Dumped another 6 hour shift into this thing on a weeknight last night - we're now squarely in the "annoying little parts of a build that become interminable" phase. I like building fincans and mixing motors but the other stuff I can do without. I have travel plans for the weekends of Mar. 1 and Mar. 8 - which means that the motor needs to be mixed in one monster 10kg batch this weekend, which means I'm running short on time here for the Mar. 14 launch.
I finally got some boxes in yesterday, one of which was a scrap 4" tube and coupler length and some old bulk plates from my dad. One man's trash is another man's treasure.
He sent me a 22" length of tube, and the days of me adding extra length "just because it can't hurt" are gone. I decided I'd cut a 16" piece for my upper airframe, which along with the 44" booster will be an even 60" of airframe (which is the piece I would have bought if I wasn't cheap and wasn't building this from scraps). Squaring ends to perfection on my janky bench sander jig takes a hot minute, and I think we squared 16 ends last night. Who knows how my dad cut it, so we squared it beforehand, cut with a hacksaw, and then squared the two cut ends:
While we have the squaring jig set up and calibrated, let's go ahead and cut all remaining necessary pieces. First, we cut a 1" ring of coupler for the "frisbee" at the top of the motor. Square/square/cut/square/square. Then, a 3/4" belt for the nosecone coupler/av-bay to prevent shear pins from breaking prematurely. Since we've already squared the scrap airframe piece from the first cut, it's simply cut/square/square. Squaring a 3/4" long piece doesn't exactly lend itself to a good outcome, but with some time and luck we get it to within about 1/3mm of perfect all the way around and we move on.
To complete the frisbee, we need a bulkplate. It appears my dad only sent me (or only had) airframe bulk plates, so the drill press lathe is back in action for another 20 minutes to get the airframe bulkplate down to coupler size. Then it's time to drill a 1/2" hole in the middle for the motor eyebolt - I have closures with 3/8 and 1/2" holes, so we'll go with 1/2". Oops! My Wal-Mart drill bit set only goes up to 1/4", so let's drill a cluster of 1/8" holes and then use our grinding stone from the other day to sand it out to size. One thing that kills me about these builds are the $8 trips to Home Depot and add up, add up...so time to improvise.
Then we rough everything up that is to be bonded, put a tape "shelf" on one side of where the av bay ring is to be mounted, and Rocketpoxy the ring on. The excess glue spills on to the "shelf" by design, and while it sits on this shelf, we put a shelf on the other side, flip it over, and peel off the original tape with the dripping glue.
Then, we use the rest of the Rocketpoxy to fillet the frisbee.
The nightcap was mounting the nosecone tip with the shoulder - the shoulder throws off the whole wedge washer ratio, so we sourced a new washer, cut the eyebolt to the proper length, and then improvised a way to get the eyebolt to thread. It's a lot easier when there's no shoulder and you can see where the threads are going while reaching your hand 20" up into a nosecone where it doesn't fit, but we're all set.
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