Parametric Robot Wheel (Spiral)

NOTE: This has been upgraded to a much more flexible version that incorporates all previous designs and adds lots of new features.

The new version is here: http://www.thingiverse.com/thing:21486

This is a flexible parametric robot wheel with a "spiral" pattern for o-ring tires. It's a variation of the biohazard wheel code here thingiverse.com/thing:21010 -- but it's tweaked a bit to support the spirals design specifically. (At some point I'll probably try to join them all together...)

You can modify a number of properties in the OpenSCAD file to suit your needs, including tire size, wheel width, rim height, number of spokes, spoke width, spoke curvature, spoke direction, hub height/diameter, shaft size, set screw diameter/thickness, number of set screws, and fillets/chamfers. Or, if you need an STL for a specific size o-ring, just let me know and I'll try to accommodate.

This spoke design with some tweaks is coincidentally very similar to the excellent "Parametric airless tire" created by tjhowse at http://www.thingiverse.com/thing:17514, except that I didn't even consider that it could function as an "airless tire" -- this was intended to be rigid. This design also started off as a logarithmic spiral, but I abandoned that idea for the much easier to render semicircles. But because it's pretty configurable, this can be probably be used get a nearly identical look -- just without the tread, of course. I'm not really sure about springiness, because this design incorporates a rim an o-ring.

Wheel Designs using the same foundation:
Biohazard: http://www.thingiverse.com/thing:21010
Circles: http://www.thingiverse.com/thing:21065
Spoked: http://www.thingiverse.com/thing:21064
Spiral: http://www.thingiverse.com/thing:21277
...and more in the works!

For detailed instructions, including how to work with these printed STLs and how to modify all the parameters in the OpenSCAD file, see the instructions for the biohazard wheel here: thingiverse.com/thing:21010. There are a few extra parameters in this model:

• spokeWidth - how wide each spoke is (as opposed to how thick the wheel is)
• curvature - how curved the spoke is. This must be greater than 0 and less than or equal to 1. I very low number will create a nearly straight but offset spoke. (See images.)
• reverse - reverses the direction of the curves. You use to make matching (mirrored) wheels.

The other parameters are the same as in my other wheel variations. They are tireCSDiameter, tireID, tireStretch, wheelWidth, rimHeight, numberOfSpokes, hubDiameter, hubHeight, shaftDiameter, setScrewDiameter, setScrewNutDiameter, setScrewNutThickness, setScrewCount, hubZOffset, baseFilletRadius, topFilletRadius, and chamferOnly.

Instead rending and uploading a bunch of STLs now, this time I'm just uploading a number of examples that illustrate how the wheel can be configured. The one included STL is based on a 93mm ID (100mm OD), 7mm CS o-ring that I had on hand. For complete control, edit the OpenSCAD file. If you're not comfortable with that, let me know and I can try to get an STL uploaded for you.

I included a couple of images that mimic tjhowse's airless design. I don't expect these will actually function quite as well as his airless tires, but I'd be interested in hearing your experiences if you try it. The other images illustrate things like fillets/chamfers, hub placement & configuration, spoke settings, etc.

Enjoy and please post pics if you make them!

I'm still planning to:
* (possibly) Combine all the tire styles, or at least make some of the code reusable
* Add support for multiple o-rings for wide wheels.