# Tube with variable diameter

hello!

I am interested to know if a tube can be created that with some kind of mechanism, its diameter will increase on demand

the range of the diameter should start at the smallest possible (0.01 mm or less if possible, even if the walls of the tube virtually concur) and increase up to 1mm or something

the tube must have walls so that it will not bend easily (with less than 500grams force or so)

any hints?

thanks!

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Danger
Gold Member
What are the physical requirements of the tube? ie: Does it have to be waterproof, airtight, just cohesive enough for a ball to run along...?
If the latter, a braided structure like what we Canucks call "Chinese finger puzzles" might work. Aside from that, I'm at a loss for now.

It has to be absolutely liquid-proof

NascentOxygen
Staff Emeritus
A tube made of a synthetic rubber will expand its bore on demand (the demand being pressure). House it inside a PVC pipe to contain its expansion. May not be able to quite meet your demanding specs, though.

A tube made of a synthetic rubber will expand its bore on demand (the demand being pressure). House it inside a PVC pipe to contain its expansion. May not be able to quite meet your demanding specs, though.
it shouldnt be able to bend, it should only be able to increase its diameter in a specific amount

I imagine some force/energy would be needed to do the diameter increase

that force/energy could be mechanical, like the above mentioned chinese puzzle, or in another direction, ie. something like a few rails running inside through the tube in parallel, and by moving them with a direction opposite to the centre of the tube, to increase tube's diameter, given that tube's walls are able to expand (tube can still be non bendable, because of the rails inside it)

or there maybe other mechanical techniques for this?

or maybe some kind of magnetic, electric, thermal etc energy could achieve that better?

or there could be a specific material with such properties?

Danger
Gold Member
Does the expansion have to be linearly consistent, or are bulges allowed? I'm thinking along the line of NiTiNOL, specifically Biometal. That .01mm scale pretty much pooches anything that I can come up with, though.

it has to be linearly consistent
the 0.01mm scale is a must! :/

Danger
Gold Member
You have definitely piqued my interest, and I'll continue to monitor this thread. Unfortunately, I have absolutely nothing to offer. I hope that someone else can help you.