What to adhere aluminum frame to the back of a facemount with?

[P2R2]

What is the best way to adhere an aluminum square tube frame to the back of a facemount?  For the backer layer  I typically used black acrylic.  I have also experimented with haircel abs and dibond type material such as ACM and max-metal.
Since I prefer the black acrylic, what would the best adhesive be for a 100% never fail solution?  So far I have used expensive vhb tapes, a lower cost foam tape, a mix of the two and a methyl methylacrilate 2 part adhesive caulk that has extremely impressive tensile, stretch and shear numbers.  The aluminum  tubing has been anodized, which I now sand off on one side with a belt sander.  In the future I will purchase un-finished  aluminum tube and spray paint on 3 sides as it much easier to paint than sand  There are primers available for the aluminum as well.

Any advice or experience appreciated.  I don't ever want to have a customer callback .

[mearussi]

What is the best way to adhere an aluminum square tube frame to the back of a facemount?  For the backer layer  I typically used black acrylic.  I have also experimented with haircel abs and dibond type material such as ACM and max-metal.
Since I prefer the black acrylic, what would the best adhesive be for a 100% never fail solution?  So far I have used expensive vhb tapes, a lower cost foam tape, a mix of the two and a methyl methylacrilate 2 part adhesive caulk that has extremely impressive tensile, stretch and shear numbers.  The aluminum  tubing has been anodized, which I now sand off on one side with a belt sander.  In the future I will purchase un-finished  aluminum tube and spray paint on 3 sides as it much easier to paint than sand  There are primers available for the aluminum as well.

Any advice or experience appreciated.  I don't ever want to have a customer callback .

Why do you want to use aluminum? I just use square acrylic tubing and adhere it with acrylic glue.
https://www.tapplastics.com/product/plastics/plastic_rods_tubes_shapes/clear_square_acrylic_tubing/142

[P2R2]

I use the 1" square aluminum tubing to add another layer of rigidity to the final product.  I looked at the hollow square tube, but I did not think it strong enough for my larger pieces.

My maximum image has increased from 24x60" up to 36x90".   There is considerable weight.  My face acrylic is 1/4", the backer is 1/8" acrylic or aluminum composite(dibond).

Also the aluminum tubing comes in a profile option to use a french cleat on the top of the frame.

I tried cutting, routing, sawing 3/4" solid acrylic but getting a 45 degree angle was difficult to get a professional look.  I used dichloromethan to adhere.  It is an extremely strong bond.

[Zachary Goulko]

VHB 5952 tape and some pressure. Expensive but instant, and creates an extremely strong bond, so be sure to get the positioning right. I get the same width as the anodized tubing I use so it's flush.