Daily Equation #5 - Fermat's Spiral

This is Day 5 of my collection of printable equations. To see the whole collection, go to: http://www.thingiverse.com/thing:227210

For today's equation, I'm revisiting the Archimede's spiral (r = atheta) of day #3 (http://www.thingiverse.com/thing:228425). A variant is Fermat's spiral, r = +/-atheta^0.5 (http://en.wikipedia.org/wiki/Fermat%27s_spiral). In contrast to Archimede's, Fermat's spiral exhibits a flat region near theta = 0 and a continuously decreasing distance between turns. It also, to the best of my knowledge, has no practical application. But it looks cool.

Details:

• units are in mm
• curve thickness was reduced from 5 to 3 mm to avoid overlap.
• a = 1.5 (to give a diameter of 100 after 3 turns)
• Range(theta) = 0 to 1080
• stl resized to make x axis = 100 mm

As always, I'm going to continue to post one equation per day until get bored or people lose interest. If there's a particular equation you'd like to see, leave a comment and I'll give it a shot.