GK fairing cracked. Plastic Repair.

[Burque73]

What I have done is used a standard soldering gun. Let it get up to temp then gently push it into the start of a crack, ensuring it melts both edges of the crack, following with exact same pieces of plastic for your "welding rod" . Works very well. The key is to get the "exact same" plastic as the filler/ welding rod. Go to a wrecking yard and look for the plastic. Should be easy to find. Not all plastics weld to different plastics, they crack pretty easy if your using two different plastics.

That sounds very interesting. Would you make two passes with the iron or melt the new material into the weld in the same pass?

If this is similar to what you're describing, I'd really like to try it.

https://www.youtube.com/watch?v=xnrpxDqn2z4

[2BRacing]

…….I do recall years ago, someone (Dale RustyBronco?) cut up a fairing like this and shipped halfway around the world (SouthAmerica?) and then someone glued it back together.

Yes Dave, it was RustyBronco (Dale) and Chuck Hahn that cut a Vetter fairing up for transport in smaller parcels and shipped it to South Africa, for member Matchless. I thought I had saved the thread that Matchless wrote on putting the fairing back together, but now I cannot locate it. Maybe your or someone else's skills in retrieving old threads is better than mine, and you find it!

Good luck with your repair!

[MR.G]

That sounds very interesting. Would you make two passes with the iron or melt the new material into the weld in the same pass?

If this is similar to what you're describing, I'd really like to try it.

https://www.youtube.com/watch?v=xnrpxDqn2z4

I did both in the same pass, but you could do a second pass with the filler plastic just make sure you get the crack and the filler rod nicely melted so they mix. Either way is fine. If you can do both sides even better.

[Gorminrider]

I've been using a similar method aka soldering iron...with a "widish" tip, push it across the crack, "upwards" or "downwards" to make a little bridge. This will hold your bits together..then, if you want to melt material into it or if you want to add jbweld after, thats ok too....

To hide the crack from the outside, cosmetically, is a bit more involved -ideally, cut a slight vgroove in to fill with the material of your choice....I put masking tape both sides to isolate the fix from accidental scratches while I fair it. Likewise, if you want to prime and paint it without redoing the whole thing....

JBweld now makes a two-part plastic cement that is more flexible than their good ol epoxy. I'm experimenting with it but so far the ol stuff seems stronger. People have said that epoxy is too stiff and a fix rebreaks around it but on a place that is supposed to be stiff and strong, I don't even understand the complaint...

ABS plumbers cement can work too but I've depecrated it in favour of the tack-welding and jbweld...it is harder to fair and paint and takes awhile to adequately harden.

[Redman]

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The soldering gun method seems good and strong, but I think will exceed my manaul dexterity.

[Redman]

Finding the stuff at hardware store:

Went to local bigbox Store (HomeDepot) plumbing section. Saw lots of PVC stuff and no ABS stuff. Lots of choices of PVC cement, and some genral purpose that said for PVC & ABS & CPVC & somethingelse. I asked about ABS plumbing fittings and all the guy said was "what we have is right here".
Over in the paint section, THey had acetone, but only in gallon cans($18). THey also had the KEP.


Went to a larger store (Menards) and found the PVC stuff. And then another smaller section of ABS stuff, mostly white but some black.
And they had cement specific for ABS, small can for 4 bucks.
And acetone in quart cans($8). Got a 1 1/2 inch black ABS coupling for 60cents.

Got the ABS cement in plumbing section, and the acetone in the paint section.


So my advise would be if you you are looking to make the ABS slurry, need to go to a bigger store and look for section that has black plumbing fittings. THe black fittings will likley be the ABS, and will be labled as ABS.
(I dont know where-why would use ABS plumbing verses PVC.)

If going to use the slurry then dont need the cement. But I dont know what I am doing, so got both.

[Redman]

Making the slurry:

Did this mostly as an experiment just to gain some experience.

I cut up half of the 1 1/2 inch black ABS coupling into somewhat little pieces.
Enough to cover about 3/4th the bottom of small tuna can. I cut the pieces mostly so would lay flat on the bottom of the can.
And poured in enough acetone to just cover the pieces.

Did not know what to expect.
In less than a minute the acetone started turning black (right side picture).
After a couple minutes, Took a nail to stir stuff and found the pieces somewhat stuck to bottom of the can, and the pieces were soft on the surface. If did move the pieces together they would stick to each other.

Went to get a fan (should have done that first).

After a few more minutes the pieces were softer. Could scrape some of the soft surface off into the acetone, that was getting darker.

After about an hour, the pieces were lot softer.
At about 2 hours was thick gooie stuff, with still parts of the chunks.
I put in a little bit more acetone, a couple caps full.
But after about 2 1/2 or 3 hours it was getting pretty stiff real quick, and turned back into hard plastic on short order.

Was a good experiment.
Concluded a couple things:
- needed a lot higher ratio of the acetone to make something spreadable.
- if made thinner (more acetone) would be about the same as the ABS cement, smelled the same, seemed about the same. But sure could make a lot more than the little 4oz can.
- slurry would be good for filling in a gap or bridging over an area. slurry can be made thinnner for more like adhesive-cement, or can be made thicker for filing in or for building up (like sidecover posts) or for bridging across a crack.
- seems like if made it too thin, and wanted to add more plastic to thicken up, that would take a while. Maybe better if could make the plastic in smaller pieces, more like with a file or something, or shave off thiner.
- will want a container with a cover, especailly if going to keep it for a while. I put something over as a cover just so didnt evporate as much, mostly for the concern of breathing the stuff.

[Redman]

Playing with the ABS cement:

In the meantime I experimented with the ABS cement and some pieces of plastic I had.
First conclusion was that dont need that big dobber that comes in the can.
Man, that stuff is something of a solvent, but is just thick enough so it doesnt runn too easy (but will if too much). Put a little bit on one surface, and a little bit on another surface, and it softems up the surface. THen put the two surfaces together, and hold, and it solidifyes back to hard stuff, like was welded together.



Concluded that this stuff should work well on my cracks, since they are cracks that fit back together fairly well. Trick will be getting it inbetween the cracks and not out on the outside surface. Which I think I can do by holding the crack open, and using tie-wraps (nylon, I think) of a couple different sizes as little spatulas, then close the crack back up and then hold closed lightly with clamps.

(will report on progress later, well, hopefully progress....)

[robertbarr]

OOOOOO - Klahoma where the wind goes sailing --

Oh, wait. That's 'Surrey'.

Never mind.

[Redman]

. . . . . .

hee hee
(a little more of these fumes, and I will be singing too)

[Steve]

(I dont know where-why would use ABS plumbing verses PVC.)

I don't know what the pressure rating might be for ABS, but in general, you might find PVC on the supply side or the drain side, but will only find ABS on the drain side.

.

[Redman]

...................but will only find ABS on the drain side.
.

Ah, probably why is mostly 1 1/2 inch, and why not in smaller stores.

[Redman]

Used the ABS cement.
Let it sitt clamped together for about 16 hours.

Did somewhat good at getting it into the crack, while holding the crack open. And let it work as a solvent for a while. Then when closed up the crack, some of the cement then came up and out of the crack. I tried to scrape the excess away with a exactoknife, but ended up slopping it around on the surface some. Drat!

If I had some more expereince, maybe would not have put so much in the crack, and/or maybe not try to scrape away the excess (let it harden that way and cut off later). I thought I clamped it lightly, just enough to get the edges closer to each other, but maybe I over did it.

Seems like good solid repair.

After took pics, I tried to touch up a bit with steel wool and then shined up some with armorall. A little bit of improvement in appearance.

[Steve]

You can also thin out the cement just a bit so it's more fluid, then spread a second layer over the rough stuff.

It should dry out as a smoother blob that covers the rough area.

.

[Dogma]

I've been away for a little while, so I hope I'm not too late.

...
Trying to find where I can get some of that toluene.
...

I think maybe you can extract it from trinitrotoluene by the judicious application of heat, but that stuff is even harder to source. Go with the acetone or better yet the stuff for plumbing, as others have suggested and you've already done.

I've done the plastic welding with heat, both from a hot air gun designed for the purpose, and using a soldering iron. It's very hard to regulate the heat. The soldering iron will very quickly degrade the ABS, making it quite brittle. The hot air will soften more than you bargained for, distorting your parts. I'm sure with enough practice it works great.

I'm wondering how much the solvent weld should be trusted. Can you get access behind the repair to add some fiberglass?