How would you know if you made it stronger?Originally posted by Mad Rocketeer
Can JB Weld be amended like epoxy? Fillers? Hardeners/Strengtheners? Balloons? Can it be rendered more sandable, lighter, less brittle, more heat resistant, etc.?
JB Weld for the heat exposure, definitely. That's what it's for. I'm sorry I didn't use it in all such places on mine. I do now. The savings in lost fins justifies the small difference in weight. And rather than try to use different epoxies between the body and motor tubes, I just use it on all parts that have even some contact with the motor tube.Originally posted by Mad Rocketeer
My thought was to possibly use JB Weld for my LOC Graduator's fin-tab-to-MMT and CR-to-MMT joints and fillets, since these locations are likely to get pretty hot. My understanding from other posts here is that epoxy will or may weaken over time under such exposure. I think Aeropoxy makes a high temperature resistance (~500 F) epoxy, but I doubt I could justify the cost.
I'd use Bob Smith 30-minute epoxy for the fin-tab-to-CR, CR-to-body-tube, and internal and external fin-to-body-tube joints and fillets.
For the external fillets, I'd make the initial fillet hard and strong but relatively small. Then I'd go over the top of it, before it cured completely, with the same epoxy with microballoons added. Alternatively, this outer fillet could be done with Fill-N-Finish.
Will JB Weld be good for this application? Is it necessary? Will it be too heavy? Too thick?
That's good to know. I found a page on Rocketry Online!'s Info Central site on "epoxy and heat" that likes West Systems for hot locations, preferably with fiberglass or similar over the fin joints, but doesn't like the hobby store stuff like the Bob Smith I have.Originally posted by stymye
I have never lost a fin joint to heat,Imoh that is rare with epoxy.
I don't really want big fillets, just smooth pretty aerodynamic ones. When I think about layering them, I'm thinking about thin layers, built into relatively small fillets.Originally posted by stymye
large fillets are for looks more than strength and degrade performance(increase interference drag)
You got my number there. I do tend to overanalyze and achieve paralysis through analysis. It's fun to explore techniques and pick experienced and thoughtful people's brains though. The brainstorming and exploration are part of the fun.Originally posted by stymye
you can glue the rocket together with minimal amounts of plain ole epoxy and no nose weight .anything beyond that is just weight and cosmetics and more effort ,but results in a pretty rocket
no need to over-analyse it MR, winter is coming. just grab that glue bottle and start building.