Reply To: So you want to make a hairspring….

[david pierce]

Tom,
The problem with the blue tempered steel is it turns your balance wheel into a thermometer. This presents a problem maintaining equal time over a temperature range. This was the reason, as you already know, for the split bimetal compensating balance wheel. The modern hairspring metals did away with the need for the split balance wheel and watches made with modern manufacturing techniques now use a solid monometalic wheel. If you notice the underside of a modern balance wheel you will see little holes drilled on one side of the rim. This is because the wheels are now dynamically balanced and the holes are the removed metal on the heavy side of the wheel. This is a better manufacturing process as it produces a more stable and in balance wheel, but would be finanically out of reach for a company making a small quantity of wheels. This is why some of the small low production shops still use wheels with balance screws. This, of course, flys in the face of observation when one looks at a master watchmaker selling only a few watches a year for $100,000 and up per watch. When the customer looks at all of the timing screws on the balance they feel that they are looking at the very finest quality available today.
david