Glue for repairing wall warts and laptop batteries?

Been fixing wall warts and laptop batteries. I'd normally glue them back together with the stuff used for plastic plumbing. But the stuff has a short shelf life after opening and I waste 90% of it. Every time I try to use it, the can contents is solid. I spend $4 on a can of glue to fix a 25-cent wall wart.

So, Is there a glue that works well holding wall warts back together and has a long shelf life? I have no idea what type the plastic is.

Looking for a recommendation that you have actually used successfully.

I really don't want to unplug the wall wart and find myself with a handful of AC when the lid comes off.

Reply to
mike
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Try removing the air with one of these: I'll admit that I haven't tried doing this, but I've been thinking about it for fixing the same problem with rubber cement. Try it and report back.

Nope. The brittle glues, like cyanoacrylate adhesive will crack and you'll have a potential shock hazard. I've done so-so with the rubbery RTV adhesives (not caulk), but they tend to be messy. They also have a short shelf life. Even if you don't open the tube, 1 year maximum is the mfg recommendation.

Solvent welding works. You'll need a syringe applicator to keep from making a mess. Also, lots of ventillation and gloves. Most of the plastic cases are ABS but a few are polycarbonate. My solvent of choice is methyl chloride, also known as paint stripper, which will work with most thermosetting plastics.

For just ABS, straight acetone, or some plastic scrap dissolved in acetone works well. Lots of other YouTube videos on plastic welding.

Your existing pipe glue is a solvent with some thin plastic filler. The problem is that it's rather weak to prevent softening the pipe if overused.

Get a sticker that says: "No user serviceable parts inside".

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Thanks for the link. I'll try the acetone.

For today's fix, I took the hot air rework pencil out to the garage. Heated the seam with 360C air and pinched it together with tweezers to melt it all together. Doesn't look pretty, but I can't break it apart, so guess it works.

Reply to
mike

Yep. It's called "plastic welding". My hot air SMD desoldering tool (Saeke 852D+) produces far too wide a heat affected zone with the standard tips. For big pieces of plastic, such as case parts, it works, but not for small and thin parts like battery and wall wart cases. I also like to work from the back of the plastic part, so as not to make the cosmetic side look bad. That's impossible with batteries and wall warts. I get best results with a tiny tip, high heat, very low air flow, and working fast. As always, there are YouTube videos on plastic welding.

This might offer a clue: Note the tiny tip and low air flow.

I guess I should mention that I tried a narrow nozzle on my heat gun that is normally used for shrink tube. Since I had little control over temperature or air flow, my first attempt blew a hole through the plastic parts. Not recommended.

I forgot to mumble something about the horrors of polyurethane welding. Unlike ABS and PVC, polyurethane is a themosetting plastic, instead of thermoplastic. That means it burns when heated, instead of melting. The fix is to not let oxygen anywhere near the joint by using nitrogen to displace the oxygen. I modified my hot air SMD rework tool to work this way and found that my reflow soldering somewhat improved. See Item #7 at: Typical automotive plastic welder that uses nitrogen: (See speed welding tip) You probably won't run into the thermosetting problem, or need nitrogen, but it's a good thing to know.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Get the clear liquid solvent weld glue sold in glass bottles and with an applicator brush in the screw-on cap at hobby shops and electronics parts supplies, like Testor's #3502 or "TV Radio Cement". They usually work better than lacquer thinner or carburetor/throttle body cleaner. They also have a much longer shelf life than PVC pipe glue.

Reply to
larrymoencurly

I would try a glue for plastic model kits

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Reply to
Martin D. Bartsch

Superglue (cyanoacrylate) works well for me, but don't buy the cheap stuff.

Getting the wall-wart apart neatly is an art form in itself. I use a bench vice (with protectors if the vice jaws are serrated) and try the wall wart in various positions, tightening the vice to probe for the weakest part of the joint. Once you get the seam separated at one point, the rest is easy to gently crack open.

This is a better method than cutting, because it doesn't wreck the seam, and re-gluing with superglue will be successful as the maximum contact area between the two halves will have been preserved.

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Reply to
Mike Tomlinson

Superglue scares me for something that can electrocute me. Works great when it sticks, but doesn't stick well to some plastics. When I'm fumbling around in the dark under the desk, I really, really want the wall wart to come out in one piece.

I've never had much luck with that. End up tearing the plastic instead of separating the joint. I use a wood chisel to whack the seam sharply. Splits nicely, but does break a lot of the overlapping plastic. With the plumbing pipe glue, I can get it back together with reasonable aesthetics.

Reply to
mike

It takes time, but I read on a newgroup you can hold the power supply and just beat on it with a hammer all around the edges over and over again and it will split open, like a nut.

It does work. I told the power supply in fluffy glove and whack at it with a small hammer. All the little whacks crack the welds inside. Everything pieces together nicely with no stretched or deformed parts like you get if you chisel, cut or pry thing thing open. The tough things like laptop power supplies will open up this way if you have several minutes.

Reply to
Cydrome Leader

Some come apart easily, and some will never come apart without a lot of effort. Those that appear to be really welded together are the ones I'll just zip down with a Dremel and cut-off wheel (making sure to not go too deep).

If fixed, I'll either run some solvent in the seam if it came apart cleanly, or stuff it with RTV and rubber band it for 24 hours. BTW, you can make a nice RTV seam by wetting your finger with oil (or spit) and wipe it down to a smooth shiny fill.

Reply to
John-Del

That work, sometimes. These 2wire power supplies, and about 10 more, all came apart with only a gentle tapping: However, the new and improved model power supply from the same vendor could probably survive an attack with explosives. I couldn't tell if it was solvent welded or ultrasonically welded, but it certainly didn't want to come apart. Sorry, no photos of the mess I made with a hacksaw.

I'm partial to the bench vise method of case cracking. If that fails, I escalate to beating on it with a hammer. If that also fails, I beat on the seperation line with a concrete chisel. Last resort, I saw it open with a hacksaw.

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

RTV has the same shelf life problem. And it's GAWD awful expensive. All the stuff I've found at reasonable prices or at the hardware store exude acetic acid.

Reply to
mike

The trick is to use a large wrench to tighten the PVC cement lid down. You don't use a lot of gripping force, or it will crush the lid. But, you use a big wrench so you can get a solid grip on the knurled cap. I've done this for years, and my PVC cement usually lasts a couple years before drying out. You WILL need the wrench to get it open the next time, though.

Jon

Reply to
Jon Elson

Yep. 1 year at best. One part RTV cures by the action of atmospheric water (humidity) on acetoxysilane to form acetic acid. All it takes is a little water in either a porous container or lousy cap fit, and you have a guaranteed limited shelf life. I've tried vacuum sealed bags over rubber cement, silicone, and some smelly solvents, with generally good results. Whether it's worth the effort is debateable.

You can also get two part RTV. The most common types are rubber casting compound and high cure rate production line adhesives commonly used in appliance assembly. For example: The problem is that these don't have any better shelf life than the one part RTV, about 1 year.

You can get non-acetic acid RTV, also known as non-corrosive silicone.

This might be enlightening:

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

I've had good success with the glue that's sold for repairing swimming pool vinyl liners. Seems to last quite a while in the tube too.

Clifford Heath.

Reply to
Clifford Heath

The RTV type 2 stuff smells like alcohol, not acetic acid. I just make sure to get a tube that has a good cap that won't clog up and can be resealed nicely. The GE branded stuff in plastic tube works well. The last tube had to be around $4 at home depot.

Reply to
Cydrome Leader

Got a part number? The GE Silicone II seems to say, non-corrosive, but there are additives for mildew resistance and color change while curing etc. that may or may not be good for electronics. There's a zillion choices with very little info. Some of the stuff says, "use on aluminum, copper, stainless...", but when you finally find spec, it's acetic acid based.

Still, all the ones I've found that actually say, "safe for electronics" are $30 for a 3oz. tube, 99% of which I'm gonna watch harden in the tube.

An actual part number for a product you've actually used successfully on electronics would be helpful...until they change the formula...sigh...

Reply to
mike

I realize some of the problem is in the curing, and in a tight space some of what dissipates during curing may cause problems to metallic components.

But there has to be a distinction between glopping this stuff over electronic components to insulate them (or hide them away so the competition can't see what you're doing) and sealing up the casing. The former seems very finicky, the latter less so. But I don't know how much less so.

Michael

Reply to
Michael Black

Back in the day, I built a pirate TV receiver. Sealed the box with household caulk. About a month later, it quit working. Opened it up and youda thunk it had been under seawater for years. Corrosion everywhere. Had to trash it and start over.

Reply to
mike

I just use this stuff- it's cheap and has a nice nozzle and no threads to get gunked up after the first use. NO oozing messes like with metal squeeze tubes either.

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It's the type II stuff, so no acetic acid. There are "aquarium" grade silicones, but they all use acetic acid. I've also used Permatex "blue" RTV gasket sealant. It's packed with some additive to give it strength, it's also the non-acetic acid based stuff. Never used either on sealed electronics though. Cap makers always warn to stay away from halogens, so plastic welding solvents may be bad news for closing up power supplies.

All that stuff is ultrasonically welded at the factory, so they never have to worry about drying times and stuff like that.

Hell, plain old superglue will probably work fine if you clamp the shells together under some pressure while it all dries. It's cheap and there's quite a bit of surface to be joined so the strength should be excellent.

Reply to
Cydrome Leader

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