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. :-(
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View attachment 503484
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.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.
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.Tell us how it broke!
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.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.
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?Bottle of super glue , and your done
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.
Do it if you want to, to get the practice with epoxy.. (you can then respond to 'glue threads' with authority & wisdom! )
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.
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.
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.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.
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).You don't get as strong a joint... Quick & Thick tends to bridge over gaps instead of filling them.
People I trust claim that most of the strength comes from the fillets anyway.Sure, it's great for fillets..
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!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.
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.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.
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