Please help me identify these rail buttons..

Discussion in 'High Power Rocketry (HPR)' started by Tim51, Jul 11, 2018.

  1. Jul 11, 2018 #1

    Tim51

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    Hi all

    I picked up these streamlined rail buttons a couple of weeks back. They came in an unlabeled ziplock poly bag, have UNC threaded hex drive counter sunk machine screws, but I later realised they came with no backing nuts or inserts. So I'm wondering if there should be some inserts/nuts that somehow got lost along the way, and if so what will work as a substitute ?

    Thanks,

    rail buttons.jpg
     
  2. Jul 11, 2018 #2

    rharshberger

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    Possibly SC Precision, iirc Apogee still sells them.
     
  3. Jul 11, 2018 #3

    cwbullet

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  4. Jul 11, 2018 #4

    Tim51

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  5. Jul 11, 2018 #5

    Bat-mite

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    Weld nuts, which need to be epoxied in. Or some people use well nuts. You can use T-nuts, but you have to grind off the prongs.
     
  6. Jul 11, 2018 #6

    Tim51

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    Good idea - thanks!

    Tension here as a silent city watches the World Cup Semi Finals: England 1 Croatia 1 into extra time...
     
    Last edited: Jul 11, 2018
  7. Jul 11, 2018 #7

    Titan II

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  8. Jul 11, 2018 #8

    rharshberger

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    Grinding prongs off not necessary, grab the prong and bend it back and forth several times with a pair of pliers and they will come right off.
     
  9. Jul 11, 2018 #9

    Tim51

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  10. Jul 11, 2018 #10

    Tim51

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    I've done that on occasion. Also when securing fixings for payload / AV bay sections, I've filed t nut prongs just part way down (so they stand proud but the thread is flush with the outside) then filled the small gap on the inside with JB Weld - it's a bit fiddly but works well.
     
  11. Jul 11, 2018 #11

    Nytrunner

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    I would normally say weld nuts from Lowes but.......M4? Tim are you located in England?
     
  12. Jul 12, 2018 #12

    Tim51

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    Yes.
     
  13. Jul 12, 2018 #13

    Nytrunner

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    Darn, didn't see your location tag.

    You're outside my circle of experience, I've only been as far as Iceland in your direction.
     
  14. Jul 12, 2018 #14

    Tim51

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    No worries - thanks anyway - I've only been as far west as Philadelphia (!), although aiming to be part of a Brit 'delegation' to Black Rock at some future date..
     
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  15. Jul 12, 2018 #15

    markkoelsch

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    Depending on the airframe, you can possibly drill and tap the airframe. Depending on weight it can work on filament wound airframes.

    If you want a nut, I would look at a pem nut. Specifically a broaching nut
     
  16. Jul 12, 2018 #16

    Tim51

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    Actually this isn't a FWFG airframe - it's a FG wrapped Loc tube, but thanks anyway. The reason I'm using rail buttons - a new experience for me - is I've been unable to get hold of Acme conformals for 5.54" (not sure Acme even make conformals that size..?)
     
  17. Jul 12, 2018 #17

    cwbullet

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    I have drill and tapped fiberglassed LOC. I treat the hole with CA prior to tapping.
     
  18. Jul 12, 2018 #18

    Tim51

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    Thanks that's good to know. I was thinking I would need to use some sort of plywood strengthener. Did you back the screw with a kerf ?
     
  19. Jul 12, 2018 #19

    cwbullet

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    Yes and no. It depends on the size of the rocket and then number wraps of fiberglass.
     
  20. Jul 12, 2018 #20

    Tim51

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    So far the intended tube just has one wrap of 200gsm (= 6 ounce) 2/2 glass weave. As mentioned it's a reasonably heavy 5.5" which will fly on bigger J - mid K impulse.
     

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