InvGears2

New version, see here:
http://www.thingiverse.com/thing:1654911

I no longer like the bevel gears in the lib, will deal with them later.
Now got worm drive, created manual examples, 2 sizes, both work much nicer than I expected, next I'll try in ABS with a 500 rpm motor, see if it works or melts!

The worm algorithm is quite 'sexy'.
set:
iShowC = 1;     // 1=Show all calculation circles
iShowT = 1;     // 1=Show all calculation tangents
iDemo = 1;      // include demo code

In InvGears.scad, you now see just the points that make up the worm:

It's even nicer in OpenSCAD where you can view it from different angles.

Now set iShowC to 0 and re-build and you see worm surfaces:

See how ends are flattened so it keeps to correct length? That is accomplished using 'conditional', see OpenSCAD manual.