Heart Gears

by emmett, published

Heart Gears by emmett Feb 11, 2011

Featured Thing!


I highly recommend using the most current version of this design, found here: thingiverse.com/thing:243278
For a very nerdy Valentine's Day, I give you heart gears. This was inspired by Greg Frost's Broken Heart thingiverse.com/thing:4683, but it fits in the palm of your hand and can be twisted like some kind of worry ball. It makes use of the heart shape from thingiverse.com/thing:6190, the MCAD involute bevel gear script from thingiverse.com/thing:3575, and nophead's polyhole script for making properly dimensioned tap holes thingiverse.com/thing:6118.

UPDATE: If you lack a 3D printer, you can now buy these from CarryTheWhat at etsy.com/shop/CarryTheWhat.

I was daunted by the complexity of Greg's design, so this one is much simpler, having fewer gears, and a much simpler attachment design (simply thread the bolts into tight plastic holes). It also uses a smooth heart shape and is made for the hand instead of the desk.

Recent Comments

view all

Is there any screws that would fit if I scaled my Gear Heart down to 75%?

I'm having problems with it too can you please upload your stl file to thingiverse and tell me

Made one, but Slic3r had troubles with the center part, so I imported it in Google Sketchup, exported it as stl and then the slicing worked well

More from Interactive Art

view more

Liked By

view all


Give a Shout Out

If you print this Thing and display it in public proudly give attribution by printing and displaying this tag. Print Thing Tag


Each gear is unique, so print one of each (gears 5 and 7 are so similar, they can probably be interchanged). Skeinforge can be a pain, but to get around one bug I found, uncheck "infill in direction of bridges" in Carve. The one pictured was printed on a TOM.

For assembly, I recommend screwing each gear tightly into the center block so it can't turn and place each gear so they are smooth and continuous. The complete stl file is for assembly reference. Once they're all in place, loosen each screw a turn or two until the gears spin freely. Give to loved one.

The OpenSCAD file is fully parametric, so feel free to adjust to your heart's content. It's designed for M3 screws right now, but that's an easily adjustable element.


You must be logged in to post a comment.

blk380 on Sep 14, 2013 said:

Is there any screws that would fit if I scaled my Gear Heart down to 75%?

3v3 on Feb 11, 2013 said:

Made one, but Slic3r had troubles with the center part, so I imported it in Google Sketchup, exported it as stl and then the slicing worked well

alef on Aug 24, 2013 said:

I'm having problems with it too can you please upload your stl file to thingiverse and tell me

RoyOnWheels on Sep 20, 2012 said:

 Hey, the new makerbot store is selling this object for only  $50-$750!

Salted on Jun 22, 2012 said:

Made one, motorized it, put it on my wedding cake. Thanks for designing it! It was awesome!


idolcrasher on Dec 26, 2012 said:

Wow, that was epic! Have you posted instructions for this yet?

Anonymous on Feb 11, 2012 said:

This is my gear heart. Bought from Etsy, painted by me. hope you like it.


emmett on Feb 12, 2012 said:

Thanks for sharing! That's a cool paint job, and I'm glad to see our friends at Etsy are helping to bring these to a wider audience.

Anonymous on Aug 5, 2011 said:

Since I was giving this to my three year old to play with and she can be a bit rough with things I drilled out the a counter-sunk hole in the core around each screw hole and used a glue gun to glue a nut into each countersunk hole. Then I drilled out the holes in the gear pieces a bit bigger so that they would spin freely around the bolt. Lastly I put thread-lock in the nuts and put everything together.

The end result is tight, doesn't have any slop and movies quite nicely. I'm not so hot with openscad yet but I'll see what I can do about modifying the design so it prints my modifications..

Pictures to come.

bre on Jun 9, 2011 said:

If you scale this 1.7X you can use M5 hardware. BIG!

Jolijar on Jun 7, 2011 said:

I have all the parts printed out but my screws keep on coming loose when I turn it... Then when i tighten it a few times it strips out the center and I have to reprint it... There is alot of binding esp with the small gears. I have done a ton of sanding and It only improved marginally... printing out my fourth center piece now... *DONT_KNOW*

emmett on Jun 7, 2011 said:

If your screws come loose, then the center holes may be too large or perhaps the gear holes are too small. You can adjust them in OpenSCAD, but it's kind of a pain. Sometimes it's easier to drill out the holes a little, and perhaps even use slightly larger screws. You should have to tap them pretty forcefully into the center in order for them to stay firm.

Tunicate on Mar 30, 2011 said:

This is a very cool print. I feel silly asking this, but I am having a hard time figuring out the order of the gears. I know in the directions it refers to looking at the stl file, but I have no way of pulling it apart to see how the gears mesh.

emmett on Mar 30, 2011 said:

It's easier to understand once you have the pieces in hand. I usually start with gears 1 and 6, because it's pretty clear how to align them by symmetry. Then work your way around, making sure that where each new gear meshes, the surface is continuous. I'll admit, it's a bit of a puzzle in its own right.

NewPerfection on Mar 25, 2011 said:

My wife loved this! She's been showing it off to all her friends.

dermartin24 on Mar 7, 2011 said:

I animated the heart with Pro Engineer and published the video on youtube. In the description I added a link to this page. Hope that's no problem for you.

Here is the link: http://www.youtube.com/watch?v...

emmett on Mar 7, 2011 said:

Thanks for sharing, that's a great way to visualize the motion.

RobertHunt on Mar 6, 2011 said:

Just started printing this out in tranclucent blue PLA, looks good so far.

Zh4x0r on Feb 15, 2011 said:

Awesome gears!!! Here's my print: http://blog.zinventions.com/20...

davr on Feb 14, 2011 said:

My cupcake is choking on the overhangs on a couple of these :/

brucedjones on Feb 14, 2011 said:

Confirming that this made an excellent valentines present :)

Thanks for the upload emmet.

cbiffle on Feb 14, 2011 said:

Since I had to loosen the bolts a bit to get everything turning smoothly, I added M3 washers on the large gear shafts. This made it feel significantly sturdier by reducing wobble and play.

Anonymous on Feb 14, 2011 said:

how do i make it half size but still retain the same bolt hole sizes?

can i resize the heart STL then run it through openscad?

i tried running the Stanford bunny and only got one ear rendered, not really sure what happened.

these geared things are really fantastic.

Anonymous on Feb 14, 2011 said:

ok dumb question.. how do i export all of the parts? all i can get to render/export is the top middle gear

JadeKnight on Feb 12, 2011 said:

A bit of warning for those attempting to print this... DO NOT use '0 extra shells' on these gears!

I did that with gear 2, and it ended up doing basically 100% infill for pretty much the whole print to compensate for the lack of shells on the slopes... =-O

After it finished printing, I confirmed that with '2 extra shells' the infill was my normal 25% (through the SkeinLayer tool)...

In the f
uture I'll definitely be checking the SkeinLayer screen after slicing to make sure I'm not in for an unnecessarily long and wasteful print...

JadeKnight on Feb 12, 2011 said:

Well, avoid '0 extra shells' on the big gears at least. The little ones may benefit from it, but the larger ones definitely do not...

ScribbleJ on Feb 12, 2011 said:


Is the 'one bug' you mention working around that when you have infill in direction of bridges on, it drops all your extra shells and makes the layer look awful?

That's a one-line fix to the SF source code that I've been using for a while now.

emmett on Feb 12, 2011 said:

Yes, exactly. I just submitted a bug report about it to Enrique. I'd be happy to have your fix though. Any idea when that will make its way into a SF release?

cyclone on Feb 11, 2011 said:

This is great. Also, I too would like a 1,2,3 on the script. Something like a howto take a shape (like a heart) and gearify it. :)

emmett on Feb 12, 2011 said:

Well, if all you want to do is make this type of gear arrangement with a different outer shape, that's very easy. Just replace "heart.stl" with whatever other stl you have in mind in the OpenSCAD file. Changing the gear arrangements themselves is the harder part. I did my best to comment the code thoroughly, so take a gander.

Linkreincarnate on Feb 11, 2011 said:

Would you mind helping me understand the involute gear script? Maybe a short tutorial or im session just t help me understand it better...

emmett on Feb 11, 2011 said:

That's a good idea; I bet you're not the only one who'd like a tutorial on that. Makerblock has been doing his tutorial series on OpenSCAD already, so I'll talk to him and see if we could work a gear script session into his tutorials.

Have you tried using it already? Do you have any specific questions?