Adding rail buttons to an already-built model

Discussion in 'Mid Power Rocketry (MPR)' started by SierraDrinker, Jun 29, 2018.

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  1. Jun 29, 2018 #1

    SierraDrinker

    SierraDrinker

    SierraDrinker

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    I want to add rail buttons to my Estes Star Orbiter. It is already full assembled and I have had successful launches on E engines. I'm planning on doing a launch with a little bit bigger engine than recommended and I want to get a little more stability at launch. Any suggestions?
     
  2. Jun 29, 2018 #2

    Mr Rocket

    Mr Rocket

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    Drill holes, squirt wood glue in (enough to form a mushroom cap over the top), screw in rail buttons, allow to dry with tube horizontal and rail buttons facing down.

    Option 2: Use surface mounted rail guides
     
  3. Jun 29, 2018 #3

    K'Tesh

    K'Tesh

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    A variation on Mr Rocket's idea... Drill a hole close to a centering ring, but above it. Then inject some 15 minute or 30 minute epoxy, seal the hole with some tape, rest the rocket hole side down and tilted to concentrate the epoxy at the hole/centering ring. When it's set, redrill and add your rail button. I think this would have less chance of shrinkage that could deform the body tube.

    Depending on where the break is (did you build zipperless?), you could always glue a block of ply sandwiched with some balsa sanded to shape, then drill into that for your forward button.
     
  4. Jun 29, 2018 #4

    krislhull

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    With my mid power rockets, such as my Ventris, PSII Nike, and my Madcow Mini Tomach, I just epoxied the rail guides right to the side of the tube. Works great!
     
  5. Jun 30, 2018 #5

    Mr Rocket

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    I have never drilled the epoxy after installing it. That is an interesting concept. I'll have to give it a try.

    K'Tesh is right though. Using epoxy, which does not shrink, can make it less likely for the screw shaft to snag the laundry. I always consider this before selecting my glue. Lately I have been using longer motor mounts. This means that both rail buttons are usually concealed by the centering rings. If that is the case, I just reach for the wood glue. It is so much easier, and plenty strong.
     
  6. Jun 30, 2018 #6

    BradMilkomeda

    BradMilkomeda

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    I have had to do this a couple times now.

    Epoxy does not stick to Vaseline. Drill a hole in the tube so that it grips the threads. Coat the proper sized screw with Vaseline working it into the threads. Inject epoxy into the whole. Screw the coated screw in. Leave it to dry with the screw down and level.

    After the epoxy is dry remove the screw and replace with the tail button. You will have threaded epoxy to support the rail button from behind. If you have doubts of the method, just use the button the first time so if it gets stuck it won’t be a problem.
     
  7. Jun 30, 2018 #7

    SaintJohn

    SaintJohn

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    roytyson likes this.
  8. Jul 1, 2018 #8

    DavidMcCann

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    Drill, epoxy, screw in buttons.

    Had to do this after walking to the pads and realizing I never installed any before. Just tell people you saw the ignitor wires were broken and act like using a drill to fix this while swearing is normal. No one will know.
     
    SierraDrinker and captbk like this.
  9. Jul 1, 2018 #9

    captbk

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    Really?? All the way to the pad BEFORE you relized, no buttons? Thats a good one!
     
  10. Jul 15, 2018 #10

    brewster_rockit

    brewster_rockit

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    I just succeeded in adding a rail button using a variation of K-Tesh's approach. For the forward rail button, I first made a block from several sheets of balsa (glued with perpendicular grains) and drilled a hole in it, a hair wider than the screws for my rail button. Next I epoxied the nut for my rail button over the balsa block. Lastly I put epoxy through the hole just above the forward centering ring and maneuvered the balsa block into the epoxy, with the nut between the balsa block and body tube. I made sure the bulk of the epoxy was on top of the centering ring, so the balsa block is glued to the centering ring (not the body tube.)

    Getting the balsa block + nut into place isn't easy, but it helps to use a magnet on the outside of thin-wall body tube to maneuver the nut. Once it's close to the body tube hole, you can use a pin or toothpick to center it. I also used a yardstick to put pressure on the block + nut for a good epoxy bond. A small flashlight was essential to see what was going on inside the tube!

    The aft rail button was easy to add: just drilled a hole aft of the bottom centering ring, and used a crescent wrench to hold the nut on the inside of the tube's open end while tightening the screw for the rail button.
     
    K'Tesh likes this.

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