A cuckoo clock made for the Setechnic’s clock contest, features a standard clock with a cuckoo.
The clock has a standard minute-hand and second-hand with 1/60 gear ratio composed of worm/24t, 20/20t and 16/40t. There is not hour-hand because of the available place. The pendulum mechanism is not a vertical pendulum but a double horizontal pendulum with two masses (61mm wheels). The escapement wheel is composed of two 6-tooth wheels. The accuracy is +-10% for 1 second because of play. The autonomy is rather good, with 50cm string, a 5/1 ratio before the escapement wheel and 150g of counterweight, the autonomy is 30min. With a pulley and 1m of string and 300g, it may be reach 1h of autonomy.
Concerning the cuckoo, it is powered by a weight lifted up by the minute-hand (one time each hour), when it reaches a special point, it falls down and make the cuckoo get out . The mechanism is simple and has no need to be lifted. Consequently, the clock has one counterweight to power all functions. The counterweight can be easily lifted up thanks to the sliding wheel.
Despite the fact that the cuckoo out mechanism has a non-linear motion, I think that it doesn’t get out enough time. The ideal behaviour must be a normal behaviour during the lifting and a viscous behaviour during the fall in order to slown down the cuckoo. To finish, I will certainly create the building instructions !
The building instructions are available. You can watch them by browsing my website or
Design in 2011