The Grand Astronomical Clock

[Davidz90]

I'm proud to present my newest build, which took me almost half a year: Grandfather clock with 19 different functions, possibly the most complicated Lego clock in the world.

20240210_133209 by David_Z1, on Flickr

Standing almost 2 meters tall, this pendulum clock was an engineering challenge on multiple aspects, but the biggest problem was how to power all 19 functions and how to handle a highly variable friction produced by them. The answer was to use several electric motors triggered at the right time. There's no electronics, just mechanical contacts. Escapement - the central part of the clock that powers the pendulum, is powered by a small dropping weight that is frequently lifted back up by electric motor. This ensures a very steady input power, and thus good accuracy; the mean error is less than 3 minutes/day (after a day of working, it is off by less than 3 minutes). This is possible due to the use of John Harrison's grasshopper escapement, which is the most accurate type of pendulum clock mechanism.

The electrical system is based on custom DC motors fitted with RCA plugs:

20240210_163033 by David_Z1, on Flickr

Above You can also see the Westminster chime mechanism - at every quarter, it plays a melody like Big Ben. The chimes are made from aluminium pipes, 70-110 cm long, length tuned to specific musical notes. 

Here's the list of functions:

Schem_front by David_Z1, on Flickr

Schem_back by David_Z1, on Flickr

And here a video demonstrating all of them:

 

[2GodBDGlory]

Very impressive! I always love seeing complex Lego clocks!

[Davidz90]

 

14 minutes ago, 2GodBDGlory said:

Very impressive! I always love seeing complex Lego clocks!

Thanks!

[Davidz90]

Some extra info on various parts/mechanisms:

1. The auto-rewinder uses a magnet to close the circuit. This ensures that electrodes actually stick together instead of being 0.01mm apart due to a random speck of dust, which was a major headache in trying to trigger motors reliably. 

2. The chime mechanism uses a set of four custom cams (basically slope pieces attached to 4x4 round brick with electric tape) to encode the melody. While there are several ways to do this encoding in a "legit" way (for example, with threads), none of them were as compact as this.

and here is an earlier prototype, with thread encoding and gravity powered (note the fan used for speed regulation):

3. To get the necessary musical notes, I had to cut the pipes to proper length. The math behind this is remarkably simple:

4. The calendar uses 1:365 gear reduction and a custom dial with all months and days, attached to a large ring gear.

 

 

[Murdoch17]

I'm gonna quote Indiana jones here: It belongs in a museum!

 

....no really, this should be a exhibit on clocks or a science / children's museum somewhere as it's too beautiful to ever disassemble!

[Davidz90]

6 hours ago, Murdoch17 said:

....no really, this should be a exhibit on clocks or a science / children's museum somewhere as it's too beautiful to ever disassemble!

Thanks! I'm going to use it in science fairs etc. in my university, but contacting some science museum is a great idea too. One of my Youtube colleagues (Darrell Aldrich) did exactly that with his clock.

[EmHolloway]

It's truly grand, and it should be in some physics museum! Such a complex mechanism and six months of work on it, it's impressive. The results are definitely worth it.

 

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When I asked to do my physics homework, I never imagined it would lead me to an interest in building Lego projects. Here's what support from experienced tutors means.

Edited April 16, 2024 by EmHolloway

[Davidz90]

5 hours ago, EmHolloway said:

This is truly magnificent, and it should be in some scientific museum! Such a complex mechanism.

Thank you!