FreeCAD Gears
thingiverse
Not a model for anything in particular, nor is it meant for directly printing, but just an easy way to make gears. Contains a spreadsheet where you can enter the number of teeth you want, how far apart the gears are, and how thick they should be. Holes for shafts and keyways can then be made using sketches and cut out of the gears. Made with FreeCAD 0.17 (build 12643), may not work with other/earlier versions. Ignore the STL file, thingiverse apparently wants some sort of model file for the thing to be valid and doesn't recognise FreeCAD files as being valid design files. *DISCRIMINATION@!$* Come on thingiverse, FreeCAD has been around forever. Get it together.
With this file you will be able to print FreeCAD Gears with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on FreeCAD Gears.