What epoxy is best for bonding aluminum?

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I need to construct a frame for a project out of aluminum angle stock. I plan to use epoxy to connect everything.

What surface prep and epoxy would be best? (This might be too detailed a question for the GTP audience, but someone might have experience. You never know :))

I was planning to use a wire brush on a drill to rough up the surface, wash it with acetone, and then use PC-7 epoxy.

I was also (unsuccessfully) trying to find a list comparing the characteristics of PC-7 and PC-11 epoxies (as well as any other varieties I don't know about).
 
It looks to me that PC-7 is the way to go, based on the short descriptions, anyway. Provided the aluminum is dry, of course.

PC-11
 
Thanks, TB. I'll go with the PC-7.

I wonder if alcohol or acetone would do a better job of cleaning the metal?
 
J-B weld is an incredibly tough epoxy also.

use acetone or lacquer thinner to clean the metal.
 
Yeah, JB Weld or PC-7 would be the way to go.

If possible, scuff the gluing surfaces up with a little fine grit sandpaper to promote a good bond.
 
Personally, I would TIG weld it, but PC-7 would do the job I guess. As for prep, you could also try a flap disc on an angle grinder, but be gentle, as it won't need a lot of pressure to clean the material. A wire brush could contaminate the surface, and cause tarnishing around the joint.
 
I've gotta vouch for JB weld.

I'd suggest using isopropyl alcohol or acetone to clean the surface. Just be careful if it's a complex part with nooks where the solvent might be trapped. Give the part a good blast with an air compressor after cleaning to get all the solvent out/off or you may get some mild corrosion.

Also, do not use any high rpm rotary tools or grinders for scuffing/prepping. They can create enough heat on the surface to create an oxide layer on the aluminum -and will result in a weaker bond. Do it by hand, or at low speed.
 
A lot of good advice here, frankly more than I expected!

Boundary Layer, you have a good point with the oxidation. I'll use high grit sandpaper as Duke suggested instead.

I'd TIG weld but I don't have access to a welder (and I only have experience with MIG welders anyways). I'm not using JB weld because PC-7 can be had much cheaper (I bought a pound of it earlier today for under $20 shipped).

The parts would be angle stock, so no complex surfaces. I hope I don't loose too many brain cells assembling this thing!
 
My recomendation:
3M Scotch-Weld 2216 B/A Epoxy Adhesive.
It's gray when it's done, but it is the single toughest and best bonding epoxy I've ever seen. 90-Minute work life, and harden/cure time is simply described as "overnight".
Might be a titch hard to find, though. The only way I've been able to acquire it is through my dad, who gets it from the airline he works for, because it's got a mandated shelf life.
 
2216 is a decent structural adhesive, but really more for smaller sized projects...I've been using about 20 years as an optical epoxy to bond optics into mechanical mounts in systems that will be subject to high stress (mil spec stuff).

The shear strength of 2216 is about 3000 psi at 75° F, which sounds great, but falls off rapidly starting at 100° F to about 400 psi at 150°.

Here's a pretty good bonding guide from Hysol/Loctite, that covers a lot of what has already been said in this thread: Loctite Design Guide for Bonding Metals (it's a pdf, so you'll need Adobe Acrobat reader).
 
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