Removing a fiberglass tubing from Aluminum mandrel...

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DPatell

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I layed up a 38mm fiberglass tube on a piece of 1.5"OD aluminum stock. I sprayed it a with a lot of mold release from US Composites, and I got the kind that was recommended by the owner. My problem now is that the tube is stuck, and I can't get it off. I have tried putting it in the freezer to get the aluminum to contract, but doesn't seem to be working...

any ideas?
 
Is the aluminum solid or tube? If it's tube, you may be able to fit some dry ice into it to help shrink it away from the fiberglass. Although aluminum and fiberglass probably contract or expand at different rates, putting it in the freezer is contracting both substances together so it won't help much.
 
Dan, I had the same problem and i tried everything but I'm pretty sure the epoxy locked into the tube, even with lots of mold release on the tube, so i cant help with this tube but for next time try reading https://www.aeroconsystems.com/tips/cloud_FG_tubes.htm i got some mylar sheet and tried that way and the tube came off very easily and the mylar was very easy to pull of the tube, so for the extra price of mylar its well worth it , i got mylar sheet from TAP plastics https://www.tapplastics.com/shop/product.php?pid=255&.

matt
 
Did you try lightly heating the epoxy/composite tube? That might be enough to work it loose.

Edward
 
I had a tube turned for me from a piece of steel pipe. Similarly my first atempt was fuitless even with several layers of mould release. In the end I wraped a layer of wax paper over the tube then layed the glass over the wax paper.
 
I have experimented with candle wax. The idea is to heat some candle wax until fairly hot and brush on successive layers onto the mandrel until a thickness of say 10 thou. When fully hardened you can then layup the glassfibre.

For releasing heat up with a hot air gun until wax melts and hey presto tube releases from mandrel. if the mandrel was made of tubing then alternative is to heat inside either with hot oil or again with hot air gun.

https://raysrocketry.websanon.com
 
Originally posted by DPatell
I layed up a 38mm fiberglass tube on a piece of 1.5"OD aluminum stock. I sprayed it a with a lot of mold release from US Composites, and I got the kind that was recommended by the owner. My problem now is that the tube is stuck, and I can't get it off. I have tried putting it in the freezer to get the aluminum to contract, but doesn't seem to be working...

any ideas?

What is melting point of aluminum?

shrox
 
Banging the glass with a rubber mallet might break it's hold.
 
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