How we developed the Juntor Crystal
The problem that exists when designing a watch from the beginning is that all elements have to be developed from the ISO standards, which in the case of crystal construction refers to ISO 14368-1: 2000.
The standard refers to crystals glued and crystals with joint together to describe the design of edges will adapt to the step of the wacth case and compress the Teflon gasket for sealing. The rule explains that the most important thing about the crystal design is the height h1 that should be equal to or less than the subtraction of t with the sum of h2 + h3.
Thus the equation would be h1 = t (h2 + h3) where t is the thickness of the crystal, h2 the lower edge, which would be between 0.15 and 0.40mm.The angle β is between 35°≤β≤ 40°. In the Juntor crystal is of a size of 36.4 mm and a thickness of 3.14 mm.
So from h2 not very pronounced, not to widen much the support step in the middle case, we chose 0.20 mm plus an angle of 37 °. The result was h1 of 2.7 mm, sufficient for the design of the joint.
The problem with the Juntor crystal is that it protrudes out of the middle case, so it is necessary to provide very good adaptation to the joint with the size indicated.