Parametric airless tire
Description
physorg.com/news/2011-12-bridgestone-airless-concept-tokyo.html
Using the natural springiness of plastic, this design can absorb shock and vibration in a manner similar to a pneumatic tire, but cannot be punctured.
Videos here:
youtube.com/watch?v=3LctFwZhY1M
youtube.com/watch?v=sXBgaaI7dHY
This design is fully parametric.
Update: Added tiny (0.001) offset between spirals. Openscad errored when trying to export an STL otherwise.
Instructions
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Cool! It would be neat to make one that could interface with LEGO axles . . .
Any guess if this design is strong enough to replace a 32cm (12-13inch) wheel for a light-weight (aluminium) wheelbarrow? (Pumping the tire every time before use tiring :-P)
Neat! I played with this a while back but mine was too stiff and I never tried again. How does this work?
Also, I designed mine just like yours, but later noticed that the tweel and others have spirals that go both ways. Prevents deformation both front and back.
Very cool!
Have you made a double spiral like Bridgestone's airless tire? A small change to the code but not printed yet:
for (i = [0:spoke_count-1])
{
rotate([0,0,i * (360/spoke_count)]) translate([(spoke_dia/2)-(dia_in/2)-hub_thickness,0,0]) spoke();
rotate([0,180,i * (360/spoke_count)]) translate([
(spoke_dia/2)-(dia_in/2)-hub_thickness,0,-height]) spoke();
}
Probably much less soft.
I think the reason they have two counter-rotating spirals is such that the characteristics of the wheel don't change too much under torque. If the hub is accelerated quickly it tends to twist independently of the rim, splaying or twisting the spokes, changing the spring constant. Stiffness isn't an issue with my design, since you can add spokes or make them thicker until you reach the desired stiffness.
I added a "double_spiral" boolean so people can generate counter-rotating spiral wheels if they want.
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Nice! :)
Ron Arad made a bicycle with spring-steel tires based upon a similar concept:
http://www.core77.com/blog/mat...