Making a carbon fibre tube

[CarpeDiem 512]

I would like to make a non structural tube.  The ID will be about 200mm and the length 2.5m.

It doesn't need to be very strong, it just needs to be able to survive the odd hard bang, probably from a head.

The purpose of the tube is to provide a cavity for the prod to get retracted into.  So it will be installed on the roof of the forward berth.

Currently when we plough through a wave the boat fills with water, our usual solution to this problem is extract the prod and fill the void with Bed-IT tape - this results in the boat being water proof but we can't retract the prod unless the conditions will be such that we won't be taking waves over the bow.

So, I have purchased a plastic drain pipe of suitable dimensions and while I could just use this drainpipe and glass it in, adding 10kg of plastic to the front of the boat is something I would like to avoid.  So I am wondering if anyone has any ideas of how to use it as a mandrel?  My biggest concern is that no matter how much release agent I use, the epoxy will lock around the tube and I then I won't be able to extract it.

Ideas?

[Psyche 755]

Have you priced one? might be cheaper and easier to get one of the rack.

or

 

[CarpeDiem 512]

27 minutes ago, Psyche said:

Have you priced one? might be cheaper and easier to get one of the rack.

or

 

yeah - very expensive $3k+

Thanks, I have seen that video and several others - they tend to use an Al mandrel which has the unique properties that it expands when heated and shrinks when cooled, so it compresses the tube and then shrinks away from it

Obtaining an aluminium tube that is of suitable dimensions is very expensive as well - hence I have a plastic drainpipe that doesn't have the unique properties of Al

[aardvarkash10 1,072]

Cut the drainpipe into three sections longitudinally. Reassemble the pipe around three circular formers.

Lay up your CF tube with lots of release coat on the drainpipe.

Remove the circular formers and knock out the three pipe sections one at a time.

[MartinRF 64]

https://www.reflectometrist.eu/doc/The_Plym_Method_OO.pdf

/Martin

[ballystick 79]

If you are near Rotorua, the Kilwell factory has a huge range of carbon tubes with small defects and priced very well too. Their range changes regularly so its worth a visit, often

[funlovincriminal 197]

2 hours ago, ballystick said:

If you are near Rotorua, the Kilwell factory has a huge range of carbon tubes with small defects and priced very well too. Their range changes regularly so its worth a visit, often

I got a Melges 24 tapered carbon prod there a few years back for my 830. It had a small blemish and was half normal cost.

[khayyam 96]

Wait for someone to drop a carbon rig and cut down what's left?

[LE Bb 27]

ptfe film ( teflon ) is whats used now ... not cheap but it works

The old way was to wrap mylar film around the tube, then tape another one over that but independant so it would slide off.

for what your  trying to do you i would suggest that you glass around the tube but place somthing like holey plastic between the join. this will allow you to peel it of then glue it back together.

 

See pic Green = tube , Black carbon, Red holey plastic

[LE Bb 27]

Fyi in the video above the heating is the key. the alloy tube expands with the heat, as it cools it srinks back again more than the carbon. doesn't work on a pvc mandrel

[Addem 120]

21 hours ago, aardvarkash10 said:

Cut the drainpipe into three sections longitudinally. Reassemble the pipe around three circular formers.

Lay up your CF tube with lots of release coat on the drainpipe.

Remove the circular formers and knock out the three pipe sections one at a time.

I did this as an experiment and used plasticine and packaging tape to shape/hold/seal the joins. First version the joins didn't let go. Lots of release wax and it fell apart beautifully.