Sunglass Repair

Making the fixture
Making the fixture

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).

Clamping and curing
Clamping and curing

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.

cimg2858-sunglass-repair-success
Success!

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!

Geek Scratch Paper

Grid scratch paper pad
Grid scratch paper pad

Everybody needs doodle paper, but geeks need graph paper. What to do?

Go to http://incompetech.com/graphpaper/ and set up a half-page grid with 5×8 1-inch divisions, 0.5-inch mid divisions, and 0.1-inch minor divisions (I think 1 / 0.6 / 0.3 pt line widths look nice). The obvious metric divisions are a bit too fine for my taste, but 2 cm – 1 cm – 2 mm might work.

Fetch the PDF, load it into The GIMP at 300 dpi, expand the canvas to a full-page sheet (8.5×11 inches), duplicate the grid so you have two on one sheet, save it as a PNG for later use.

If you don’t have a full-bleed printer, pick a full-page size that’ll print within whatever margins your printer enforces. You really want those one-inch grids to remain one inch, right?

Print a few dozen copies, whack ’em in half, and bind ’em on the long edge. Add a thin cardboard backing sheet (Mr Breakfast Cereal Box, meet Mr Paper Cutter) so the bottom sheet stays neat.

I have an old IBICO (since absorbed by GBC) plastic comb binding machine, but it’s easy enough to line the sheets up and coat the edge with white paper glue, rubber cement, or, for the true geek, liquid electrical tape.

Pre-position pads wherever you’re ordinarily at a loss for scratch paper: neat doodles!

PS: Put some money in his tip jar when you use his graph paper. It’s a nice gesture.

[Update: Inexplicably, I didn’t have a picture of a pad. Here you go… low res, but you get the general idea. Great for off-the-cuff graphing, too.]