Plastics Repair

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runner4065

Filing Flight Plan
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runner4065
What do you recommend for repairing interior plastics? I have a panel that is cracking and want to stop the crack from progressing further.
 
Replace

Alternatively I wonder if the auto body shop guys could heat weld it like they do with auto bumpers.
 
There is a kit for this, its a powder that you dissolve with MEK, then it becomes a googy glue.

there are several

plastic repair kit
 
Duct tape in the inside where it doesn't show.
 
Call Bruce Jaeger at the contact below. He has a system that includes cutting out the crack, applying an aluminum backing, epoxy filling, texturing, and painting. Did an owner assist with him on an old, cracked Mooney interior and it was really transformed.

The process is a bit complicated and technique dependant, but the results are very good. Not sure where you’re at, but if you’ve got a lot to do, it might be worth the effort to stop in and have him assist, or watch him do a panel first.

http://www.jaegeraviation.com/Do-It Yourself Plastic Repair Kit-2017.pdf

http://www.jaegeraviation.com/contact
 
runner4065 said:
What do you recommend for repairing interior plastics? I have a panel that is cracking and want to stop the crack from progressing further.
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Cover panel with fiberglass cloth and squeegee epoxy down through cloth to plastic. Essentially like building a fiberglass wing for an experimantal aircraft. Trim excess fiberglass and paint. Worked great on my panels. Much stronger than original plastic but still light weight.
 
What I've done is buy a fiberglass repair kit from Walmart, Home Depot, etc. It consists of the fiberglass cloth, resin and hardener. I cut the fiberglass cloth into very small pieces and then mix it into the resin with a popsicle stick. then I apply it to the break, let it dry and then trim or contour with a dremel and/or drill if the break is over a screw hole.
 
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Most interior panels are thermoformed from ABS plastic sheet; some might be polycarbonate (Lexan). These materials deteriorate due to exposure to UV light and to a lesser extent through exposure to various air pollutants. So the first step to preservation is to protect them from the sunlight as much as possible and keep the surfaces treated with 303 Aerospace UV Protectant. The kits mentioned above include solvents which will literally melt the plastic and allow cracks to fuse back together (never to be quite as strong as the original panel). If you don't want to spend the time purchasing these kits you can simply buy a small can of MEK and a syringe which will allow you to inject the MEK into the cracked area. First take a hair dryer and heat the material then use the MEK, then clamp or support the joint for several hours. On the back side of the panels you can build up some re-enforcing structure by making a slurry of the ABS material (scavenged either from some hidden panel area or from your kids LEGO blocks) plus the MEK - mix it to the consistency of pancake syrup. Depending on the nature of the crack you might stop-drill a hole where the crack seems to end and then completely fill the hole with the plastic concoction you mixed up. The fiberglass approach is more like putting a cast on a broken arm - not a bad idea if there is room to do this without creating interference, but still fuse the crack with the MEK. One word or caution: MEK is nasty stuff which is absorbed directly into the skin - wear gloves!
 
I've been told to take window screen material from lowes etc., then use abs cement. Haven't tried it yet but people swear by it.
 
The Grumman Tiger maintenance manual has instructions for repairing cracked ABS plastic cosmetic parts. It consists of dissolving pieces of ABS plastic in MEK and using that as a glue. If needed a backing of ABS plastic sheet may be used as a doubler. Turns out that ABS plastic cement used for ABS plumbing drain pipe is just ABS dissolved in MEK and so it can be as the adhesive. 10 mil gray ABS plastic sheet from Amazon works well as the backing.
 
1RTK1 said:
I've been told to take window screen material from lowes etc., then use abs cement. Haven't tried it yet but people swear by it.
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This rear bulkhead was destroyed. Window screen material (fiberglass) and plastic epoxy.
 

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Finished repair.
 

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Depends on how bad it is, for small breaks and cracks I used modelers fiberglass cloth and bind it across the crack using superglue or similar. Then use a lightweight filler (bondo or similar) on the front to fill the gap, sand and paint.

Larger cracks and gaps need more reinforcement and backing.
 
I have a large chunk of plastic missing from my right front door pillar, roughly 1.5" x 3". Here's the part I'm referring to (not my actual part): rightplastic.jpg Seeing that window screen makes me wonder if I could glue that on the plastic front and back to give it strength and then cover the entire piece with a fabric such as a wool blend.
 
I've done a lot of these kinds of repairs on my airplane interior and panel plastic parts over the years with no experience except what I learned while doing them. This is ABS plastic which is very repairable using acetone and making your own ABS "glue" for holes and crack repairs. For additional strength I've backed some of them (the windshield trim) with aluminium tape. I've also repaired thicker plastic like my tailcone using the same techniques supplementing the job with a dremel for "V" shaping cracks for additional plastic fill and a soldering iron for first pass crack repairs. After a sanding and repaint they look and often hold up as good as new. There are many videos on Youtube for doing this on motorcycles fairings, etc. and these take much more of a beating. MEK is an alternative but it evaporates too quickly and is more difficult to work with.
 
First, stop drill any cracks. Then, reinforce. Anything with a fiberglass mesh (fiberglass cloth, fiberglass window screen, etc) can be glued or epoxied to the back to add dimensional stability and crack resistance. After that, you can reinstall, or you can do some cosmetic work on the front of the piece.
 
kyleb said:
First, stop drill any cracks. Then, reinforce. Anything with a fiberglass mesh (fiberglass cloth, fiberglass window screen, etc) can be glued or epoxied to the back to add dimensional stability and crack resistance. After that, you can reinstall, or you can do some cosmetic work on the front of the piece.
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I'd suggest just staying with the ABS "glue" and/or melted ABS rods rather than using multiple materials to make the repair. As you will note from the Youtube videos it is sufficiently strong when melted together, in some cases as strong or stronger than new.
 
The plastic is ABS (acrylonitrile-butadiene-styrene). Fiberglass resin (polyester) and epoxies don't bond well to it. Nothing does, really, except adhesives containing MEK. I've had to repair previous repairs that used those resins. They just fall off.

So you go to the hardware store and buy a small can of that yellow ABS solvent cement used on the black plastic (ABS) drain pipes in your house. You buy some fiberglass cloth (not fiberglass mat, not window screen, not plastic backing). Buy a bit of MEK or the "primer" sold with the solvent cement, which is just MEK. Clean the backside of the cracked part with the MEK. In a well-ventilated area. Cut fiberglass cloth into patch-sized pieces, but pay attention here: if it's a straight crack, cut the patch so that the fibers are at a 45° angle to the edges of the patch. That makes ALL the fibers work for you, since they're all crossing the crack, and they also prevent any shearing motion. If it's a compound curve, that 45° angle also allows the patch to conform to the compound. Buy some cheap throwaway half-inch paintbrushes and apply the goop to the plastic, lay the patch in it, and apply some more over top, not too heavy. Don't drown it. Let it cure overnight.

Of course, some of those panels are just not worth fixing. If they're coming off as big crumbs, don't bother. Check out the Vantage Plane Plastics website.

Edit: It helps to apply some masking tape on the outer side (cosmetic side) of the part so that the yellow cement doesn't leak through. The masking will also help keep the surfaces aligned. Pieces broken right off can be held in place with the masking tape.

For larger parts that need more stiffness, additional layers of the cement and fiberglass add immensely to the repair. They can be laid up one right after the other. It just takes longer to cure hard. Bits of fiberglass that stick out beyond the edge of the part can be trimmed off with a knife after the glue has stiffened up but not gone hard, but it's not too difficult to trim them after full cure, either.
 
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I just rebuilt one of my plastic air vents (that venders wanted $32+ to replace) with some blue masking tape and a small can of black ABS plastic cement. (less that $5 for both) Half of the vent was broken off. After the initial layer was set, I took the masking tape off and applied two more layers. I need to do a little dremel work and some painting now but I'm happy with the result. I regret not using this method before on my other repairs in which I used the fiberglass repair kit but this thread wasn't even around when I did those.
 
Just did this on my Mooney. Used ABS pipe glue (the black stuff) and fiberglass. I was surprised how well it worked.
 
runner4065 said:
What do you recommend for repairing interior plastics? I have a panel that is cracking and want to stop the crack from progressing further.
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You Can put some spare plastic in MEK it will soften it and make it like a tar. you can then use a Q-tip to soften the edges of your piece then add some of the melted plastic from the MEK. Let stand for a day and it will harden back. You can then sand and re-contour. if the plastic is brittle... Just replace. Hope this helps or you can bring it by.
 
Resurrecting an old thread.

MEK is no longer available in California. Is there anything I can use instead?
 
SoCal 182 Driver said:
I've read that. Is it as effective, or will it take longer?
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I've actually never used MEK. But reports are acetone is less aggressive, so it will likely be slower. I used it along with some scrap abs to patch my glare shield. Major problem was my lack of skill, not the material.
 
When you guys get done playing with your chemistry sets trying to melt plastic in acetone...

91%2Bmv%2BSpMTL._SX679_.jpg


This from a guy who used to melt plastic in acetone, then used ABS plumbing cement and then discovered something that works better and easier.
 
Hi Tim,

I've used the Black plastic welder as well... I should have included it in my video too, as it works really well when you want to reinforce a repair and add some strength (I didn't have any on hand, and I don't use it too much). I used it for some areas of the center console refurb on our 210.

Cheers!

Dana
 
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