Tight fit? E-Bay Coupler Tube vs. Body Tube

[JSW]

I'm starting my first L2 rocket. It has an e-bay, but I intend to launch the first time with a single parachute and a Jolly Logic Chute Release. Maybe later get into BP-based dual-deployment.

The problem is: The e-bay tube is a really tight fit into the body tubes. I feel like it must be too tight for the engine eject charge to push it apart.

I've slightly rounded the e-bay tube ends to make easier to push into the body tube. I've run my fingernail around the inside of the body tube to get rid of that slightly crimped edge. Still too tight.

The e-bay tube is a heavy wall 4" cardboard coupler (see Apogee 4" e-bay). Should I sand down the outside of the e-bay tube until the fit with the body tube is about the same as nosecone vs. body tube? Assuming the outside of the cardboard coupler tube will get fuzzy after sanding,... maybe put some liquid superglue on it to harden it up?

Any other advice on how best to adjust the fit of the e-bay tube vs. body tube?

Thanks in advance!

Note: Testing with BP charges is not really an option. I'm not equipped for that.

 

[Ryangengler]

Even when I run motor ejection I like to test to ensure I get clean separation.
Not sure you mentioned the kit you were building. You could always reach back out to TVM to see if they could supply a different tube. I have noticed tolerances vary and sometimes things are tight — other times they are not…

 

[Titan II]

sandpaper...no glue

 

[heada]

I use thin CA to harden the coupler and then sand it smooth. This gives a better fit and allows me to sand it easier. Lots of different ways to do it, just pick one that works best for you.

 

[Rex R]

Try turning your coupler around they are not all symmetrical, one end may fit looser than the other.

 

[Sooner Boomer]

Note: Testing with BP charges is not really an option. I'm not equipped for that.

I bet you are. The minimum you would need would be a used motor case in the size you want to fly with, an igniter, and some black powder. Use a rod to poke a hole through the spent motor, and run the igniter leads through it and out the nozzle. Put the bp in the ejection well, and put the motor (case) into the rocket and secure it. You can do something similar using RMS cases. If you don't have a safe way to fire the bp, take it to your next launch, and ground test it there. (actually, if you're going to test it at a launch, wait until then to add the bp and putting the motor in - safety)