This was my first attempt at a Lego / Knex hybrid plotter — constructed back in 2008. And, as with many of my firsts I over engineered it quite a bit. While I got it to move successfully, I couldn’t get enough precision to draw anything legible for a variety of reasons.

I had hoped the large gears would both provide more precision, as well as feedback from the Lego light sensor. Unfortunately, I wasn’t able to get the servo mechanics working in the amount of time I dedicated to the project, but I still think it could have worked. If I were building it again, I would start with the motor/gear/light sensor construction initially and attempt building my own servo motor. Then, if I got that working I would build the plotter using that component design.