It didn't affect my diamentional accuracy as its very thin, perhaps 0.2 mm.

its unlike other plastic films I've seen, it has very little stretch and is heat proof, would say its a little like the antistatic bags that computer parts come in but thinner.

@vvs

Does using a un-perforated film cause loss of dimensional accuracy?

I'm probably following the same road you've been down.

Restoring an old race bike and foolishly decide to replace glass with carbon.

The important dimension with the tube was the inside so that o could reuse the ti end caps.

Back to the initial post and there will be different issues with the much thicker wall thickness, should be much easier to remove due to the extra mass of the tube.

Haaah  ... Thats exactly the same thing I made my first tubes for ... using EC high Temp Resin -- Mine were plain weave CF surface though.. I made my own "pro-finish" plain weave, by spraying the reverse (in) side with Cytec spray ..  so no "wonky weave" on mine ... i know I have a picture somewhere ...

Nice look with the Kevlar though ---

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Yeah ... I did some electronics work, using glue lined shrink tube, and we had all kinds of problems with overheating other parts of the assembly with the heat gun. I then tried putting the assembly with the shrink tubing in place, into a curing oven and ramped up the temperature until I had a complete shrink down of the tubing .. that required the oven to ramp up to +120 degrees Celcius.. Thats why I am a bit wary of using shrink tubing for making CF tubes...
 I've gone the other way and made up a "mandrel + outside compression mould" setup.  I found a local company that makes Nitrile rubber parts, they made some inflatable thick walled tubes for a friend, who wanted to produce a lot of composite tubes.  Fo my use I could not justify the cost of these tubes, so for some of my CF-tubes I used bicycle innertubes as internal compression.
I inflated the inner tube to hold the fabric and resin in place, then envelope bagged the whole setup and then vacuum on

I made some "precision" tubes by first turning a tube mandrel to the desired outside diameter, then polishing it and making up a split mould from that. I then turned down a piece of the same Alu tube to the desired inside diameter and polished that .. I "cheated" a bit on the inside mandrel and made it very slightly tapered, about 1/10 of a mm over 50 cm length .. That makes releasing it a lot easier




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103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

You could be right about the expansion although I tried to keep the heat down as much as possible because its very easy with the heat gun to get local hot spots and either melt through the shrink and or boil the resin, obviously scraping the finished tube.




one thing I learned was the tape is pretty much unusable with a hot gun as it melts at the slightest over heat but the shrink tube is fairly workable.

@VVS

With your method of using heatshrink tubing you start off wrapping a relatively cold Aluminium mandrel. then heating the entire thing to a high temperature (to activate the heatshrink tubing/tape you will be well above 100 degrees)

The tubing shrinks, and the Alu mandrel expands (more than you would think)!, and since both shrink tape and especially the tubing is elastic, it will keep a tight wrap on the CF/resin as the mandrel cools down, keeping the CF tube tightly pressed against the mandrel. Which is all good, from a curing point of view, but the heat also deteriorates the thin layers of wax or chem release, and may distort the combination of release film and wax/release to the point where it locks the composite into any microscopic imperfection in the mandrel.

It is quite possible that cooling the mandrel will not shrink it enough to have any effect on the CF tube, a 1 mm tube will still be a bit elastic on the circumference, and so it just stays attached to the mandrel.

As I said, I think the vaseline works because it forms a thicker layer, and in effect also "lubricates" the inner surface of the release-film, making it possible to slide the tube off the mandrel, wax or chem-lease does not have that "lubricating" effect.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)

Unsure why the Vaseline worked when the others didn't, Paul at EC put me on to it.

I think perhaps Vaseline forms a slightly thicker layer on the mandrel, leaving some room for movement when the CF tube has cured.

I know this sounds a bit far fetched, but have you considered using an aluminium tube for the mandrel ?   If you heat the CF tube slightly from the outside, and cool the Alu tube, by putting one long end in ice water, the CF tube will not shrink, but the alu tube will.. That may be enough to free the CF tube from the mandrel, even with only a thin layer of release wax or chem lease ..

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)