Super strong glue for plastics

[voir dire]

The JB Weld 24-hour cure is the best, but on a small surface like a pump bracket where the glue must stay only within the broken area, and which can't even be clamped let alone pinned, nothing will be as good or better than the original molded plastic. That joint will always be fragile and will eventually crack again. A new bracket might be the better option.

[Black Dog]

Originally Posted by Veloo

Thanks.
Does a tube have much shelf life or does it tend to dry up like Krazy Glue after the one application?

Long shelf life. The syringe seals well after each use. Very well designed. I have about 7 separate uses out of my current syringe over the last year.

[Mikej]

What about a solvent like PLASTRUCT?

[Tony]

I would just weld it. Use a heated spoke with a flattened tip and knead the two sides together. Use a zip tie as a rod to fill any voids.

[Clancy]

Originally Posted by p nut

My pump mount cracked earlier this year. I just used super glue and sprinkled baking soda on top of it. Instant bond and is holding so far.

Why the baking soda?

I’ll pile on the praise for JB Weld, good stuff.

[jemoryl]

There are really two ways to bond plastics: glues like epoxy (e.g. JB Weld) and chemicals which fuse the plastic together. The latter often used for polycabonate: clamp the items together and introduce the solvent which fuses the two parts together. Or, if you ever made model cars or airplanes, polystyrene fused together with toluene based 'glue'.

Epoxies usually hold out well if you don't mix the two components. Sometimes I prefer individual tubes rather than the syringe thingie for just this reason.

[Veloo]

Lezyne describes the material as a "composite matrix frame pump mount".

[2LeftCleats]

Does the JB Weld stand up to heat? I’ve tried a couple different glues for a plastic light fixture, but the heat of the bulb caused failure.

[jemoryl]

Originally Posted by 2LeftCleats

Does the JB Weld stand up to heat? I’ve tried a couple different glues for a plastic light fixture, but the heat of the bulb caused failure.

Most epoxies don't hold up to heat very well. But when you say heat, I'm not sure this would be an issue for a bike application. We used to mount optical components on a table with 5-minute epoxy and then use a heat gun to soften and remove - quite hot.

[Veloo]

Came across this vid as I'm searching for the J-B Weld Plasticweld syringe which no one seems to carry in Toronto.

May be other out there vids with similar tests.

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

[Veloo]

Whoops, didn't realize BD already posted this.

Originally Posted by Veloo

Came across this vid as I'm searching for the J-B Weld Plasticweld syringe which no one seems to carry in Toronto.

May be other out there vids with similar tests.

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

[spank]

Originally Posted by Tony

I would just weld it. Use a heated spoke with a flattened tip and knead the two sides together. Use a zip tie as a rod to fill any voids.

+! or a soldering iron that you don't care if you get melted plastic on.

[Bob Ross]

Originally Posted by spank

or a soldering iron that you don't care if you get melted plastic on.

When I was a kid in the early 1970s I had a "hot knife" for modifying all the plastic model cars I built. It was essentially a soldering iron with a removeable/replaceable Exacto Knife blade for a tip. Nowadays I think of a use for one maybe once a year...but if it were any more frequent I'd definitely try to find one. I presume such a tool is still made?

[voir dire]

Originally Posted by 2LeftCleats

Does the JB Weld stand up to heat? I’ve tried a couple different glues for a plastic light fixture, but the heat of the bulb caused failure.

I have used the 24-hour cure (grey color, 2-part) JB Weld for exactly that situation, repairing a broken plastic lamp housing, with 100% success.

The housing holds not only the bulb but also the 3 "arms" for the heavy shade, so it is under constant stress. The tabs that held the "arms" broke off when the housing fell and cracked. The JB Weld has held up perfectly, at least over 5 years now, with hot 100W incandescent bulbs which are on all evening every day since it is a lr lamp, for much of that time (the new ES LED bulbs are much cooler). No issues at all, still solid as a rock.

[fmradio516]

had an incident with the mountain bike the other day and broke my Hammerhead GPS mount. I have replacements but theyre kinda lightweight and idk if theyd hold up to the heft of the Karoo.

Got some of the JB Plastic Weld and did my worst. Very messy but i dont care.

Also, warning, this stuff is pretty thin compared to other epoxies and regular JB weld. Comes out fast.

Will find out in a couple days if it holds up. Not sure how only a 30 minute cure could be...

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