Modifying AT kits post-build for rail buttons

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OC_Rocket_Man

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What's the best way to modify an AT kit post-build for rail buttons?

My first inkling was to use well nuts /rawl nuts, but I'm thinking the expansion idea won't work well on glorified paper towel rolls.

I've seen images here of people putting rail buttons right into the plastic launch lugs which seems like workable approach. Drill a small pilot hole and use a self-tapping screw to affix the button to the lug? Put an actual nut inside the lug? Tap a thread into the actual lug?

Any other approaches? Links?
 
I've used well nuts for this purpose, but I reinforce the hole with CA before expanding the nut. Drill hole -> soak with CA, let dry -> redrill hole, repeat if necessary, then install well nut. Has worked well so far...

-Robert
 
What's the best way to modify an AT kit post-build for rail buttons?

My first inkling was to use well nuts /rawl nuts, but I'm thinking the expansion idea won't work well on glorified paper towel rolls.

I've seen images here of people putting rail buttons right into the plastic launch lugs which seems like workable approach. Drill a small pilot hole and use a self-tapping screw to affix the button to the lug? Put an actual nut inside the lug? Tap a thread into the actual lug?

Any other approaches? Links?

Ive always just drilled a 5/32 inch hole in the outer surface of the launch lug and screwed a regular rail button into it. Nothing fancy.
 
Ive always just drilled a 5/32 inch hole in the outer surface of the launch lug and screwed a regular rail button into it. Nothing fancy.

Screwing it on with a wood screw? Ooph, if I didn't see that survive durably, I'd probably never try it.


@Original question: For cardboard tubes (cuz that's all I build), I use a weld nut (toothless t-nut) on the inside. You can order them from Mcmaster, Apogee, or buy them in store from Lowes
 
Screwing it on with a wood screw? Ooph, if I didn't see that survive durably, I'd probably never try.

No, not a wood screw; what kind of butcher do you think I am? :)
I use the standard machine screws provided with the rail buttons. The threads self tap right into the Aerotech plastic lugs and hold very well.


Steve Shannon
 
@Original question: For cardboard tubes (cuz that's all I build), I use a weld nut (toothless t-nut) on the inside. You can order them from Mcmaster, Apogee, or buy them in store from Lowes

This Initiator in question has been built for over a decade...with epoxy. There's no way for me to get weld nuts in it now.

I realize sanding it down and installing rail guides is probably the best option for a completed build, but I'd prefer not to sand/repaint.

When I built this Initiator originally, I followed instructions for HPR builds (except I left in the thrust ring/flange/motor hook). Epoxied everything, foamed the fin can, lead shot/epoxy/foam in the NC etc. As it sits now it weighs 888g sans motor. If I add any more weight it will never fly again. Yes, 888g for a kit listed at 400g :facepalm:
 
Glue a balsa/basswood strip to the side of the rocket, use the screws from the rail buttons to screw into that. You can pre-drill and tap the holes if you;d like and stiffen them with CA glue.

kj
 
I put mini rail buttons on my Arreaux after experiencing rail whip on its maiden launch. I cut off the guides and patched the areas with auto glazing putty and spot primed. I drilled holes for the 4-40 tap and treated them with CA. Tapped the holes and applied a drop of CA on each hole...and retapped the hole. The rocket has flown twice with AT F20-7 power.

IMG_5752.jpg
 
I've used well nuts for this purpose, but I reinforce the hole with CA before expanding the nut. Drill hole -> soak with CA, let dry -> redrill hole, repeat if necessary, then install well nut. Has worked well so far...

-Robert

Ended up going similar to this approach. Drilled then CA'd. Went in with a hobby knife to clean up the hardened burring. Took a bent paperclip with tiny amounts of CA and worked it around inside the BT to reinforce it more. Then round filed until the well nut would go in snugly without deforming the BT. Used airfoil rail buttons because they looked slick. LOL.

Used the same approach on my Warthog. The Cheetah will now undergo the same procedure since she damaged a launch lug today.
 
What's the best way to modify an AT kit post-build for rail buttons?

My first inkling was to use well nuts /rawl nuts, but I'm thinking the expansion idea won't work well on glorified paper towel rolls.

I've seen images here of people putting rail buttons right into the plastic launch lugs which seems like workable approach. Drill a small pilot hole and use a self-tapping screw to affix the button to the lug? Put an actual nut inside the lug? Tap a thread into the actual lug?

Any other approaches? Links?

Give Wildman a call he sells glue on rail guides that you glue on. There not the old metal guides that have been out for years. They are some kind of plastic. I have not used them but have seen many who do. Much easier to put on a pre built rocket.
 
People, please realize that soaking any kind of paper with ca turns said paper into very brittle phenolic like what PML sells. Of course you can get an expanding well nut into a 10 yr old Initiator, why wouldn't you. I put rail buttons 180° opposite my lugs on my paper rockets. No issues so far. Don't ca paper, leaving yourself open to weak points. The only thing I use ca on paper is to take something in place prior to epoxy.
 
Give Wildman a call he sells glue on rail guides that you glue on. There not the old metal guides that have been out for years. They are some kind of plastic. I have not used them but have seen many who do. Much easier to put on a pre built rocket.

X2...
 
No, not a wood screw; what kind of butcher do you think I am? :)
I use the standard machine screws provided with the rail buttons. The threads self tap right into the Aerotech plastic lugs and hold very well.


Steve Shannon

+1, This is a great approach. No need to even add glue. So if for some bizarre reason you do need to launch from a 1/4" rod, you can simply unscrew the lugs, and replace them when you are finished. I also like that this does not have anything project into the airframe where it could snag the laundry.

I did this to my Aerreaux several years ago, and it has over a dozen flights on it with at least 3 on an F39-6.

Here's how I handled it on my Aerotech Arreaux. Aerotech provides an interesting opportunity due to the style of their launch lugs (I assume the G-Force uses the same ones)

View attachment 287401
 
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My first inkling was to use well nuts /rawl nuts, but I'm thinking the expansion idea won't work well on glorified paper towel rolls.

I have many cardboard rockets from the pre-rail days that have been converted with well nuts. No CA reinforcement. I've not had any issues doing it this way.
 
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