Aurora 38mm MD rocket

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conman13 said:
I was able to get about 6" of it off the mandrel. The rest wouldn't budge. I'm definitely not wrapping my Mylar tight next time.

View attachment 186164
Click to expand...

Connor, my recommendation would also be to warm the tubing (being careful not to liquify the epoxy) and, to continue with a cooling method using the ice/salt above. :point:

In effect keep working on heat/cool cycles and, see how it goes. Been there, done that...know how frustrating it CAN be. Keep trying.....;)
 
I had a similar problem with a long carbon tube getting stuck on the mandrel, and like you freezing didn't help enough to get it all the way out. What worked for me was drilling a hole through the side of the mandrel, and then sliding a long metal rod through that that hole. Clamp the carbon tube vertically in a vice that is strongly secured to a table, and then using the metal rod it is pretty easy to spin the mandrel inside the carbon tube. While you are spinning, push up using the strength of your legs.

I think the reason this works is that since you are spinning the tube while pulling it out, you are fighting against kinetic friction rather than static friction, and so it requires much less force.

With a bit of work you should be able to get it out of there. Also some lubricant/WD-40 probably couldn't hurt.
 
RocketHunter said:
I had a similar problem with a long carbon tube getting stuck on the mandrel, and like you freezing didn't help enough to get it all the way out. What worked for me was drilling a hole through the side of the mandrel, and then sliding a long metal rod through that that hole. Clamp the carbon tube vertically in a vice that is strongly secured to a table, and then using the metal rod it is pretty easy to spin the mandrel inside the carbon tube. While you are spinning, push up using the strength of your legs.

I think the reason this works is that since you are spinning the tube while pulling it out, you are fighting against kinetic friction rather than static friction, and so it requires much less force.

With a bit of work you should be able to get it out of there. Also some lubricant/WD-40 probably couldn't hurt.
Click to expand...

Tried this and no movement. It was hard to get a good grip on the carbon tune because it crimped when I clamped It together. The tube was so stuck it bent the brass rod i was using. Maybe I'll let the cure/sit for a week and try again.
 
conman13 said:
Tried this and no movement. It was hard to get a good grip on the carbon tune because it crimped when I clamped It together. The tube was so stuck it bent the brass rod i was using. Maybe I'll let the cure/sit for a week and try again.
Click to expand...

One thing to think of doing is trying to heat up the tube but not cooling it off immediately. There's a concept out there that states that when two objects stuck together expand due to temperature the space between them expands as well. I'm not sure if this only applies when you get something red hot but it might help if you combine it with rockethunter's idea.
 
conman13 said:
Tried this and no movement. It was hard to get a good grip on the carbon tune because it crimped when I clamped It together. The tube was so stuck it bent the brass rod i was using. Maybe I'll let the cure/sit for a week and try again.
Click to expand...

Try increasing the surface area by clamping it between wooden blocks or something to reduce crimping. Also, duct taping the tube where it is clamped can make it less slippery and easier to firmly clamp down. Also you will probably need something stronger than brass to rotate it, its going to take a lot of force.

Make sure you are both rotating it and pushing it out at the same time. Just rotating it will not pull it out any farther, and if you are just pulling without rotating no matter how hard you pull it probably won't budge.

Lastly, if you are willing to drill into the carbon tube, you could try this with two people, having one person rotate and the other pull - one person pulling the mandrel, the other rotating the carbon tube. This way you should be able to put more force into pulling it because you don't have to try and be rotating it at the same time as you are pulling it, and you can secure the carbon tube more effectively than clamping it.
 
Definitely you dont want to trash that tube. Keep trying, it should come out eventually.


Alexander Solis

TRA - Level 1
Mariah 54 - CTI RedLightning- I-100 - 6,345 Feet
 
I do have about an inch of tune that I was going to cut off so I could still a hole there get some steel rod and have someone else turn an pull on the tube with me.
 
conman13 said:
I do have about an inch of tune that I was going to cut off so I could still a hole there get some steel rod and have someone else turn an pull on the tube with me.
Click to expand...

Did you try compressed air? A quick blast at 150psi should loosen the Mylar just enough to get it to slide


Sent from my iPhone using Rocketry Forum
 
I could try that but would have to get the right nozzle for my air compressor. Where do you suggest I blow the air?? In the tube??
 
Your best play is capitalizing on the aluminum mandrel. Have you tried heat cycling it a few times? Try a few rounds of pouring in hot, almost boiling water, allowing it to heat up, draining it, then pouring in the water/salt/ice mixture and allowing it to cool down.

Then, drill a hole through the diameter of the exposed aluminum tube. Put a 1/2" steel dowel through the diameter, trap it, then pull/twist the tube off. Wear a pair of leather gloves.
 
patelldp said:
Your best play is capitalizing on the aluminum mandrel. Have you tried heat cycling it a few times? Try a few rounds of pouring in hot, almost boiling water, allowing it to heat up, draining it, then pouring in the water/salt/ice mixture and allowing it to cool down.

Then, drill a hole through the diameter of the exposed aluminum tube. Put a 1/2" steel dowel through the diameter, trap it, then pull/twist the tube off. Wear a pair of leather gloves.
Click to expand...

Thanks Dan. I see that as my bests play too. I am going to get some steel rod and next weekend after the tube has completely cured do this.
 
conman13 said:
I could try that but would have to get the right nozzle for my air compressor. Where do you suggest I blow the air?? In the tube??
Click to expand...

Between the Mylar and the aluminum. It takes a lot of trial and error to get it to work right. Just think of it as a last option


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Joker050608 said:
Between the Mylar and the aluminum. It takes a lot of trial and error to get it to work right. Just think of it as a last option


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Click to expand...

Ok I'll try that as a last resort.
 
Joker050608 said:
Between the Mylar and the aluminum. It takes a lot of trial and error to get it to work right. Just think of it as a last option


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Click to expand...

Are you suggesting the method used to install golf club grips?
 
patelldp said:
Are you suggesting the method used to install golf club grips?
Click to expand...

Well now that never crossed my mind. I actually had to do this a while back when I was making a customer some custom vinyl fence post sleeves. He wanted chain link fence all dipped in vinyl. (I know it sounds stupid but he wanted to pay me for it) and the only way I could get the vinyl to release was to force compressed air between the galvanized post and the vinyl. Thought it could work for this as well.


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And trust me I know how dumb that sounds but I couldn't make that up. Some people will just pay for anything.


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Glue a centering ring to the section of tubing your going to trim off . Then if you can , secure the mandrel in a vice and tap the tube off the mandrel with a peice of 1 3/4 pvc tube acting as a slide hammer .

Eric
 
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3stoogesrocketry said:
Glue a centering ring to the section of tubing ypur going to trim off . Then if you can , secure the mandrel in a vice and tap the tube off the mandrel with a peice of 1 3/4 pvc tube acting as a slide hammer .

Eric
Click to expand...

thats also a great idea i may try that first.
 
Dry Ice is easier to get and probably slightly safer than liquid N2.


If you want I can show you some pictures of my mandrel and the puller but it would take some milling equipment to make.
 
flynfrog said:
Dry Ice is easier to get and probably slightly safer than liquid N2.


If you want I can show you some pictures of my mandrel and the puller but it would take some milling equipment to make.
Click to expand...
I agree that the dry ice would be safer and easier to get. I have no way of machining any parts so no need to waste your time but thanks. :):):)
 
Did you manage to remove the tube from the mandrel yet?


Alexander Solis

TRA - Level 1
Mariah 54 - CTI RedLightning- I-100 - 6,345 Feet
 
SinfulDarkLord said:
Bummer,

Conman how much overlap of the mylar did you have?


Alexander Solis

TRA - Level 1
Mariah 54 - CTI RedLightning- I-100 - 6,345 Feet
Click to expand...

no overlap. the mylar met perfectly. i haven't even tried anything yet. I have been way too busy in school in the past couple of weeks.
 
nothing else done but I received my 38mm 1200 case from Loki Research yesterday. It looks great and Scott switched out the forward closure for a plugged forward closure with a 1/4"-20 threads for the eyebolt that the shock cord will be attached to. Still working on getting the tube off the mandrel still no movement but I won't stop trying!!!
 
I would try wrapping the tube with hot steamy rags and stuff dry ice in the mandrel. Could even try hot rags and just ice on the inside first.
 
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