HarryvL wrote: ↑
Fri Jun 15, 2018 4:56 am
Mark, that is indeed very confusing. I had another close look at the paper and see that I was referring to Table 1, whereas you were referring to "nomenclature" at the end. You are right. The paper contains an error in that part. The description for "I" is simply wrong and the explanation of the author does not help. I is the second moment of inertia of the cross section of the hairspring and the unit is m^4
Yeah I was suspecting something similar but since I do not have the required knowledge in this area I differed to Dr. Ru's authority. Maybe he just did not take my query seriously and forgot what was written??
In anycase, thanks a lot for the help
BTW, I see that high end manufactures of watches are going to silicon hairsprings.
http://www.woundforlife.com/2014/04/23/ ... airspring/
I do not know yet if this is some special, secret type of silicon, or whether i can 3D-print it in an effective manner to the size I plan to scale my spring. I can scale up to 75mm diameter to the stud. In any case your ceramic suggestion is something to look at. An example of the steel spring size i will scale up is a metal band of 0.1 mm thickness, 0.6mm width, and about 603mm length. The number of turns is 12, inner diameter is 4mm (size of collet) and a pitch of 1mm.
The collet/balance-wheel rotates +/- 270 degrees (+/- 2pi/3 radians) with each swing (i.e. +/-1.5 turns to each side of it's equilibrium position).
In 3D-printing, a rule of thumb for say SLS and vat-pho is that feature thickness should be not less than 1mm. So I cannot go below 1mm for the thickness of the band.