Kythera is a simple spur gear editor for the Macintosh.

With Kythera you can quickly design complex gear trains, and visualize their motion on the screen. You can also quickly export your gears in DXF format, STL, or as PDF templates, and Kythera will also generate OpenSCAD files for frames to hold your gears that you can quickly modify to your own purpose.

Kythera also has a number of powerful tools, including tools for reshaping a chain of gears to fit a particular linear dimension, and for quickly constructing custom motion works, which allow you to design custom clocks with a custom rate of motion separating two arms of your clock.

Kythera also includes a gear calculator which allows you to find fractions which approximate certain decimal values–helping you make quick work designing gear trains for approximating other celestial movements, such as the phase of the moon.

We intend Kythera to be a starting point for designing complex gear trains which you can either then print directly on your 3D printer, or import into a 3D CAD editor (such as OpenSCAD) for building more complex mechanisms, such as gear trains for your robotic projects.

What’s New

Version 1.0.3

Change how DXF and PDF files are generated to eliminate "shrinkage" used for 3D printing.

Ratings and Reviews

Dennis2641 ,

Awesome little app, tons of potential!

This app saved my project... or at least made it way faster to complete. It essentially does a lot of the work for you.
My only complaint is that I want more otions for export... ie I want to export gear 1 to this format... or I just want a bottom plate. That sort of thing.
Otherwise keep going!


Glenview Software Corporation
1.5 MB

OS X 10.11 or later, 64-bit processor



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.