Geared Heart, Hand Crank Edition

by gzumwalt, published

Geared Heart, Hand Crank Edition by gzumwalt Feb 21, 2014

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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 http://www.youtube.com/watch?v=70dKZjP4NOo and was intrigued. And then I found emmett's Thingiverse Featured http://www.thingiverse.com/thing:243278 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 http://www.youtube.com/watch?v=6V-IYuWghAQ.

And if you don't like cranking the heart by hand, then a motorized version is at http://www.thingiverse.com/thing:255280.

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.

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Hi Greg, I've got the heart working fine but the crank has been giving my issues. Using my da vinci 1.0 jr and xyz, I've had to make the openings larger for the handle to fit through the gears and axles. Now the two gears aren't working very well together. The main gear is rather stiff trying to turn everything, too stiff for the smaller gear and it ends up skipping teeth. Any advice?

Hi Jordan,

My first guess would be too much build plate "ooze" occurred on the build plate side of the parts (gears and handle). And with gears, filing is quite an arduous task. I suggest try printing these parts on a "raft", which minimizes the oozing of the first layer. You can also set the first layer height to the lowest value possible. Finally, as always, make sure your build plate has been precisely leveled and not too close to the print head.

Hope this helps!


Hello Greg, when I try to open the Assembly.skp, I get a screen full of gibberish. Do you know how to fix this, or could you just tell me how to build the model??? Thanks.

Hi Eli,

Sorry for the difficulties.

I no longer use Sketchup, but I downloaded the file and opened into the last update of Sketchup (version 17.0.18898) and it did open fine. The file is simply the completed base with no printable parts, so it's not really needed for anything other than a simple assembly.

I've attached a screen grab of the contents.

Sorry again,


Con Heart Base 1-2.stl" se tiene que imprimir "HeartGears1-2.stl o HeartGears2-3.stl ?

Con "Heart Base 1-2.stl" debe usar "Heart Gears 1-2.stl". Con "Heart Base 2-3.stl" debe usar "Heart Gears 2-3.stl".

¡Espero que ayude!

pero funciona la heart base 1-2? porque ponia que no habia sido probado aun. o mejor imprimir heart base con heart gears 2-3 ?

"Heart Base 2-3 .stl" ha sido probado con "Heart Gears 2-3.stl". Nunca imprimí ni probé "Heart Base 1-2.stl", otro usuario pidió uno así que tomé el tiempo para diseñarlo, pero nunca lo probé. Yo usaría el testado "Heart Base 2-3.stl" con el "Heart Gears 2-3.stl", esos trabajos.

muchas gracias!! imprimire entonces heart gears 2-3. heart base es heart base 2-3?? porque en archivos solo esta ese!

¡De nada!

Sí, "Base del corazón 2-3.stl". También puedes usar los engranajes originales de 2-3 corazones de emmitt aquí: "http://www.thingiverse.com/thing:243278/#files."

Three Heart Gears
by emmett

Mate there are parts missing. You refer to HeartGears2-3.stl in your instructions there is no such file...

so...i printed all the necessary rts for emmets 2-3 heart. i`m unable to move the heart by turning the axle. it looks like the gears are to small to interact with eachother and the heart is only moving up and down but not turning. i can turn the heart only by hand. so what i´m doing wrong? :-(

See this video: https://www.youtube.com/watch?v=o8CkCe5A-1w.

When assembling each heart piece onto "Heart Center.stl", make certain the piece spins freely, so freely that when you flick it with your finger, it spins easily.

Also, if you add the spacer for the motorized Version between the main gear and top, it will assist in keeping the heart assembly from moving up and down if your heart hears aren't loose enough.

Don't give up, I just printed yet another one and it worked, just be patient with the heart assembly.

The description for what to do is so confusing.

Any questions I can answer for you?

which center piece and heart base goes with Emmett geared heart 2-3?

The center piece is the same, the original heart base (not "Heart Base 1-2.stl") is for the 2-3 gears.

Is it just me.. or.. is my printer completely out of wack ?

or is this an early fools day project instead of Valentines day

proportions just seem all wrong... had to file (A LOT) just to make the top piece fit in to the center groves of the box.

then the axel is WAY to big to fit through the axel cap or the small gear.

if you decrease the axel size to 80% (YES.. that much) it fits beautiful through the axel cap and the small gear

BUT... now the axel is too short to reach the other side of the box...

and to top it off.. the small gear is MUCH too small to interact with the large upper gear.

So.... Where am I going wrong here ?

Last night I increased the small gear and axel caps by 10% they fit the axel "just right."

But alas....

Now the small gear teeth no longer mesh with the large gear teeth.

I give up.

I'm really sorry about this.

Could you tell me if your printing in PLA, and what slicer you are using?

Thanks and I'm again sorry.

Using cura
On a maker select V2
Which is a rebrand of Wanaho V2

I printed the all parts except the heart gears and pins themselves, and they assembled fine.

I'm wondering if it's a slicer issue. I originally used Sailfish with a Makerbot Replicator 2, and now use Cura 2.3.1 with an Ultimaker 2+ Extended and an Ultimaker 3. I printed half the parts on the 2+, and the remaining on the 3.

I'm still at a loss except for the slicer.

I downloaded all parts and will print them overnight, I'll let you know what I find. I'm slicing with Cura 2.3.1 and will print some parts on an Ultimaker 2+ Extended and an Ultimaker 3 Extended.

Sorry again.

I'm at a total loss. I printed over 15 copies of this thing, and while I haven't printed one in awhile, I did not experienced the issues you are experiencing.

I'll try to find an answer.

How does one separate the parts? My printer does not accommodate the "whole" stl file? Currently using Netfabb to cut the parts into individual ones? Is there a better way?

Not that I'm aware of. I believe I saw somewhere here in Thingiverse that some one has separated them into individual pieces.

Any instructions on how to build it? Do i just build emmett heart first than include your crank? I am using emmett 1-2. Has this been tested yet? Thanks for the great work.. Its mind blowing..

You need to print Emmett's 2-3 heart gears, then assemble them onto "Heart Center.stl". I am not sure if anyone has tried the 1-2 heart gears, someone asked for the 1-2 base quite a few months back, and I posted it but am not sure it it works.

Thanks, glad you like it!

Comments deleted.

ok thanks.. guess gotta go back to the printer to print 2-3.. Least now i'll have 2 hearts.. lol

FYI.. So i tested out 1-2. It does not work. The HEART_CENTER is different on the 2-3. Seems like the only version working
is 2-3.


I've the same conclusion :

I was trying the 1-2 version, but it seems the center part (with the shaft) is not aligned/sized correctly for the 1-2 version.
The center-part should be slightly bigger (I'm not fluently in 3D design yet, so I was not yet able to make a fix yet)


I was able to create a heart_center for the 1-2 (via trial & error) and on its own it seems to work, but, connecting it to the gears doesn't really work, the gears seem to be too light, there is a lot of force needed.

So I'm trying now to make the gears wider/bigger


i'd like a copy of the 1-2 heart center.... Did you use washer, etc to push the gears closer together?? I had to do that to get the 2-3 to work.. Took some fiddling with though.. Now its smooth as butter..

Hi, I published my modifications.

I'm not a pro designer, so forgive me the raw trial and error approach

Geared Heart - Modified parts

I'm sorry to say I have been unsuccessful in locating the design files. Still looking, and I'm truly sorry for the problems you are experiencing.

I can share you the files as a result of my trials if it helps


Comments deleted.

Hi, is it possible to buy one of these from you?

Hi Mike,

I am not in the commercial "printing" business, and as such do not sell prints.

Is this a special needs situation? If so, I may be able to find a solution for you.


Thanks for the quick response Greg! I know you're not, but I contacted Makerbot to see about purchasing one and they referred me to this site and said to contact someone such as yourself to possibly buy one. I actually had bought the same one for my gf at the old MB store, which now closed down. Then a subletter took it and my gf is really upset about it, so if I can replace it that would be amazing! Please let me know if this might be possible...thank you :)

Hi Mike,

Please send a direct message, I may have a solution.


Hi Mike,

Please send a direct message, I may have a solution.


Comments deleted.

Hi Mike,

I am not in the commercial "printing" business, and as such do not sell prints.

Is this a special needs situation? If so, I may be able to find a solution for you.


Hi, is it possible to buy one of these from you?

Hi, we´re Mario and Manuel and we can´t see all the parts of the heart
Are there more parts?

Download emmitts geared heart 2-3 or 1-2 (see instructions). Hope you like it!

Hi, we´re Mario and Manuel and we can´t see all the parts of the heart
Are there more parts?

Download emmitts geared heart 2-3 or 1-2 (see instructions). Hope you like it!

it doesn´t got all the parts of the heart

Is there any chance there will be 1-2 version of heart center in future? I printed 1-2 heart, most of this parts and now i see it does not match :( Really dont want to print heart again, it is 20 hours of printing...

Can you please add "heart center 1-2" to this wonderfull collection?
That's the only part missing for me to get cranking!

How about the 5-6? Does it works for 5-6?

I'm sorry but no it does not.

I'm using xyz printer and I'm trying to print out the Heart_Base part. However, after slicing it came out not the same. Should I try and print it anyways?

For the 2-3 gear, do we download the "heart center" or the "heart center new"?

Try " heart center new" first as some slicers had problems with "heart center". I use Makerware and have no problems with either.

Thanks for the reply, will there be any difference?

Depending on your slicer, one may print and one may not. Once successfully printed, they are bith the same.

Congrats, your model made it on my top 3D Printed Valentines Day Gifts! See here for the article: http://3dprintingninja.blogspot.com/2015/02/top-5-free-3d-printed-gifts-for.html

Many thanks! I am truly humbled.

missing pieces of the heart ... where are they?

See the instructions. You can print either of two of emmitt's geared heart pieces depending on which gear ratio you desire. Make sure you pick a "Heart Center.stl" to match the gear ratio you choose.

Sorry for the confusion!

Does the heart-center also work with the 1-2 design of the heart? I might be wrong but i think the center pieces for the 1-2 and 2-3 desings look different.

There are two heart centers, heart center 1-2 works with the heart 1-2, and heart center 2-3 works with heart 2-3. You only need to print the heart center compatible with the heart gears you print.

Thank you for your reply but i can only see heart_center.stl, heart_center_new.stl and heart_center_drill_motor.stl. There is a heart_base_1-2.stl so i thought i could make a hand cranked version of the 1-2 heart.

Am I missing someting. Trying to make this as a demo for my studets but there are no files for the actual heart, the moving parts above the base. The main part that form the shape of the heart.

I'm sorry I didn't clarify in the description, but you must print emmet's geared heart from his thing. The instructions describe the process.

Again, I apologize for not clarifying this point in the description!

The Center piece, at least for the 2-3 is not manifold so it gives me alarms in Repetier Host. Slicer slices it but stops when it gets to the shaft. XYZware prints it just fine, but I'm about to switch firmwares and wont' be able to print with XYZware anymore. Is there any way to get the center piece "fixed?" Additionally, have you considered making the bottom heart piece and the top of the base seperately so that those of us who can't (my software doesn't allow a filament change during a print), or don't know how to change the filament colors can change it?

Ovrclck350 -
Regarding change of colors, will your printer "pause"? If so, pause it, change to a new color, then resume printing. That's the method I used.

Ovrclck350 -
I just uploaded "Heart Center New.stl". Try it and let me know what happens. I have heard of similar problems in other threads, and all said they updated their slicer to fix the problem, but still, let me know.

Downloading it now and trying. The weird thing is that XYZware always printed it with no problem, but since I'll be switching firmwares soon I won't be able to use XYZware (Davinci 1.0 printer). And unfortunately, until I do, I can't pause and change to a new color--which is one of the reason's I'm switching.

Just a quick check with Slic3r and viewing with Repetier Host shows this one should work just fine! Thanks. I'll spit some out to the printer in a few. If I don't check back in, that means everything went great. I appreciate it!

Just wanted to update--everything worked great. I did add a washer above the large gear, and beside the small gear to help eliminate movement and keep them in contact. I wish I was smart enough to just make the washers about 2mm thicker to help gear mesh, but maybe someday I'll figure that out. I'm still learning regarding 3d modeling. I'm a CNC programmer and drafter, but my line of work RARELY requires 3D design. That's why I bought my printer, so that I could be forced to learn. UNFORTUNATELY, after making my first geared heart, now all my friends want one.

Great! Glad it worked for you, now you're in production mode!

BTW, nice job and thanks! I did sucessfully print 2. I just have problems with the center piece........and the pins. I always have issues with the pins, but that's on my end.

Soon to be leaving thingiverse because of Makerbot's behavior towards open source.
Details: http://www.fabbaloo.com/blog/2014/5/25/has-makerbot-crossed-the-line-for-some-yeshttp://www.fabbaloo.com/blog/2...

I am trying to print this using PrintRBot Simple, Repetier-Host, and Slic3r. When I try to print Heart_Center.stl and Heart_Base.stl, they do not print the same as they look on the Repetier-Host screen or on Thingiverse. The Heart_Center prints with the long shaft the same diameter as the base rather than a skinny shaft on a large base. The Heart_Base gear prints with rectangular, vertical gear teeth rather than the sloping gear teeth shown. What am I doing wrong?

A commenter below having similar problems switched to slicer 9.9b, hope it solves the problems you are having.

I miss the pins to put it together

The pins are included in emmett's "HeartGears2-3.stl".

I just noticed that the heart base is a single piece, but on your print it shows two colors.. are you using dual extrusion for this print? I'm glad I noticed this before starting to print as I'd like the heart to be a different color than the base, but it seems un-achievable with the current design. I'll see what I can come up with.

Pause your printer at the 2.2mm level and change the filament to whatever color you desire.

I removed the center and bottom from Emmett's 2-3 plate for whoever doesn't have the capability to do it themselves, or just doesn't want to: http://www.thingiverse.com/thing:266448http://www.thingiverse.com/thi...

I'm printing it now as well.

Modified Emmetts Geared Heart 2-3 for Cranking

I printed the original heart, then printed the gear box top (that replaces the bottom of the heart) and then printed the crank, box and other 2 gears. The crank is too large to fit through the small gear or the cap. Then the large gear is too small to fit on the end of the shaft going up into the heart. Printed all with Makerware on a Makerbot Rep2 with default settings -- except when I printed the gears and box I printed with 100% fill so they would be sturdier. It's disappointing, but I'm still going to try and figure out a way to get it to work.

They fit very tight so they won't move on the crank. I printed at 10% (default) and then used a modeling knife to slightly clean out the holes in the gear and cap.

Weird....slic3r doesn't like the heart_center and heart_center_drill_motor....always cuts off the shaft. Maybe Its my version of slic3r 1.0.0.RC2

I checked the .skp file for holes in the shaft and cannot find anything out of the ordinary. If needed, I can post the .skp file for you to modify as needed. Just let me know, sorry for the problem.

I have the same Problem with Slic3r - the shaft is removed. Maybe the STL is not manifold at that place and slic3r "corrects" it by removing the shaft?

Any chance of getting the other gear ratios?

The heart gear 1-2 one. The bottom gear of the heart has a total of 18 teeth.

I just uploaded "Heart Base 1-2.stl". My printer is busy with a long print so I did not get a chance to test it. Let me know if it doesn't work and I'll see what I can do.

Hope it works!

So I printed out the base and center and it appears that the center may be just a little bit undersized causing the gears to not entirely align correctly. I'm going to play with your sketchup model to see if I can get the right size.

Thanks, I'll give it a try and let you know.

hi jenilliii, did this heart ever work with 1-2?

Many thanks Thingiverse for featuring this thing! I was wondering why my dashboard was lighting up, and now I know. Thanks again!

And thanks emmett and whomever made the paper hand cranked gear heart, they are both brilliant designs.

insane! this is really,really,really cool!

Thank you very much! Glad you liked it.

This is very neat and eliminates the problem that comes with the original heart gears. That is, the tendency of them to slip out of your hands as you turn them. (Or is that just my problem?). Have you considered or maybe even tried using one of the small geared DC motors which you have employed in other GZumwalt projects? Thinking about it, introducing a motor may well make the thing too noisy as a desk object but it would definitely look impressive. As ever, excellent work and superb documentation. Thank you.

Thanks! Regarding a motorized version, stay tuned...