west epoxy disaster

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HVArcas

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well after 14+ years of using/loving this glue I finally mixed a bad batch. I am going to go ahead and blame my scale which was giving me the battery warning that I happily ignored, and the hunch that there was too much hardener that I also suppressed.

So what now? I have a bulkplate-in-nose and centering-ring-in-airframe that will be easy to clean up, but the drizzled-in-gap fill and the TTW fin root seem significantly harder to abort/clean/retry. Any tips?

Also, should DNA do the trick or do I need to go all the way to acetone?
 

David Schwantz

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What materials? Glass, wood, paper?? This will work for any but may need to go slow with paper. Heat is your friend today. Heat will soften the epoxy, use a heat gun. Do small spots at a time so that you can keep it soft. Scrape with a long blade screw driver or what ever can get inside to the glue. After that, then your heating it up should cause the now, much thinner epoxy to harden. Go ahead and sand the remaining glue and surrounding area to prep for glue again.
 

HVArcas

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Thanks. 3 of the 4 "jobs" i did were fiberglass to fiberglass so not much worry there. the last was quantum-to-wood-to-phenolic (wood centering ring) so that might be more tricky.

So you do not recommend any chemicals? That would have been my first guess.
 

David Schwantz

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As a last resort, maybe. But chemicals will soak into the surface, as the epoxy would also and then weaken any new joint. I would sand with 36 grit before gluing again. i also will use a burr in the dremel and cross hatch surfaces getting them ready for glue.
 

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o1d_dude

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As a last resort, maybe. But chemicals will soak into the surface, as the epoxy would also and then weaken any new joint. I would sand with 36 grit before gluing again. i also will use a burr in the dremel and cross hatch surfaces getting them ready for glue.
Fin pockets.

Awesome.
 

Steve Shannon

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Common chemicals will do nothing to cured epoxy. Some very strong paint removers might attack cured epoxy, but I’ve never found anything that works well. Not only that, but the resins used to bind phenolic tubing or plywood layers together would possibly be damaged as well.
Heat does soften epoxy, but only if you heat the epoxy to the point where it is destroyed. It’s not easy to do that without similarly damaging nearby materials. I use heat to remove Aeropack retainers, but I fully expect everything except the motor retainer to be damaged beyond the ability to use. A cheap chisel heated almost to the point of discoloring works really well for a short time until it cools down. Weller makes knife blades for their soldering guns that look like they would work, but I haven’t tried them.
Mechanical means of removing epoxy have been the most reliable for me. I have a Fein tool that works great if I can get it where it needs to be. I’ve used Dremels as well, but the blades gum up pretty quickly.
Another thing that might help, although I haven’t done this myself, would be to freeze your rocket and then chip away the brittle epoxy. That might also help when using something like the Fein tool because it’ll keep the epoxy swarf from gumming up the blade.
At some point it gets easier to cut away anything that doesn’t look like what you planned and start over.
Good luck!
 

mrwalsh85

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Good practice is to weigh your container, write the weight down somewhere (clearly labeled CONTAINER or some such), then weigh out your hardener, write that down, then your resin. That way if anything goes wrong, you can rescue yourself. My dumb scale likes to turn off after a certain amount of time, so this has saved my hide many a time.
 

David Schwantz

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Fin pockets.

Awesome.
[/QUOTE
Thanks Old Guy. This thing will handle Warp 9 "O" motors:) I layered carbon cloth and the 4 oz glass on the pocket to tube joint. 1 reason I did it like this was I built the fin can before installing, it is a 6 fin rocket, and I could slide the can in and epoxy in place. Then when I installed the fins I just had to fill the pocket with glue. No fillets required this way. Just fillets on the outside.
 

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HVArcas

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Good practice is to weigh your container, write the weight down somewhere (clearly labeled CONTAINER or some such), then weigh out your hardener, write that down, then your resin. That way if anything goes wrong, you can rescue yourself. My dumb scale likes to turn off after a certain amount of time, so this has saved my hide many a time.
Oh I follow a fairly foolproof set of steps, but they require the scale to still be accurate lol

cannot say for certain but fairly sure that is what broke down on me this time
 

HVArcas

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Common chemicals will do nothing to cured epoxy. Some very strong paint removers might attack cured epoxy, but I’ve never found anything that works well. Not only that, but the resins used to bind phenolic tubing or plywood layers together would possibly be damaged as well.
Heat does soften epoxy, but only if you heat the epoxy to the point where it is destroyed. It’s not easy to do that without similarly damaging nearby materials. I use heat to remove Aeropack retainers, but I fully expect everything except the motor retainer to be damaged beyond the ability to use. A cheap chisel heated almost to the point of discoloring works really well for a short time until it cools down. Weller makes knife blades for their soldering guns that look like they would work, but I haven’t tried them.
Mechanical means of removing epoxy have been the most reliable for me. I have a Fein tool that works great if I can get it where it needs to be. I’ve used Dremels as well, but the blades gum up pretty quickly.
Another thing that might help, although I haven’t done this myself, would be to freeze your rocket and then chip away the brittle epoxy. That might also help when using something like the Fein tool because it’ll keep the epoxy swarf from gumming up the blade.
At some point it gets easier to cut away anything that doesn’t look like what you planned and start over.
Good luck!
It is a classy guy that you can argue with in one thread and still get great advice from in another, thanks :)
 
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