Quick answer about putting on too much.

I'm still trying to find my way building these new bigger MPR rockets. As a teenager I had Elmer's Glue and spray paint. Now, for the fin fillets I apply wood glue, or in the case of my NCR SA-14 Archer epoxy (what a mess). After the fillet I applied slightly diluted minwax wood filler. Perhaps I applied too much, I used a Q tip and then sanded it all down first with varying Dremel tips (Minwax wood filler is damned hard) and 220 sand paper then 400. It took all morning for four fins. Holy Moly! Then I applied basic Spackle and sanded again.

Am I overworking and overthinking this process? I think I could've just applied some spackle to the first fillet and be done with it. I want to build a super clean rocket but I don't want to spend all morning sanding just to apply Spackle for the final smoothing in order to apply sander/primer to sand all over again. Welcome to MPR I guess?

What shortcuts do you find helpful in the preparation of your rockets?

The good thing with straight epoxy is you can mix in additions to work it's properties to suit, so chopped glass or carbon fibre to make strong fillets or microspheres to make it easier to sand. You can also often get a good result by a well timed wipe over with a gloved finger dipped in acetone. When starting out it can help to have some scrap material, do a mock fillet in that and practise to get the timing right. You need it firm enough not to pull from the groove but still soft so it becomes smooth.

Have a look at this thread for some excellent tips on getting nice fillets, CJ provides a lot of photos and breaks it down really nicely


Edit: Also just saw you've put this in the LDRS section, you'll probably get a lot more help in the MPR or HPR sections on the forum.