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I've gone on quite a few sites (thingiverse, grabcad, etc) in search for a coiled tube, but I have yet to find anything suitable. There are a few coils ("springs") but no coiled tubes (i.e. the springs are hollow). Maybe my searching hasn't been good enough! But I was wondering if this is a limitation to 3D printing models?

Mr. Meeseeks
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3 Answers3

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I managed to do it in the end using AutoDesk 123D.

enter image description here

Did it by making two coils of differing radius, then subtracting the smaller from the larger. I made each coil using the instructions found here:

So there we go...

Printed it out just now without supports - in the orientation shown - and it came out fine. Used a brim, though (don't want it rolling away!)

0scar
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Mr. Meeseeks
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No, this is not a limitation. You should be able to create a coiled tube in almost every 3D design software package. However, how to do this depends on the specific 3D design software in use.

You'd generally do so by creating a cross-sectional profile (i.e. a hollow circle) and then sweeping it along a helical path. Another option is to first create a spring/coil, and then hollow it out (some CAD packages have a tool/command for this, usually called "shell").

Tom van der Zanden
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Openscad Proof of concept

// Openscad proof of concept
$fn=90;

linear_extrude(height = 50, center = true, convexity = 10, twist = -1000)
translate([10, 0, 0])

difference()
{
    circle(r = 3);
    circle(r = 2);
}
EvilTeach
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    Drawing it with OpenScad (and some mathematics) is one thing. But printing it without support is an other big challenge! – ON5MF Jurgen Jul 04 '17 at 11:20
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    The question did not inquire about that aspect, nor specify no support. With an adequate base/brim, it's probably do-able without further support by choice of helix angle, but that would be printer/settings dependent. Mind you a question of the utility of such a printed tube also crosses my mind, but again, not in the question. – Ecnerwal Jul 04 '17 at 16:11
  • This is awesome! I'll see if I can download OpenScad, enter that code & turn it into an stl. The printing software I use (XYZware Pro) has the ability to add supports to stl objects I add in there so that might be okay...! – Mr. Meeseeks Jul 04 '17 at 17:13
  • Probably you'll also need to remove the supports from inside the tube. Good luck with that. – ON5MF Jurgen Jul 04 '17 at 17:25
  • A picture and a snippet of OpenSCAD code doesn't really make an answer, in my opinion. Why not add textual some explanation of how the code actually works? The question doesn't even focus on OpenSCAD in particular. – Tom van der Zanden Jul 04 '17 at 20:34
  • Hey, I'll be happy with what I get. The inquiry was for any/all 3D printing software, so includes OpenSCAD. Of course, I'd be happy for a more detailed inspection of what's going on, but I realise you guys are taking time out of your days to answer for free, which I appreciate. – Mr. Meeseeks Jul 06 '17 at 12:53
  • Although having just downloaded OpenSCAD the coil is a bit squashed so I'm still open to alternatives while I play around with some of the variables in OpenSCAD! – Mr. Meeseeks Jul 06 '17 at 13:02
  • I would probably set $fn=6, to turn it into a hexagon, then make the gap between coils zero, so that support material would not be needed. – EvilTeach Jul 15 '17 at 13:55