VHB for exterior sign - Polycarb to Acrylic?

[DisplayWorks S&G]

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Hello sign making friends.

I am fabricating a “push through” style sign here and wanted some final advice prior to applying the logo and letters. Acrylic to polycarb.

Can I be confident attaching these with High Bond tape only or should I take the extra step and add a few blobs of Lexel sealant as well? The largest pcs are 16in tall.

I’ve never used lexel but see it mentioned on here a lot.

Thanks!

 

[JBurton]

Lip on the acrylic, studs mounted to the aluminum face, holes drilled through lexan to bolt down to aluminum face. But, based on you wanting to mount the two together, I'm guessing you have everything flat cut already? In that case, I hope it's inside... Wait! You have opaque brushed faces? Run a self tapper into a predrilled hole from the back side after double sticking them down! Extra Lexel wouldn't hurt.
Ah ha! Off to the beer store I go...

 

[DisplayWorks S&G]

Lip on the acrylic, studs mounted to the aluminum face, holes drilled through lexan to bolt down to aluminum face. But, based on you wanting to mount the two together, I'm guessing you have everything flat cut already? In that case, I hope it's inside... Wait! You have opaque brushed faces? Run a self tapper into a predrilled hole from the back side after double sticking them down! Extra Lexel wouldn't hurt.
Ah ha! Off to the beer store I go...

 

[DisplayWorks S&G]

I am applying the letters directly to the lexan in this case.

 

[GaSouthpaw]

My .02 is that you'd be better served using a thicker piece of acrylic and milling the material to make your push thru. That way, there's no gluing, taping, etc.
Adhering two different types of plastic together is inviting material failure.
Again, my .02.

 

[ProntoPrinter]

I am applying the letters directly to the lexan in this case.

Southpaw is 100% correct. I have seen a sign like this assembled relying on adhesive, which failed. Several letters fell off, and the ones that didn't would have eventually. You don't want to be liable for someone catching an acrylic letter with their head. Your safest bet is to do as Southpaw recommends so that everything can be secured with hardware versus adhesive. If you've already cut the letters, you're better off starting over than rolling the dice. You'll sleep better.

 

[JBurton]

You don't want to be liable for someone catching an acrylic letter with their head.

Yup, and even in a best case scenario like we had where the letters were low to the ground on an island in a parking lot, you don't want to be apologizing and replacing letters that fell out of a cabinet one cold morning.

I am applying the letters directly to the lexan in this case.

In an ideal world, you want 100% coverage of adhesive to prevent water intrusion/expansion. 3m 467MP is a double stick sheet material that may work for this, all depending on size of materials and letters.

 

[DarkerKat]

If you're dead set on using the 2 layer method, why complicate it with polycarb, use 2 layers of acrylic and acrylic glue which would melt and fuse them together?
(but like everyone else said, milling those push-throughs is the right way to do it)