2-56 Nylon Screw Shear Pins on AeroTech ARCAS

Discussion in 'Mid Power Rocketry (MPR)' started by bronicabill, Dec 3, 2019.

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  1. Dec 3, 2019 #1

    bronicabill

    bronicabill

    bronicabill

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    I am building my 2nd ARCAS (the first one was over 15 years ago), and when ordering stuff I decided to throw in a bag of 2-56 nylon screw shear pins to experiment with. However, I did not use shear pins of any kind on my first ARCAS, and I'm not sure exactly how to make use of them! So a few questions from a mid-power almost-newbie...

    1. If I use 2 pins to retain my nosecone (rocket is being converted to dual-deployment) until the proper time, how does one go about removing the sheared-off portion of the screws after deployment???
    2. Since the main body tubes are a paper fiber, what do people use to reinforce the holes in the body so they don't elongate with use? Thin CA adhesive?
    That's all for the moment... I'm sure I'll come up with more later! Thanks!
     
  2. Dec 3, 2019 #2

    mbeels

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    For 1., I just stab the sheared off portion with a #11 xacto blade, and that lets me screw it in until it falls out.

    For 2., Assuming a thick wall body tube, I just reinforce it with CA glue, medium or thin. I also used a small piece of brass shim stock to make sure that the screw shears cleanly, and doesn't just strip out threads or deform.
     
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  3. Dec 4, 2019 at 10:03 PM #3

    Nytrunner

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    Check the nosecone plastic for stiffness. I had some mishaps when the pins twisted in the nose shoulder walls of my Pro Series II rockets, since then I've just friction fit the nosecones for dual deployment on small rockets.

    I see you're in Madison! If you're free tomorrow night, bring it on by the HARA meeting and folks will be happy to chat!
     
  4. Dec 4, 2019 at 11:56 PM #4

    bronicabill

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    I’m hoping to be there. Will bring the rocket if I make the meeting!
     
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  5. Dec 5, 2019 at 12:02 AM #5

    Nytrunner

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    Excellent

    The meeting location changed for this week, so make sure to check the notice on website/facebook
     
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  6. Dec 5, 2019 at 2:05 AM #6

    David Schwantz

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    I have used the exacto blade method also, but have had a few get stuck. I now use a 2-56 blind nut in a ply backer. My screws are longer so that now I can just reach inside and screw them out with my fingers.
     
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