Stuck friction fit motor casing

[jnmiller]

I launched my Madcow Trinity today, the flight was flawless! This is a clustered High Power rocket. I friction fit the motor casings as a redundancy safety measure because the motor retainer (which holds in all 4 motors) partially failed on a previous flight. So after today's flight when I removed the motors, the last one I tried to remove was STUCK bad! I have tried pulling and twisting with pliers. I have tried banging with a dowel. I have used the maximum force I feel I can exert without damaging the rocket. Any ideas? Its too big to fit in a freezer! Should I get some dry ice and touch it to the casing? Squirt some kind of solvent in from the top? Any other ideas?

 

[crossfire]

I launched my Madcow Trinity today, the flight was flawless! This is a clustered High Power rocket. I friction fit the motor casings as a redundancy safety measure because the motor retainer (which holds in all 4 motors) partially failed on a previous flight. So after today's flight when I removed the motors, the last one I tried to remove was STUCK bad! I have tried pulling and twisting with pliers. I have tried banging with a dowel. I have used the maximum force I feel I can exert without damaging the rocket. Any ideas? Its too big to fit in a freezer! Should I get some dry ice and touch it to the casing? Squirt some kind of solvent in from the top? Any other ideas?

View attachment 435373

What happens if you can get case very cold? Or would heat work.

 

[Spitfire222]

Perhaps get a can of compressed air (for cleaning electronics) and spray it upside down on the casing to cool it and hopefully shrink it enough to be removed?

 

[tim cubbedge]

What if you remove the aft closure and push it out the forward end of air frame?

 

[Jay Rairigh]

Use Spitfires' method. I've used it on other stuck pieces before. It works.

 

[HyperSonic]

Never mind, I thought It was a paper rolled casing.

 

[Rocketjunkie]

If you used masking tape to friction fit, you probably rolled the tape. Does the motor tube go through the centering rings so you can access the front of the motor? If so, then remove the rear closure and try shoving it forward with a dowel. It will be messy due to all the motor crud coming out during this operation.

 

[jnmiller]

I tried Spitfire's suggestion.. cooling it with an inverted can of compressed air.. and it worked! It still required some muscle but it worked!! Many thanks to all who left suggestions! This is why this forum rocks!

 

[Cameron Anderson]

Acetone works too when you're not worried about cardboard. Really destroys the adhesive.

 

[jnmiller]

Acetone works too when you're not worried about cardboard. Really destroys the adhesive.

Good to know if it happens again, thanks for the tip!

 

[schworer]

Glad you got the casing out.

I've had the same problem on a minimum diameter 54mm rocket that flew on a very large J motor. I solved it by wrapping the bottom of the rocket in a trash bag and then putting it into a bucket filled with ice cubes. I let it sit for about an hour and then pushed the casing out without too much trouble using a large diameter wooden dowel.

 

[David Schwantz]

when using tape to friction fit a motor I like to apply the tape at the rear most portion on the motor case. This way if it gets stuck, you do not have to far to push it out.