Scratch Builds - 18 & 24mm

[futurepotato]

I've decided to use some of my spare time at home these days to design and build a couple of low power rockets to go fly at the next local launch, and document it in my first build thread for any that are interested.

This design is a downscale of my L2 rocket "Scarab" (currently in work, build thread to come) to a 38mm airframe with 3D printed nosecone and tailcone with integral motor retainer. Since I have the time, I figured I would build both an 18mm MMT (green) and a 24mm MMT (red) version of the same rocket.

First, some renders to show off what I hope the final product will look like:



And a quick shot of the "kit" for both rockets. The body tube, MMT and coupler for the 18mm are hand wrapped paper as the blue tube I had on hand was a little heavy for the lower powered motors. The 18mm also has a small aft centering ring that was eliminated from the 24mm design, and does not yet have fins as I still need to get some balsa to make them from.

 

[BABAR]

Nice!

 

[PXR5]

Looks good

 

[futurepotato]

Started work on the 24mm version. First step is to open up the fin slots. To get a good print of this, the part is modeled with a single wall thickness in the fin slots. This keep the thin walls of the tailcone from warping as it prints, but means the fin slots need to be cut out and cleaned up post-print.


Next, the centering ring and fin alignment can be epoxied to the body tube, and then the whole thing assembled into the tailcone section, making sure that the fin alignment ring is lined up with the slots in the exterior.


Finally, a test fit of the fins. They seem to align very well, no jigs or measuring needed.

 

[mooffle]

Those 3-d printed parts look awesome, what setup are you using to make them?

 

[futurepotato]

Those 3-d printed parts look awesome, what setup are you using to make them?

I have a Monoprice i3 with a Micro Swiss all metal hotend. These pieces were printed with a carbon fiber filled PLA. A little higher heat tolerance and stiffness than a normal PLA and a really neat matte grey finish. Unfortunately it destroys nozzles so tool steel is necessary.