Flying tourbillon clock


 A complicated clock made in wood featuring a flying tourbillon escapement, moon phase and perpetual calendar displays and daisy wheel motion work.


This view shows the main dial and the perpetual calendar
 
The moon phase dial. The background shows the night sky with the Neowise comet. The picture was taken by myself


The flying tourbillon escapement has a simplified Swiss lever escapement. The balance spring is 3d printed in PLA. This material unfortunately sags after time and other materials are being investigated. A carbon fibre infused PLA is looking promising. The frequency of the balance wheel can be easily regulated by changing the oscillating mass of the wheel. In this instance a small screw in one the pockets can be slid away or towards the rim. The clock keeps time to a minute or two a day.


The front dial has a seconds sub dial and daisy wheel motion work. This interesting mechanism provides a 12:1 reduction ratio between the minutes hand and hour hand. Traditionally this is usually done by a train of 4 gears. This is known as the motion work in clock talk. The daisy wheel was invented in the 1850's by an American clockmaker with the wonderful name of Aaron Dodd Crane. It is a form of cycloidal motion that almost defies description. I had to build one and still don't properly understand it. The bearing in the middle of the is driven off centre by the minutes arbor. This causes the daisy to oscillate in a small circle but it is prevented from rotating by  a small restraining lever. This cycloidal motion causes the three armed carried  which has pins to engage the petals to rotate 12 times slower. You may be surprised as I was that the daisy has 11 petals!


This is the perpetual calendar.dial . It is skeletonised because I thought it a shame to hide the mechanism. The dial shows date, day and month. Unfortunately I could not include year because of size restrictions. This is a first order calendar in that it only accounts for correct leap years up to 2100. After this time it will need to be reset manually once until 2200. There are mechanical calendars that deal with the 100 year cycle  and the 400 year cycle but they get very complicated.



This view clearly shows the parts of the perpetual calendar. Over a few hours around midnight the £ shaped lever moves to the right at the top. This movement comes from a cam and lever behind the mechanism which is driven by the clock on a 24 hour cycle. The pawl at the top of the £ pushes the date wheel on one day at each movement and sometimes more at the end of a month .The number of days advanced at the end of the month is decided by the finger engaging in the count wheel which  rotates once in 4 years. It is advanced at the end of each month by a large tooth on the date wheel at the top right. The month wheel is driven off this. This design was reverse engineered from some photograps of the calendar in an IWC watch. The video below shows this action.


A rear view of the clock. The large lantern pinion is on a shaft which is directly connected to the rotating carriage of the escapement.This shaft is driven by a permanently engaged and powered electric motor. The rubber band acts as a buffer. 
The electronics on the right is a step down power supply powered either by a 12v wall block or a 7. volt battery. Satisfactory operation of the clock occurs with about 2.4 volts supplied to the motor and the whole system uses about 10mA. The motor will happily stall with no ill effects.
The large lantern pinion engages with a wood contrate wheel and further gears to reach a one hour arbor, the lantern pinion of which which can be seen just behind the two vertical contrate wheels. The one hour arbor drives the clock dial in one direction and in the other engages with two contrate wheels which drive the calendar to the left and the moon phse to the right through further gears.
Again the vide below shows clearly how it all works.




No comments:

Post a Comment