Clockwork Heart (dual ulysse escapement)

by A26 Mar 30, 2018
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Hey, would you be able to minimalize the case and remove the heart stuff? I'm working on a Nerf time-delay grenade and I need a fairly compact escapement. I'll probably print at 75% scale anyways as my printer can handle this.

If you decide not to or don't have it done soon I can always do it myself, but I thought I'd ask.

I'd not recommend this escapement for your application as it would tick down very rapidly (especially with a much lighter balance wheel). The drive gear already spins at 5rpm. A "folded in half" version of a swiss lever would likely be more compact and reliable. Here's some STL's from another project of mine that could be modified for that purpose (you'd need to add frames, and I would change out the pinion perhaps even putting it on the bottom of the escape wheel rather than the top). Weakening the balance spring would also offer longer run time.

Thanks! I'll take a look at those files.

I actually only need it to run for about 5sec. maximum as the jolt from when the grenade lands will start the escapement.

Can't wait for someone to design some cool stuff around the dowel pins so I have a use for the remaining 96 pins lol.

God i wanted to love this, even printed it as a valentine's day gift...
but this is levels of fiddly and difficult to get working right i didn't think were possible. the video supplied is this thing performing at a level i don't think is feasible for anyone else. Couldn't give it to my SO, too frustrated with it
hoping for a redesign one day that makes it much less inconsistent :(

and yes it is assembled correctly, and i can get it to "tick" properly for about three ticks in a row at once before it jams

Tight tolerances I made 2 on different printers and one runs forever and one I get 3 clicks before the balance wheel jumps out of the fork (I think my hairspring might be too strong). Here is a video of my longer running one https://www.youtube.com/watch?v=w35rXktOcIk

  • Get the balance assembly running smoothly first
  • 1.75 filament and graphite powder from my kids pinewood derby kit for the axles
  • I used 50% infill on all gears then cleaned all the edges with an exact-o knife

Radial thrust escapements usually have a certain level of "user hostility" not seen in other types. I cannot remember the required XY precision off the top of my head for this model, but it is likely on the order of 200um. If you care to attempt it further, scaling up by 50% or so might make for an easier print (though the timing will be different). I'll see it I can't create a sloppier Swiss lever version at some point. Regardless, Valentine's Day already creates enough stress and frustration, and I regret contributing to yours.

Ah, sorry for being harsh, I wrote that comment after about two hours of trying to make it work :(

However, upscaling sounds like an interesting move, the only problem being the use of 1.75mm filament as dowels won't work anymore at that scale.

I wonder though, should I have done 100% infill on the rotational weight and the spring? There's some energy in there but it feels like it's not enough to reliably swing the escapement consistently. Also there's very little slop on the escapement so the notch on the rotating wheel will drag heavily on it and it'll get "stuck" instead of smoothly swinging it back and forth.

Printed at 0.1 resolution since I realized this would be really sensitive to tight tolerances

The hairspring and the main weight (balance i think its called) are tricky. You want some weight obviously but too much and it won't bounce back. Of the 2 i built so far, 1 was 20% on the balance and 50% on the spring and the other i did 100% on both and it doesn't run very well. #1 runs perfectly with 1.75 pla spindles, #2 i get about 3 clicks before the balance jumps out of the fork. I think there is too much rotational mass.

This is a pretty cool project. I printed it using .1 resolution and all the parts turned out great. I filed down any rough edges and after much fidgeting I finally got it assembled correctly. The exploded diagrams helped. I can only get it to work though if I flick the balance wheel as sarf2k4 shows in his video.

Is there some part that needs to be filed down more to get it to work with just a turn of the gear or is flicking the balance wheel the way it is supposed to work?


Most common cause for it to cease operation would be friction on the balance assembly. Here are some possible sources:

-Compression on the frames is friction due to pressure on the ends of the balance assembly. Sand down the 2mm high conical cap on the top frame to permit more end shake.
-Shaft friction between the balance wheel part and staff. Ream out the balance wheel with a drill bit of the proper size until it rotates freely
-Balance spring mounted obliquely. If the balance spring is tilted such that it rubs the frame as it "breathes" it can stop the balance (you should be able to hear the rubbing). Ensure that it is mounted flat. I recommend using PVA glue (or some other easily removable adhesive) to secure the end of the balance spring into its mount.
-Balance spring end freely rotating in mount. If the end can rotate about in its mount, that can depower the spring significantly. Solution is the same as above
-Fork and roller are over-extruded/too big for each other. If one or the other is oversized that can require addition energy to unlock the escapement. File both parts down to where they interact freely.

Some combination of the above is usually the cause of stoppage. I hope that helps.

Hi, I've made video here

If A26 don't like this commend, please delete this comment

Thanks for making the video. Do you mind if I post the link above?

You are welcome, I don't mind you post the link above into the description, it will help my channel grow as well =)

Can we get assembly instructions please?

I've printed everything and assembled, but it's not working. I've checked the assembly several times, but I'm not doing anything wrong. The issue is that both toothed gears catch on the fork at the same time trying to push it two different ways at once. I don't see how this isn't happening with yours. Please help. There are no incorrect dimensions or elephant footing.

Mind posting a photo? The gearing of the escape wheels should keep them out of phase. Not to insult your intelligence, but do you have the escape wheels mounted on the opposite sides? Impacting the pallet with the rounded rear tooth profile rather than the flat impulse face would cause it to lock in a similar manner to what you described.

I have them mounted on the correct sides. I decided to just redesign your version of the fork into one that works for mine. I still don't understand how yours isn't locking up though.

i'm not gonna bother printing this till it gets some real instructions. how about a PARTS LIST

Parts list is easy. all printed parts, 4 x 16mm long 2mm diameter shafts, a strip of straightened 1.75mm PLA filament cut to length for the balance staff.

If the exploded views are insufficient, user sarf2k4 has posted a how it's made video via the following link: https://www.youtube.com/watch?v=VlL9tIjvARk that might prove helpful.

feel free to post any further questions.

Don’t know if you are still tracking this one but any progress on a winding base? My girls thought it would be cool to set this into a base that you could wind up. That way you are not limited by the heart shape for the base. I might be able to remix one from some of the other wonders on here but I am not very good with gears in openscad.

Getting featured on Thingiverse proved quite unexpected. I will see if I can make a base for this one within the month. Instead of containing the spring within a heart profile as with my previous, unsuccessful efforts, I think I will design a base that allows the heart to perform similarly to my flying tourbillon designs while also being removable for hand-powered operation. Ping me again in a month if I haven't uploaded one.

Will do, thanks! We are thinking about making a steampunk/clockwork inspired Tinman where this is his heart that you plug in. Very ambitious but I think it will force me to get better with openscad/tinkercad.

i like the design but it would have been nice to have a video of how it gets put together, the balance spring was incredibly tight fitting on to the balance wheel granted I didn't make any adjustments other than making a raft

My phone camera (eight years old and counting) and videography skills are lacking. However, user sarf2k4 has posted a video via the following link: https://www.youtube.com/watch?v=VlL9tIjvARk that might prove helpful.

Tolerances are extremely tight in this model (and really all radial thrust escapement design), and I adjusted everything based on my printer/slicer performance at a certain. I can't claim it will work for everyone.

despite the assembly as exploded does not work the gears are blocked. what is the solution ???

-If a part is blocking the movement of the geartrain, it is not assembled correctly.
-If the gears are jammed, it most likely means the part dimensions are off. Elephant footing and over-extrusion would both cause the parts to be oversized. Excess may be trimmed or sanded off. Aside from the escape wheels, the other typical place a design of this nature might jam would be in the roller/pallet fork interaction.
-Another possibility is that roller (printed as part of the balance wheel) is outside of the fork slot in the pallet piece. Manually resetting it inside the fork should restore functionality.

it keeps locking up on the thing.. holding the spring that's moved by the gears.
i cant figure it out and i've spent some time on it now. :(

I used large paper clips and thoughtfully located dabs of super glue, Worked awesome and saved me buying a pack of 100 for $15. :)

So, how many shafts TOTAL for this thing?

Thanks again for the help, we featured you on our instagram page https://www.instagram.com/p/BhPPNcUggam/?hl=en&taken-by=goengineer

I've made one. Printed fine with almost no support needed...

But, once assembled, it's not working. The gears keep getting stuck.
I've checked the assembly and all is right.. Wondering.

Will this fit work with these pins? http://a.co/iHlNdjA

I noticed you said you changed it to fit 2mm x 16mm pins now, so I'm wondering if I'm out of luck if I got the 2mm x 15.8mm ones.

Yes. Those will work. .2mm of endshake won't present any problems. Consider the 16mm a nominal dimension.

Hello, this must be a lovely project, so I ask if do you have the time to add a picture that shows how to mount the assembly?
Best regards

I posted exploded view. I hope that they help. Please let me know if you have further questions on how it fits together.

Hello A26, I just saw the exploded views and seems that they are perfect. You must be patient but who doesn't know this kind of mechanisms, the risk is to mount some parts in a wrong way. So, thank you so much for the ready answer... I'll post mine as soon as I'll complete it. :-)

I want to learn how to draw swiss lever.. but i have no idea how to design it...
Anyway, Very Nice work!!
I Love Your design!!!!

Very cool. Printed out one. I'm still trying to fine tune it. Could I get the exact pin lengths? I tried cutting them by eye but it's not working well.

All shafts are 2mm diameter. I modified two of the parts so that all shafts but one are 16mm in length. The sole exception is the balance wheel which requires a 20mm shaft. I have had success using a filament strip there.

Thanks, I've been using filament too. Seems to work well. I hope to recut the shafts soon to the more exact measurements you provided.

Also, one key thing was not apparent to me at first. I had installed the escapement gears backwards. After switching them, things started moving a lot smoother. Thanks for posting the exploded view. An underside view might be helpful for people to avoid my simple mistake.

Yeah, that’s what I was thinking! An underside view would be very helpful for us!!!!! Also for the the green 1.5 version tourbillon. That would save me from having to keep coming back asking questions and being frustrated, that’s for sure!!