Restoring broken plastic parts

Hi guys, I wont try to make you believe I invented something but Im practicing the art of restoring broken plastic parts and I would like to show you how you can do it. For example I took a part of a seat hinge side cap. Theses parts breaks easily, there is no real way to make it hold proprely once they are broken and are costly ( They were priced at 190$ each but now they probably went up to 10000$ a side as we speak....) Joke aside, I found this particular part pricey for what it is so In my atempt of restoring my car to its original beauty I repaired mine a while ago using this very simple technique. My friend had theses 2 pieces laying around, broken by the past owner so I showed him how to do it and decided to take a couple pictures at the same time. Please note that it took 20mins to complete so the part still shows few sings of old age but I guess you get the point... a solid piece of plastic that can be re-used. So if you ever break a plastic part dont panic and try to keep all bits you find. First, use something like crazy-glue to hold the plastic parts together. A few spots here and there should do it. Next grab a soldering iron.. Not any kind of soldering iron especially the nice ones that come on digital soldering station..... A workhorse like this one will do the trick: Next step is to go over every crack and seams to weld the plastic together inside and out depending on the surface finish. If the surface finish is a leather imitation avoid going on the outside of the part and do the major soldering from inside: As you can see the finish look rough so you need to sand down, apply puttey if needed (I didnt do this step) and dye to your favorite color. And voila, I could have taken time to finish this project and re-use the part but there no point at the moment. Again this is just a quick example as my friend really wanted me to share the process I did this real quick. Once done nobody could tell it was broken before and its solid as it was. Hope it will be usefull to the ones restoring their cars, or repairing their kids toys, or wife stuff and so on! Hugo

Plastic parts get brittle faster than we like, and once they loose that ability to flex, results are pieces. I have tried adding other similar fillers, shapers, epoxies, I haven't tried Weller big watt gum.

Try the Urethane Bumper Supply Plastic Reweld kit. Comes with a special plastic rod for welding the pieces back together, been using it professionally for thirty years.

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I use ^^this^^ as well. It works ok, but depending on the type of "plastic" (of which there are MANY) the results vary. I also use a "hot air plastic welder" - same deal (works great on certain plastics, not so well or not at all on others). The bottom line is that my brain tells me it's always worth it to try fixing something that's broken - the time clock doesn't always bear that out though (although on expensive pieces it usually does). In my experience, the fixed part is rarely as strong as the original, so if it's something that relies on structural strength/integrity, you're usually better off just buying a new/used one that's in one piece...

You should add a little more plastic instead of just melting what is left on that piece. It will make ti stronger. BUT instead of some fancy "plastic welding rod" just try using strips from an used oil can or other plastic containers laying around the house.

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Sure you could do that, however the � special� plastic rod has carbon fibers in it for strength plus is formulated to adhere to 99% of all plastics used. I do this professionally on aircraft , and exotic vehicles locally

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Is carbon fibre really needed when the native material didn't have any?

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It probably adds some (needed) strength to the repair... FWIW, I've found that adding some fine mesh screen (not the stuff they give you - unless it's something like a underbody panel-unseen) to bridge the break works better than just the plastic.