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#bitify Lego Tower Bridge

by 3DPrintingGirls

Published on December 2, 2014

The original Tower Bridge was opened to the public in 1894. It is a combination of a bascule and suspension bridge that crosses the River Thames in London, England.

My #bifity LEGO version of the bridge has 4296 pieces. While it took a while, it was super fun to build and what a better way to make the walkways go up and down than with littleBits.

I #bitified the walkways to simulate the real one by pressing on a toggle button the bridge opens/closes accordingly.

The movement of the two walkways are by using  two Arduinos, controlling correspondent Stepper motors. The stepper motors rotate a Lego beam attached to the base of each sidewalk.  

I had to design a custom 3D printed adapters for attaching the motors to the base of Tower Bridge. 

I did it this way because I didn't want to change any part of the original Lego product.

I really liked participating in this contest, since It got the opportunity of combining, the History of  a well known  World's iconic symbol with Technology.  

How To Make It


Brief design and implementation description

a) Don't want to modify original Tower Bridge Lego product.
b) Sidewalks need to move smoothly and would required certain amount of torque to move.
c) Bridge activation using a toggle button.


Get 3D printed 28byj stepper motor Lego and the shaft-beam adapters. It allows to attach the motor to a Lego base. Stl files are provided in Additional files section.


Assemble the motors to the 3D printed adapters and attach them to the base of the bridge using a cross axle 6M and a 4x2 90 deg beams Lego parts.


Solder header pins to the Arduino bit additional I/Os. Two Arduino bits are required. This will allow to easily connect the stepper motors drivers controlling the sidewalks. Use following link as reference: http://discuss.littlebits.cc/t/using-the-additional-i-os-on-the-arduino-bit/1019


Assemble LB circuit as shown in picture #4 above. Make sure Pin D0 is the designated input  pin for the button signal for both Arduinos.


Deploy the code to both Arduino bits. Important: The coordinated sidewalks movement requires that the stepper motors rotate on opposite directions. This is easily accomplish by changing the sign (+/-) multiplying the motor steps.

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