One of the screws on Mary’s sunglasses came apart. Wonder of wonders, the nut fell off in the kitchen, made a click when it hit the floor, and we managed to collect all the pieces.
The temples attach to the lens frame with two tiny screws apiece. The screw heads are slightly embedded in the temples, but you can see why this didn’t work nearly as well in practice as it did in the design studio.
The trick is to align the screw properly so it fits through the lens and frame after the adhesive sets up. The holes are 6 mm on center and more-or-less 55 mils in diameter (obviously, they’re metric screws, but this is the US and we do the best we can with antique units).
That’s what CNC is all about: making it trivial to poke holes exactly 6 mm apart on center. I drilled two holes in some scrap acrylic sheet using Manual mode on my Sherline / EMC2 mill:
g83 z-7 r1 q0.5 f100 g0 x6 g83 z-7 r1 q0.5 f100 g0 z100
I have it set to start up in metric units, which still seems to be legal here.
Add a teeny dab of JB Weld, hold everything together overnight with a clothespin, and it’s all good in the morning.
The trick is to check the leftover epoxy first to see if it’s fully cured before you move the actual piece.
Memo to self: epoxy takes forever to cure at 55 F.
Update: Pretty much as expected, that little dot of epoxy didn’t hold nearly as well as the original brazing. I tried a somewhat larger dot, but Mary was unhappy with the glasses anyway and we finally tossed ’em out.
Of course I salvaged the screws & nuts & suchlike: you gotta have stuff!