The bevel looks good. Were you just using a steady hand to keep the sander level, or did you have some sort of jig?
Coming along nicely! This thread is inspiring me to use blue tube for one of my upcoming scratch builds.
Very cool. I'm planning to attempt a layup like this in the near future. What weight if cloth did you use? And are you planning to extend all of the layers past the beveled edge of the fin?
Thanks, y'all. Not sure what happened to the attachment links. My friend who printed the transitions actually printed a second version of the blue one with a much tighter matrix to make it stronger. But apparently this is a tremendously weak spot, and/or ABS just isn't very strong under flexion (is that a word? I think that's a word and I'm too lazy to google). Same friend who printed these has some pultruded carbon rods. I think if I just have the carbon running down the middle & epoxy it back together, that ought to make it pretty bulletproof, especially if I glass the outside. There's no twisting forces, the ABS ought to resist compression and tension OK (especially with the carbon up the middle). The biggest weakness seems to be flexing, which would be 100% addressed with a rod up the middle.
Attempt 2 at the pictures. The ABS failed in the same way as the nose cone - a weirdly modest tap and it just fractured. I think the gist is that 3d ABS is probably OK for filling-out HPR, but needs glass or something else to be properly strong. Again, I'm glad I found this out before launch.
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ABS should be pretty strong, but like Nate said, your print orientation is the weakness.
When you bend, you're basically peeling the layers apart instead of putting tension on the filament lines themselves.
If you could somehow embed 4 small carbon rods running top to bottom along the edges (at 12, 3, 6 and 9 o'clock), that would strengthen against bending better than a fat rod in the center.
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