Soldering eyeglass Frames

You don't understand. It takes a small number of stock lenses to cover almost all the population for single-vision lenses. All you need are small set of increments of spherical powers crossed with a few astigmatic cylinder increments. These are stocked as big circular blanks.

Size and shape to fit the frame, PD centering, astigmatism angle, etc., are all fitted with a jig that cuts the big round blank to a final shape, center, and cylinder angle. The "optician" doesn't grind the optical surfaces.

Now, bifocal adds, progressives, extreme Rx powers, are another matter. But even those tend to be jobbed out to factories, not done by local craftsmen any more. And those factories are increasingly found overseas in an age of air transport.

Twice in 25 years, my optician has gotten lenses back from the "lab", installed them in the frames I already owned, put them on me, and said "These are not quite right." He was correct. They were weird. He gave me the option of putting the old ones back in and coming back when the replacements were done, or living with the "rejects".

It's worth a few hundred bucks to some people to know that what they're getting is perfect the first time.

I agree. Dull minds have to pay more for the same results. You cannot shop price when you don't understand what you're buying. Guild-mentality opticians have an incentive to keep us ignorant. Intelligent, critical thinkers, with the Web at hand, can bust that racket.

How is an offshore supplier supposed to measure the distance between pupils, and determine frame size?

Both eyes are nearsighted. The first requires a cylindrical (astigmatic) correction of -0.5 diopters at an angle of 174 degrees.

Note that the angles are in one-degree increments. Is the store supposed to stock 180 different versions of a lens with -2.5 diopters refraction and -.5 diopters cylindrical? You'd need at least 10,000 different lenses to cover the common combinations. Even if the cylindrical were limited to 5-degree increments, you'd still need a huge number of lenses.

No, no, no, no, no. I don't believe it.

If this is true, how could you expect a reasonably close fit?

So take your imports to the optometrist who wrote the Rx. That's his job, to check that sort of thing. And you can check them yourself, if you know how.

He doesn't. You do.

It takes a very costly, specialized instrument called a "ruler". Opticians use a disguised version to make you think you need them to make this measurement, when in fact it is no more complicated than a tailor measuring you for pants.

What sort of work do you do? In other words, what do you do for a living?

Read my earlier reply. One lens blank covers all cylinder angles for a given spherical power and cylinder power. The angle is determined by the trimming of the blank.

Various engineering things, including optical engineering.

Do you work for free in all your "things", or do you get paid for some of them?

Ya sure? ;-)

Their web site quotes:

Zenni Optical

27 Sunny Oaks Dr. San Rafael, Ca.94903 Phone 1-800-211-2105 Fax 1-415-491-4516

And their domain registration is "domains by proxy" with no contact info, which is usually a very bad sign.

But not always.

They seem to at least have some US presence, which is a very good sign.

[I buy rechargeable batteries from a company which has dozens of different "customized to different demographic" web sites, based in HK, but ships from CA. No problems with them.]

--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.

The blanks are circles. They spin the blank around to 174 degrees and cut it with a machine to fit the size and shape of the frame.

Anthony

Duh. Duh, duh, duh. Of course.

Instead they rotate the stock lens 174 degrees, one -.5 lens for all angles!!

Huh? You asked me what I did for a living. That means I get paid for engineering. Unless I've missed your point.

The cost me an extra $5.00 They didn't want to sell them, and advise against it because of the extra weight. When I tell them I work in electronics with chemicals that will fog plastic lenses, and splashes of hot solder that will melt spots they agree make them.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

You're both right. The 1 hour places stock a bunch of lenses and cut to fit frames as needed. Not a big deal. If, however, you have more complex needs, progressive lenses, etc, you won't get them in an hour. Those will be sent out and the stock lenses are modified to your particular prescription. There are many labs that do this on a regular route basis. They pick up at the optometrist and drop them off a few days later.

The lenses are mostly plastic today. They are molded as a round lens and cut to shape as needed and the optic center is placed as needed. The same was done with glass lenses years ago but they make a tiny percentage of the market today. Plastic is optically clear, safer, cheaper, lighter, easier to work with. They are not "ground" as glass was years ago, but molded to the proper diopter. Most of the work is done by machine and it takes but a few minutes.

Before they moved out of town, I used to sell lens trays to American Optical. The glass making sections of the factory were being replaced by molding machines. They make the lenses for pennies.