Hi Nickelsilver, Thank you for all the help. Will search for the tech sheet.
I have many used genuine hairsprings and balances that I have been vibrating together. Need to place order for more hairsprings of compatible springness.
Been trying to experimentally find a compatible HS of known CGS.
Strength is proportional to area of the coil outer circle.
I think I may find CGS direct out of this tables.
Will keep you posted. Thank you, great help. Best

Found one of the tables, it's in French but easy to figure out.
If doing the test spring process, the formula is K=K' (D/D') 2
K is the CGS number you're looking for
K' is the CGS of the spring you test
D is the diameter of spring you need, at the pinning point
D' is the diameter of the correctly vibrated test spring at the pinning point.
Sorry to the OP Joe and I are hijacking the thread a bit, maybe a mod could move it to a new thread?