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

4.0 out of 5
2 Ratings

2 Ratings

btodd007 ,

Steep learning curve and a few glitchy behaviors, but seems to be worth it!

I paid for this app looking for a way to easily design gears without using my work computer for personal use and without paying for a subscription-based design software. I had a few issues that made me regret paying for this, but after working with the software a bit, I think I've figured it out:
- I do not recommend using this in "Inch" mode, it doesn't seem like it works correctly at all. When working in inch mode, it seems like the gears cannot go below a certain size before they completely loose their shape and turn into some weird spiny cylinder. Creating gears of similar size in "metric" mode does not seem to have this issue.
- Specify the number of teeth and the diametral pitch ONLY. Don't click the "Pitch diameter" box ever. If you click in the "pitch diameter" box and then click in the diametral pitch box, it recalculates your gears and breaks everything.

I think this app has a lot of potential, and if it ever gets updated to fix the issues that I mention above, I'd rank it at 7 stars out of 5, because this type of software is exactly what I needed!

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!

App Privacy

The developer, Glenview Software, has not provided details about its privacy practices and handling of data to Apple. For more information, see the developer’s privacy policy.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

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