Geared Heart, Hand Crank Edition

Author: gzumwalt, published on 2014-02-20

Click this button to get the 3D model


Geared hearts fascinate me (perhaps because I was born on Valentines day?). I’m unsure as to who created the first one (sorry for being unable to credit the original creator) as I was unaware that geared hearts had been around for a while. For example, I found this 2008 video of a paper hand cranked geared heart and was intrigued. And then I found emmett’s Thingiverse Featured and, well, here it goes.

Inspired by the paper hand cranked geared heart video, and emmett’s brilliant geared heart design, yet having too little time to create one entirely on my own, I incorporated emmett’s geared heart into this design to create my hand cranked PLA version of the hand cranked paper geared heart.

The video of my version is at

And if you don’t like cranking the heart by hand, then a motorized version is at

Designed using Sketchup 8, and printed in PLA on a Replicator 2 using Makerware “Standard” settings.


1) Added “Heart Base 1-2.stl” to work with emmett’s “HeartGears1-2.stl”. Has not been tested yet, printer be warned!


Study “Assembly.skp”.

Print emmett’s geared heart “HeartGears2-3.stl”. As of update 1, you can also print emmett’s geared heart “HearGears1-2.stl”, but it has not been tested. The bottom and center pieces are not used, nor is one of the clips, so if you can edit the .stl file and delete these components, you can save print time and PLA.

Print “Heart Center.stl”, then using emmett’s instructions, assemble the heart onto “Heart Center.stl” noting again that the bottom piece and clip are not used.

Print the remaining parts and assemble as per “Assembly.skp” except for “Heart Center Drill Motor.stl”. Also note I printed “Heart Base.stl”(or “Heart Base 1-2.stl” for emmett’s “HeartGears1-2.stl”, but not tested)” in white for the first 4mm height to match the color of “Base.stl”, then switched to red for the remainder of the print. If you use Sailfish firmware on your Replicator 2, you can program the print to pause at 4.2mm while the print is in progress and allow a change in filament color.

If you find your heart is too tight, then disassemble it, and reassemble it using “Heart Center Drill Motor.stl” through “Heart Base.stl”. Chuck the shaft of “Heart Center Drill Motor.stl” into a hand drill, and while holding onto “Heart Base.stl”, spin the assembly forward and backward at low to moderate speeds until it loosens up. Once loosened, disassemble and reassemble using “Heart Center.stl”. Even if you do not wish to build this thing, you can loosen up your emmett heart using this technique.

With emmett’s “HeartGears2-3.stl” gear ratio and the gear ratio of “Gear Main.stl” to “Gear Handle.stl”, 5 turns of the handle will completely cycle the heart from start to finish.

Hope you like it.

License: Attribution – Non-Commercial – Share Alike

Tags: Geared_Heart, Hand_Crank