little help needed

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#1

Hello,

I am going to make a series of tubes that are about 6 feet long and tapered from .5" to .3". I would prefer to make them out of some biaxle sleeve that I already own but am up for anything else if that is thought unwise. I’ve made long tubes with a large diameter before but never this long and this small. Is there any tips or suggestions for how to make them? Is it possible for infusion with such small tubes? I like the freedom infusion gives but am also up for wet lay up. Each tube will have at least two layers of either carbon, kevlar, or fiberglass.

I am was thinking of making a dowel that is 9 feet long and use that as my mold. Then on the last six inches on the pole after I had layed up the fabric I would make a pair of handle bars on the small tapered end. This way I could clamp the dowel down and use the built in handle on the composite piece to pull it off the mold. Then to finish the piece I would cut off the handle to make it the right size.

When I made my rocket that was 4 feet long and 3" in diameter it was super tough to get off its aluminum mold even with dry ice and liquid nitrogen, I don’t want to have to go through that twelve more times if possible.

#2

Hydraulics… Machine a taper end fitting that protrudes the laminate and gives a good overlap on the mandrel…dowel…at the small end. Lay up over the whole thing. Infuse it. Then plug an air over hydraulic pump into the fitting and let hydraulic pressure break it all free. Might be a little messy. Might be able to use mineral spirits instead of hydraulic fluid also.

The machined fitting would slip fit the small end of the mandrel and have a protruding threaded fitting. Plug it with a threaded plug during infusion. Basically the mandrel acts as a piston and the cured composite a cylinder. Slight increases of pressure with soft taps of a rubber mallet would allow the tube to break free.

A single high pressure push might blow up on you and be dangerous.

#3

Thanks that helps a lot and is definitely doable. I still wonder how to infuse only cylinder parts though. Mostly in terms of positions feed lines, mesh, vacuum sources. How would you go about the lay out? I image so far that I would just lay the mesh around the cylinder and have the feed tube on one side but was wondering if that would be enough.

#4

Hmm whats your time frame looking like…

#5

Have to make at least six pieces by October but sooner is better.

#6

Man that’s very tight schedule.