mainspring and strength

[guychampeau]

I am asking this question just for discussion...all else being equal...width...length...a mainspring for an 18-size pocket watch...what would be the result of using a strength 02 instead of a strength 03 as stated in the factory guide...I have heard tell that it should not be an issue because modern mainsprings are alloy and the older original are steel....thanks...

 

[doug sinclair]

I had to check my conversion tables to be sort of certain of an answer. I suspect you are using Dennison numbers, but it am accustomed to dealing with metric. My table say that a Dennison .02 strength is equivalent to .019 mm, and Dennison .03 strength is .018 metric. If that sounds correct, there shouldn't be enough difference between the springs to make a difference.