External fillets question

[Rocket Reverend]

Would it be better to use the 205 West Systems hardener with the 105 resin for external fillets, or does that harden too fast? I haven't ordered it yet, so I could just as easily order the 206 hardener. Also, does it matter if I add the 406 filler before or after mixing the resin and hardener? Last question: for a 2.1 in. diameter rocket (Darkstar Jr.) is 1 in. pvc pipe too large for shaping the fillets? That's what was recommended on the build instructions I'm following, but I don't think it's for a Darkstar Jr., so the diameter could be different. I think I need 1 in. because at least one of my holes won't be covered with anything smaller. Thanks for your rocket-building wisdom!

 

[dr wogz]

Welcome!

and welcome to the world of FG rockets!

I did my L1 with the DS Jr. and have pushed it to over a mile..

First off, wash the parts, well! and scuff up the areas to be glued. 205 takes a few hours to cure / harden. like, 4 or 6 hrs.. so you have pu-lenty of working time! Don't expect to build this all in one night. 3 nights at least for the fins, another 3 for the fillets. Get the scales too!! Using the pumps, you'll mix a batch and use 0.025 of it.. (wasting it)

I typically mix up the epoxy, then add the filler till I get the consistency I like. I prefer the 407 fairing filler; easier to sand & sculpt. I also use a hotel key card (the corner of) to make my fillets radii. (we all have our own techniques..) Ideally, for this, a 3/8" or 1/2" dowel is big enough for the filet radius. You don't need massive fillets..

To fill the holes (the ones you made to inject the internal goo) just add some epoxy, then tape the hole shut & flip over. Once the epoxy cures, peel off the tape & sand smooth.