I love sub-projects.  Some people start a lot of projects totally divorced from each other.  I like projects that are building towards a greater goal.  They have added purpose, makes them feel more important, I guess.

For example, I really enjoyed making the bearings that turned out to work really well.  Seems other people did, too.  Now I'm wondering if there's opportunity there for my first kickstarter - money would be used to make an injection mold for higher quality mass production and contributors would get bearings at a discount for their projects.

As the arm is coming together I can see that I'm going to need a gearbox to get enough power from my stepper motors to lift at the shoulder.  I've been in love with the idea of hypocycloidal gears for a long-ass time now.  

I'm filming Matthew (a Solidworks master) back in 2012.    I was originally inspired by this other guy:

Who's website I found here: http://www.zincland.com/hypocycloid/

This morning I decided to download zincland's python scripts and see if I could generate some of these profiles.  Save File > My Documents > Design - oh, there's already a folder for gearboxes?  Hey!  There's a folder for hypocycloids, too...and the files I'm trying to save are already here!  But then what's this HTML file?

Turns out in Two thousand and eleven I had started creating a Javascript version of the DXF generator and then completely forgotten it.

So here it is for you: https://www.marginallyclever.com/other/hypocycloid-generator.html

No need to install or run anything.  Just change your parameters and then save the DXF file contents (in the textarea) to a file of your choice.

If that's helpful to you, let me know and share with your friends.

Next update I should have a prototype gearbox.