Resources

Components for 3D printing

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2 comments on “Resources

  1. Hi Joseph,
    I’m also an L2 (TRA) and am starting my L3 design/build. I’ve recently found your website and am very impressed and enjoy your design and building approach. If you might respond to a couple of questions, that would be very helpful:
    1. For one of my designs, I also need to build a transition in which I was going to cast Alumite to a PETG printed mold. Some have strongly suggested using the alumite product as the transition, since its thermal properties, integrity, and strength should survive most normal flights. What are your recommendations?
    2. I haven’t worked with acrylic fins but I do have access to a laser printer. The acrylic fins you cut, are they the main fins of your fin can? If so, please inform me of the limits to its use (e.g. thermal, able to handle mac+ flights, and can one use a router for fin beveling without cracks occuring?)

    Thank you for your consideration.

    Regards,
    Fred

    • Hi, Fred. I’ve actually been pretty lousy about updating this blog recently, but I’ll definitely be trying to write more often.

      1. I haven’t worked with cast metals for amateur rockets, but my first impression is that they are usually massive overkill. Of course, it may actually be a good material if you’re pulling a lot of G’s or doing supersonic. Straight ABS has worked great for me in my flight envelope (granted, I don’t venture into supersonic after one unintentional bad experience with it). The only time 3D printed parts have failed me is when they hit the ground without a parachute. I am printing molds so I can cast mandrels for custom-sized composite tubing. I think it would be a bit more difficult to due a composite layup of a transition section unless it’s a composite overlay of a printed transition.

      2. I do use acrylic for my primary fins when doing scale models that require bonus fins to be stable. Again, I’ve never tried acrylic in supersonic, but I can tell you that around 350F, acrylic is a bit gooey (source: my oven). I imagine this would be an issue if you flew fast enough to warm the fins up. The biggest issue I’ve experienced with acrylic fins is aspect ratio and span divided by thickness, or some combination of those. Common sense here, I guess, but I’ve found acrylic fins do like to crack and snap much sooner than plywood fins. I made the mistake of making some really big 1/8″ acrylic fins with less than 6 inches of root chord. I haven’t finished building the rocket yet and one of the fins has already snapped off and I’m seeing root chord cracks on two of the others. I plan on breaking all the fins off and reevaluating more square fins in 1/4″ acrylic and printing out some surface-conforming fin mounts. I have not put acrylic under a router, but I imagine that would be fine. They rout those acrylic statues, don’t they? Or do they do something else? YouTube probably has some good videos for this.

      Best of luck!
      -Joseph

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