One Plate Mechanical Clock

by A26, published

One Plate Mechanical Clock by A26 Aug 27, 2016
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8158Views 1858Downloads Found in Mechanical Toys


I designed this clock so that all parts comfortably fit within a 180mm x 180mm square. Just hit print and in about 6 hours, you will have everything you need for a functional weight-driven mechanical clock. It was a fun exercise in minimalism and a test of my printer's fine detail capabilities. In addition to the plastic, the clock requires the following:
1 x 200mm 3mm diameter shaft
1 x ~75mm 3mm diameter shaft
1 x ~45mm 2mm diameter shaft
3 x RC Helicopter bearings 6x3x3 (or 6x2.5x3)
1 x 450g weight
8 x coins - I'm overseas with foreign coinage, but quarters should work
~3m string - I'm using 550 cord guts since that is all that I currently have available
2 x nails to mount it to the wall.

It can run 1.3 years on a single wind provided you mount it above the Mariana Trench, but on my wall it goes over 12 hours. Doubling the weight with a pulley provides more than a day. I'd recommend using the larger frame should you decide to go that route. Tugging the coins outward slows the clock down and shifting the whole pendulum assembly sideward balances it increasing reliability, mechanical efficiency, and aesthetic appeal.

I will post assembly instructions and possibly an exploded view in due course.

UPDATE: 20160831 Here's a video of it in action: https://www.youtube.com/watch?v=I5wlcmDbiXc
Note: I have yet to adjust the pendulum for accurate time keeping.

Also, utilizing my limited Tetris skills I managed to fit the bigger frame and pulley onto the same size plate (labelled v2), so I guess they no longer count as accessories. I added a small clock face that you can glue on the front if desired.

UPDATE: 20161010
To accommodate smaller build plates, I split the frame piece in to separate top and bottom parts (bigframea and bigframeb) so now people with build plates as small as 110 x 110 can print this design. I also uploaded an updated wheel 4 so that it uses a metal shaft rather than a plastic one. Below are my non-printable parts:

UPDATE: 20170219
I posted an exploded render of the clock (finally). For assembly, I jammed "druma" onto the 3mm shaft ensuring a tight fit with no freewheeling. After that, I threaded everything else on in order. For the weight drum, I tied the string through the small hole in the middle flange and wrapped it opposite directions around the top and the bottom. The pendulum assembly (anchor, penweights, and 3mm shaft) slid on over the lower post. Once all was in place, I covered it with bigframa-v2. The front gear train is pretty self explanatory.

Print Settings












Printed with Inland natural PETG on my Reach 3D printer http://www.reach3dprinters.com (probably one of the best bang/buck printers out there) at 30 mm/s with 250/70 C. Total print time was around 6.5 hours. Supports are required everywhere due to the drum piece.


Clean up all parts with a knife to ensure no artifacts that could interfere with the gear train. Any "elephant footing" can easily stop the escapement, so ensure your printer is well calibrated.
Wheel four in particular requires a bit of post-print attention since its integrated shaft is so tall and thin.
Ream out shaft holes as required. Wheel two should spin freely around its 2mm shaft, as should wheel one, the outer drum, and the hour hand/wheel five. The inner drum/ratchet and the minute hand must be snug enough to turn with the shaft (hence the ball bearing (yes I know that it's cheating)).

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Just printed one of these. I noticed the sun gear in the pulley for the weight is backwards.

Its nice to see one of very few complete working clocks with successful makes. Any chance you want to share the SCAD files to help others learn? Even if its not pretty?

I'm not sure how helpful my scad files would be. I'm pretty much doing linear extrusions of 2D turbocad files. Gears are simple involute profiles scaled for the axle spacing with .2mm slop. Are there any specific questions you have with regards to the design?

A26. can you please get in touch? i have a couple of questions. Thanks

To answer your earlier question regarding the pulley, it is an accessory to double the run time (also doubling the weight, and the string length). The weight attaches to the pulley hanger (I used another string: primitive and not all that aesthetically appealing, but effective nonetheless). The string coming off the right side of the drum hangs down whereupon it loops back up via the pulley which falls with the weight. I tied the end to a third nail hammered in about 30 cm left of the drum so as not to add additional stress to the clock frame. I hope that explanation helps. Feel free to post any other questions you might have.

Thanks heaps for your reply and explanation. Can you please possibly take a photo of the complete pulley and weight set up? Pic of the original set-up and also with additional weight and bearing? That would be awesome. Thanks heaps. Great work

Hi. Firstly, thanks heaps for all the work you have put into this. Love your work.
Please forgive me if I've missed something but where do the 6mm bearings go? and where/how is the printed gear pulley bearing used?
Thank you!

Sorry i can see where 6mm bearings go now :)

Hi! Can you give the calculations of the wheels? like the number of teeth? Sorry for my bad english, i'm mexican.

Gear ratios for this design are very simple. The pendulum has a 2 second period, which coupled with a 30 tooth escape wheel, results in one rpm. The next ratios are 8:60 and 8:64 for a 1:60 reduction to get the minutes. After that, it's 10:30 and 8:32 to get the 1:12 reduction for the hour hand. Hope that helps.

Would this also work if I replaced the 2 weights with a pendulum?

The two weights are technically a pendulum, albeit a compound pendulum. If you wanted a more typical simple pendulum (long, thin rod with a weight at the bottom), I suppose it could be arranged. However, it would need to be ~1m long to get the right period. To my eye this would be out of proportion for the size of the clock. It might also bonk the clock weight depending on the design.

Thanks that makes sense, could you also explain how the pulley is supposed to work? I don't get how the weight would drop if the string is attached to both channels of the drum. The way you described it in your description makes it seem like as one side unreels the other reels up so the weight wouldn't drop.

Mar 9, 2017 - Modified Mar 9, 2017
A26 - in reply to taitywaity

Your understanding is correct. The weight is attached to one side. As the weight drops, it winds the other side. Pulling on that side rewinds the weight.

Any tips on printing the pulley bearing. I have tried different slicers, different plastics and different printers. I even netfabbed the file but just get a solid bearing. Everything else printed beautifully. Thanks

The posted stl for that part has .3mm slop between the gears. When I print it, I go 100% on the the bottom layer and 93% everywhere else. The bottom layer fuses, but I can easily force the gears apart. If playing with the extruder % doesn't help, you could even scale up the part which would also scale up the amount of slop.

I have printed the parts. So far so good. Since my build plate is smaller, I have regrouped into a few prints instead of doing all at once.

I have been trying to figure out how to put all these parts together and I just cannot seem to get it right.

Please advise the proper build sequence of it you have one a exploded view of the parts.

Also, I am trying to get all this done in 1 week so I can show what can be done with a 3D printer to the High School kids during a science fair.


I posted the exploded view as requested. I hope that clarifies assembly. If not, let me know, and I will attempt to provide more detail. Good luck with your build.

Thanks. This will help a lot.

I do have to ask where you placed the bearings you mentioned.

Thanks for your response.


No problem. Three bearings are located as follows: on the exploded render along the z axis in both the top and bottom frames and in the top frame in between "wheel4a" and "wheel4b". There are 6mm diameter holes into which the bearings press-fit.

how is the string attached to the drum? i don't understand why it has 2 slots, is one meant to be for some sort of pull cord rewinding system?

You are correct. One slot is for the weight while the string in the other slot gets wound as the weight falls. I used one long piece of 550 cord guts with a knot tied in the semicircular hole in the drum to prevent it from just sliding out. I put the weight on the back slot so that it is directly supported on the shaft. Just be mindful to always support the weight with your hand while rewinding to not overload the frame.

Dec 10, 2016 - Modified Dec 10, 2016

Thanks for sharing this beatiful clock. Can i ask you if you can upload the wheel 5a, seems to be missing on separate parts.
Another question. Is possible to have all wheels running on 3mm shafts? 'cause in my city is impossible to find 2mm...

"wheel5a" is just the hour hand. The hex shaped shaft slots inside wheel5b. Sorry for the confusion. The naming convention made sense to me at the time. 3mm shafts all around should work. There might be ever so slightly more friction and wobbliness on wheel2, but I don't foresee either being an insurmountable issue. You could either drill out the holes post printing or do a little openscad wizardry to widen them prior to printing. The code would be similar to the following:
import (whatever file path you have\wheel2.stl);
render and STLify and you should be good to go. Since my printer undersizes shaft holes I would probably set the radius to about 1.65 instead of 1.5. A similar process would enlarge the frame holes.

Hi. Already printed all parts but can't figure out how to assemble it.

What size build plate is needed to fit the full plate of parts?

Beautifully done. I hope a few people make it with different color filament or a dual extruder - it would be very striking.

Do you have video of it running? like on youtube or somewhere?

Great idea, but also a dangerous one. In printing all at once, if one piece fails, you're done for lol. I've slowed down my first few layers to a whopping 25mm/s so i can make sure each part adheres properly. It would be nice if you also uploaded each individual part for download incase of certain parts failing to print properly. Thanks!

Uploaded as requested. Also, no shame in going slow. I did my first two layers at a solid 10mm/s for a 6:34 print time. I'd be curious to see what other times people manage.

are there any instructions on how to assemble?