This is just a trip down memory lane. What was used for frame measurements before the boxing system What year did the boxing system go into use and who invented it.
This is just a trip down memory lane. What was used for frame measurements before the boxing system What year did the boxing system go into use and who invented it.
Datum system, which was well suited for the then current 1930s symmetrical, non-gendered lens shapes and frame styles that predominated before the rise of asymmetrical female/harlequine and aviator shapes in the 1940s. These shapes posed layout challenges with the limited diameters of finished and semi-finished glass lenses of the day.
Someone at Winchester Optical of Elmira, NY, in the late 1950s, came up with the boxing system as a way to more predicably arrive at the minimum blank size needed to obtain the finished PD when the OC was assumed to be placed in the geometric center of the blank.
This boxing system was adopted as a standard for frame marking by the American Optical Manufacturer’s Association in 1961.
B
Last edited by Barry Santini; 02-28-2021 at 03:17 PM.
Great job it was Tom Lynch at Winchester optical they are still in business today as an Essilor lab. His concept was not well received and to this day many people in the industry cannot measure the ED on a frame using his method they believe that the longest diagonal is the ED. There was a publication called frame Facts that came out once a month with all the new frame information included from every domestic frame manufacturer
it Had a picture of the frame,colors, sizes and the A,B,AND ED measurements. It never included foreign manufacturers as they were insignificant in the market.
Another common misconception created by the boxing system is if you double the decentration and add it to the ED you will have the minimum blank size for that frame. Anyone care to explain this concept and why it is not correct under all circumstances.
Because some shapes—aviators to name one—have something my Dad called “automatic decentration”—meaning the minimum blank size needed to just cut out included extra decentration from the mechanical center of both datum and boxed formats.
Barry is correct another way to express this is if the longest radius is nasal than the built in decentration is equal to how much longer the nasal radius is than the temporal. The same issue is present if you happen to decenter out where the longest radius is found in the majority of cases.
MBS might seem like magic but is important to know how things work.
Way back in 1956 I worked at "The AO in Southbridge" after school. As a "spare hand" I got to work in most of the departments. I spent many an afternoon putting frames fronts and temples in envelopes. I do recall the boxing was marked on the envelope along with a diagram. Every frame came in a whole range of sizes. For example the Stadium came in 42, 44, 46, 48, 50, 52 and 54 Eye and 14, 16, 18, 20, 22 and 24 Bridge. Spatula temples went from 125mm to 160mm in 5mm increments.
No inventory problems as your local AO (or B&L) lab had them in stock and in most towns you had two courier deliveries every day.
I have a minimum blank size calculator open and use it daily as do all of our other opticians. It has drastically cut down on errors when ordering finished lenses. I just ran into the aviator issue last week, it would supposedly cut out in the calculator but the ED is >>> than the ED used in the formula in the calculator. Understanding the theory behind it I agree is important.
Yes and no. If you fit a frame that fits their eyes well it tends to cut out most of the time. Although my office tends to have more larger eyesize frames because that is the style in our area. And I almost always double check the MBS with plus power Rx's because they come in smaller blank sizes.
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