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Do you install rail buttons before or after you paint the rocket? I've seen a few build threads that install them before. Do they mask the rail button to keep the paint off the button?
Rail Button Question
- Thread starter Jeff Curtis
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It depends on how I am installing, but I generally don't install the actual buttons until after the final clear has dried. If I'm using a t-nut as a backer, I'll install and mask those for paint and put the buttons in after the final clear coat. If I'm to install into a wood centering ring, I have done it both ways - install and mask, and drill the hole but install after paint. Do it whichever way makes sense for you, but I've found it easier to install after paint.
I put the rail buttons on before I do anything else. I just give the centering rings a touch with my Dremel. They get painted with the rest of the rockets. That way they blend in. The paint does not interfere with their function. The button to rail fit is not tight. If you have trouble sliding the rocket down the rail it's not because there is paint on it. It's because the rail is dirty.
JimByrne
Well-Known Member
I would never paint a rail button.
This causes more friction, and you want to avoid that.
Our clubs launch rails are cleaned, inspected & wiped with spray was after each event
to reduce friction.
This causes more friction, and you want to avoid that.
Our clubs launch rails are cleaned, inspected & wiped with spray was after each event
to reduce friction.
I've done it both before and after painting. Before is best since it's stronger to have it backed with something like a blind nut or block of wood (if not on a cr).
Sometimes you'll find you have to install after because you forgot to install them before!
After should be fine as long as you're not going beast mode motors. Just drill the hole, add epoxy into the hole all around the inside repeatedly with a toothpick, spread some epoxy on the bolt extending out of the button assembly and install. For really big rockets there's other ways, but if you're asking, you're probably not there yet.
Fyi I've never had a button tear out. YMMV
Sometimes you'll find you have to install after because you forgot to install them before!
After should be fine as long as you're not going beast mode motors. Just drill the hole, add epoxy into the hole all around the inside repeatedly with a toothpick, spread some epoxy on the bolt extending out of the button assembly and install. For really big rockets there's other ways, but if you're asking, you're probably not there yet.
Fyi I've never had a button tear out. YMMV
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I usually install them last, but sometimes they end up on there before painting or clear and I just wrap a piece of masking tape around them. As some others have said I don't use any sort of backer. Sometimes it works out that I get one into a ring but usually not. I just drill a slightly undersized hole, use the screw itself to 'tap' the hole and then add some thick CA and screw it back in. This works well with the machine screws that come with the rail-button.com buttons (doesn't work well with buttons that have more coarsely threaded screws or wood screws). I have also never had a rail button rip off (but I have never had a rocket over about 8 lbs loaded), obviously for larger rockets I would probably change my tactic (but then its also much easier to get a backplate nut inside when you can easily fit your arm in the body tube (and then I would just keep it covered with masking tape for the rest of building)
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My current plan is to use well nuts where i can't reach the inside of the tube. T-nuts where i can reach.
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Just working on my L1 rocket, the LOC Semper Fi. But I've also just completed the North Coast Lance Delta and the Loc Onyx, and want to use rail buttons on them too. Both are ready to paint, so hence my question. I appreciate the feedback.
waltr
Well-Known Member
I always have a threaded hole to attach rail buttons. This is typically threaded into CRs (if thick enough) or a hardwood block glued to the CRs.
This allows replacing buttons that got worn.
Then insert a screw, without the button and tape it off to do the painting.
This allows replacing buttons that got worn.
Then insert a screw, without the button and tape it off to do the painting.
A simple trick to make masks for the rail button hole (button assembly removed) is to use a hole puncher on masking tape to get little circular masks to cover the spots for painting.
Sticky side down and use a toothpick to grab it out.
Sticky side down and use a toothpick to grab it out.
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I like this for composite airframes. Was just looking at well nuts on AliExpress yesterday for another use, but I could totally see them for round rail buttons on bigger rockets. They are cheap and available in quantity down to M4 threads.
My rail buttons get screwed to the centring rings. I'll measure and drill before painting so the paint covers the pencil marks. Actual installation happens after paint.
Interesting, I usually just insert a screw into the tube as a placeholder for the rail button. After painting, I complete the drill out and insert a weld nut when I don't have a CR to attach to.
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I used to insert the bolt and tape that, but found that it sometimes made the spray painting a tiny bit more bothersome to spray around and maybe cause drips and then removing the painted tape off the screw was a pain too.
There are many methods and I like yours too, but I always have trouble finding the right size screw or misplacing the one used as a dummy, so I usually just used the rb bolt and masked that (if not just masking the hole).
There's also hurricane nuts... similar to T-nuts, but without the T(eeth).
I sometimes use these epoxied in on my hp stuff. It's also flatter, which means little chance of the chute getting caught on it.
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I believe that is what Apogee includes with their rail buttons. Tim calls them weld nuts.
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I tape mine before painting. I use above techniques. I have some that are epoxied in and others that can be replaced. Yes, I've had several wear out so that they wouldn't stay in a rail, so they were replaced. Also, I usually use basswood standoffs for the buttons. It adds drag but keeps the rail off of the AF. The standoffs are very important when using piston ejection as you don't want the screw/bolt/nut to inhibit the piston. Another different approach is to use Giant Leap's Al Acme conformal rail guides for using on a 1010 rail. They come in sizes to match common AFs. I've retrofitted some old kits that had lugs with these.
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I looked at conformal rail guides, but a lot of people seem to have issues with them popping off the rocket while loading on the rail. I'm still thinking of using them on my Loc Weasel, which is barely bigger than minimum diameter.
For the Acme rail guide, do you stick that onto a painted surface?
I felt that they were best suited for fiberglass since it can stick well to that unpainted surface.
I had a set and used it on my Madcow 4" Phoenix. However, since it was cardboard and already painted, I actually cut out the painted layer and also drilled holes to act as "rivets" with the JB Weld I used to glue them on. (Note that I will be launching using some Warp motors.)
I use the Apogee rail buttons. I like their T nus/ Hurricane nuts because the lay flush with the inside of the BT. When I first started building I used rail guides. After having them pop off the BT when loading the rocket on the rail I stopped using them. I retrofitted buttons on the ones that had guides.
Capt. Eric
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I install before paint, but if you want a coordinating color without painting the button, eRockets sells them in a few different colors besides black and white.
What kind were the rail guides? Were they surface mount?
There's also bolt on rail guides and I have ones made by PML that were installed in my X-15 with about a dozen hp flights and no issues (it is sometimes a bear to get it on the rail though since it has to go on very straight while buttons have more leeway). Ymmv. Also I paint over these.
I now sometimes will use a button on top and a rail guide on the bottom so there's less chance of pivoting after the first button leaves the rail. I've done this on several rockets (including a 3" Punisher that was punished lol) and last night I was setting up my 7.5 V2 for the same.
Of note is that my set of PML rail guides I got in 2015 had holes drilled crooked. I notified them and they said that no one had ever mentioned it! Lol
Top doesn't look bad, but...
Bottom you see the right hole is slightly higher.
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I haven't had a problem with them popping off. When I go to install them, I rough up the backside with coarse sandpaper plus the AF surface and then clean with 91% IPA. I use epoxy to secure. To line up two of them, I use a straight metal yardstick.
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For a new install, no. I have added those to old, painted rockets, but roughed up the surfaces as I mentioned above to Jeff. I've not had a problem when I've added them to painted rockets either. I have used Aeropoxy to secure for larger rockets.
I use well nuts, going through a baffle wall or a coupler used to strengthen the body tube ahead of the motor mount. The increased wall thickness helps the well nut lock the rail button down. It's a rock-solid setup.
Here's my installation test on some scrap tubing:
After the hole is cut, I seal it with CA, then paint the rocket. Rail button goes on after painting and clear coats are completed. The rail button can be replaced when it becomes worn, and the well nut can be pulled and inspected.
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Yes, surfaced mounted and they came from Apogee. I was uneducated when I started building. Which is why I cut up so many of my early rockets. Most of them popped off when it was cold.
No matter how I attach them, blind nut, backing plate, CR, they are always added after paint.
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So you don't epoxy the well nut into the tube?
WELD nuts get epoxied to the airframe, some even just Loctite the screw and don't epoxy.
WELL nuts are compression rubber nuts. When you tighten the screw, the rubber expands to hold the nut.
WELL nuts are compression rubber nuts. When you tighten the screw, the rubber expands to hold the nut.
