Let's Build Knex Season 2 – Ep 1 – Robot Project Introduction


Hello everyone! This is the start of a new Knex project where I’m building a fully mechanical robot arm. This robot will be programmable, so it’ll be able to go through different sequences for applications such as transporting items. This project is mainly just a proof of concept; I’m not sure how accurate and useful it will actually be, but I’ll try to make it be as accurate as possible.

This video is slower because it’s a lot of explaining, but it’s necessary to let you know how I plan to make this work. After the initial explanations there’ll be faster build progress.

I hope you enjoy, and let me know if you need any better explanation or have suggestions! These videos are being recorded shortly before uploading so I can respond to people’s feedback.



  1. If you think about the tape as a binary system then you could conceivably build mechanical “and” “or” or “nor” gates. Meaning that a motors acting together could create more output modes than the motors acting alone. Also have you ever looked at a “core XY” 3D printer? I would require a lot of chain but in my imagination it would require less complex transitions.

  2. Impressive work! I like your compact designs you showed, even if you say they are prototypes. I am curious to see how your neutral gear will work, because wouldn't that be an additional instruction to put on the tape? Maybe you don't need a neutral gear, and instead if you need a motor to hold position, alternate directions every pin. Or will your "program" always keep all three motors moving to a new position? Keep up the good work, this is an exciting project!


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