Epoxy to aluminum RIB floor?

[HopCar]

I think what is happening is that aluminum expands and contracts quite a bit with temperature changes. The epoxy isn't flexible enough to move with the aluminum.

3M 5200 might be flexible enough to stay bonded. If the aluminum gets hot enough, even 5200 will let go, but I think that would take the heat of a torch.

Another option would be 3M VHB (very high bond) double faced tape. I believe it is used to bond aluminum panels in aircraft.

[HopCar]

Here is info on the VHB tape. Says it sticks to aluminum and sealed wood. With all the epoxy you've put on the wood, I think that counts as sealed.
3Mâ„¢ VHBâ„¢ Tape 4979

[Paul L]

VHB is an interesting possibility. Sometimes you need the special primer to get a good hold.
I had decided to re-do the attachment with 5200, but stuff got in the way. First my tube of 5200 that I had stuffed away turned out to have gone off and was hard. Then I stopped by the only place I could find 5200 in Fiji. They only had the large tubes at usd$40. So it's on hold for now.

I do have a roll of VHB but it is really narrow, so not sure it work.

[SecondBase]

Originally Posted by a64pilot

On aircraft we bond aluminum vortex generators to the aluminum wing with Loctite depend adhesive, pretty strong bond, but it's not wood though

Maybe bookend the wood with Aluminum C-channel & screw together. Then use Loctite to bond the aluminum deck to the aluminum of the C-Channel.

[minaret]

If you must bond to alu as opposed to fastening, Belzona. As for getting it on a plane, dunno...

http://www.belzona.com/en/products/1000/1111.aspx

[Cheechako]

https://www.youtube.com/watch?v=EfHAccRW0PQ

[Paul L]

Originally Posted by minaret

If you must bond to alu as opposed to fastening, Belzona. As for getting it on a plane, dunno...

Belzona 1111 (Super Metal) composite

Surprisingly the msds says " Non-regulated for transport under current Domestic, or International Air and Sea Regulations ".
Would this stuff be too brittle yo withstand the AL dinghy floor flexing?

[Paul L]

Originally Posted by Cheechako

I don't have the bandwidth to watch videos. Clickbond is restricted as a hazardous material for shipping. It sounds like it would a perfect choice for the application.

[sailah]

VHB tape is awesome but super expensive in wider widths. I have a bunch of it that was sent to me by 3M to test on bonding low energy plastics. Used it for a lot of projects and a little goes a long way.

I'd be trying a 4200 or 4000 adhesive sealant. Doesn't sound like this is really structural and those are easier to remove.

[minaret]

Originally Posted by Paul L

Surprisingly the msds says " Non-regulated for transport under current Domestic, or International Air and Sea Regulations ".
Would this stuff be too brittle yo withstand the AL dinghy floor flexing?

No, it's made for exactly this sort of application. But it's $$$. Over 3k psi to debond, it's basically as good as a weld if done properly.

Note that click bond sells several different adhesives for bonding their hardware in place. None will approach the bond strength of Belzona on alu. No reason you can't Belzona on a click bond fastener, though.

[Suijin]

I would consider having the platform fabricated from aluminum and welded on, depending on what it is for.

[boatpoker]

I did exactly what you are attempting for a bow platform for a fuel tank and has worked fine for the last year.
Aluminum roughed up with 40grit, cleaned with acetone and bonded the wood to the aluminum using System 3 epoxy on two layers of 4" wide, 8oz. glass tape.

[Paul L]

Originally Posted by boatpoker

I did exactly what you are attempting for a bow platform for a fuel tank and has worked fine for the last year.
Aluminum roughed up with 40grit, cleaned with acetone and bonded the wood to the aluminum using System 3 epoxy on two layers of 4" wide, 8oz. glass tape.

I'm bonding it further aft under the seat. This is a thin skinned AB and maybe it flexes more than yours. My epoxy has cracked off twice now.

[boatpoker]

Originally Posted by Paul L

I'm bonding it further aft under the seat. This is a thin skinned AB and maybe it flexes more than yours. My epoxy has cracked off twice now.

Single skin Highfield 9' 2"