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  • Writer's pictureDr. Tõnis

Mechanical 7-segment Digit


Somewhere mid November 2022 I saw a very interesting 7-segment clock project that utilized mechanical segments. Here is the link to this project: I wanted to build something similar.

Project summary

The inspiration project has all the necessary info to build the device. After ordering missing parts I noticed that one needs to bend his own springs and that’s not very easy at all. I took it as a challenge and decided to design my own 7 segment clock.

My responsibilities

  • Develop the mechanical design to control the segments

  • Make the CAD design

  • 3d printing and assembly


My wish was to avoid all kinds of springs and wire bending. I thought about different possibilities and in the end I decided to try a similar approach as ekaggrat. However my dials fall thanks to the gravity and rise due to mechanical push. It took several iterations till the mechanism was working as intended, at least sort of.

My first prototypes were nice and small. I was not thinking about the drive system before the prototype worked. When I inserted the motor in the Fusion360 I noticed that the motor was huge. Nevertheless, I didn’t have any other smaller or better one available and had to adjust the design accordingly.

As I designed everything for the 3d printer I had relatively large tolerances. Thus, the end result was not as precise as expected. Especially the segments that were furthest away from the base were not in the spot where they should be. There was just too much play in the mechanical construction.

Since it was not possible to make the design with tighter tolerances I decided to stop the project and carry on with other challenges. Nevertheless, I am very happy with my dial movement design, it worked as intended. Using more accurate production methods one could build a mechanical 7 segment digit following this approach.

Used tools

SW: Fusion 360

HW: 3d printer, stepper motor


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