Acrylic to Glass with Silicone??

[BCOrchidGuy]

I've built my external overflow but am worried about drilling the glass for the bottom of the overflow. I need a 1 3/4 inch hole but the only glass saw is 1 1/4 inch. I could wait till Monday and see if I could buy the bigger hole saw but for only two holes it seems like an extra expense that I could avoid. I've cut the smaller holes and am going to try grinding them out with the rotary tool. If it doesn't work can I silicone acrylic to glass for the overflow and feel secure in it's ability to hold. The acrylic would be 18 inches long by 3 inches wide, 1/4 inch thick siliconed to 1/4 inch glass.
Suggestions? Ideas? Anything?

Doug

[trilinearmipmap]

I have siliconed acrylic to glass to make sump baffles and it worked, however I wouldn't count on if for an application that needs to be strong and watertight.

I have read that acrylic expands by absorbing water, this would throw your seams off. Overall I wouldn't do it.

[adidas]

i had acrylic baffles siliconed to my glass tank..was pretty damn strong.

[fkshiu]

Mixing materials is always a bit iffy. Silicone tends to stick to glass far better than to acrylic.

GE I silicone is "good", GE II is "better" while GE 1200 is the "best" if you can find it. 1200 is what aquarium manufacturers use.

I used 1200 to silicone acrylic baffles to a glass sump and it's watertight, but having to hold up against gravity and water pressure (being an outside pane as I understand your intentions) is another matter.

[BCOrchidGuy]

Thanks for the replies, yes I've got some concerns about the weight of the water, I made the overflow to be about 4 gallons so there is a real concern. I thought about sanding the silicone to give it more surface but I think I'll just head over to Rona and buy another diamond bit and keep cutting.

Thanks again.

Doug

[Tangman]

I think I'll just head over to Rona and buy another diamond bit and keep cutting.


Good idea, acrylic doesn't really bond to silicone any way...

[BCOrchidGuy]

Glass is cut, two 1 3/4ish inch holes. I cut the holes with my 1 1/4 hole saw then used the diamond bit on the rotary tool to enlarge it. Things went well until the clean up when I dropped my drill press on my toe. Usually it wouldn't be a big deal as I wear heavy shoes when working outside with power tools but we are having a birthday party and I didn't want to track all the crap through the house and the nice clean carpets so I took my shoes off at the door.

Anyway, the overflow is all glued up and will be glued to the aquarium tomorrow. When working with bulkheads it's nice to know the holes don't have to be perfectly round.

Doug

[StirCrazy]

don't use silicone as the bond won't be strong enuf to be safe. that is a lot of weight and silicone bond strength isn't as high on acrylic. there are some epoxys that would work good for this but the best bet would be to make your external overflow out of glass.

Steve

[BCOrchidGuy]

Thanks Steve, I've done the glass and got the bulkheads installed, one thing about your post I wanted to ask though is how do you bond epoxy to glass, I've tried it a few times and it's always peeled away with out any trouble. How do you clean or treat the glass so the epoxy sticks to it?

Doug

[StirCrazy]

how do you bond epoxy to glass, I've tried it a few times and it's always peeled away with out any trouble. How do you clean or treat the glass so the epoxy sticks to it?

Doug

you need the right type of epoxy, some are good on non-pourous and suck on pourous and some are the other way and some are inbetween.

Steve