Excessive gap between motor tube and CRs

The Rocketry Forum

Help Support The Rocketry Forum:

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
8,183
Reaction score
2,989
DON'T USE Gorilla Glue to FILL GAPS. YES it foams up and looks nice. But the OVERLY Foamed Glue, has almost no real strength. I will do that to fill a gap for painting, but do not use it to fill a gap in a structural joint.

Here is a really good write up and test. Plus the manufacturer responded, and agreed exactly with what the testing found.
I see and agree that for most joints gorilla glue wouldn’t be as good. I am wondering if centering rings are a bit different. Because of the geometry, the glue acts like a shoulder above and below the ring, it’s almost more of a block than an adhesive. It doesn’t have much Of any shear strength between pieces. I may play with this a bit. On the other hand, I am using it for D motors and lower, and using foam board for centering rings, so perhaps my success is less to do with good glue as it does with little stress. I tell you, for scratch building it’s hard to get anything to stick to the inside of a Pringle’s Can!

or now That I think of it, I tend to oversized my foam rings and undersized the holes in my foam board rings, then sand them so they fit tightly without any glue at all. So maybe thats why it works well for me, I am using it not as a gap filler.
 

Five

Well-Known Member
Joined
Jun 10, 2020
Messages
273
Reaction score
176
I'd make sure there is plenty of contact from tube to glue to component.
  • First, notify Apogee of the issue. Include pictures. See what they have to say.
  • Carefully trim the paper under the rings so that it barely sticks out, then apply fillets wider that the paper strip.
  • Put paper at the aft end of the tube no wider than half the insertion depth into the retainer.
That way the paper assures theverything is centered around the tube, but you don't have the paper in the load path. In other words, the paper functions as a spacer, but is not structural.
[/QUOTEa couple pictures
 

Five

Well-Known Member
Joined
Jun 10, 2020
Messages
273
Reaction score
176
A couple pictures never hurt anyone.
 
Top