Repairing cracked/broken plastics

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Meatball
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Repairing cracked/broken plastics

Post by Meatball »

So after countless hours searching for plastics for my scoot Ive decided to try and repair mine. There aren't any chunks missing, just cracked everywhere. One piece looks like a road map of plastic with crack veins in a cluster. Im pretty meticulous when it comes to intricate repairs from my model building days as a youth. My question is: What is the best adhesive/glue/epoxy to use for a solid plastic-to-plastic bond? Ive been looking at Loctite A/B Epoxy as in the link below but Im not sold on it yet. Im looking for something I could later sand smooth and paint. The Loctite says you can sand and even DRILL into it when cured...hmmm


http://www.homedepot.com/p/Loctite-0-85 ... /100371824
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Meatball
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Re: Repairing cracked/broken plastics

Post by Meatball »

I once brought my Traxxas Rustler into the local hobby shop and the guy fixed a wheel hub for me. It was a plastic-to-plastic application and he used some sort of liquid that actually MELTED the plastic together on contact. It wasn't hot but I'm guessing a chemical reaction or acid of some sort. Maybe try and get some of that? Not sure what it was.
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Re: Repairing cracked/broken plastics

Post by R1Titan911 »

D@mn I miss my Rustler, Brushless with Lipos!I would be interested too in what i can use for plastic repair. Some tabs are broken (not broken off) and need to be put back in place.
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Re: Repairing cracked/broken plastics

Post by eclark5483 »

At Polaris, we use a 2 part epoxy from 3M, though I don't think it is commercially available, maybe it is, guess I've never looked for it anywhere. I can't remember the name of the stuff the guys at SS C&C used on my Spree, I'll have to ask them, It's some kind of new epoxy that has been introduced, but it's real good stuff too, it's made for automotive and motorcycle plastic. Next time I'm up there, I'll ask for you. Otherwise, there is some stuff called "Amazing GOOP", which I believe you can probably find on Amazon, and maybe your local hardware store that will do a decent job as well. Other options are urethane based construction adhesive. For ALL of these types, use them in conjunction with some fiberglass cloth for added strength.
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Re: Repairing cracked/broken plastics

Post by noiseguy »

Depends on which panel you're repairing and what's wrong with it. Need more specifics.

For Spree side panels... any epoxy will work, just make sure it's high quality and you mix it properly. You should not be repairing top surface with anything other than Bondo (which is itself an epoxy). You will need to reinforce the back with fiberglass. I've found the self-adhesive mesh tape strips used in drywall are by far the easiest to manage and work well for reinforcement.

Cut 2-3 strips, place over back of repair item. Tape front with masking tape to level the front surface and reduce epoxy run-through. Add epoxy to back and work into fibers with stir stick or spatula. When dry, remove masking tape, sand smooth, filler prime, sand, paint.

The tupperware parts (Spree leg shield) can be melted back together with chemicals or plastic welded, which I'll leave to others to describe. These I find rarely cracked, rather dented, and a heat gun can be used to soften and re-bend parts, with patience. For cracks I use above treatment but obviously repair is visible from back in this case.

In any case you can't reinforce the front, sand it, and expect it to look right. It will either look lumpy, or you'll sand away all reinforcement and part will crack again.
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Re: Repairing cracked/broken plastics

Post by MrJumps »

For a strong fix used steel stic and flatten it into a sheet and roughen up behind the crack and apply it behind then bondo the fron. My panal looks like it has never been cracked.
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Re: Repairing cracked/broken plastics

Post by Meatball »

So the glovebox on the Elite has the front blinkers mounted to them like the 87' Spree does and both sides are bashed in. Looks like one side got laid down and the other side mustve just clipped something while riding(not as bad). The actual blinker mounting surfaces are good but the surrounding areas are cracked up. The other pic is of one of the side panels where the tab that mounts to the rear taillight assembly snapped off.
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Re: Repairing cracked/broken plastics

Post by benji »

For abs plastic I've used acetone as a cement - it melts the plastic and allows you to hold it together as it dries. You just apply it to the edge of a cracked piece (both sides) like you would glue. I haven't tried this method on my body panels, but they feel like a type of abs plastic to me so it should work I think. You will still need to reinforce it somehow to keep it from re-cracking.
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Re: Repairing cracked/broken plastics

Post by Wheelman-111 »

Greetings:

This forum rocks! Most anything you need is here. Mousewheels posted this back when flying reptiles filled the skies. Exploring the site, I found this video for polyethylene and polypropylene repair. Watch to the end if you have time. https://www.polyvance.com/Hand-Seamer-1/6146/ This is the material from which the floorboard is made, for example.

The colorful outer shell plastic is a very different material, however. I found epoxy and cyanoacrylate (SuperGlue) not to stick particularly well to it, especially trying to bond small tabs back on. I once posted Quick and Dirty Plastic Repair, but I think the pics vaporized.
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Re: Repairing cracked/broken plastics

Post by noiseguy »

So, for the tab, I'd create a steel piece the size and shape of the tab. Thin steel; 1/16" or less. Epoxy that to the back.

For the shattered grey part, I'd use the drywall fiberglass tape on non-show surface to hook it together, then epoxy. Repaint with rattlecan bumper paint which is a close match on color.

In all cases you should lightly sand / rough up glued areas with 60-100 grit sandpaper prior to gluing.

Just saw you're working on an '87 SE50. I redid one of those once... body looked like it had been dropped from a moving truck; completely crushed. Came out nice when finished.
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