source of cheap narrow thin tube?

[desbromilow]

Hi,

I have a design for something I want to build, and part of it will require several (20) thin tubes - say 1/8" (3mm) OD, and with an ID which can allow an insulated wire to pass through (say 1/6" (1.5mm))

If the tube is metal - I would need to be able to solder to it for electrical connections, but if non-metallic, I need to pass 2 cores of insulated wire through it - the wire only needs to handle 50mA, so wire wrap or similar guage is sufficient.

The tubes ideally should be around 2' (600mm) in length, or longer... shorter means making up some kind of joiner which can work, but reduces the effect, and adds mass which has it's own complication.

Does anyone have any suggestions on suitable (hopefully inexpensive) tubing which can meet that requirement? it is an indoors installation, so weather resistance is not a requirement.

Any suggestions gratefully received.
Thanks,
Des

[Toolmaker51]

First that occurs might be brake line, web search of 'hobbyist supplies' 'craft tubing' etc didn't do much, especially 9,000 miles away. There are marshland plants we call 'reeds' that might do. Also wondering about drinking straws, I'm sure those are extruded, then cut to length.
I'd literally write in 1/8" tubing .010 wall, and start there. 40' worth will be too long for mill length, tubing might be 10' or 21' purchased here.

[mklotz]

Is there any chance you could use shielded wire? Normally it has only one conductor but multi-conductor may exist.

Two foot lengths of hobby tubing are unlikely; I've never seen lengths longer than one foot. However, telescoping brass tubing is commonly available in the hobby market. Soldering two pieces together to obtain the required length would be easy and there would be negligible added mass.

A quick Google for "telescoping brass tubing" yielded this hit...

https://componentsupplycompany.com/p...-tubing-sw.php

which, in addition to the 1 ft lengths, shows 3 ft lengths.

If they don't ship to Oz, look for 1 ft telescoping lengths in the local hobby shops and consider the soldering suggestion.

BTW, "guage" is a small town in Kentucky, correct spelling is "gauge"

[Toolmaker51]

Oh man, I leapt on 'telescopic tubing' quick; but too small.

Some day will find replacement, cannibalize or conjure larger sizes adequate for coolant drain of horizontal mill. Guess I could build a pull expander swage, there is at least one commercial rotary swage shop in Paramount, CA.
There are DIY challenges aplenty, to slide without jamming or disconnecting, but just gravity operates them.
Common setup is a double swivel banjo/ elbow on the back of the table, the tubes (3 or 4 pieces) increase size toward the machine base, entering a second double banjo. Each is coupled perpendicular to manage X-Y-Z table movements.

[Frank S]

What is that supply chain there that is similar to the ww Grainger's here. Blackwoods or something like that when I was in Sydney back around 1989 what ever the company was called, they boasted nearly 6 million line items at the time

[desbromilow]

Thanks all, I will look at the tubing options. Whatever I use has to have some rigidity similar to a tig rod since it needs to support itself, and a small weight at the end of being cantilevered.

[nova_robotics]

Thanks all, I will look at the tubing options. Whatever I use has to have some rigidity similar to a tig rod since it needs to support itself, and a small weight at the end of being cantilevered.

What about wire + a tig rod for stiffness + a few layers of heat shrink to pull it all together?

I've used wire loom that's like a Chinese finger trap before. I generally hate the stuff, but it might be useful in this particular application. You can get it in nylon, probably some other plastics, stainless, and I also have tinned copper out in the shop. It's a pain to deal with, but if you're only going short distances it might work out.

[Toolmaker51]

What about wire + a tig rod for stiffness + a few layers of heat shrink to pull it all together?

Assembling those three is a great concept. Almost any piece of solid wire can be straightened on a flat countertop, pressing a wide board diagonally across it, like a rolling pin. Two straight wires encased tightly in shrink tubing would be rather stiff, three even better.
I'd try shrinking the tube in an oven to be as uniform possible.

[desbromilow]

great ideas - thanks!!! what I'm building is a kinetic model/ sculpture - basically a wide (2"/ 50mm) ribbon dropped from the ceiling, with a series of "cross bars" (about 600-800mm long (24-32")) on 150mm (6") centres.
The ribbon is turned via a mechanism at the top (attached to the ceiling) so the ribbon allows the cross bars to form a spiral shape in the air - the speed and direction of the turning changes the shape of the effect. I saw this many many years ago in a casino, and on the tips of the cross bars were small crystals... my version (I'm hoping) will have SMD LEDs on the the tips of the cross bars, with the electrical connections inside the supporting ribbon. With a black ribbon, and black/grey cross bars, the lights will be the main visual feature.
the turning mech at the top is the easy bit, the lightweight cross bars is the challenge since they have to be light enough that the ribbon is not being pulled so taut it dampens the twisting of the setup.