Screwless Heart Gears

by emmett, published

Screwless Heart Gears by emmett Oct 5, 2011

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UPDATE: There is a new version of this design which is more reliable to print and easier to assemble. I highly recommend you use it instead: http://www.thingiverse.com/thing:243278

At last, here is the much-requested 100% printable heart gears. No more ugly bolt holes! This was designed along the same lines as the screwless cube gears: http://www.thingiverse.com/thing:10483, and in fact uses the exact same center block (though the pins are slightly shorter).

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

The size has been increased a bit from the previous version to accommodate the printed pins, so it now measures 100mm across when assembled. Since everything is now printable, it should be easy to scale this design up or down as you see fit. At this size it took me ~6 hours of printing time on my TOM.


Print the parts list. The separate files for gears 1, 3, 5, and 7 are just there in case you have a problem with the four gear plate, or if you want them in separate colors. Use multiply to print four of the pin pairs at once.

Plug the short pins into the holes on the small faces of the center block; plug the long pins into the large faces. Slide each gear onto its corresponding pin. I like to start at the top, because it's more obvious how the gears align with each other when you work your way down.

It's always difficult to calibrate a printer to make perfectly fitting bushings, but the good news is if your heart comes out too tight to turn nicely or so loose it's wobbly, all you have to do is make new pins. You can either regenerate them with different parameters from the scad file, or you can just take the existing pin file and stretch it as required in the various axes. This means the big prints won't be ruined by a miscalibration.

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printed perfect. all at once on glass PLA.

How many pins of each size do we need?

If you have made a sucessful print, can you please list your filament, speeds, later height and temp? And fan or no fan? I am having trouble with the gear tee,th badly warping upwards and causing them not to mesh together. I've tried several times and just have a mess of 3 usable hearts.
Or can someone upload save and upload a settings cfg? Would appreciate it. I'm getting a little pissed off. I don't have problems printing anything else, printer is dialed in.

Hi, really a great job!
Could i ask you what software you used to create it ?

printed great, used cura 1.2 on my typeamachines 2014 series 1, with time and play it's smooth as butter only issue is the girlfriend wants me to print in any color filament i purchase. grrrr

uneusefull but very design ;-)

I printed this off on my UP! 3D Printer (2 years old). I did it on the fine print setting (.2) and everything came out perfect. No issues with the pins or assembling the pieces. They all fit together perfect and move great. This was a great Valentines Day gift. Thank you for making it Emmet!

Slic3r complained a lot about the dirty models, but they printed out OK. The pins were too long for me and I had to reprint them scaled down to shorter length(?)

Printed with blue glow PLA but the pins does not seem to fit?, i need to make them slightly smaller ?

Slic3r is telling me "Warning: The input file contains a hole near edge 94.722260,100.376305,28.111151-94.265778,99.876762,28.801149 (not manifold). You might want to repair it and retry, or to check the resulting G-code before printing anyway." when trying to slice heartcenter.stl, and it comes out with most of the holes pretty well broken. Am I doing something wrong here?

I am having the same issue. Anyone have an idea on how to print? I am using a bukobot v.2.

Hi. Do the gears require supports if printing with a makerbot replicator 2? Thanks.

No it does not.

how do you alter the code for a difrent model

Learn OpenSCAD, read my .scad file, replace heart.stl with your different model, fix any resulting problems.

all i could find in the code was heart.stl but it was in comments. i also relized there was this in the code
use <../MCAD/involute_gears.scad>// GregFrost's Thing:3575
include <../pins.scad>// tbuser's Thing:10541

where could i get the 2 files because all i am geting right now is a box when i render the code.

Look at your browser address; those thing numbers will take you right to the required files here on Thingiverse. As for heart.stl, it's not a comment: look at lines 115, 127, etc. You may want to start with something simpler if you're not that familiar with OpenSCAD.

i want to be able to do a tardis from doctor who

i couldn't get it to work. but i do have a idea for you but i couldn't do it because i am not knowledge enough. so the idea is a program that all you have to do is import the model "stl" you want to change and it would compile the model and you could export it as a gear.or you could just put a zip file on this page will all the other files that the code needs and make it so you only have to change the heart.stl file once and at the top of the code. i don't know how heard it would be to modifie the code to be like that.

i want to be able to do a tardis from doctor who

For those using Rep2, I used whpthomas' pins in his version of this for PLA material http://www.thingiverse.com/thing:38571http://www.thingiverse.com/thi...

They fit fine.

PLA Heart Gears for Replicator 2

Great model. Very big though. I was happy shrinking it to 50% in x-y-z. The center block gave an "unclosed contours" error but printed just fine.

I did not have such a heard time, but required a pliers to put in the pins. This is awesome!

I'm having a hell of a time putting it together. Even after downloading the old version complete STL to see how it fits together, the top piece still feels 'off' to me - seems to hang too high up on the one side. Prints came out perfectly on makerbot replicator. I had it together and it spun freely, but it just didn't seem to take a perfect heart shape like in the photos...

The top piece is symmetric across the top bumps of the heart. I had this problem too but I noticed that one end has 1 gear and the other has two. Try rotating it 180 degrees and see if that fits better.

Yeah, That was one issue I had when assembling the second heart.

I have the same problem :(

Eventually I got it, but it took a lot of pulling apart, repositioning and reassembling. And after I finished one, I still had a heck of a time assembling a second one even after I had a fully assembled one in front of me!

Just think of it as a puzzle. :)

Very cool. I found the original pins too large to fit; the pins from http://www.thingiverse.com/thing:31936http://www.thingiverse.com/thi... fit better but were too loose. I found that scaling those pins 90% in x only (using netfabb) was perfect.

Heart Gear Pins

Only way to get those pins in was to lube them up, but boy once I did it was smooth sailing

I used "Super Lube" which is PTFE based

I am having trouble with the scad file. I have downloaded the latest version of openscad, I have the heart.stl file, the pins.scad file and the involute_gears.scad file. Yet it still crashes every time I try to run it.

This is awesome, I'm printing one for a friend, I have the hub, the pins and two of the gears printed so far, the third gear is on its way. My printer isn't fantastic but with some careful filing and reaming the parts fit together like a jigsaw puzzle.

Had a little trouble printing the pointy edges of the gears because of curling. Printing at 180 C with just two outlines in sequence; loops-infill-perimeter worked out pretty good. This way the fill and outline get to cool before being fused together by the loops.

The pins fit perfectly. Everything snaps right in. Just squeezed them together a bit before inserting to make them more flexible.

Printed in galaxy blue and mother of pearl. Very happy with the results!

Printed pins are almost a waste. ugh all of that and the gears just pop out / dont fit right. i've printed 6 different sets of pins trying to get something that works. why arent the pins round? or roundish? It looks cool, but thats all you can do is look at it

Hi lazerusrm! I'd be glad to help you troubleshoot your printer! Hit me up and I'm sure we can your printer tuned. I've been working with 3D printers professionally for about 2 years now.

 The pins are round, with flats sides just large enough to make them stick to the platform so they'll print. Many people have printed these and they've worked, so have you checked your printer? Sometimes a loose belt or something causes problems.

Made one yesterday for my wife's birthday!  All parts printed out okay, but it was very difficult to insert the pins (requiring a lot of force) - is it normal?  I finally had to sand them down a little bit to put them in. 

Yeah, the pins were always a pain. I finally just updated tbuser's pin library; I should probably update these files using the V3 pins one of these days...

It would be great if you can update the pins to make them easier to work with.  Really look forward to that!

WOW!  We made Popular Science.  All credit goes to Emmett for the heart design, I just made the holder, but, 


So I was going to start assembling this and there is really no way that the pins are going to fit into the holes of any part. Also even if they did how do I know the top of the center part to put the top of the heart on?

Hey, I had the same thing and this might be too late but i was trying to compile the scad file with openscad and it kept crashing, sooo... i remade the stl with the dimensions I needed you can download the stl here. It worked for me and i hope it works for everyone out there too. http://www.thingiverse.com/thing:31936http://www.thingiverse.com/thi...

Heart Gear Pins

I keep getting the tips of the gear teeth curling up when it's printing. Eventually they curl up and in enough that there's no material for the next layer to hold on to and it starts drooping over the edge. I've tried varying the extruder temperature, print speed, layer height, and extruder steps per mm. Nothing I've tried has shown any significant difference one way or the other. What am I missing here?

25 aborted attempts later: I believe the problem is there's not enough time for each layer to cool before the extruder comes back for another pass, causing hot layers to stick together and pull up.  My solution is to print at least two parts at a time, on each side of the build table.  This gives each layer ~20 seconds of extra cooling time.

 Exact same problem... I've tried to print gear 1 about 10 times now.  The first 1mm is fine, after that the tips curl up and it all goes to hell.

If I blow on the part while its printing, the tips dont bend up, it comes out good...  I've tried lowering the extrusion temps and HBP temps, but I still have to blow on it.  hmm...

yeah same here but i just had to push them down with my finger and it came out alright

i was trying to print this, but i ran in to a problem of slic3r complaining about the center piece. i ran it through netfabb, and it stopped complaining but it didnt print correctly. see attached image.

I'm also getting the same problem, thanks for the new part. This one is currently printing and so far no issues to report.

Its a problem with the geometry, too many duplicate vertices. I've fixed it and test printed with Slic3r 0.8.2. You can find the fixed center piece here.


Heart Gear Center for Slic3r
by Salted

thanks very much!

Well, perhaps you've found a bug in Slic3r. I use skeinforge, and it has plenty of bugs too, but it usually does okay with this shape.

yeah, ive been working at getting set up with skeinforge, but there are so many settings to tweak.

Printed a full version, and is loved by every one ive shown it to. My much mocked printer is finally getting some cred thanks to this guy.

I would love to scale this down to a roughly keychain sized version, print a bunch and give them out to everyone (burning man gifts, cuties at a bar, etc). Would it be feasible to just use the simple scaling function in replicatorg, or would some openscad trickery be better?

Thanks, always glad to help a fellow printer get some cred. It looks like someone had a similar idea: http://www.thingiverse.com/thing:16893http://www.thingiverse.com/thi.... It sounds like making it keychain sized is possible, but may require some tweaking; they have a discussion going.

Keychain Screwless Heart Gears
by Zh4x0r

Printed most of this with Helsinki Hacklab's printer "Torsti" during Reaktori youth event and finished it off at the lab. Great conversation piece and printer demo :)

I just printed and assembled this...it is AWESOME ! !

I did it for one of my friends and we used it in this music video!


That's awesome, thanks for sharing!

Whenever I open the scad file it crashes OpenSCAD. Has anyone else had the same experience?

Hmm, does it crash when you open the file, compile or render? Do you have all the libraries and external STLs it calls? It takes a very long time to render, so I recommend only compiling at first. Just because it hangs on render for ten minutes doesn't necessarily mean it's crashed.

Thanks, that worked. I didn't have all the libraries and OpenSCAD was set to compile automatically upon open.

I printed this for my wife for Hallmark Day, and she loved it. Thanks for sharing this with the community.

This is neat! I wanted to get it done for V-day for my wife, but my printer's not done with its shakedowns, so I have only been able to print 5, 7, and then with more futzing 1, and 3. The overhanging plus the curling at the tips on gear 2 is my next challenge!

I've been working on this for most evenings the past week, and I finally had to tell my wife that I couldn't get this present done in time -- but I showed her this Thingiverse page, and she thought it was the coolest thing!

Looking forward to completing this one!

Maybe someone smarter than I can create some sort of way for the rest of us to input ANY model into something and get screwless pieces out :)

THAT would be awesome!

Actually, the OpenSCAD file is designed with a base module that you put whatever shape you want in to make a different design. Several derivatives have already been made by different people: http://www.thingiverse.com/tag:gear_mashuphttp://www.thingiverse.com/tag...

You may have to learn a little bit of OpenSCAD, but not too much for a relatively small change like this.

Just wanted to share, one of our hackerspace members printed this and it came out looking good: http://www.midsouthmakers.org/2012/02/a-very-maker-3d-valentines-day/http://www.midsouthmakers.org/...

Having difficulty with Gear 6 - I'm getting some layer separation near the top (see picture below. Otherwise the gears print perfect. I tried 1 shell 0% infill and 2 shells 0% infill with similar results...actually the 1 shell setting came out better. Any suggestions? What should I be printing with for settings on these? Would going faster/slower help? I'm printing with a ToM with a HBP.

I had better results with 30% infill than 20%. On the 20% infill print I watched the top surface sag into the holes between the infill. 30% had a better finish but still not perfect. Needs more infill or more skins/shells to be perfect.

See link for more details.

I have similar problems on Gear 8. Not sure what to do.

I've had that problem as well. I find that some infill (10-20%) tends to help hold up those inwardly slanted walls (I find rectangular works better than hexagonal). Make sure Cool is on as well and maybe increase the layer time.

Help!!!!! I printed all the pieces, but can't figure out how to put it together. To say that I'm not good at puzzles would be an understatement. Can someone point out which piece goes where? thanks!

nevermind, finally figured it out! really nice model, thanks

;) ;) ;) ;) ;) ;) :) ;)
amp;gt;:o =-X DONT_KNOW ;)

Hi - I created this thing, http://www.thingiverse.com/thing:16381http://www.thingiverse.com/thi... as a stand for your item. I imported your Exploitable Heart shape as an STL into OpenSCAD, subtracted it from a tapered cylinder, and then added a small cutout for the bottom tip of the heart. I think it shows off the heart nicely, it's stable, and it self-aligns when you set the heart into it.

Hi Emmett. I guess I am a wannabe 3d printer. So fascinated by these gear box and heart. I am also a newly to thingiverse. Do you or others print for others? Sell your things? Is that done? I don't want to be asking inappropriate questions. Thanks for your help.

Thanks, I don't have time to print these as a business, but lucky for you someone else does. I just added a link in the description where you can buy a copy.

Great "Thing" ... am happily printing for my wife! One (or rather, two) small problems: when I try and slice the heart pins and heart centre, I get a "non-Manifold" error. Any ideas on how to fix?

Many thanks

I got them fixed on iMaterialize's www.STLFIX.COM website. They now slice with Slic3r, and are printing as I type.

I will put the two "fixed" STLs on a website to make them available.

hey are your cad files compatible with autodesk inverter?

OpenSCAD is it's own language, so .scad files are just text files. The STLs should be importable to just about anything, but I'm not sure how easy it'll be to work with them in autodesk. I'd recommend trying OpenSCAD: it's pretty simple, free, and can do most things.

hey thanks a lot worked like a champ ;) you guys should sell these things they'd go fast.

This is so beautiful! sadly i dont own a 3D computer, could i buy a plastic heart from you?

Thank you, I've actually gotten this question a lot. I'm not really in the business of selling my designs. I have started thinking about putting some of my designs on Shapeways, http://www.shapeways.com/http://www.shapeways.com/, so people like yourself could order them. Would that be interesting to you?

I cannot figure out how the heck to stop the gear teeth from curling up on me. :(

My build platform is cranked up to 130 and I have checked to make sure my heiight is good. Any advice?

It's because the print is too warm. Print more than 1 at a time and it will help a lot.

It is a tricky print. If it's peeling off the build platform, try changing the z to squish the first layer. If the warping is happening higher up, I find blowing the prints a little can bring them back into line. A lot of it is also calibration; low width / thickness tends to work better (~1.4).

This was fun. I think my little gears show an issue with my .15 layer height profile.. the border/infill gaps. Not quite sure what to tweak for that.. hmm. Anyhoo, I didn't actually expect the gears to work, but they do. They work great. Thanks! :)

Beautiful print! What gaps are you referring to?

Could you make some "heartless screw gears"? :-P

jbs - in reply to

Very funny.

Wowza! Some time ago I printed "with screws" version of the heart gears, and so now I clearly need to print this one as well.

Where is the file "heart.stl"?

It is needed to compile the scad file.

The heart shape is here: http://www.thingiverse.com/thing:6190http://www.thingiverse.com/thi..., but you'll also need some other scad files. I believe everything you need to compile is listed in my scad file.

Exploitable Heart
by emmett

Thanks. That's what I needed to know. Now it compiles.


Now all we need is to get dougc314 to motorize it!! 8-)

MOTORIZED screwless heart gears!
by Zh4x0r

In case you're having trouble visualizing what happens when you spin this around, here's an animation:

Hey! Do you mind if I use this GIF on my Etsy?