Small Eight Day Pendulum Clock

This is an eight day pendulum clock, so it needs winding once a week. The 2kg weight falls 1 metre to power the clock. The pendulum has a period of 1 second, so the clock ticks every half second.

Detailed printing and assembly instructions are in the attached PDF “wall_clock_40.pdf”.

This is an Open Hardware project and is licensed under the CERN-OHL-S v2. This means you're free to do with it what you want: make it, sell it, give it away, but you must provide the source code for the clock with the physical clock under the same terms. For those familiar with software, this is like the GPL, but for hardware. This isn't an option on Printables for some reason.

The project is written in Python and uses CadQuery to generate 3D models. The source code is available on GitHub: https://github.com/MrBunsy/3DPrintedClocks. I wrote this as an experiment into configurable clocks - the python library can be used to generate a wide range of types of clock.

I have printed most of my clocks entirely in PETG and the oldest have been running for three years without issue. However, as an experiment this clock has been printed in PLA and appears to work fine, but I don't know how well this will hold up long term. Regardless of material used, your printer will need to be well calibrated and able to produce clean strong prints for the gears to work reliably.

Slicing
It is vital to get the slicing right for the gears, as any extra friction introduced from printing artefacts will severely impact the reliability of the clock. I used seam painting for the gears to ensure that seams do not start on the teeth, springs or pallets of the anchor.

Nearly everything needs to be strong, so I sliced with 3 perimeters, 6 bottom and top layers. If you have larger nozzles, I would recommend printing the plates and pillars with 0.6mm.

The attached PDF provides detailed printing instructions for each component, assembly instructions and some tips for setting up your clock to run reliably.

A note on bearings

This clock uses ball bearings. These come packed with grease, and if used like this the clock will require over 4kg to work. I recommend instead degreasing the small (3x10x4mm) ball bearings and oiling them with synthetic motor oil. I use two drops of 0W-40 per bearing. Save the most free running for the highest up the gear train (also literally highest up this clock).

I've experimented with running stainless steel bearings dry, but without success. I recommend chrome steel ball bearings. I use high quality EZO bearings for the pendulum and escape wheel, and cheap bearings for the rest of the clock.

I degrease bearings by leaving them in jars of Isopropyl Alcohol, using tweezers to spin them inside the IPA and replacing the IPA every day until there is no more visible grease to be removed. Dry the bearings out thoroughly before oiling. If successful the spin freely.

The larger bearings are further down the train where there is more torque, so the friction has less effect. These can be left with their original grease.

Full Parts List

• 1 x Bearing 15x24x5
• 10 x Bearing 3x10x4
• 1 x Bearing 4x13x5
• 2150 x Cord 1.0mm thick
• 1 x Cuckoo hook 1mm thick
• 1 x M2 half nut
• 1 x M3 crinkle washer
• 2 x M3 dome nut
• 3 x M3 half nut
• 9 x M3 nut
• 5 x M3 nyloc nut
• 1 x M3 spring washer
• 1 x M3 threaded rod 240mm
• 3 x M3 threaded rod 56.8mm
• 1 x M3 threaded rod 94.1mm
• 1 x M3 threaded rod 94.8mm
• 1 x M3 thumb nut (3.0mm thick)
• 6 x M3 washer
• 4 x M4 dome nut
• 4 x M4 nut
• 4 x M4 rod 97.3 (+ top fixing nut)mm
• 1 x M4 threaded rod 75.8mm
• 4 x M4 washer
• 5 x Machine screw M2 (pan) 6mm
• 2 x Machine screw M3 (CS) 10mm
• 1 x Machine screw M3 (CS) 12mm
• 1 x Machine screw M3 (CS) 14mm
• 6 x Machine screw M3 (CS) 18mm
• 5 x Machine screw M3 (CS) 25mm
• 1 x Machine screw M3 (CS) 35mm
• 1 x Machine screw M3 (pan) 30mm
• 2 x Machine screw M3 (pan) 6mm
• 10 x Steel dowel 1.00x18mm
• 1 x Steel shot