Plastic Welding for The Win

I can now heal broken plastic things and make stuff out of plastic pieces! Very exciting!
It all started with this broken plastic cover for Junior’s clutch fan:


It had both the Big Tear all the way through on top here:

…and the Big Chunk ripped out by the helpful drunk claiming to be an aircraft mechanic in Abilene here:


I had welded it with a soldering iron several times before without adding material, but it just kept breaking. The repair was too thin and brittle. It was very hard to find a replacement part, so it looked like repairing it was my best option. A bit of Googling lead to this:

Viola! With a simple soldering iron, some zip ties for feed stock, and thin wire for re-enforcement, anything is possible!

This longer video with more details was the main one I used:

The key is to keep the temperature low enough that it doesn’t smoke. The smoke is toxic, and also the plastic gets more brittle if it’s burned. This technique can be used to repair any compatible plastic, and also starts to make any random bit of plastic garbage look useful!

The ability to add metal wire re-enforcement and extra plastic fixed everything! Here I used the zip ties not only for feedstock, but also to bridge large gaps in the material like a mesh.



I sunk some thin wire into weak points like corners to make them stronger. You just heat up the metal and it sinks into the plastic, then you cover it with more plastic afterward.


Here it is fat and happy back in the van!


My biggest issue was that none of my soldering irons had wide chisel tips, but instead had needle tips, which suck for this kind of work. I also used too much heat to speed things up, generating a lot of toxic smoke and making the repair more brittle. However, the final result was flexible, strong, and will probably last the lifetime of the part. And I’m very excited to be able to make things out of plastic without having to use a 3D printer or special tools. This technique could also be combined well with 3D printing, where the printer is used to make the detailed, fussy part, but a large block of plastic is added to the end to be welded to something bigger using this technique.

Bonzai! Please work in a well-ventilated area and use a respirator. The smoke is awful!

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