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  1. #1
    Join Date
    11th February 2017
    Location
    south Florida
    Posts
    572

    Rail button installation questions

    At Saturday's launch, I had rail buttons break on two different rockets. One was a standard round button, the local vendor was able to sell me a new one and help me install it, after some debate about the proper way to mount it (see below). The second was airfoil-shaped, the vendor did not have any so the launch was scratched. There must be a more durable version of these things, I've had at least 4 break since I got back into rocketry in February. Anyhow, a couple of questions:
    1) Do you put some epoxy or CA in the hole to secure the button, or is the screw enough? (Does the answer differ if the airframe is fiberglass or cardboard?)
    2) On the round buttons, should the button be loose so it can spin, or should it be tightened down?
    3) Are the round buttons compatible with the airfoil-shaped? (It was suggested I could replace the broken airfoil with a round button.)
    4) Any advice for mounting buttons in a manner that will last?
    Thanks,
    Bill


    L1 3/25/17 H135
    L2 8/12/17 J180

  2. #2
    Join Date
    13th June 2014
    Location
    Cocoa Beach, FL
    Posts
    3,561
    Unless itís an MD rocket, I epoxy a T-nut on the inside of the airframe. Fiberglass or cardboard or blue tube.


    Sent from my iPhone using Rocketry Forum

    Tim
    L3 NAR 98225

  3. #3
    Join Date
    26th January 2010
    Location
    Northern California
    Posts
    13,180
    I always epoxy blocks on my centering rings for the rail button screws to screw into. Haven't had one fail yet.

    http://www.rocketryforum.com/showthr...42#post1675042

    http://www.rocketryforum.com/showthr...02#post1675402

    http://www.rocketryforum.com/showthr...83#post1676783
    NAR 91107, Level 2

    I really, really hate bugs.

  4. #4
    Join Date
    26th January 2010
    Location
    Northern California
    Posts
    13,180
    As for the buttons themselves, I prefer the so-called "low-profile" rail buttons from Wildman. You can see the difference between the one-piece and the low-profile. For already built rockets, I know a lot of people swear by "well nuts".

    https://www.homedepot.com/p/Everbilt...4338/204276115
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    NAR 91107, Level 2

    I really, really hate bugs.

  5. #5
    Join Date
    17th February 2014
    Posts
    542
    That's interesting. I've got around 70 HPR flights off rails, and I've never had a rail button break.

    I install them at the rear and forward centering rings.

    In cardboard rockets with wood centering rings, I screw them into the centering rings with wood screws.

    In fiberglass, I screw them into the fiberglass with machine screws.

    On my fiberglass L3, I added some wood backing to screw into and I added some epoxy so they don't spin. In all my others, I screw them in until tight, then back them off a hair so they spin.

    What's breaking on yours? Are they splitting so they come off the screw? Or are the flanges that grab the rails coming off? Are other people in your clubs breaking rail buttons too? If so, there might be something wrong with the rails.
    NAR
    L1: 2/2/13, Madcow 4" Patriot. CTI H143
    L2: 9/2/14, Madcow 4" AGM33 Pike. CTI J335. 2,878 ft, 418 mph
    L3: 1/7/17, Wildman Drago XL. AT M1500. 13,559 ft, 1,017 mph, Mach 1.2

  6. #6
    Join Date
    11th April 2009
    Location
    SF Bay Area
    Posts
    857
    I use well nuts for rail buttons on my mid power rockets with cardboard body tubes. I have never had a problem. I tighten them tight so that they are secure and do not rotate. I do not use any adhesives or lock tight.

    I don't know how they would break. There is very little stress put on the button during its trip up the rail.

    As long as everything aligns there would be no reason not to use round rail buttons with aero buttons.

  7. #7
    Join Date
    9th April 2009
    Location
    Lancaster, Ohio
    Posts
    693
    Quote Originally Posted by billdz View Post
    At Saturday's launch, I had rail buttons break on two different rockets. One was a standard round button, the local vendor was able to sell me a new one and help me install it, after some debate about the proper way to mount it (see below). The second was airfoil-shaped, the vendor did not have any so the launch was scratched. There must be a more durable version of these things, I've had at least 4 break since I got back into rocketry in February. Anyhow, a couple of questions:
    1) Do you put some epoxy or CA in the hole to secure the button, or is the screw enough? (Does the answer differ if the airframe is fiberglass or cardboard?)
    2) On the round buttons, should the button be loose so it can spin, or should it be tightened down?
    3) Are the round buttons compatible with the airfoil-shaped? (It was suggested I could replace the broken airfoil with a round button.)
    4) Any advice for mounting buttons in a manner that will last?
    Thanks,
    Bill
    It sounds as if you are breaking them loading the rocket. Are they actually breaking, which would seem to be the case since you needed to buy new ones, or just coming loose? If they are breaking you are likely binding them when you are loading. It's easy to do. There is a learning curve going from lugs to buttons. Not sure your attachment is the problem but trying to load on a bind. That will get you every time. Often it is worse if you have an abundance of helpers.
    Joe Grubb
    TRA 1206 /TAP NAR 78797 / L3
    Tripoli Mid Ohio
    http://www.tripolimidohio.com/
    WVSOAR564 WSR703
    AMA 2610 FORKS

  8. #8
    Join Date
    24th June 2011
    Location
    Whitney Point, NY
    Posts
    367
    Hi Bill, I am the manufacturer of the airfoil rail guides. I have never once heard of any broken rail guides. Is the actual guide broken or had something pulled out of the airframe? Do you have any photos of what happened? I can pay shipping if you want to send any broken guides to me and I will replace them as well.

    Scott

  9. #9
    Join Date
    27th March 2013
    Location
    Has Changed
    Posts
    9,569
    Me, I epoxy blocks to the motor mount/centering ring for the rear button, and install a small scrap of balsa/ply sanded to conform to the interior curvature of the body tube for the forward one. Key thing to remember about the forward one is to make sure that there is no way that the laundry can snag on it upon deployment. Since my large rockets typically have a baffle, that's usually not a problem, but on the smaller ones, I do make sure that there's nothing to catch the shock cord or parachute.

    Dreaming of making the rockets I dreamed of as a kid (and then some).


    NAR L1 Cert flight: Sheridan, Oregon, USA. Sept. 19, 2015. Flew Deep Space OFFl on an I357T-14A Blue Thunder

  10. #10
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    2,273
    Iíve also never seen the actual buttons break. Iíve seen rail guides twisted off the airframe, especially those mounted near the aft end. Iíve seen screws ripped loose from body tubes, and Iíve seen flats worn onto the sides of much flown rockets, but Iíve not seen a button break.
    I mount mine so I can spin them easily. I have no data to suggest that helps, but I do it anyway.
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  11. #11
    Join Date
    5th February 2009
    Location
    Montreal, Qweebec
    Posts
    3,402
    Mine don't spin, but they are snugged up, not overly tightened (I don't tryto get 40+ ft-lbs into them!)

    I try to get them into the CRs. And, I've started adding a chunk of wood to the CRs, at the intended button installation location. Gives me more 'meat' to aim for with the drill & screw.

    I'm also curious as to what's breaking..
    -paul

    NAR# 101258 - L1
    www.CRMRC.org
    I don't know the same things you don't know..

  12. #12
    Join Date
    19th January 2009
    Posts
    3,394
    I found these at McMaster-Carr. They will be good for retrofitting cardboard rockets. Bend flange to fit airframe diameter, remove paint and epoxy on.
    Click image for larger version. 

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    https://www.mcmaster.com/#98007A013 in stainless, https://www.mcmaster.com/#98007A110 plated steel

  13. #13
    Join Date
    24th June 2011
    Location
    Whitney Point, NY
    Posts
    367
    Gotta love McMaster!

    Quote Originally Posted by Rocketjunkie View Post
    I found these at McMaster-Carr. They will be good for retrofitting cardboard rockets. Bend flange to fit airframe diameter, remove paint and epoxy on.
    Click image for larger version. 

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    https://www.mcmaster.com/#98007A013 in stainless, https://www.mcmaster.com/#98007A110 plated steel

  14. #14
    Join Date
    5th April 2015
    Posts
    49
    +1 on well nuts

    Never had a problem on cardboard, blue tube or fiberglass. I use them on new rockets and to retrofit old ones.
    Seth Cooper
    L3
    NAR 75427
    TRA 15793

  15. #15
    Join Date
    11th February 2017
    Location
    south Florida
    Posts
    572
    Thanks for the replies, and special thanks to Scott for offering to replace the airfoil guide. I have had 4 issues since February, two with rockets I built and two with pre-built rockets that I purchased. The first time, I noticed on recovery that one of the rail buttons was gone, apparently it the screw came out during flight, as there was nothing but a hole. When I went to replace it, I started to put some CA in the hole so that the screw would hold tighter, and that's when I was told not to use CA because it might bind the button, which is supposed to be loose so it can spin. The second incident happened a couple of months later, nothing major, the screw had come partially out and the button was tilted sideways. Then last Saturday two separate incidents. First the top of a round button broke when loading the rocket onto the rail, see picture. Later the top portion of an airfoil guide broke, also when loading, I recall hearing the sound of plastic cracking as the rocket was sliding down the rail, even though I was trying to be extra careful in light of the first incident, see attached "before and after" picture. Joe may be onto something when he says, "If they are breaking you are likely binding them when you are loading. It's easy to do. There is a learning curve going from lugs to buttons." Please explain further about "binding them when loading," not sure what that means. I see that some people spray silicon or WD-40 on the rail before loading, maybe that's what I need to do. I did notice on both occasions that the rocket did not seem to be sliding down the rail as easily as usual.
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    L1 3/25/17 H135
    L2 8/12/17 J180

  16. #16
    Join Date
    13th June 2014
    Location
    Cocoa Beach, FL
    Posts
    3,561
    Bill the rocket I helped you with Saturday went on rail very easy. We clean our rails regularly. Iíve never had a button hang up since Iíve been flying there. You really need to be careful that the rocket is parallel to the rail when loading rocket. Were they the forward or aft buttons that cracked? I would guess the aft?
    Tim
    L3 NAR 98225

  17. #17
    Join Date
    11th February 2017
    Location
    south Florida
    Posts
    572
    Yes Tim, I recall asking you for help because I was so worried about a third incident and that rocket went on easily. I also remember that the rails looked nice and clean. You are right, it was the aft button on both rockets, I was trying to keep the rockets parallel to the rail but apparently I failed.

    L1 3/25/17 H135
    L2 8/12/17 J180

  18. #18
    Join Date
    24th June 2011
    Location
    Whitney Point, NY
    Posts
    367
    Bill man what the heck are those?!?!?! They are not airfoil rail guides I manufacture. Where are they from?

    Here is another idea - I am still interested in the failures. Send them to me, and I will still send you a real genuine SCP pair. I should post my load testing data if I can find that, or just redo it in the next few days. I wonder if the guides you have are made from a less robust, but easier to purchase material , or something..........



    Quote Originally Posted by billdz View Post
    Thanks for the replies, and special thanks to Scott for offering to replace the airfoil guide. I have had 4 issues since February, two with rockets I built and two with pre-built rockets that I purchased. The first time, I noticed on recovery that one of the rail buttons was gone, apparently it the screw came out during flight, as there was nothing but a hole. When I went to replace it, I started to put some CA in the hole so that the screw would hold tighter, and that's when I was told not to use CA because it might bind the button, which is supposed to be loose so it can spin. The second incident happened a couple of months later, nothing major, the screw had come partially out and the button was tilted sideways. Then last Saturday two separate incidents. First the top of a round button broke when loading the rocket onto the rail, see picture. Later the top portion of an airfoil guide broke, also when loading, I recall hearing the sound of plastic cracking as the rocket was sliding down the rail, even though I was trying to be extra careful in light of the first incident, see attached "before and after" picture. Joe may be onto something when he says, "If they are breaking you are likely binding them when you are loading. It's easy to do. There is a learning curve going from lugs to buttons." Please explain further about "binding them when loading," not sure what that means. I see that some people spray silicon or WD-40 on the rail before loading, maybe that's what I need to do. I did notice on both occasions that the rocket did not seem to be sliding down the rail as easily as usual.

  19. #19
    Join Date
    17th February 2014
    Posts
    542
    Quote Originally Posted by billdz View Post
    Thanks for the replies, and special thanks to Scott for offering to replace the airfoil guide. I have had 4 issues since February, two with rockets I built and two with pre-built rockets that I purchased. The first time, I noticed on recovery that one of the rail buttons was gone, apparently it the screw came out during flight, as there was nothing but a hole. When I went to replace it, I started to put some CA in the hole so that the screw would hold tighter, and that's when I was told not to use CA because it might bind the button, which is supposed to be loose so it can spin. The second incident happened a couple of months later, nothing major, the screw had come partially out and the button was tilted sideways. Then last Saturday two separate incidents. First the top of a round button broke when loading the rocket onto the rail, see picture. Later the top portion of an airfoil guide broke, also when loading, I recall hearing the sound of plastic cracking as the rocket was sliding down the rail, even though I was trying to be extra careful in light of the first incident, see attached "before and after" picture. Joe may be onto something when he says, "If they are breaking you are likely binding them when you are loading. It's easy to do. There is a learning curve going from lugs to buttons." Please explain further about "binding them when loading," not sure what that means. I see that some people spray silicon or WD-40 on the rail before loading, maybe that's what I need to do. I did notice on both occasions that the rocket did not seem to be sliding down the rail as easily as usual.
    I've noticed my rockets will sometimes bind when I'm sliding them on the rail. it's because they're rolling over to the side, twisting the button in the slot. maybe i haven't torqued them enough to break one yet. I've found that laying the rail so i load the rocket hanging from the rail instead of laying on top of the rail, the rolling over and binding doesn't happen. It's especially easier with the heavier fiberglass rockets.
    NAR
    L1: 2/2/13, Madcow 4" Patriot. CTI H143
    L2: 9/2/14, Madcow 4" AGM33 Pike. CTI J335. 2,878 ft, 418 mph
    L3: 1/7/17, Wildman Drago XL. AT M1500. 13,559 ft, 1,017 mph, Mach 1.2

  20. #20
    Join Date
    26th November 2009
    Posts
    4,939
    Wellnuts or on glass rockets, jack nuts. I have never had a jack nut pull out of a glass airframe. Kurt

  21. #21
    Join Date
    11th February 2017
    Location
    south Florida
    Posts
    572
    Scott, I will send you what I have. This is a rocket that I purchased already built, don't know where these guides are from. Kurt, the wellnuts/jacknuts look like a great idea, I'll use on future builds.

    "I've found that laying the rail so i load the rocket hanging from the rail instead of laying on top of the rail, the rolling over and binding doesn't happen." That does sound like the best method.
    Last edited by billdz; 21st November 2017 at 08:06 AM.

    L1 3/25/17 H135
    L2 8/12/17 J180

  22. #22
    Join Date
    5th February 2009
    Location
    Montreal, Qweebec
    Posts
    3,402
    When the rail is down, do we load on top of the rail or the bottom? (is the rail above or below rocket when loading / in the horizontal position?)

    I always try to load the rocket onto the rail so that it is hanging. I feel this make it less likely to 'roll off' the rail when loading / getting eth rail back into a vertical position. When I can't I try to cup the rail in my hand, and have my fingers support the rocket so it doesn't roll when I 'top load'. I also try to lower the rail to just as low as I need to get the rocket on, so there is still some angle (and 'hang') to it..
    -paul

    NAR# 101258 - L1
    www.CRMRC.org
    I don't know the same things you don't know..

  23. #23
    Join Date
    30th May 2017
    Location
    vermont
    Posts
    56
    Quote Originally Posted by Rocketjunkie View Post
    I found these at McMaster-Carr. They will be good for retrofitting cardboard rockets. Bend flange to fit airframe diameter, remove paint and epoxy on.
    Click image for larger version. 

Name:	IMG_20171116_005550.jpg 
Views:	139 
Size:	128.8 KB 
ID:	332602
    https://www.mcmaster.com/#98007A013 in stainless, https://www.mcmaster.com/#98007A110 plated steel
    Those look awesome, how easy do they bend and take shape?
    Eric M
    NAR#85115 L2

  24. #24
    Join Date
    24th June 2011
    Location
    Whitney Point, NY
    Posts
    367
    You will see the difference with the TRUE airfoil guides we manufacture. For the record, those do not look like an airfoil shape, very curious to see them up close. Not sure who made those but I am anxious and happy to get another set of SCP guides out in the world, especially since it seems you may be a good TEST PILOT!! Please let me know directly what you think, and I sent you the address in a PM. I will pay you to ship them to me, and I will cover shipping the SCP guides to you. Consider it a sponsorship for a new test pilot haha! And lots of good comments on loading in this thread too I see. Interestingly, I know you are no slouch either! So I am super curious to see what kind of failure we are looking at here. I wonder if they are just using a brittle material. We shall soon see. Thanks for the effort of sending these to me Bill!



    Quote Originally Posted by billdz View Post
    Scott, I will send you what I have. This is a rocket that I purchased already built, don't know where these guides are from. Kurt, the wellnuts/jacknuts look like a great idea, I'll use on future builds.

    "I've found that laying the rail so i load the rocket hanging from the rail instead of laying on top of the rail, the rolling over and binding doesn't happen." That does sound like the best method.

  25. #25
    Join Date
    7th August 2013
    Posts
    362
    Quote Originally Posted by SCP View Post
    You will see the difference with the TRUE airfoil guides we manufacture. For the record, those do not look like an airfoil shape, very curious to see them up close. Not sure who made those but I am anxious and happy to get another set of SCP guides out in the world, especially since it seems you may be a good TEST PILOT!! Please let me know directly what you think, and I sent you the address in a PM. I will pay you to ship them to me, and I will cover shipping the SCP guides to you. Consider it a sponsorship for a new test pilot haha! And lots of good comments on loading in this thread too I see. Interestingly, I know you are no slouch either! So I am super curious to see what kind of failure we are looking at here. I wonder if they are just using a brittle material. We shall soon see. Thanks for the effort of sending these to me Bill!
    I rip off tons of rail buttons every year, blow out a ton of thrust plates also ��
    John Haught L3
    Prefect Tripoli Pittsburgh

  26. #26
    Join Date
    21st January 2009
    Location
    Manitowoc, WI
    Posts
    2,221
    Quote Originally Posted by billdz View Post
    Thanks for the replies, and special thanks to Scott for offering to replace the airfoil guide. I have had 4 issues since February, two with rockets I built and two with pre-built rockets that I purchased. The first time, I noticed on recovery that one of the rail buttons was gone, apparently it the screw came out during flight, as there was nothing but a hole. When I went to replace it, I started to put some CA in the hole so that the screw would hold tighter, and that's when I was told not to use CA because it might bind the button, which is supposed to be loose so it can spin. The second incident happened a couple of months later, nothing major, the screw had come partially out and the button was tilted sideways. Then last Saturday two separate incidents. First the top of a round button broke when loading the rocket onto the rail, see picture. Later the top portion of an airfoil guide broke, also when loading, I recall hearing the sound of plastic cracking as the rocket was sliding down the rail, even though I was trying to be extra careful in light of the first incident, see attached "before and after" picture. Joe may be onto something when he says, "If they are breaking you are likely binding them when you are loading. It's easy to do. There is a learning curve going from lugs to buttons." Please explain further about "binding them when loading," not sure what that means. I see that some people spray silicon or WD-40 on the rail before loading, maybe that's what I need to do. I did notice on both occasions that the rocket did not seem to be sliding down the rail as easily as usual.
    Whoa, I'm with SCP in the "what the heck are those?" category!

    Are both styles pictured aluminum?

    If so, aluminum binds on aluminum, and indeed when stressed Al will yield or tear. Thus, most people use delrin/acetal, or nylon for buttons; airfoil or round in shape. The plastics are self-lubricating and will wear down before sticking or gouging the rail. SCP, Railbuttons.com, Wildman, Loc, Apogee, and others are good sources.

    Many clubs used to forbid the use of aluminum guides (such as Acme conformal) on their rails because they would gall, mar, and otherwise wear on the club rails. Haven't seen that enforced much recently, however.

    Anywho, plastic guides are the way to go!
    Eric Cayemberg
    TRA 7783 L3
    TAP

  27. #27
    Join Date
    19th January 2009
    Posts
    3,394
    Quote Originally Posted by ericm541 View Post
    Those look awesome, how easy do they bend and take shape?
    They bend pretty easy with a couple pairs of pliers. The flange is about .045" thick. I haven't done under 3" airframe yet.

  28. #28
    Join Date
    24th June 2011
    Location
    Whitney Point, NY
    Posts
    367
    Do you have an address with a loading dock and forklift?


    Quote Originally Posted by sharkbait View Post
    I rip off tons of rail buttons every year, blow out a ton of thrust plates also ��

  29. #29
    Join Date
    30th January 2016
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    US > OK > NE
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    Quote Originally Posted by ECayemberg View Post
    Whoa, I'm with SCP in the "what the heck are those?" category!

    Are both styles pictured aluminum?

    If so, aluminum binds on aluminum, and indeed when stressed Al will yield or tear. Thus, most people use delrin/acetal, or nylon for buttons; airfoil or round in shape. The plastics are self-lubricating and will wear down before sticking or gouging the rail. SCP, Railbuttons.com, Wildman, Loc, Apogee, and others are good sources.

    Many clubs used to forbid the use of aluminum guides (such as Acme conformal) on their rails because they would gall, mar, and otherwise wear on the club rails. Haven't seen that enforced much recently, however.

    Anywho, plastic guides are the way to go!
    Does anybody do UHMWPE? I understand it's about as slick as acetal w/ ~4% ptfe IIRC. Tricky to machine though?

  30. #30
    Join Date
    13th August 2017
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    SEPA
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    157
    Do you have an address with a loading dock and forklift?
    I do

    NAR# 104365

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