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> Turn signal lens repair, What's the right glue?
bbrock
post Dec 24 2017, 12:17 AM
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I few months ago, I had several tubs of parts take a spill when an overloaded shelf in the garage collapsed. The worst casualty was one of my Hella rear signal lenses. Luckily, it broke cleanly along the glue line between colors. It should be easy to fix, but I'm not sure what the best glue for the job is. Anyone have advice?

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mark04usa
post Dec 24 2017, 01:12 AM
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I've used 3M # 08061 Plastic and Emblem Adhesive. It is clear, and holds well for years.
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mepstein
post Dec 24 2017, 09:12 AM
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super glue, gell type. cost about $2 for a generic brand.
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bbrock
post Jan 12 2018, 09:48 PM
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I finally got back to this task. I wound up going a different way, sort of. I was hoping for a good solvent fusion bond and assume the lenses are acrylic, or maybe polycarbonate. Either way, the proper weld solvent would be methylene chloride. Turns out that aircraft paint stripper is basically a gel form of methylene chloride. That might be what the 3M adhesive is too. But I had a can of stripper on the shelf and an old and busted up tail light lens to test on. It worked great. Nice, strong, solvent weld. I have my good lens clamped and curing now... and the price was right.
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porschetub
post Jan 13 2018, 12:49 AM
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QUOTE(bbrock @ Jan 13 2018, 04:48 PM) *

I finally got back to this task. I wound up going a different way, sort of. I was hoping for a good solvent fusion bond and assume the lenses are acrylic, or maybe polycarbonate. Either way, the proper weld solvent would be methylene chloride. Turns out that aircraft paint stripper is basically a gel form of methylene chloride. That might be what the 3M adhesive is too. But I had a can of stripper on the shelf and an old and busted up tail light lens to test on. It worked great. Nice, strong, solvent weld. I have my good lens clamped and curing now... and the price was right.


Clean very carefully with a loctite primer then use loctite plastic gell superglue,not the $2 shite,considering the value of the lense don't cheap it ok,you will be good.
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rick 918-S
post Jan 13 2018, 07:54 AM
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QUOTE(porschetub @ Jan 13 2018, 12:49 AM) *

QUOTE(bbrock @ Jan 13 2018, 04:48 PM) *

I finally got back to this task. I wound up going a different way, sort of. I was hoping for a good solvent fusion bond and assume the lenses are acrylic, or maybe polycarbonate. Either way, the proper weld solvent would be methylene chloride. Turns out that aircraft paint stripper is basically a gel form of methylene chloride. That might be what the 3M adhesive is too. But I had a can of stripper on the shelf and an old and busted up tail light lens to test on. It worked great. Nice, strong, solvent weld. I have my good lens clamped and curing now... and the price was right.


Clean very carefully with a loctite primer then use loctite plastic gell superglue,not the $2 shite,considering the value of the lense don't cheap it ok,you will be good.


You have a link.or loctite number. I have a light to repair.
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mepstein
post Jan 13 2018, 08:14 AM
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Cyanoacrylate (super glue) is Cyanoacrylate whether it’s generic or a name brand.
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bbrock
post Jan 13 2018, 09:40 AM
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I'm sure super glue/cyanoacrylate would make a fine repair, but I believe methyl chloride makes a superior bond. This is the stuff used to bond plexiglass and I've used it to build water tight aquariums. The trick was figuring out what kind of plastic the lenses are made of to know if this was the right solvent. It chemically dissolves the plastic to allow the polymer chains to dangle free. The chains entangle from both sides of the joint and when the solvent evaporates, you have a strong fusion bond left. I tried breaking my test lens and couldn't. Just tried the same with the cured good lens and the weld is so clean, you'd never know it was ever repaired. Here are a couple pics of the repaired lens, including one with a gallon of vinegar (about 8 pounds) right over the weld. This is being supported by the mount studs, one of which is also solvent welded back on.

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Mikey914
post Jan 13 2018, 11:23 AM
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CA is problematic for bonding this type of plastic. It will but the bond is weak. The best way is to dissolve some filings of the plastic with solvent and bond together. You're treating a thermal reaction for a chemical reaction that has limited depth. It is however the best way to glue these together.
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