Joining fibreglass to aluminum

[watchtherocks]

I want to secure a dome of fibreglass to a flat plate of aluminum.
I know a chemical bond is very hard to achieve, but I want to try an idea, and would like to hear what people on this forum think of it.

If I were to place a positive fibreglass mold on the aluminum, drill holes through the plate just around the outside of the mold, and then insert some screws through the plate from behind, would the fibreglass mechanically adhere to the threads of the screws and hold the dome in place?

I've also got some other ideas for this, but I'd like to check if that basic concept could work before I waste too much $$.

[PAR]

You can successfully bond to aluminum with epoxy. Depending on how much strain the dome will need to tolerate, you may not need the screws. It would be helpful to better understand what you are doing, because as I mentioned, bonding to aluminum with epoxy isn't especially difficult, with the proper prep.

[watchtherocks]

I've had a look at chemical bonding, but I'd like to take a shot at the screw thing first as the dome is going to take a fair bit of stress. 3M 5200 polyurethane sealant seems the way to go through if I want to try anything.

This is the unfinished plate, and the red line is basically where the dome is going.

http://www.boatdesign.net/forums/att...1&d=1250056144

I actually have no idea if the seal is going to be waterproof. I would presume so, but I thought I might also bevel out a thin depression of 1-2mm in the plate and cast the fibreglass into that, that would introduce a 2nd way of securing the fibreglass and it would also mean there would be 3 surfaces water would have to get past, rather than just the one.

[PAR]

Given the choice between a sealant or an epoxy bond, I'd take the bond every time, unless you'll need to separate the two from time to time. If they do need to come apart, then 3M 5200 isn't the goo of choice, you'll want something with considerably less tack, like 3M 101 or a gasket material.

What is the function of this 'glass dome? Is it actually 'glass or is it a polycarbonate or other type of plastic (a really important distinction)? What does the plate attach to and how? Is the 'glass dome loaded? How much stress?

[watchtherocks]

The dome is made of normal epoxy fibreglass. I've never used fibreglass before, but I plan on using vacuum bagging. This is going to be a camera housing, so it will need fairly strong to cope with impacts. Would it be possible to make the seal both strong and waterproof without epoxy?