Semroc Micron Build 4, Part 2

So I’m back. I decided to go on and attach the fins since I felt that the body wrap spirals were now sufficiently filled, as well as all the balsa. Here’s a shot of the re-filled spiral:

It now feels a lot smoother when I run a fingernail over it. The hobby knife blade/thinned CWF for the body tube spirals is a keeper, I think, but we’ll see how it looks after priming.

So I moved on to attaching the fins. I used the new version of the Estes Fin Alignment Guide (#002231). As far as I can tell the only difference between this new version and the old one is the color. The old one was industrial gray, and perhaps a bit heavier-duty plastic. At least it felt thicker. Here’s the new one:

The fin alignment guide comes with the base and four little paddles you slide into the base into their appropriate positions, depending on whether it’s a three or four finned rocket. There are also clips to hold the fins against the paddles after the fins are in place on the body tube. It also comes with four empty motor casings: two 13 mm casings and single 18 and 24 mm casings. Before use, it’s necessary  to draw lines along the length of one of the 13 mm tubes along with the 18 and 24 mm tubes. It’s also necessary to put clear tape around one end of one of the 13 mm tubes, and both ends of the 18 and 24 mm tubes, You leave one end of a 13 mm un-taped so it can slide into the hole in the center of the base. To attach fins onto a standard 18 mm motor rocket you’re supposed to slide a regular-size (i.e., 18 mm) casing over the 13 mm which is inserted in the base.

The instructions say to carve out a little bit of an end of the empty 18 mm to make a “starter” with which to ease sliding it over the mini casing in the base. Well, I had to REALLY carve up the 18 mm casing’s insides in order to finally get it to slide onto the 13 mm.

So I applied glue to each fin’s root edge, let it dry, then reapplied a thin line of glue. I followed another piece of Apogee advice and tried to apply just enough glue to hold the fin on. This will later be supplemented with heavy fillets, in this rocket’s case with epoxy putty. I butted each root edge up against its corresponding pencil line I had previously drawn.

Here’s how the fins looked at first glance after drying. I had clipped the fins against the little paddles and let them dry in place:

They look ok, hey? Well - not so fast! But it’s too late to continue now so more tomorrow. Have a great evening!