All I Want to Do Is Glue this Fin Back on…

[brockrwood]

All I want to do is glue this fin back onto my my scratch built, mini engine cluster bird.

But work and other commitments keep me from working on it. So many rockets to build. So little time. :-(

 

[K'Tesh]

 

[BigMacDaddy]

I work on rockets while I watch TV with my wife and/or kids at night and spend more time on them after everyone goes to sleep.

 

[3stoogesrocketry]

Bottle of super glue , and your done

 

[lakeroadster]

From what I am seeing, you didn't sand the glassine off the body tube before gluing the fin. That's like gluing a fin to waxed paper: the glue sticks to the fin, but not the glassine.

Sand the body tube until you can see the little fibers sticking up.. I'd suggest wrapping sandpaper around a small (1/8" or 3/16") dowel to sand the body tube on this repair, thus minimizing damage to the orange paint.

And don't forget to sand all the wood glue / paint off the fin also, at the root edge and where the glue fillet will be on the sides. When your done prepping both parts, you should have raw cardboard tube fibers and raw wood fin fibers, no remaining glue /paint from the past.

Heck, take it to work and start fixing it on your lunch/sanity break.

 

[Back_at_it]

All I want to do is glue this fin back onto my my scratch built, mini engine cluster bird.

But work and other commitments keep me from working on it. So many rockets to build. So little time. :-(

View attachment 503483
View attachment 503484

If it were me. I'd sand the root edge of the fin and the clean up the body tube where the fin attached. That way you know you have clean attachment points. Grab your favorite wood glue and go for it.

 

[smstachwick]

I was considering building a few mini clusters. 1, 2, 3, or 4 motors. Basically convenient ways to dispose of a pack of motors that either have suffered a CATO themselves or have the same date codes as one that did.

 

[Enocelot]

Tell us how it broke!

 

[brockrwood]

I was considering building a few mini clusters. 1, 2, 3, or 4 motors. Basically convenient ways to dispose of a pack of motors that either have suffered a CATO themselves or have the same date codes as one that did.

The two engine mini cluster in the long, 29 mm body tube concerned me. I wondered if there was enough ejection power from the mini engines to push the laundry out and pop the “payload section” off. (The top part of the rocket is a payload section.). I need not have feared - Estes “shotgun” ejection charges to the rescue! No problem ejecting parachute, shock cord, wadding, and top of rocket.

In fact, on the second flight, the top of the rocket came off just fine AND the two mini engines self-ejected themselves. Oops! I will wrap more masking tape around the engines before inserting them next time. I may just tape the engines, which stick out a quarter inch, to the OUTSIDE of the engine mount tubes. That should do it, no?

 

[brockrwood]

Tell us how it broke!

Rocket placed in plastic “Kohl’s” bag in back of car. Girlfriend thought it was just clothes or something in the bag and placed a heavy bag of clothes on top of it (to take to donate at Goodwill store). Snap! Those Astron “Cobra” type fins are cool looking and give lots of stability, as they stick out a lot, but they are easy to break off.

The fins are made of chipboard from the back of a legal pad, so the fins are tough and flexible and don’t tend to break. But they stick out so much that pushing on the tip of the fin torques it right at the root where it is glued to the body tube and snaps it off at the body tube. This is the second time this fin has snapped off right at the body tube.

 

[brockrwood]

If it were me. I'd sand the root edge of the fin and the clean up the body tube where the fin attached. That way you know you have clean attachment points. Grab your favorite wood glue and go for it.

Like the plan. This is the second time this fin has popped off right at the body tube. I need to sand the fin and the tube and rough ‘em up really well, methinks. Then use epoxy? That should hold the fin on.

 

[brockrwood]

Bottle of super glue , and your done

That was the first thought that popped into my head. . I fear that a superglue bond between fin and tube will be a little brittle and tend to let the fin snap off again right where it is glued to the body tube. No?

 

[brockrwood]

Just for the record, two A10-3T’s really get this rocket moving fast off the launch rod. No problem with initial velocity. The altitude is acceptable - sort of like launching it on a fairly strong B motor.

 

[brockrwood]

Also just for record, I love launching clusters because the initial thrust “kick” of each motor sort of add together to give a huge initial impulse. Whoosh! The rocket may or may not go high, but it gets off the pad FAST. I have a Semroc Goliath (18 mm three engine cluster). I launch it using three A8-3’s. I get whiplash trying to follow it as it leaves the pad.

 

[markschnell]

View attachment 503493

This is really helpful stuff. I've been doing this for forty year and never considered the that the divots were a good thing that indicated good coverage. I always thought they were just a pain in the butt that required other coats to fill in.

Thanks for that. Learn something new everyday, huh?!

 

[cbrarick]

no to epoxy - it's like using a sledgehammer on a flea.
All you need is carpenter's glue - eg tightbond, and the glue will be stronger then the cardboard.
The pluses are it's cheaper, easier to use, easier to clean up and you can even just use your fingers.
Epoxy not so much....

 

[Back_at_it]

Like the plan. This is the second time this fin has popped off right at the body tube. I need to sand the fin and the tube and rough ‘em up really well, methinks. Then use epoxy? That should hold the fin on.

No point in using epoxy on cardboard and wood. If you sand the surface so that you have good adhesion, the materials will break before a standard wood glue bond. I'm thinking the issue here besides the heavy bag on top of the rocket, is that the body tube still had the coating on the outside. Sanding this off before gluing makes a huge difference.

 

[dr wogz]

3rd for "no to epoxy".. Nor to CA / Superglue..

Do it if you want to, to get the practice with epoxy.. (you can then respond to 'glue threads' with authority & wisdom! )

 

[Back_at_it]

Do it if you want to, to get the practice with epoxy.. (you can then respond to 'glue threads' with authority & wisdom! )

And you will get lots of practice doing so as that question seems to come up at least once a week

 

[GlenP]

I also have a hard time doing a simple repair, I usually end up starting a new build.

This is the LPR forum, right?

 

[Grant_Edwards]

No point in using epoxy on cardboard and wood. If you sand the surface so that you have good adhesion, the materials will break before a standard wood glue bond.

I'm fond of Titebond quick-and-thick for gluing fins and especially for doing fillets. It's not quite as fast as thick CA, but it is much easier to work with.

 

[lakeroadster]

I'm fond of Titebond quick-and-thick for gluing fins and especially for doing fillets. It's not quite as fast as thick CA, but it is much easier to work with.

You don't get as strong a joint... Quick & Thick tends to bridge over gaps instead of filling them. Sure, it's great for fillets.. but for the initial process of gluing wood based fins onto a wood base body, the thinner wood glue formula's are superior.

 

[Back_at_it]

I'm fond of Titebond quick-and-thick for gluing fins and especially for doing fillets. It's not quite as fast as thick CA, but it is much easier to work with.

I typically reserve thick and quick for my final fillets. It's generally too thick to soak into materials so it tends to sit on top but I will admit that it's does a great job even just sitting on top. For the initial bond and the first fillet I typically use TBII to TBIII as they are thinner and soak in better.

 

[BABAR]

Rocket placed in plastic “Kohl’s” bag in back of car. Girlfriend thought it was just clothes or something in the bag and placed a heavy bag of clothes on top of it (to take to donate at Goodwill store). Snap! Those Astron “Cobra” type fins are cool looking and give lots of stability, as they stick out a lot, but they are easy to break off.

The fins are made of chipboard from the back of a legal pad, so the fins are tough and flexible and don’t tend to break. But they stick out so much that pushing on the tip of the fin torques it right at the root where it is glued to the body tube and snaps it off at the body tube. This is the second time this fin has snapped off right at the body tube.

Hmmm, if made of chip board from a legal pad, I guess these are really cardboard? So this is a paper to paper bond. In that case, plain old white glue should work as well as wood glue, but wood glue tacks and Dries a bit faster I think. Epoxy is definitely overkill, costs more, is heavier, smells, and has potential for allergic Sensitization if you don’t wear nitrile gloves. CA is too brittle, it will bond quick but break easier.

@kuririn has a nice trick, tacks the ends with CA but uses regular glue (for balsa, wood glue) for the main attachment and fillets. Has the advantage of quick tack and full strength.

 

[Grant_Edwards]

You don't get as strong a joint... Quick & Thick tends to bridge over gaps instead of filling them.

I wouldn't be surprised if that was true for certain types of joints/materials. I would be a little surprised if it was true for balsa fins glues to cardboard tubes (with fillets).

Sure, it's great for fillets..

People I trust claim that most of the strength comes from the fillets anyway.

 

[ThirstyBarbarian]

… Hit it
This ain't no disco
It ain't no rocket club either
This is TRF

… "All I wanna do is glue this little fin before I die"
Posts a man in a thread out of nowhere
It's apropos of nothing, he says his name is Brockrwood
But I'm sure he's Bill or Billy or Mac or Buddy

… And he's plain ugly to me
And I wonder if he's ever glued a singe fin in his whole life
We are drinking beer at noon on Tuesday
In a bar that faces a giant work bench

… The good people of the world
Are gluing their fins on their lunch break
Sanding and gluing as best they can in skirts in suits

… They fly their shiny Rockets and Gliders
Back to the fin company, the rocket store too
Well, they're nothing like Billy and me

… 'Cause all I wanna do is glue this fin
I got a feeling I'm not the only one
All I wanna do is glue this fin
I got a feeling I'm not the only one

… All I wanna do is glue this fin
Until the sun comes up
Over Santa Monica Boulevard

 

[cbrarick]

Thirsty:
Is it any wonder you're not in jail
Is it any wonder you've got too much time on your hands
It's ticking away with your sanity
You've got too much time on your hands…

 

[kenstarr]

Major thread hijacking here. But when I saw the title in less than a second I thought, "don't you wish your girlfriend was a freak like me". Same rhythm and all.... And I don't even know the song or like that type of music (Gwen Stephanie???)

But to be more productive here, I'm a huge fan of the super glue for low power fin gluing and repair. I feel epoxy is too tricky for small things usually and isn't justified in these situations. As a side note, the largest rocket I've built, flew on an L something, I used hot glue to hold the fins while the epoxy cured...
Ken

 

[brockrwood]

Hmmm, if made of chip board from a legal pad, I guess these are really cardboard? So this is a paper to paper bond. In that case, plain old white glue should work as well as wood glue, but wood glue tacks and Dries a bit faster I think. Epoxy is definitely overkill, costs more, is heavier, smells, and has potential for allergic Sensitization if you don’t wear nitrile gloves. CA is too brittle, it will bond quick but break easier.

@kuririn has a nice trick, tacks the ends with CA but uses regular glue (for balsa, wood glue) for the main attachment and fillets. Has the advantage of quick tack and full strength.

Yep! I thought the cardboard to cardboard bond would be a cinch, but as commenters have pointed out, I think I did not sand off the glassine finish fully. I will really sand it well this time, and the fin, too, and try again!

 

[brockrwood]

I typically reserve thick and quick for my final fillets. It's generally too thick to soak into materials so it tends to sit on top but I will admit that it's does a great job even just sitting on top. For the initial bond and the first fillet I typically use TBII to TBIII as they are thinner and soak in better.

I have really started liking TBIII. As long as you can hold the parts together until it sets, it makes a really strong bond. TBIII is superb on centering rings and tube couplers where you don’t want stuff to freeze in place before you get the part where you want it.