Experience the magic of pure mechanical calculation! Inspired by the vintage Lightning Adding Machine, this functional 3D-printable calculator brings retro engineering right to your desktop.

This model isn't just a display piece—it is a fully functioning mathematical tool. Utilizing a precise mechanical carry-over gear system, you can physically dial in numbers and perform basic addition. It serves as a fantastic STEM educational model, a highly satisfying desk toy, and a testament to the capabilities of FDM 3D printing.

✨ Key Features:

Zero Hardware Required: 100% 3D printed parts. No screws, metal springs, or glue are needed! Everything snaps or slides into place.
Mechanical Carry-Over: Accurately transfers values to the next digit when completing a full rotation.
Two Casing Versions Included:
- Standard Version: Single-piece casing for standard printers (220x220mm build volume or larger).
- Split Version: Two-piece snap-fit casing for smaller printers (180x180mm build plate).

⚙️ Material Recommendations & Color Guide:
To ensure the tight tolerances and smooth gear rotation work flawlessly, please follow this material guide (refer to the Grey and Orange display photos):

High-Stress Mechanisms (Grey): Use PLA Plus High Speed for the bottom casing, internal gears, and pins to withstand rotational friction.
Aesthetic Covers (Orange): Use Standard PLA for the top covers.
Numbered Dials (Multicolor): Print the base gear in PLA Plus High Speed (Grey), and insert a pause/filament change to print the top numbered face in Standard PLA (Orange) for high contrast and readability.

⚠️ Important Operational & Tolerance Notes:
Because this is a 100% 3D-printed mechanical device, it relies heavily on print tolerances and friction. Please keep the following in mind:

Smooth Operation is Key: When dialing the numbers, use smooth and deliberate rotations. If you spin the dial too forcefully or too fast, the momentum can cause the mechanical carry-over to "overshoot" or skip, advancing the next digit by two instead of one. Treat it like a vintage machine!
Print Spare Gears: The small legs/pins on the internal gears take the brunt of the rotational force. While using PLA+ and 6 wall loops significantly increases their strength, we highly recommend printing 1 or 2 extra number dials/gears as backups, just in case one snaps during assembly or after heavy, repeated use.

🛠️ Assembly Guide & Demonstration:
Need help putting it together or want to see the mechanism in action? Watch the full step-by-step assembly and demonstration videos here:

TikTok Assembly Video:
https://www.tiktok.com/@twomakers3d_studio/video/7625973288723909909?is_from_webapp=1&sender_device=pc&web_id=7626599318106932754
YouTube Assembly Video:
https://www.youtube.com/@TwoMakers-3D
Instagram Assembly Video:
https://www.instagram.com/twomakers_3d_studio/reel/DW1AvJUTt4t/

Happy printing, and enjoy the click-clack satisfaction of mechanical math!

Mechanical Adding Machine - Retro Lightning Style

0.2mm layer, 6 walls, 15% infill

0.2mm layer, 2 walls, 15% infill