Pi CNC Plotter Fail

Several issues have been pointed out that would not be fixed by replacing the wobbly worm gears.  Each issue could be addressed individually, but this would be time-consuming.

Therefore I've decided to reduce the scope of my efforts.  I plan to continue testing the Pi and DC motors, but to use a conventional, cartesian robot that will be similar (or identical?) to existing open-source designs.  This will reduce complexity and make debugging much simpler.

Since I'm rebuilding the robot anyway, I might as well invest in higher-accuracy sensors.  Perhaps I'll get some optical encoders.  Alternatively, I might make an attempt at using computer vision- others on this website have had success with this approach.  I would have to purchase and calibrate a camera of sufficient resolution, but OpenCV definitely has the capability to do this sort of thing (at least to moderate accuracy).

I'll probably post something to this website when (if) I get another robot built and working.  But it will probably be a few months (or even a few years).

This shows that the motor shafts are loose, causing inaccuracy.  I can rotate the motor shafts several degrees before encountering resistance from the gears.  This reduces the accuracy of the machine.

The robot attempted to write "HI".  The writing is difficult to read, but it is possible to distinguish the letters if you look carefully.