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Welding plastic (soldando pl�sticos)

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No todos los plásticos se pueden soldar, y algunos de ellos sueldan mejor que otros, pero la mayoría de los de uso habitual en el hogar sueldan bien. Es una lástima tirar a la basura algo que puede ser reparado con muy poco esfuerzo y sin costo. Además es poco amigable con el medio ambiente.

Muchas veces se puede utilizar algún adhesivo para solucionar una rotura en un plástico, y suele ser una buena solución. Yo les presento acá una alternativa gratis, ustedes deberán evaluar la conveniencia de usarla en cada caso particular.

Not all plastics can be weld, and some of them weld better than others, but most commonly used at home do it well. It is a pity to throw away something that can be repaired with little effort and no cost. It is also unfriendly to the environment.

Many times you can use some glue to fix a broken plastic, and is often a good solution. I am presenting here a free alternative, you should assess the appropriateness of use in each particular case.


 
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Step 1: Decide (decidir)


Como dije antes, es necesario evaluar si conviene usar un adhesivo o una soldadura. Eso dependerá de varios factores, entre los cuales no es menor el de la estética. La accesibilidad de la pieza a reparar también importa: si está dentro de un hueco difícil de acceder, tal vez lo mejor sea usar adhesivo. La robustez de la reparación también importa.

En mi caso, arreglaré una banqueta plástica, que presenta dos fracturas que obligan a descartarla o repararla. No me interesa demasiado la estética, porque la utilizaré principalmente en mi taller, pero sí la solidez de la reparación, porque es muy peligroso para una persona de mi edad estar parado sobre una banqueta que se desbarata súbitamente por la rotura de una pata.

La accesibilidad de la rotura era excelente, así que no dudé ni un segundo en inclinarme a usar soldadura plástica.


As I said before, it is necessary to evaluate whether to use an adhesive or welding. That depends on several factors, including not least of aesthetics. The accessibility of the repair piece also matters: if it is within a gap difficult to access, may be best to use adhesive. The strength of the repair also matters.

In my case, I will fix a plastic stool, having two fractures requiring disposal or repair. I'm not too interested in aesthetics, because I will use it mainly in my workshop, but the strength of the repair, because it is very dangerous for a person my age standing on a stool that suddenly breaks down by a broken leg.

The accessibility of the break was excellent, so I did not hesitate a second to myself to use plastic welding.

Very innovative. A friend of mine put an ATV body back together with cable ties similar to your nylon string idea. I will have to try this some time.
rimar2000 (author)  guicarlorobelli1 year ago
Thanks for comment, guicarlorobelli. Sometimes I used cable too, instead of nylon.
Chrislee3 years ago
Great instructable! Thank you. And to "pretty up" the piece, how about the
finishing touch - acrylic nail product from any beauty supply or drugstore?
rimar2000 (author)  Chrislee3 years ago
Yes, it is possible there are many alternatives to enhance the aspect. It depends on each case. Thanks for your comment.
SharpyWarpy3 years ago
Nice Instructable very well done, rimar2000. I like the way you think. I don't like throwing things away either. I have tried welding plastic and the best method I've used is a flat tipped screwdriver and a propane torch. I get the torch going and put it on a level, stable surface. I then introduce the screwdriver tip to the flame just long enough to melt the plastic without burning. It takes some practice but Welding at a colder temperature enables better control of the weld. Of course it all depends on which method you are most comfortable. Your method works well with most plastics. I found it quite tricky with some plastics, though. It might be good to mention here there are many different kinds of plastic some of which lend themselves better to welding than others. Again, very nicely written with good photos. Thank you.
rimar2000 (author)  SharpyWarpy3 years ago
Thanks, SharpyWarpy. My English is precarious, "yes bwana type". Google helps a lot.

In Introduction I say "not all plastic can be welded", but you are right, is better to add "and some of them weld better than others". I will edit the instructable.

The use of the tin solder ensures you will not apply too heat, or at least greatly diminishes the possibility of that happening.
Your English is better and better all of the time.

Many years ago my mother had a plastic water pitcher. It touched the corner of a hot electric fry pan and got a hole in the side. I used a soldering gun like you have and plastic from a bottle of dish washing soap to make a patch. It required several tweaks before I fixed every leak, but it worked for many years. It was very ugly, but she did not mind.
http://castbullet.com/misc/hdpe.htm
rimar2000 (author)  kill-a-watt3 years ago
Interesting, thanks.
rimar2000 (author)  Phil B3 years ago
Thanks, Phil. Google translator is better and better all of the time ;)

Maybe somebody among Instructables readers can contribute with an easy method to enhance the aesthetics of plastic welds... I tried using sandpaper, it is a little solution, but not fix the problem.
You know those fingernail tools that have the multiple sides with varying grits of sandpaper glued to them? They are numbered from most coarse grit up to the finest grit. I've used those with good results. You wind up with a sheen like a polished fingernail. I wouldn't bother unless the repair is in a place that's highly visible and might embarrass somebody.
rimar2000 (author)  SharpyWarpy3 years ago
Thanks newly, SharpyWarpy. I will try that next time. In this case it not worth.
I understand. I had to come up with something when I was building custom headphone amplifiers that were in plastic enclosures. Sometimes modification was necessary to implement all the features my customers wanted which left an ugly spot. I used the aforementioned method to clean it up.
Yes indeed, right there in the first sentence "Not all plastics can be welded". Sorry about that. You are very kind. Thank you for the tip on using tin solder. By the way, I thought your comment in the second photo pointing out the other break showing up in the shadow was pretty cool. Took me a while to understand that was a shadow and the light coming through the crack. Maybe I should change my alias!
karlpinturr3 years ago
Nice, logical solution that I bet we've all considered briefly - just not done anything about it...

The staples idea, harking back to the methods used to repair pots, is a good one for strengthening the weld.

If you're careful, nylon line can be melted/welded by putting a match flame to it for no more than half-a-second or so (maybe not even that long). It won't look pretty, but as it's hidden away anyway, that won't matter.
rimar2000 (author)  karlpinturr3 years ago
Thanks for your comment, karlpinturr.

I tried to weld the nylon line using the solder, but it is not easy. I will try your suggest.