I'm starting to discover that JB Weld is actually a "normal" epoxy that has a denser hardener and uses iron powder in its formulation. The prime benefit is it's thermal resistance (to about 500 degrees F). It was designed for repairs on engines and engine blocks. And you guys are right about the comparative cost. It's not cheap, though those little $6.99 tubes fool you into thinking it's cheap.
Here is what I find funny about all this epoxy discussion: have ANY of you had a MMT or fin fail due to the epoxy not holding? Because I've been using off-the-shelf epoxy from Lowes and Home Depot on Mid-power rockets (up to G75s) and I've never had a failure like that. It is my opinion - based on those experiences- that the cardboard or balsa or fiber glass would fail long before even the cheap epoxy. Now, in the L3 world, well maybe. But I wonder if we're all over-buying complex epoxy formulations when even the standard stuff would be fine?
we'd have to do an experiment where we build 2 of the exact same rockets; one with cheap epoxy and one with one of the premium aerospace epoxies. Then launch them both on the same engines, increasing in power until one fails structurally. Then note if that rocket had "inferior" epoxy.
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