Aeropoxy vs 30 min BSI for cardboard

Iamtannorv

Active Member
Joined
Sep 19, 2021
Messages
35
Reaction score
30
Kind of a glue thread so beware. Planning on building my first cardboard HPR, a 5.5in loc big nuke 3E, and I remember reading somewhere that at a certain point with cardboard rockets the epoxy you are using can be stronger than the material it is being used to bond. I normally use aeropoxy laminating epoxy with some milled fiber glass for my fiberglass birds, with 5 min BSI for tacking. Is 30 min strong enough to use on a cardboard bird to the point the cardboard would fail before the epoxy or is aeropoxy a good choice?
 
Joined
Jul 25, 2009
Messages
14,889
Reaction score
11,966
Location
NC
sure, I would feel comfortable using either one.
As cardboard has proven for decades in the rocketry world to rip apart easily. Just look at any CATO video or pics.
 

SmurfTacoSupreme

Well-Known Member
TRF Supporter
Joined
Sep 23, 2018
Messages
134
Reaction score
180
Location
western MA
Either should be dandy. I feel that Aeropoxy (or other slow-cure adhesives) have more time to seep into the fibers of the substrate resulting in a "stronger" bond. Whether that stronger bond is necessary may or may not matter, but it feels more belt and suspenders. That being said a good wood glue joint is stronger than the wood itself so maybe splitting hairs regardless. 🤷‍♂️
 

MidOH

Well-Known Member
Joined
Jun 3, 2021
Messages
618
Reaction score
516
Location
Lexington, OH
Where I sanded off the glassine layer, my 30min epoxy really soaked in well. Not sure how deep, but it's an impressive grab. I don't think my Titebond3 wood glue does that.

Glue thread punishment:
funny-gif-rocket-launch-fail-gif.1045041
 

dr wogz

Fly caster
Joined
Feb 5, 2009
Messages
8,893
Reaction score
4,853
Location
Land of Poutine!
To echo the others:
  • the longer the cure time, the better it 'bites into' the parts being bonded.
  • Yellow glue is great on paper & wood (what it was designed for) Epoxy & filler for the fillets..
  • the rougher the surface, the better the bold with either (sand / peel off the smooth glassine layer - I sand where I need..)
 

bobbyg23

Well-Known Member
Joined
Apr 15, 2020
Messages
1,274
Reaction score
1,314
Yes. BSI is strong enough. Either product will work just fine. I tack with gorilla wood glue and then fillet with BSI.
 

gary7

Well-Known Member
TRF Supporter
Joined
Aug 2, 2009
Messages
735
Reaction score
112
Location
Mattoon, IL
Draw a parallel line on the tube where you want the fin parallel to the tube. Cut your slots. These two steps can be eliminated most of the time on kits because the slots are already there. Then you only have to do the perpendicular part of the "alignment". To make sure it is perpendicular to the tube I have just “eyeballed” it alot. But there are any number of jigs you can use for both axes.

But that's a different thread.
 
Last edited:

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,991
Reaction score
3,815
Location
Pasco, WA
Draw a parallel line on the tube where you want the fin parallel to the tube. To make sure it is perpendicular to the tube I have just “eyeballed” it alot. But there are any number of jigs you can use for both axes.

But that's a different thread.
Do two opposing fins at the same time, use a angle iron clamped across the two flats on the fins. The lines locating the fins on the motor tube sets their location, and the angle make them both in the same plane.
 
Last edited:

Dane Ronnow

Well-Known Member
TRF Supporter
Joined
Dec 15, 2020
Messages
640
Reaction score
414
Location
Las Vegas, NV
This thread would not be complete without someone (in this case, me) advising that in a paper/wood rocket, epoxy is overkill and that wood glue will create a joint every bit as good (and possibly better) than epoxy.
True for some, maybe even most. Personally, I have more confidence in the rocket—a 2.6" MPR flying on a G80—with centering rings that are epoxied to the motor tube (J-B Weld) and body tube (BSI 30-minute). Beyond that, I use epoxy on couplers because Elmer's White glue dimples the BT when it shrinks, and Elmer's Carpenter's has a nasty habit of seizing. Besides, doesn't epoxy last longer?
 

jimzcatz

Boss, Carolina Rocket Mafia
Joined
Jan 22, 2009
Messages
4,747
Reaction score
870
Location
Hurdle Mills NC
Where I sanded off the glassine layer, my 30min epoxy really soaked in well. Not sure how deep, but it's an impressive grab. I don't think my Titebond3 wood glue does that.

Glue thread punishment:
funny-gif-rocket-launch-fail-gif.1045041


Once again I must say this. You don't have to sand glassine. A mildly damp sponge will remove it without damaging the cardboard.
 

bobbyg23

Well-Known Member
Joined
Apr 15, 2020
Messages
1,274
Reaction score
1,314
How do you make sure the fins are properly aligned when building like that without the CR slots from the loc n rings?
Insert the motor mount into the rocket then tack the fins through the slots.
 

jimzcatz

Boss, Carolina Rocket Mafia
Joined
Jan 22, 2009
Messages
4,747
Reaction score
870
Location
Hurdle Mills NC
None of my rings have fin notches. I attach fins to mmt /crs extend slots all the way to the rear and install as a complete unit.
 

rharshberger

Well-Known Member
Joined
Oct 13, 2014
Messages
11,991
Reaction score
3,815
Location
Pasco, WA
What now? Like just wipe the tube a few times with a damp regular old sponge and glassine be gone?

View attachment 509031
yes and no, glassine is not plastic like a lot of people think it is, it is actually Supercalendared Paper aka Glassine, which is paper that has been run through a special rolling process (high pressure rollers) that gives it a smooth and glossy appearance. So when you dampen the surface of glassine, I use a dampened paper towel and rub it around until the tube starts to feel gritty, and it will change color slightly due to the moisture (the color change is temporary). After the tube had dried the surface will no longer be shiny instead it should be a matte/satin sheen, and no material has actually been removed from the tube (or at least very little), unlike peeling which removes an entire layer of paper.
 

H_Rocket

Death by Powerpoint
Joined
Jan 18, 2009
Messages
4,313
Reaction score
757
Location
North Central Texas
True for some, maybe even most. Personally, I have more confidence in the rocket—a 2.6" MPR flying on a G80—with centering rings that are epoxied to the motor tube (J-B Weld) and body tube (BSI 30-minute). Beyond that, I use epoxy on couplers because Elmer's White glue dimples the BT when it shrinks, and Elmer's Carpenter's has a nasty habit of seizing. Besides, doesn't epoxy last longer?
It comes down to what makes you happy. It’s a hobby and if epoxy makes you feel good and works for you, have at it. I, for one, have never seen the appeal of JB-Weld for anything other than the retainer mount. That said, if the guy next to me wants to dip his rocket in it, that works for me.

I also find the way white and yellow glue seizes frustrating on small paper rockets.
 

H_Rocket

Death by Powerpoint
Joined
Jan 18, 2009
Messages
4,313
Reaction score
757
Location
North Central Texas
never heard of glue "seizing" :questions:
If you take white or yellow glue and apply it to a model rocket tube coupler then slide that into the outer tube, the water in the glue can rapidly wick out of the glue as you slide the pieces together. Instant bond as the glue dries while in motion. Also happens with centering rings, engine blocks, etc.
 

SmurfTacoSupreme

Well-Known Member
TRF Supporter
Joined
Sep 23, 2018
Messages
134
Reaction score
180
Location
western MA
If you take white or yellow glue and apply it to a model rocket tube coupler then slide that into the outer tube, the water in the glue can rapidly wick out of the glue as you slide the pieces together. Instant bond as the glue dries while in motion. Also happens with centering rings, engine blocks, etc.

Only had that happen to me once when using Titebond (original). You quickly learn that you don't wanna experience it again. :)

I mainly use Titebond III now which is a little more forgiving, but still best to get things in place ASAP.
 
Last edited:
Joined
Jul 25, 2009
Messages
14,889
Reaction score
11,966
Location
NC
If you take white or yellow glue and apply it to a model rocket tube coupler then slide that into the outer tube, the water in the glue can rapidly wick out of the glue as you slide the pieces together. Instant bond as the glue dries while in motion. Also happens with centering rings, engine blocks, etc.
thanks, I'll watch out for that in the future.
 

waltr

Well-Known Member
Joined
Jul 17, 2021
Messages
1,213
Reaction score
710
Location
SE Pennsylvania
If you take white or yellow glue and apply it to a model rocket tube coupler then slide that into the outer tube, the water in the glue can rapidly wick out of the glue as you slide the pieces together. Instant bond as the glue dries while in motion. Also happens with centering rings, engine blocks, etc.
Exactly. I had this happen once and now use 30min epoxy on couplers.
 
Top