAR]

Home Depot normally carries the 3M Hi-Strength 90 spray adhesive, as well as the low/medium strength 77 spray.  The 90 spray is very strong and makes a permanent bond.  That would be the first thing I would try for your setup.

[DrewKaree]

Thanks Oscar.  Mebbe I was looking in the wrong section, but I didn't see it.  They had the "77" stuff by the box, and some other "generic" versions of spray adhesive in the same section.  It was with all the caulks.    I'll give it another look, but if it's the same (but stronger), that'll fit the bill PERFECTLY!