Future is dry, looks good but no pic right now because really it's just about the same as before. Eventually I'll take some beauty pics outside.
Down to the end game: Tying the shock cord and installing the nose retainer. The former is pretty boring, so let's talk about the latter.
Because this all seemed to go pretty well in the
Diamond Cutter build, I decided to do it again here pretty much the same way, except here I've got a BT50 to work with instead of a BT60, so things are tighter. As before, the objective is to have a good way to secure the nose cone without having to make it extremely tight, while also being easily removable so I can shove an altimeter in there eventually. In fact, with the thin-walled BT50 in the payload section of this rocket, this is even more important because it is *so easy* to mess up a BT50 while grabbing it and trying to pull out a tight nose cone (don't ask me how I know this.
) So I really want the nose cone to be reasonably loose but secure.
The retainer is simply a smaller-diameter version of the BT60 design. Unfortunately, the quality of print I got this time was not great, and I had to do a lot of sanding to get the fit to be just-tight-enough-without-being-too-tight. Eventually I achieved satisfactory results, although I believe the design can be improved to reduce the chance of the problems I experienced here. But that's for the next rocket.
Anyway, here are the two pieces:
On the left is the nose cone piece, and on the right is the piece that inserts into the BT. Orientation is upside down, this is essentially looking up to the nose cone from below. Here are the two pieces locked together:
Installing these guys is a two-stage procedure. First I must glue the nose cone piece to the nose cone. There are two things of paramount importance here: (1) positioning the piece correctly, and (2) not accidentally gluing together the wrong things. The design of the retainer is actually intended to help with #2, but #1 is all about the process.
With the two pieces locked together, I inserted them partway into a piece of scrap BT50, like so:
Next I dolloped a bit of 30-minute epoxy onto the back of the NC piece:
Then I stuck the nose cone onto the glue. With 30-minute epoxy I have plenty of time to work, so initially I'm just looking to get the balsa set into the glue nicely, in *approximately* the correct position:
Finally, I push the entire assembly gently into the tube. Initially I only did it partway, just enough to ensure good alignment of everything:
Later I decided that there was no real reason not to push it in all the way, so I did. Here's a peak in from the other end; with everything looking good:
The BT piece is a fairly snug fit, so once the nose cone is pushed in nothing is going to move on its own. Now I let it sit for a day, and then I'll pull out the nose cone, and if all goes well everything else will come out with it (remember the BT piece is not glued in at this point, but it is locked to the NC piece).
A couple of notes:
1) for this process I mixed an almost ridiculously small batch of epoxy, and because I didn't have anything good on hand to mix it with, I used a Q-tip. The Q-tip did a fine job mixing it, but it also absorbed almost 100% of the epoxy. On my second try I used a long screw. I will have to find my wooden craft toothpicks that I normally use for this.
2) The retainer pieces were printed in ABS, which I know is troublesome to glue. I'm hoping that the 30 minute epoxy does the trick; fortunately this joint is not going to be particularly stressed, so I hope it'll be OK. If it were to let go, it wouldn't be a tragedy anyway.