Elliptic involute gear cutting with toothed rack

thingiverse

!Be sure to always have downloaded the newest version! I was always fascinated by elliptic gears, knowing well that they are not really useful in a practical sense. Some weeks ago I found a gear pump in the internet that was indeed using elliptic gears and after all gained some advantage out of it: http://www.ingo-laemmle.de/Imm.htm Having this application in mind I decided to go a bit deeper into the math of curves and to find out, how to do involute gearing properly on (almost) arbitrary curves in an efficient way. The method I used is a generatlization of the subtractive method I have published previously in my gear cutting projecthttp://www.thingiverse.com/thing:636119 It's in principle applicable to put involute gearing onto any convex shape or body. To describe it in a sentence: Roll a toothed rack with the right amout of theeth along the curve and let it carve out what it touches - just like a real world gear cutting tool. What you get: a nice kinetic object or wall teaser lots of usage examples in the code an easy and well defaulted API neat documented code showing you how that all works What you need: OpenSCAD 2015 (Toothbar uses a dynamic array). It renders much faster ShortCuts.scad library (sorry for that, but it simplifies programming so much). Description in: http://www.thingiverse.com/thing:644830 Hint: To also do concave curve pieces, my idea would be to roll along their convex inner sides and complement the result. This works well, but needs some fiddling around with piecewise definitions and makes the code cumbersome. Have fun and let me know, how you put it to use. Instructions The best way to use it as a teaser is to print two or more gears and a single bracket for each gear. Snap the brackets and glue the systems somewhere, where people pass by. I used double faced tape. This is one of my makes: http://youtu.be/o9NxBw0blQc