7-Segment Display is 3D Printed and Hand Cranked

[Peter Lehnér] has designed a brilliant 7-segment flip-segment display that doesn’t really flip. In fact, it doesn’t use electromagnets at all. This one is 3D printed and hand cranked. It’s a clever use of a cam system to set the segments for each digit (0-9) makes it a perfect entry in the Hackaday 3D Printed Gears, Pulleys, and Cams contest.

We find the nomenclature of these displays to be a bit confusing so let’s do a quick rundown. You may be most familiar with flip-dot displays, basically a dot-matrix grid of physical pixels that are black on one side and brightly colored (usually chartreuse) on the other. We saw a giant flip-dot display at CES four years ago. Akin to flip-dots are flip-segment displays which do the same thing but with segments of a digit rather than dots. We featured a 3D printed version of these last week. The common aspect of most flip displays is an electromagnet used to change the state of the dot or segment.

The version [Peter] designed gets rid of the magnets and coils, replacing them with mechanical logic instead. Each segment sits in a track on the frame of the digit. When slid to one position it is hidden by the bezel, in the other position it slides into view. A cleverly designed set of cams move the segments at each of 10 positions. The animated graphic here shows three cams which are responsible for moving just two of the segments. More cams are added to complete assembly, a process shown in the second half of the demo video found below.

We’re delighted to see this as an entry in the contest and can’t wait to see what kind of gear, cam, or pully scheme is built into your projects!


17 thoughts on “7-Segment Display is 3D Printed and Hand Cranked

  1. The mechanism will be found inside the next limited production, massively over-complicated, costs more than a Ferrari, wrist chronograph. Remember the belt drive watch? Tag Heuer Monaco V4

    1. I immediately fell in love with this because this is perfect mechanical symplicity for a very complex long-sought idea.

      And being watchmaker on top of a machinist, I am reminded of a watch that did a mechanical version of this display by DeGrisogono. That watch is insanely complex, but I’m willing to bet this mechanical design maybe the simplest mechanical version possible to create this kind of display and one-ups them.

      I can easily see this miniaturised for use in a mechanical clock, but I am not sure how accurate it would be as a display powered by mechanical means, friction may be more of an issue here then with the multitude of gears used in the DeGrisogono watch, but I’m not sure.

      While I find many things on hackaday brilliant, this is utterly so. I think I want to make one of these in metal now

  2. This so cool! I want one! Or 4 and turn it into a clock.

    One improvement i can think of rhough is to have the segment edges also in black. Or rather only the infil of the segment in color., as ypu can see the bright color when looking sideways. But that is probably easier sais then done

    1. Well, i don’t want them to be visible when they should be off. Thats one of the point with this sliding design. In next version i can just retrack them 1 mm more or even make them black, and have the background be in color instead. (would also be good for backlighting). And it should be possible to modify them for clock, just change the indexwheels on one to go to max 5 instead of 9. The secound hour digit would be a bit more tricky, but can be done with 14 index positions. 0-1-2-3-4-5-6-7-8-9-0-1-2-3-4 and need to flip the first hour digit at 9-0 and at 4-0 , have a nice day !

      1. Yeah i like the sliding design, but because the sides of the digit is bright, you see it when looking sidewise into the opening.

        Wih dual material print this would ve easier, the outside/edge is printed in black, the inside yellow. With a single material print tgis could still be done as two parts, just more finnicky.

        Alternativly, the digit is mated with a ‘shield’ where the yellow not only slidea out of sifht, but drags in a shield, to block whatever is behind. If the yellow was a tranalucent/clear pla type, backlight would even be an ootuon. But then, with backlight, there is not much point of the mechanical side of it all ;)

  3. Peter,
    I love your design. It is very clever and elegant. I’d like to take your prototype 1 version and modify it for a clock I am working on. Would you be willing to make the CAD files available?

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