Help needed: How to Seal a Lens / How to remove Barge Cement from Acrylic Glass ?

[Martin]

I was just working on my Triple Rebel bike headlamp, sugar-caster style. The cap of the sugar-caster, net removed, holds the acrylic glass lens.
I was looking for a way to seal the glass to the metal, while the glass doesn't sit on a nicely flat surface that would allow the use of an O-ring.
So I thought, why not use Barge Cement. This would fill any gap that there might be.
What happened is that when squeezing the glass into the metal part, barge cement squeezed out of the gap and got onto the front of the acrylic glass. I knew this was likely to happen and should have covered it. Hmm..:thinking:
The glass sticks nicely, but any clue how to remove the unwanted Barge Cement without doing damage to the acrylic glass ?

Or what should I have used instead ? Silicone could work, but is difficult to handle due to the monster-size tubes. And it doesn't stick like Barge Cement. And hard to get off acrylic glass.

Anyone found a better way to seal a lens to a metal body ?

 

[Torque1st]

Use epoxy or silicone. Use a toothpick to apply the adhesive. Good luck removing the cement.

 

[mahoney]

Barge is "rubber" and some rather nasty solvents. Once dry it might roll off the surface if encouraged with another piece of rubber, like a pencil eraser, rubber band, etc. But it is likely that the solvents in the Barge may have left some surface damage on the acrylic.

Small tubes of silicone are sold in pet shops for fish tank repair, the solvents in silicone might do less damage to the acrylic.

 

[Torque1st]

Epoxy and RTV silicone don't use solvents. They cure by chemical reactions.

 

[Martin]

Great, the pencil eraser did a perfect job. So simple. And luckily no damage from solvents.
I found silicone glue under a different name, they call it "liquid rubber". I've sealed two lenses with this and it seals fine. I have added mechanical support from behind as I don't trust the strength of the glue.

Thank you for the advice, guys. I'm happy I can soon present the finished light in the bike light section.

Martin

Barge is "rubber" and some rather nasty solvents. Once dry it might roll off the surface if encouraged with another piece of rubber, like a pencil eraser, rubber band, etc. But it is likely that the solvents in the Barge may have left some surface damage on the acrylic.

Small tubes of silicone are sold in pet shops for fish tank repair, the solvents in silicone might do less damage to the acrylic.

 

[Torque1st]

Many silicone adhesives can be purchased at any auto parts store. Just ask for "RTV" then look for the adhesive types, not gasket sealers etc.

Many types of epoxy can be found in the same stores.

Whenever you mix epoxy never scrape the surface of the container for the last of the epoxy. The material near the surface may not be mixed properly or in the right proportions.

 

[fxstsb]

You could take a piece of paper and put a strip of RTV on it. use something to maintain a constant height. One it is uniform take your clean lens and roll it along the RTV. It should come out uniform. after it dries you could trim the edge if necessary.

 

[Martin]

Thanks to everyone for the ideas, my new bicycle headlamp is done. Pictures here !