The mechanism finally works! The prototype can now successfully lift the arbitrary target weight when connected to the stepper motor.

Overnight, the 3D-printer has been producing new parts for the new generation prototype. The major changes included:

• String attachment on arms placed further out
• Guiding loops for the string was placed higher up to match the new string attachment
• Better LEGO-axle adapter
• Removable clip underneath the rotating disc, to keep it in place
• Cutouts in the base plate so the inside of the prototype is easier to access
  

The print result was good, in spite of being worked on in a train and being sent back to the apartment. We only needed minor drilling and filing to make everything fit. Most tolerances and clearances were on point.

The current prototype is great for us to work with because it is easy to assemble and disassemble. Nothing is glued. Since we are constantly making modifications to our prototype, we are very happy with this “easy to change” prototype.

For the testing itself, we used the previously found LEGO-gearing and the stepper motor. We hung weights on the ends of the arms and used a 5V power supply. The system could lift the arms and weights! Our goal was met, even with only a 5V power supply (instead of 12V).

Next up, we will put the micro switches in place. We will also try to find a more durable and frictionless string.