The new/replacement hairspring is selected based on the weight of the balance wheel and stem.įirst step is to select a hairspring that is simular in strength to the old one. The term 'vibrate' is used by watch/clock makers to fit a new hairspring to a balance wheel.

Is it correct to only match the springs in terms of length and diameter or is the number of windings critical (7 vs 8)? How much deformation of the spring is ok when moving the regulator? The width of the slot in the regulator has to account for any diametrical decrease in the spring spiral, if the spring is not to deform as the lever is swung.īelow will be the proper steps to 'vibrate' a hairspring. 10 inch say), the outside diameter of the hairspring is reduced and moving the regulator deforms the shape of the spring. Therefore I want pull more spring through the anchor slot. The new one fits through the regulator slot nicely when anchored however it has 7 loops where the old one had 8. I removed the difference between the two lengths from the new one (so my new spring was the same length as the old one). I unwound the old one measured its total length and using the spiral formula calculated the length of the replacement. Attached it to the staff for a friction fit (with some shellac). After a lot of work trying to correct the spring's shape I decided to buy a spring assortment and try a new one. I damaged a balance spring on on a 40's Westclox alarm clock, after reassembling the movement.

Place hairspring in bridge