Stock gear drawing downloads???

As a model maker I occassionally need some gears in miniature.

I am wondring if there is a source, preferably free, of cad drawings of
gears. The idea is to import the needed cad drawings and scale down to
suit the model and have them 3D printed. The file needs to be in a
format that can be imported into Rhino. I think this would be a dxf
file or 3dm file???

Any ideas on how to tackle this???

Jack