Clock Repair Archive – –
popular european (Hermle) mechanism mainspring specs in inches ( LISTED width X strength X length):
#10 --- .669X .0177 X 58.6 #11 --- .669 X .0157 X 47.25 #20 --- .669 X .015 X 47.25 #21 --- .669 X .0157 X 47.25 #30 --- .472 X .0157 X 43.25 #31 --- .472 X .0134 X 45.25 #32 ---- .472 X .0165 X 43,25 #33 ---- .472 X .0126 X 45.25 #40 ---- .669 X .015 X 43.25 #41 ---- .827 X .0157 X 45.25 #42 ---- .669 X .0157 X 43.25 #50 ---- .669 X .0157 X 47.25 #52 ---- .669 X .0165 X 47.25 #54 ---- .827 X .0165 X 75 #55 ---- .827X .0177 X 71 #56 ---- .669 X .015 X 47.25 #57 ----.669 X .0126 X 59
These are approximate measurements : width and strength are plus or minus .0015 inches; and length is plus or minus .1 inch.