Modifying cuckoo clock striking speed

[Kelly Jons]

I’ve been building my own cuckoo clocks and have noticed that some of them strike quickly and some of them strike slowly.

There are slight differences in the case sizes, but they all use identical Regula 25 one-day movements. I can’t figure out why some strike fast and some strike slowly…. might it have something to do with slight differences in the bellows lift wire lengths? And if so, what is the best way to determine the length of those lift wires? Basically, I have been making sure the strike train is locked and then using a pair of dividers to measure the gap between the lift arm eye and the eye hook on the side of the bellows. Maybe there’s a better method?

I have not been able to detect any differences in fly friction, by the way.

These are all new movements straight from the packaging. Any ideas?

Thanks!

Kelly

 

[Willie X]

The weights used and bellows lift is about it.

The bellows should lift about 1/2, up to about 5/8 inch, measuring at the inside edge of the big end.

If the hammer spring is to tight, that will make for a slow start and the speed may not recover.

There is a fairly wide range of 'normal" and old leather bellows can be stiff enough to cause a speed decrease.

Willie X