Large Balance Wheel V2


This clock has some  small variation from my earlier large balance wheel clock. 

I realised that the earlier version with its hairspring was actually operating as a spring assisted compound pendulum so in this version I have removed the spring and added a small weight to the wheel to make a pendulum which has a period of about 5 seconds with an amplitude of about 170 degrees. 

The balance/pendulum also carries a small magnet and is impulse through a coil under the baseboard.

Because the amplitude is so high the circular error is high and the period varies greatly with amplitude. Thus the clock has the same time of period control via  microcontroller varying the impulse pulse length with feedback control to maintain the 5 second period. Pulses vary as required in the 30-40 millisecond range.

The balance wheel is not made of wood this time but titanium, and is is part of the braking system of a Formula 1 car, and the whole clock is a result of a challenge to incorporate it in a clock.

Just for fun and because I am a fan of John Harrison I used anti friction rollers to support the arbor of the 'balance wheel' rather than running it in bearings, plain or otherwise. This seems to work excellently well. 

Timekeeping is excellent  at better than a minute a week with the potential of tuning it further.



No comments:

Post a Comment